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Cerebellar ataxia

MedGen UID:
849
Concept ID:
C0007758
Disease or Syndrome
Synonyms: Ataxia, Cerebellar; Ataxias, Cerebellar; Cerebellar Ataxia; Cerebellar Ataxias; Cerebellar Incoordination; Cerebellar Incoordinations; Incoordination, Cerebellar; Incoordinations, Cerebellar
SNOMED CT: Cerebellar ataxia (85102008); Cerebellar ataxia (loss of muscle coordination) (85102008)
 
HPO: HP:0001251
Monarch Initiative: MONDO:0000437
Orphanet: ORPHA102002

Definition

Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly). [from HPO]

Conditions with this feature

Abetalipoproteinaemia
MedGen UID:
1253
Concept ID:
C0000744
Disease or Syndrome
Abetalipoproteinemia typically presents in infancy with failure to thrive, diarrhea, vomiting, and malabsorption of fat. Hematologic manifestations may include acanthocytosis (irregularly spiculated erythrocytes), anemia, reticulocytosis, and hemolysis with resultant hyperbilirubinemia. Malabsorption of fat-soluble vitamins (A, D, E, and K) can result in an increased international normalized ratio (INR). Untreated individuals may develop atypical pigmentation of the retina that may present with progressive loss of night vision and/or color vision in adulthood. Neuromuscular findings in untreated individuals including progressive loss of deep tendon reflexes, vibratory sense, and proprioception; muscle weakness; dysarthria; and ataxia typically manifest in the first or second decades of life.
Ataxia-telangiectasia syndrome
MedGen UID:
439
Concept ID:
C0004135
Disease or Syndrome
Classic ataxia-telangiectasia (A-T) is characterized by progressive cerebellar ataxia beginning between ages one and four years, oculomotor apraxia, choreoathetosis, telangiectasias of the conjunctivae, immunodeficiency, frequent infections, and an increased risk for malignancy, particularly leukemia and lymphoma. Individuals with A-T are unusually sensitive to ionizing radiation. Non-classic forms of A-T have included adult-onset A-T and A-T with early-onset dystonia.
Chédiak-Higashi syndrome
MedGen UID:
3347
Concept ID:
C0007965
Disease or Syndrome
Chediak-Higashi syndrome (CHS) is characterized by partial oculocutaneous albinism, immunodeficiency, and a mild bleeding tendency. Approximately 85% of affected individuals develop the accelerated phase, or hemophagocytic lymphohistiocytosis, a life-threatening, hyperinflammatory condition. All affected individuals including adolescents and adults with atypical CHS and children with classic CHS who have successfully undergone allogenic hematopoietic stem cell transplantation (HSCT) develop neurologic findings during early adulthood.
Facial hemiatrophy
MedGen UID:
8761
Concept ID:
C0015458
Disease or Syndrome
Unilateral atrophy of facial tissues, including muscles, bones and skin.
Pigmentary pallidal degeneration
MedGen UID:
6708
Concept ID:
C0018523
Disease or Syndrome
Pantothenate kinase-associated neurodegeneration (PKAN) is a type of neurodegeneration with brain iron accumulation (NBIA). The phenotypic spectrum of PKAN includes classic PKAN and atypical PKAN. Classic PKAN is characterized by early-childhood onset of progressive dystonia, dysarthria, rigidity, and choreoathetosis. Pigmentary retinal degeneration is common. Atypical PKAN is characterized by later onset (age >10 years), prominent speech defects, psychiatric disturbances, and more gradual progression of disease.
Kearns-Sayre syndrome
MedGen UID:
9618
Concept ID:
C0022541
Disease or Syndrome
Mitochondrial DNA (mtDNA) deletion syndromes predominantly comprise three overlapping phenotypes that are usually simplex (i.e., a single occurrence in a family), but rarely may be observed in different members of the same family or may evolve from one clinical syndrome to another in a given individual over time. The three classic phenotypes caused by mtDNA deletions are Kearns-Sayre syndrome (KSS), Pearson syndrome, and progressive external ophthalmoplegia (PEO). KSS is a progressive multisystem disorder defined by onset before age 20 years, pigmentary retinopathy, and PEO; additional features include cerebellar ataxia, impaired intellect (intellectual disability, dementia, or both), sensorineural hearing loss, ptosis, oropharyngeal and esophageal dysfunction, exercise intolerance, muscle weakness, cardiac conduction block, and endocrinopathy. Pearson syndrome is characterized by sideroblastic anemia and exocrine pancreas dysfunction and may be fatal in infancy without appropriate hematologic management. PEO is characterized by ptosis, impaired eye movements due to paralysis of the extraocular muscles (ophthalmoplegia), oropharyngeal weakness, and variably severe proximal limb weakness with exercise intolerance. Rarely, a mtDNA deletion can manifest as Leigh syndrome.
Laurence-Moon syndrome
MedGen UID:
44078
Concept ID:
C0023138
Disease or Syndrome
PNPLA6 disorders span a phenotypic continuum characterized by variable combinations of cerebellar ataxia; upper motor neuron involvement manifesting as spasticity and/or brisk reflexes; chorioretinal dystrophy associated with variable degrees of reduced visual function; and hypogonadotropic hypogonadism (delayed puberty and lack of secondary sex characteristics). The hypogonadotropic hypogonadism occurs either in isolation or as part of anterior hypopituitarism (growth hormone, thyroid hormone, or gonadotropin deficiencies). Common but less frequent features are peripheral neuropathy (usually of axonal type manifesting as reduced distal reflexes, diminished vibratory sensation, and/or distal muscle wasting); hair anomalies (long eyelashes, bushy eyebrows, or scalp alopecia); short stature; and impaired cognitive functioning (learning disabilities in children; deficits in attention, visuospatial abilities, and recall in adults). Some of these features can occur in distinct clusters on the phenotypic continuum: Boucher-Neuhäuser syndrome (cerebellar ataxia, chorioretinal dystrophy, and hypogonadotropic hypogonadism); Gordon Holmes syndrome (cerebellar ataxia, hypogonadotropic hypogonadism, and – to a variable degree – brisk reflexes); Oliver-McFarlane syndrome (trichomegaly, chorioretinal dystrophy, short stature, intellectual disability, and hypopituitarism); Laurence-Moon syndrome; and spastic paraplegia type 39 (SPG39) (upper motor neuron involvement, peripheral neuropathy, and sometimes reduced cognitive functioning and/or cerebellar ataxia).
Leigh syndrome
MedGen UID:
44095
Concept ID:
C0023264
Disease or Syndrome
Leigh syndrome is a clinically and genetically heterogeneous disorder resulting from defective mitochondrial energy generation. It most commonly presents as a progressive and severe neurodegenerative disorder with onset within the first months or years of life, and may result in early death. Affected individuals usually show global developmental delay or developmental regression, hypotonia, ataxia, dystonia, and ophthalmologic abnormalities, such as nystagmus or optic atrophy. The neurologic features are associated with the classic findings of T2-weighted hyperintensities in the basal ganglia and/or brainstem on brain imaging. Leigh syndrome can also have detrimental multisystemic affects on the cardiac, hepatic, gastrointestinal, and renal organs. Biochemical studies in patients with Leigh syndrome tend to show increased lactate and abnormalities of mitochondrial oxidative phosphorylation (summary by Lake et al., 2015). Genetic Heterogeneity of Leigh Syndrome Leigh syndrome may be a clinical presentation of a primary deficiency caused by genes in any of the mitochondrial respiratory chain complexes: complex I deficiency (see 252010), complex II deficiency (see 252011), complex III deficiency (see 124000), complex IV deficiency (cytochrome c oxidase; see 220110), and complex V deficiency (see 604273) (summary by Lake et al., 2015). Mutations in mitochondrial genes have also been identified in patients with Leigh syndrome: see MTTV (590105), MTTK (590060), MTTW (590095), and MTTL1 (590050). Leigh syndrome may also be caused by mutations in components of the pyruvate dehydrogenase complex (e.g., DLD, 238331 and PDHA1, 300502). Deficiency of coenzyme Q10 (607426) can present as Leigh syndrome. Some forms of combined oxidative phosphorylation deficiency can present as Leigh syndrome (see, e.g., 617664).
Metachromatic leukodystrophy
MedGen UID:
6071
Concept ID:
C0023522
Disease or Syndrome
Arylsulfatase A deficiency (also known as metachromatic leukodystrophy or MLD) is characterized by three clinical subtypes: late-infantile MLD, juvenile MLD, and adult MLD. Age of onset within a family is usually similar. The disease course may be from several years in the late-infantile-onset form to decades in the juvenile- and adult-onset forms. Late-infantile MLD. Onset is before age 30 months. Typical presenting findings include weakness, hypotonia, clumsiness, frequent falls, toe walking, and dysarthria. As the disease progresses, language, cognitive, and gross and fine motor skills regress. Later signs include spasticity, pain, seizures, and compromised vision and hearing. In the final stages, children have tonic spasms, decerebrate posturing, and general unawareness of their surroundings. Juvenile MLD. Onset is between age 30 months and 16 years. Initial manifestations include decline in school performance and emergence of behavioral problems, followed by gait disturbances. Progression is similar to but slower than in the late-infantile form. Adult MLD. Onset occurs after age 16 years, sometimes not until the fourth or fifth decade. Initial signs can include problems in school or job performance, personality changes, emotional lability, or psychosis; in others, neurologic symptoms (weakness and loss of coordination progressing to spasticity and incontinence) or seizures initially predominate. Peripheral neuropathy is common. Disease course is variable – with periods of stability interspersed with periods of decline – and may extend over two to three decades. The final stage is similar to earlier-onset forms.
Azorean disease
MedGen UID:
9841
Concept ID:
C0024408
Disease or Syndrome
Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), is characterized by progressive cerebellar ataxia and variable findings including pyramidal signs, a dystonic-rigid extrapyramidal syndrome, significant peripheral amyotrophy and generalized areflexia, progressive external ophthalmoplegia, action-induced facial and lingual fasciculations, and bulging eyes. Neurologic findings tend to evolve as the disorder progresses.
Marinesco-Sjögren syndrome
MedGen UID:
6222
Concept ID:
C0024814
Disease or Syndrome
Marinesco-Sjögren syndrome (MSS) is characterized by cerebellar ataxia with cerebellar atrophy, dysarthria, nystagmus, early-onset (not necessarily congenital) cataracts, myopathy, muscle weakness, and hypotonia. Additional features may include psychomotor delay, hypergonadotropic hypogonadism, short stature, and various skeletal abnormalities. Children with MSS usually present with muscular hypotonia in early infancy; distal and proximal muscular weakness is noticed during the first decade of life. Later, cerebellar findings of truncal ataxia, dysdiadochokinesia, nystagmus, and dysarthria become apparent. Motor function worsens progressively for some years, then stabilizes at an unpredictable age and degree of severity. Cataracts can develop rapidly and typically require lens extraction in the first decade of life. Although many adults have severe disabilities, life span in MSS appears to be near normal.
Neurofibromatosis, type 2
MedGen UID:
18014
Concept ID:
C0027832
Neoplastic Process
Neurofibromatosis 2 (NF2) is characterized by bilateral vestibular schwannomas with associated symptoms of tinnitus, hearing loss, and balance dysfunction. The average age of onset is 18 to 24 years. Almost all affected individuals develop bilateral vestibular schwannomas by age 30 years. Affected individuals may also develop schwannomas of other cranial and peripheral nerves, meningiomas, ependymomas, and, very rarely, astrocytomas. Because NF2 is considered an adult-onset disease, it may be underrecognized in children, in whom skin tumors and ocular findings (retinal hamartoma, thickened optic nerves, cortical wedge cataracts, third cranial nerve palsy) may be the first manifestations. Mononeuropathy that occurs in childhood is an increasingly recognized finding; it frequently presents as a persistent facial palsy or hand/foot drop.
Phytanic acid storage disease
MedGen UID:
11161
Concept ID:
C0034960
Disease or Syndrome
Adult Refsum disease (ARD is associated with elevated plasma phytanic acid levels, late childhood-onset (or later) retinitis pigmentosa, and variable combinations of anosmia, polyneuropathy, deafness, ataxia, and ichthyosis. Onset of symptoms ranges from age seven months to older than age 50 years. Cardiac arrhythmia and heart failure caused by cardiomyopathy are potentially severe health problems that develop later in life.
Sandhoff disease
MedGen UID:
11313
Concept ID:
C0036161
Disease or Syndrome
Sandhoff disease comprises a phenotypic continuum encompassing acute infantile, subacute juvenile, and late-onset disease. Although classification into these phenotypes is somewhat arbitrary, it is helpful in understanding the variation observed in the timing of disease onset, presenting manifestations, rate of progression, and life span. Acute infantile Sandhoff disease (onset age <6 months). Infants are generally normal at birth followed by progressive weakness and slowing of developmental progress, then developmental regression and severe neurologic impairment. Seizures are common. Death usually occurs between ages two and three years. Subacute juvenile Sandhoff disease (onset age 2-5 years). After attaining normal developmental milestones, developmental progress slows, followed by developmental regression and neurologic impairment (abnormal gait, dysarthria, and cognitive decline). Death (usually from aspiration) typically occurs in the early to late teens. Late-onset Sandhoff disease (onset older teen years or young adulthood). Nearly normal psychomotor development is followed by a range of neurologic findings (e.g., weakness, spasticity, dysarthria, and deficits in cerebellar function) and psychiatric findings (e.g., deficits in executive function and memory). Life expectancy is not necessarily decreased.
Mucopolysaccharidosis, MPS-IV-B
MedGen UID:
43376
Concept ID:
C0086652
Disease or Syndrome
GLB1-related disorders comprise two phenotypically distinct lysosomal storage disorders: GM1 gangliosidosis and mucopolysaccharidosis type IVB (MPS IVB). The phenotype of GM1 gangliosidosis constitutes a spectrum ranging from severe (infantile) to intermediate (late-infantile and juvenile) to mild (chronic/adult). Type I (infantile) GM1 gangliosidosis begins before age 12 months. Prenatal manifestations may include nonimmune hydrops fetalis, intrauterine growth restriction, and placental vacuolization; congenital dermal melanocytosis (Mongolian spots) may be observed. Macular cherry-red spot is detected on eye exam. Progressive central nervous system dysfunction leads to spasticity and rapid regression; blindness, deafness, decerebrate rigidity, seizures, feeding difficulties, and oral secretions are observed. Life expectancy is two to three years. Type II can be subdivided into the late-infantile (onset age 1-3 years) and juvenile (onset age 3-10 years) phenotypes. Central nervous system dysfunction manifests as progressive cognitive, motor, and speech decline as measured by psychometric testing. There may be mild corneal clouding, hepatosplenomegaly, and/or cardiomyopathy; the typical course is characterized by progressive neurologic decline, progressive skeletal disease in some individuals (including kyphosis and avascular necrosis of the femoral heads), and progressive feeding difficulties leading to aspiration risk. Type III begins in late childhood to the third decade with generalized dystonia leading to unsteady gait and speech disturbance followed by extrapyramidal signs including akinetic-rigid parkinsonism. Cardiomyopathy develops in some and skeletal involvement occurs in most. Intellectual impairment is common late in the disease with prognosis directly related to the degree of neurologic impairment. MPS IVB is characterized by skeletal dysplasia with specific findings of axial and appendicular dysostosis multiplex, short stature (below 15th centile in adults), kyphoscoliosis, coxa/genu valga, joint laxity, platyspondyly, and odontoid hypoplasia. First signs and symptoms may be apparent at birth. Bony involvement is progressive, with more than 84% of adults requiring ambulation aids; life span does not appear to be limited. Corneal clouding is detected in some individuals and cardiac valvular disease may develop.
Cyclical vomiting syndrome
MedGen UID:
57509
Concept ID:
C0152164
Disease or Syndrome
A condition characterized by recurrent, self-limiting episodes of vomiting associated with intense nausea, pallor, and lethargy. It is commonly a migraine precursor.
Angelman syndrome
MedGen UID:
58144
Concept ID:
C0162635
Disease or Syndrome
Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs, and unique behavior with an apparent happy demeanor that includes frequent laughing, smiling, and excitability. Microcephaly and seizures are also common. Developmental delays are first noted at around age six months; however, the unique clinical features of AS do not become manifest until after age one year.
MERRF syndrome
MedGen UID:
56486
Concept ID:
C0162672
Disease or Syndrome
MERRF (myoclonic epilepsy with ragged red fibers) is a multisystem disorder characterized by myoclonus (often the first symptom) followed by generalized epilepsy, ataxia, weakness, exercise intolerance, and dementia. Onset can occur from childhood to adulthood, occurring after normal early development. Common findings are ptosis, hearing loss, short stature, optic atrophy, cardiomyopathy, cardiac dysrhythmias such as Wolff-Parkinson-White syndrome, and peripheral neuropathy. Pigmentary retinopathy, optic neuropathy, diabetes mellitus, and lipomatosis have been observed.
Progressive sclerosing poliodystrophy
MedGen UID:
60012
Concept ID:
C0205710
Disease or Syndrome
POLG-related disorders comprise a continuum of overlapping phenotypes that were clinically defined long before their molecular basis was known. Most affected individuals have some, but not all, of the features of a given phenotype; nonetheless, the following nomenclature can assist the clinician in diagnosis and management. Onset of the POLG-related disorders ranges from infancy to late adulthood. Alpers-Huttenlocher syndrome (AHS), one of the most severe phenotypes, is characterized by childhood-onset progressive and ultimately severe encephalopathy with intractable epilepsy and hepatic failure. Childhood myocerebrohepatopathy spectrum (MCHS) presents between the first few months of life and about age three years with developmental delay or dementia, lactic acidosis, and a myopathy with failure to thrive. Other findings can include liver failure, renal tubular acidosis, pancreatitis, cyclic vomiting, and hearing loss. Myoclonic epilepsy myopathy sensory ataxia (MEMSA) now describes the spectrum of disorders with epilepsy, myopathy, and ataxia without ophthalmoplegia. MEMSA now includes the disorders previously described as spinocerebellar ataxia with epilepsy (SCAE). The ataxia neuropathy spectrum (ANS) includes the phenotypes previously referred to as mitochondrial recessive ataxia syndrome (MIRAS) and sensory ataxia neuropathy dysarthria and ophthalmoplegia (SANDO). About 90% of persons in the ANS have ataxia and neuropathy as core features. Approximately two thirds develop seizures and almost one half develop ophthalmoplegia; clinical myopathy is rare. Autosomal recessive progressive external ophthalmoplegia (arPEO) is characterized by progressive weakness of the extraocular eye muscles resulting in ptosis and ophthalmoparesis (or paresis of the extraocular muscles) without associated systemic involvement; however, caution is advised because many individuals with apparently isolated arPEO at the onset develop other manifestations of POLG-related disorders over years or decades. Of note, in the ANS spectrum the neuropathy commonly precedes the onset of PEO by years to decades. Autosomal dominant progressive external ophthalmoplegia (adPEO) typically includes a generalized myopathy and often variable degrees of sensorineural hearing loss, axonal neuropathy, ataxia, depression, parkinsonism, hypogonadism, and cataracts (in what has been called "chronic progressive external ophthalmoplegia plus," or "CPEO+").
Pelizaeus-Merzbacher disease
MedGen UID:
61440
Concept ID:
C0205711
Disease or Syndrome
PLP1 disorders of central nervous system myelin formation include a range of phenotypes from Pelizaeus-Merzbacher disease (PMD) to spastic paraplegia 2 (SPG2). PMD typically manifests in infancy or early childhood with nystagmus, hypotonia, and cognitive impairment; the findings progress to severe spasticity and ataxia. Life span is shortened. SPG2 manifests as spastic paraparesis with or without CNS involvement and usually normal life span. Intrafamilial variation of phenotypes can be observed, but the signs are usually fairly consistent within families. Heterozygous females may manifest mild-to-moderate signs of the disease.
Fatal familial insomnia
MedGen UID:
104768
Concept ID:
C0206042
Disease or Syndrome
Genetic prion disease generally manifests with cognitive difficulties, ataxia, and myoclonus (abrupt jerking movements of muscle groups and/or entire limbs). The order of appearance and/or predominance of these features and other associated neurologic and psychiatric findings vary. The three major phenotypes of genetic prion disease are genetic Creutzfeldt-Jakob disease (gCJD), fatal familial insomnia (FFI), and Gerstmann-Sträussler-Scheinker (GSS) syndrome. Although these phenotypes display overlapping clinical and pathologic features, recognition of these phenotypes can be useful when providing affected individuals and their families with information about the expected clinical course. The age at onset typically ranges from 50 to 60 years. The disease course ranges from a few months in gCJD and FFI to a few (up to 4, and in rare cases up to 10) years in GSS syndrome.
Biotinidase deficiency
MedGen UID:
66323
Concept ID:
C0220754
Disease or Syndrome
If untreated, young children with profound biotinidase deficiency usually exhibit neurologic abnormalities including seizures, hypotonia, ataxia, developmental delay, vision problems, hearing loss, and cutaneous abnormalities (e.g., alopecia, skin rash, candidiasis). Older children and adolescents with profound biotinidase deficiency often exhibit motor limb weakness, spastic paresis, and decreased visual acuity. Once vision problems, hearing loss, and developmental delay occur, they are usually irreversible, even with biotin therapy. Individuals with partial biotinidase deficiency may have hypotonia, skin rash, and hair loss, particularly during times of stress.
Hereditary acrodermatitis enteropathica
MedGen UID:
66355
Concept ID:
C0221036
Disease or Syndrome
Acrodermatitis enteropathica of the zinc deficiency type (AEZ) is characterized by intermittent simultaneous occurrence of diarrhea and dermatitis with failure to thrive. Alopecia of the scalp, eyebrows, and eyelashes is a usual feature. The skin lesions are bullous. Noteworthy is the cure by diodoquin, or diiodohydroxyquinoline (Dillaha et al., 1953; Bloom and Sobel, 1955). Rodin and Goldman (1969) described autopsy findings, including pancreatic islet hyperplasia, absence of the thymus and of germinal centers, and plasmocytosis of lymph nodes and spleen.
Abortive cerebellar ataxia
MedGen UID:
66358
Concept ID:
C0221061
Disease or Syndrome
'Behr syndrome' is a clinical term that refers to the constellation of early-onset optic atrophy accompanied by neurologic features, including ataxia, pyramidal signs, spasticity, and mental retardation (Behr, 1909; Thomas et al., 1984). Patients with mutations in genes other than OPA1 can present with clinical features reminiscent of Behr syndrome. Mutations in one of these genes, OPA3 (606580), result in type III 3-methylglutaconic aciduria (MGCA3; 258501). Lerman-Sagie (1995) noted that the abnormal urinary pattern in MGCA3 may not be picked up by routine organic acid analysis, suggesting that early reports of Behr syndrome with normal metabolic features may actually have been 3-methylglutaconic aciduria type III.
Cholestanol storage disease
MedGen UID:
116041
Concept ID:
C0238052
Disease or Syndrome
Cerebrotendinous xanthomatosis (CTX) is a lipid storage disease characterized by infantile-onset diarrhea, childhood-onset cataract, adolescent- to young adult-onset tendon xanthomas, and adult-onset progressive neurologic dysfunction (dementia, psychiatric disturbances, pyramidal and/or cerebellar signs, dystonia, atypical parkinsonism, peripheral neuropathy, and seizures). Chronic diarrhea from infancy and/or neonatal cholestasis may be the earliest clinical manifestation. In approximately 75% of affected individuals, cataracts are the first finding, often appearing in the first decade of life. Xanthomas appear in the second or third decade; they occur on the Achilles tendon, the extensor tendons of the elbow and hand, the patellar tendon, and the neck tendons. Xanthomas have been reported in the lung, bones, and central nervous system. Some individuals show cognitive impairment from early infancy, whereas the majority have normal or only slightly impaired intellectual function until puberty; dementia with slow deterioration in intellectual abilities occurs in the third decade in more than 50% of individuals. Neuropsychiatric symptoms such as behavioral changes, hallucinations, agitation, aggression, depression, and suicide attempts may be prominent. Pyramidal signs (i.e., spasticity) and/or cerebellar signs almost invariably become evident between ages 20 and 30 years. The biochemical abnormalities that distinguish CTX from other conditions with xanthomas include high plasma and tissue cholestanol concentration, normal-to-low plasma cholesterol concentration, decreased chenodeoxycholic acid (CDCA), increased concentration of bile alcohols and their glyconjugates, and increased concentrations of cholestanol and apolipoprotein B in cerebrospinal fluid.
DE SANCTIS-CACCHIONE SYNDROME
MedGen UID:
75550
Concept ID:
C0265201
Disease or Syndrome
A rare autosomal recessive inherited syndrome. It is characterized by xeroderma pigmentosum, mental retardation, dwarfism, hypogonadism, and neurologic abnormalities.
Purine-nucleoside phosphorylase deficiency
MedGen UID:
75653
Concept ID:
C0268125
Disease or Syndrome
Purine nucleoside phosphorylase deficiency is a rare autosomal recessive immunodeficiency disorder characterized mainly by decreased T-cell function. Some patients also have neurologic impairment (review by Aust et al., 1992).
Xeroderma pigmentosum group A
MedGen UID:
82775
Concept ID:
C0268135
Disease or Syndrome
Xeroderma pigmentosum (XP) is characterized by: Acute sun sensitivity (severe sunburn with blistering, persistent erythema on minimal sun exposure) with marked freckle-like pigmentation of the face before age two years; Sunlight-induced ocular involvement (photophobia, severe keratitis, atrophy of the skin of the lids, ocular surface neoplasms); Greatly increased risk of sunlight-induced cutaneous neoplasms (basal cell carcinoma, squamous cell carcinoma, melanoma) within the first decade of life. Approximately 25% of affected individuals have neurologic manifestations (acquired microcephaly, diminished or absent deep tendon stretch reflexes, progressive sensorineural hearing loss, progressive cognitive impairment, and ataxia). The most common causes of death are skin cancer, neurologic degeneration, and internal cancer. The median age at death in persons with XP with neurodegeneration (29 years) was found to be younger than that in persons with XP without neurodegeneration (37 years).
Xeroderma pigmentosum group B
MedGen UID:
78643
Concept ID:
C0268136
Disease or Syndrome
Xeroderma pigmentosum (XP) is characterized by: Acute sun sensitivity (severe sunburn with blistering, persistent erythema on minimal sun exposure) with marked freckle-like pigmentation of the face before age two years; Sunlight-induced ocular involvement (photophobia, severe keratitis, atrophy of the skin of the lids, ocular surface neoplasms); Greatly increased risk of sunlight-induced cutaneous neoplasms (basal cell carcinoma, squamous cell carcinoma, melanoma) within the first decade of life. Approximately 25% of affected individuals have neurologic manifestations (acquired microcephaly, diminished or absent deep tendon stretch reflexes, progressive sensorineural hearing loss, progressive cognitive impairment, and ataxia). The most common causes of death are skin cancer, neurologic degeneration, and internal cancer. The median age at death in persons with XP with neurodegeneration (29 years) was found to be younger than that in persons with XP without neurodegeneration (37 years).
Xeroderma pigmentosum, group D
MedGen UID:
75656
Concept ID:
C0268138
Disease or Syndrome
Xeroderma pigmentosum (XP) is characterized by: Acute sun sensitivity (severe sunburn with blistering, persistent erythema on minimal sun exposure) with marked freckle-like pigmentation of the face before age two years; Sunlight-induced ocular involvement (photophobia, severe keratitis, atrophy of the skin of the lids, ocular surface neoplasms); Greatly increased risk of sunlight-induced cutaneous neoplasms (basal cell carcinoma, squamous cell carcinoma, melanoma) within the first decade of life. Approximately 25% of affected individuals have neurologic manifestations (acquired microcephaly, diminished or absent deep tendon stretch reflexes, progressive sensorineural hearing loss, progressive cognitive impairment, and ataxia). The most common causes of death are skin cancer, neurologic degeneration, and internal cancer. The median age at death in persons with XP with neurodegeneration (29 years) was found to be younger than that in persons with XP without neurodegeneration (37 years).
Xeroderma pigmentosum, group F
MedGen UID:
120612
Concept ID:
C0268140
Congenital Abnormality
Xeroderma pigmentosum (XP) is characterized by: Acute sun sensitivity (severe sunburn with blistering, persistent erythema on minimal sun exposure) with marked freckle-like pigmentation of the face before age two years; Sunlight-induced ocular involvement (photophobia, severe keratitis, atrophy of the skin of the lids, ocular surface neoplasms); Greatly increased risk of sunlight-induced cutaneous neoplasms (basal cell carcinoma, squamous cell carcinoma, melanoma) within the first decade of life. Approximately 25% of affected individuals have neurologic manifestations (acquired microcephaly, diminished or absent deep tendon stretch reflexes, progressive sensorineural hearing loss, progressive cognitive impairment, and ataxia). The most common causes of death are skin cancer, neurologic degeneration, and internal cancer. The median age at death in persons with XP with neurodegeneration (29 years) was found to be younger than that in persons with XP without neurodegeneration (37 years).
Xeroderma pigmentosum, group G
MedGen UID:
75657
Concept ID:
C0268141
Disease or Syndrome
Xeroderma pigmentosum (XP) is characterized by: Acute sun sensitivity (severe sunburn with blistering, persistent erythema on minimal sun exposure) with marked freckle-like pigmentation of the face before age two years; Sunlight-induced ocular involvement (photophobia, severe keratitis, atrophy of the skin of the lids, ocular surface neoplasms); Greatly increased risk of sunlight-induced cutaneous neoplasms (basal cell carcinoma, squamous cell carcinoma, melanoma) within the first decade of life. Approximately 25% of affected individuals have neurologic manifestations (acquired microcephaly, diminished or absent deep tendon stretch reflexes, progressive sensorineural hearing loss, progressive cognitive impairment, and ataxia). The most common causes of death are skin cancer, neurologic degeneration, and internal cancer. The median age at death in persons with XP with neurodegeneration (29 years) was found to be younger than that in persons with XP without neurodegeneration (37 years).
Triglyceride storage disease with ichthyosis
MedGen UID:
82780
Concept ID:
C0268238
Disease or Syndrome
Chanarin-Dorfman syndrome (CDS) is a rare autosomal recessive nonlysosomal inborn error of neutral lipid metabolism. Patients present with an nonbullous erythrodermic form of ichthyosis, with variable involvement of other organs, such as liver, central nervous system, eyes, and ears. Intracellular triacylglycerol droplets are present in most tissues, and diagnosis can be confirmed by a simple blood smear, in which the characteristic lipid droplets are observed in the cytoplasm of granulocytes (summary by Lefevre et al., 2001).
Gaucher disease type III
MedGen UID:
78653
Concept ID:
C0268251
Disease or Syndrome
Gaucher disease (GD) encompasses a continuum of clinical findings from a perinatal lethal disorder to an asymptomatic type. The identification of three major clinical types (1, 2, and 3) and two other subtypes (perinatal-lethal and cardiovascular) is useful in determining prognosis and management. GD type 1 is characterized by the presence of clinical or radiographic evidence of bone disease (osteopenia, focal lytic or sclerotic lesions, and osteonecrosis), hepatosplenomegaly, anemia and thrombocytopenia, lung disease, and the absence of primary central nervous system disease. GD types 2 and 3 are characterized by the presence of primary neurologic disease; in the past, they were distinguished by age of onset and rate of disease progression, but these distinctions are not absolute. Disease with onset before age two years, limited psychomotor development, and a rapidly progressive course with death by age two to four years is classified as GD type 2. Individuals with GD type 3 may have onset before age two years, but often have a more slowly progressive course, with survival into the third or fourth decade. The perinatal-lethal form is associated with ichthyosiform or collodion skin abnormalities or with nonimmune hydrops fetalis. The cardiovascular form is characterized by calcification of the aortic and mitral valves, mild splenomegaly, corneal opacities, and supranuclear ophthalmoplegia. Cardiopulmonary complications have been described with all the clinical subtypes, although varying in frequency and severity.
Multiple sulfatase deficiency
MedGen UID:
75664
Concept ID:
C0268263
Disease or Syndrome
Initial symptoms of multiple sulfatase deficiency (MSD) can develop from infancy through early childhood, and presentation is widely variable. Some individuals display the multisystemic features characteristic of mucopolysaccharidosis disorders (e.g., developmental regression, organomegaly, skeletal deformities) while other individuals present primarily with neurologic regression (associated with leukodystrophy). Based on age of onset, rate of progression, and disease severity, several different clinical subtypes of MSD have been described: Neonatal MSD is the most severe with presentation in the prenatal period or at birth with rapid progression and death occurring within the first two years of life. Infantile MSD is the most common variant and may be characterized as attenuated (slower clinical course with cognitive disability and neurodegeneration identified in the 2nd year of life) or severe (loss of the majority of developmental milestones by age 5 years). Juvenile MSD is the rarest subtype with later onset of symptoms and subacute clinical presentation. Many of the features found in MSD are progressive, including neurologic deterioration, heart disease, hearing loss, and airway compromise.
GM1 gangliosidosis type 2
MedGen UID:
120625
Concept ID:
C0268272
Disease or Syndrome
GLB1-related disorders comprise two phenotypically distinct lysosomal storage disorders: GM1 gangliosidosis and mucopolysaccharidosis type IVB (MPS IVB). The phenotype of GM1 gangliosidosis constitutes a spectrum ranging from severe (infantile) to intermediate (late-infantile and juvenile) to mild (chronic/adult). Type I (infantile) GM1 gangliosidosis begins before age 12 months. Prenatal manifestations may include nonimmune hydrops fetalis, intrauterine growth restriction, and placental vacuolization; congenital dermal melanocytosis (Mongolian spots) may be observed. Macular cherry-red spot is detected on eye exam. Progressive central nervous system dysfunction leads to spasticity and rapid regression; blindness, deafness, decerebrate rigidity, seizures, feeding difficulties, and oral secretions are observed. Life expectancy is two to three years. Type II can be subdivided into the late-infantile (onset age 1-3 years) and juvenile (onset age 3-10 years) phenotypes. Central nervous system dysfunction manifests as progressive cognitive, motor, and speech decline as measured by psychometric testing. There may be mild corneal clouding, hepatosplenomegaly, and/or cardiomyopathy; the typical course is characterized by progressive neurologic decline, progressive skeletal disease in some individuals (including kyphosis and avascular necrosis of the femoral heads), and progressive feeding difficulties leading to aspiration risk. Type III begins in late childhood to the third decade with generalized dystonia leading to unsteady gait and speech disturbance followed by extrapyramidal signs including akinetic-rigid parkinsonism. Cardiomyopathy develops in some and skeletal involvement occurs in most. Intellectual impairment is common late in the disease with prognosis directly related to the degree of neurologic impairment. MPS IVB is characterized by skeletal dysplasia with specific findings of axial and appendicular dysostosis multiplex, short stature (below 15th centile in adults), kyphoscoliosis, coxa/genu valga, joint laxity, platyspondyly, and odontoid hypoplasia. First signs and symptoms may be apparent at birth. Bony involvement is progressive, with more than 84% of adults requiring ambulation aids; life span does not appear to be limited. Corneal clouding is detected in some individuals and cardiac valvular disease may develop.
GM1 gangliosidosis type 3
MedGen UID:
78655
Concept ID:
C0268273
Disease or Syndrome
GLB1-related disorders comprise two phenotypically distinct lysosomal storage disorders: GM1 gangliosidosis and mucopolysaccharidosis type IVB (MPS IVB). The phenotype of GM1 gangliosidosis constitutes a spectrum ranging from severe (infantile) to intermediate (late-infantile and juvenile) to mild (chronic/adult). Type I (infantile) GM1 gangliosidosis begins before age 12 months. Prenatal manifestations may include nonimmune hydrops fetalis, intrauterine growth restriction, and placental vacuolization; congenital dermal melanocytosis (Mongolian spots) may be observed. Macular cherry-red spot is detected on eye exam. Progressive central nervous system dysfunction leads to spasticity and rapid regression; blindness, deafness, decerebrate rigidity, seizures, feeding difficulties, and oral secretions are observed. Life expectancy is two to three years. Type II can be subdivided into the late-infantile (onset age 1-3 years) and juvenile (onset age 3-10 years) phenotypes. Central nervous system dysfunction manifests as progressive cognitive, motor, and speech decline as measured by psychometric testing. There may be mild corneal clouding, hepatosplenomegaly, and/or cardiomyopathy; the typical course is characterized by progressive neurologic decline, progressive skeletal disease in some individuals (including kyphosis and avascular necrosis of the femoral heads), and progressive feeding difficulties leading to aspiration risk. Type III begins in late childhood to the third decade with generalized dystonia leading to unsteady gait and speech disturbance followed by extrapyramidal signs including akinetic-rigid parkinsonism. Cardiomyopathy develops in some and skeletal involvement occurs in most. Intellectual impairment is common late in the disease with prognosis directly related to the degree of neurologic impairment. MPS IVB is characterized by skeletal dysplasia with specific findings of axial and appendicular dysostosis multiplex, short stature (below 15th centile in adults), kyphoscoliosis, coxa/genu valga, joint laxity, platyspondyly, and odontoid hypoplasia. First signs and symptoms may be apparent at birth. Bony involvement is progressive, with more than 84% of adults requiring ambulation aids; life span does not appear to be limited. Corneal clouding is detected in some individuals and cardiac valvular disease may develop.
Familial hypokalemia-hypomagnesemia
MedGen UID:
75681
Concept ID:
C0268450
Disease or Syndrome
Gitelman syndrome (GTLMNS) is an autosomal recessive renal tubular salt-wasting disorder characterized by hypokalemic metabolic alkalosis with hypomagnesemia and hypocalciuria. It is the most common renal tubular disorder among Caucasians (prevalence of 1 in 40,000). Most patients have onset of symptoms as adults, but some present in childhood. Clinical features include transient periods of muscle weakness and tetany, abdominal pains, and chondrocalcinosis (summary by Glaudemans et al., 2012). Gitelman syndrome is sometimes referred to as a mild variant of classic Bartter syndrome (607364). For a discussion of genetic heterogeneity of Bartter syndrome, see 607364.
Dopa-responsive dystonia due to sepiapterin reductase deficiency
MedGen UID:
120642
Concept ID:
C0268468
Disease or Syndrome
The phenotypic spectrum of sepiapterin reductase deficiency (SRD), which ranges from significant motor and cognitive deficits to only minimal findings, has not been completely elucidated. Clinical features in the majority of affected individuals include motor and speech delay, axial hypotonia, dystonia, weakness, and oculogyric crises; symptoms show diurnal fluctuation and sleep benefit. Other common features include parkinsonian signs (tremor, bradykinesia, masked facies, rigidity), limb hypertonia, hyperreflexia, intellectual disability, psychiatric and/or behavioral abnormalities, autonomic dysfunction, and sleep disturbances (hypersomnolence, difficulty initiating or maintaining sleep, and drowsiness). Most affected individuals have nonspecific features in infancy including developmental delays and axial hypotonia; other features develop over time.
Tryptophanuria with dwarfism
MedGen UID:
78680
Concept ID:
C0268473
Disease or Syndrome
Urocanate hydratase deficiency
MedGen UID:
120644
Concept ID:
C0268514
Disease or Syndrome
An increased concentration of urocanic acid in the urine.
Proline dehydrogenase deficiency
MedGen UID:
120645
Concept ID:
C0268529
Disease or Syndrome
Phang et al. (2001) noted that prospective studies of HPI probands identified through newborn screening as well as reports of several families have suggested that it is a metabolic disorder not clearly associated with clinical manifestations. Phang et al. (2001) concluded that HPI is a relatively benign condition in most individuals under most circumstances. However, other reports have suggested that some patients have a severe phenotype with neurologic manifestations, including epilepsy and mental retardation (Jacquet et al., 2003). Genetic Heterogeneity of Hyperprolinemia See also hyperprolinemia type II (HYRPRO2; 239510), which is caused by mutation in the gene encoding pyrroline-5-carboxylate dehydrogenase (P5CDH, ALDH4A1; 606811) on chromosome 1p36.
Ornithine carbamoyltransferase deficiency
MedGen UID:
75692
Concept ID:
C0268542
Disease or Syndrome
Ornithine transcarbamylase (OTC) deficiency can occur as a severe neonatal-onset disease in males (but rarely in females) and as a post-neonatal-onset (also known as "late-onset" or partial deficiency) disease in males and females. Males with severe neonatal-onset OTC deficiency are asymptomatic at birth but become symptomatic from hyperammonemia in the first week of life, most often on day two to three of life, and are usually catastrophically ill by the time they come to medical attention. After successful treatment of neonatal hyperammonemic coma these infants can easily become hyperammonemic again despite appropriate treatment; they typically require liver transplant to improve quality of life. Males and heterozygous females with post-neonatal-onset (partial) OTC deficiency can present from infancy to later childhood, adolescence, or adulthood. No matter how mild the disease, a hyperammonemic crisis can be precipitated by stressors and become a life-threatening event at any age and in any situation in life. For all individuals with OTC deficiency, typical neuropsychological complications include developmental delay, learning disabilities, intellectual disability, attention-deficit/hyperactivity disorder, and executive function deficits.
Argininosuccinate lyase deficiency
MedGen UID:
78687
Concept ID:
C0268547
Disease or Syndrome
Deficiency of argininosuccinate lyase (ASL), the enzyme that cleaves argininosuccinic acid to produce arginine and fumarate in the fourth step of the urea cycle, may present as a severe neonatal-onset form or a late-onset form: The severe neonatal-onset form is characterized by hyperammonemia within the first few days after birth that can manifest as increasing lethargy, somnolence, refusal to feed, vomiting, tachypnea, and respiratory alkalosis. Absence of treatment leads to worsening lethargy, seizures, coma, and even death. In contrast, the manifestations of late-onset form range from episodic hyperammonemia triggered by acute infection or stress to cognitive impairment, behavioral abnormalities, and/or learning disabilities in the absence of any documented episodes of hyperammonemia. Manifestations of ASL deficiency that appear to be unrelated to the severity or duration of hyperammonemic episodes: Neurocognitive deficiencies (attention-deficit/hyperactivity disorder, developmental delay, seizures, and learning disability). Liver disease (hepatitis, cirrhosis). Trichorrhexis nodosa (coarse brittle hair that breaks easily). Systemic hypertension.
Sulfite oxidase deficiency
MedGen UID:
78695
Concept ID:
C0268624
Disease or Syndrome
The spectrum of isolated sulfite oxidase deficiency ranges from classic early-onset (severe) disease to late-onset (mild) disease. Classic ISOD is characterized in the first few hours to days of life by intractable seizures, feeding difficulties, and rapidly progressive encephalopathy manifest as abnormal tone (especially opisthotonus, spastic quadriplegia, and pyramidal signs) followed by progressive microcephaly and profound intellectual disability. Lens subluxation or dislocation, another characteristic finding, may be evident after the newborn period. Children usually die during the first few months of life. Late-onset ISOD manifests between ages six and 18 months and is characterized by ectopia lentis (variably present), developmental delay/regression, movement disorder characterized by dystonia and choreoathetosis, ataxia, and (rarely) acute hemiplegia as a result of metabolic stroke. The clinical course may be progressive or episodic. In the episodic form encephalopathy, dystonia, choreoathetosis, and/or ataxia are intermittent.
Succinate-semialdehyde dehydrogenase deficiency
MedGen UID:
124340
Concept ID:
C0268631
Disease or Syndrome
Succinic semialdehyde dehydrogenase (SSADH) deficiency is characterized by infantile-onset hypotonia, developmental delay, cognitive impairment, expressive language deficit, and mild ataxia. Epilepsy is present in about half of affected individuals and is more common in adults. Hyperkinetic behavior, aggression, self-injurious behaviors, hallucinations, and sleep disturbances have been reported in nearly half of all affected individuals, more commonly in those who are older. Basal ganglia signs including choreoathetosis, dystonia, and myoclonus have been reported in a few individuals with earlier-onset, more severe disease. Involvement beyond the central nervous system has not been described. Individuals with SSADH deficiency typically have 4-hydroxybutyric aciduria present on urine organic acid analysis. Head MRI reveals T2 hyperintensities in multiple regions, involving the globus pallidi, cerebellar dentate nuclei, subthalamic nuclei, subcortical white matter, and brain stem, as well as cerebral and sometimes cerebellar atrophy. EEG findings include background slowing and spike discharges that are usually generalized.
Infantile neuroaxonal dystrophy
MedGen UID:
82852
Concept ID:
C0270724
Disease or Syndrome
PLA2G6-associated neurodegeneration (PLAN) comprises a continuum of three phenotypes with overlapping clinical and radiologic features: Infantile neuroaxonal dystrophy (INAD). Atypical neuroaxonal dystrophy (atypical NAD). PLA2G6-related dystonia-parkinsonism. INAD usually begins between ages six months and three years with psychomotor regression or delay, hypotonia, and progressive spastic tetraparesis. Many affected children never learn to walk or lose the ability shortly after attaining it. Strabismus, nystagmus, and optic atrophy are common. Disease progression is rapid, resulting in severe spasticity, progressive cognitive decline, and visual impairment. Many affected children do not survive beyond their first decade. Atypical NAD shows more phenotypic variability than INAD. In general, onset is in early childhood but can be as late as the end of the second decade. The presenting signs may be gait instability, ataxia, or speech delay and autistic features, which are sometimes the only evidence of disease for a year or more. Strabismus, nystagmus, and optic atrophy are common. Neuropsychiatric disturbances including impulsivity, poor attention span, hyperactivity, and emotional lability are also common. The course is fairly stable during early childhood and resembles static encephalopathy but is followed by neurologic deterioration between ages seven and 12 years. PLA2G6-related dystonia-parkinsonism has a variable age of onset, but most individuals present in early adulthood with gait disturbance or neuropsychiatric changes. Affected individuals consistently develop dystonia and parkinsonism (which may be accompanied by rapid cognitive decline) in their late teens to early twenties. Dystonia is most common in the hands and feet but may be more generalized. The most common features of parkinsonism in these individuals are bradykinesia, resting tremor, rigidity, and postural instability.
Alexander disease
MedGen UID:
78724
Concept ID:
C0270726
Disease or Syndrome
Alexander disease, a progressive disorder of cerebral white matter caused by a heterozygous GFAP pathogenic variant, comprises a continuous clinical spectrum most recognizable in infants and children and a range of nonspecific neurologic manifestations in adults. This chapter discusses the spectrum of Alexander disease as four forms: neonatal, infantile, juvenile, and adult. The neonatal form begins in the first 30 days after birth with neurologic findings (e.g., hypotonia, hyperexcitability, myoclonus) and/or gastrointestinal manifestations (e.g., gastroesophageal reflux, vomiting, failure to thrive), followed by severe developmental delay and regression, seizures, megalencephaly, and typically death within two years. The infantile form is characterized by variable developmental issues: initially some have delayed or plateauing of acquisition of new skills, followed in some by a loss of gross and fine motor skills and language during in the first decade or in others a slow disease course that spans decades. Seizures, often triggered by illness, may be less frequent/severe than in the neonatal form. The juvenile form typically presents in childhood or adolescence with clinical and imaging features that overlap with the other forms. Manifestations in early childhood are milder than those in the infantile form (e.g., mild language delay may be the only developmental abnormality or, with language acquisition, hypophonia or nasal speech may alter the voice, often prior to appearance of other neurologic features). Vomiting and failure to thrive as well as scoliosis and autonomic dysfunction are common. The adult form is typically characterized by bulbar or pseudobulbar findings (palatal myoclonus, dysphagia, dysphonia, dysarthria or slurred speech), motor/gait abnormalities with pyramidal tract signs (spasticity, hyperreflexia, positive Babinski sign), or cerebellar abnormalities (ataxia, nystagmus, or dysmetria). Others may have hemiparesis or hemiplegia with a relapsing/remitting course or slowly progressive quadriparesis or quadriplegia. Other neurologic features can include sleep apnea, diplopia or disorders of extraocular motility, and autonomic dysfunction.
Charcot-Marie-Tooth disease type 1C
MedGen UID:
75728
Concept ID:
C0270913
Disease or Syndrome
For a phenotypic description and a discussion of genetic heterogeneity of autosomal dominant Charcot-Marie-Tooth disease type 1, see CMT1B (118200).
Leucine-induced hypoglycemia
MedGen UID:
82888
Concept ID:
C0271714
Disease or Syndrome
Glucocorticoid deficiency with achalasia
MedGen UID:
82889
Concept ID:
C0271742
Disease or Syndrome
Triple A syndrome is an inherited condition characterized by three specific features: achalasia, Addison disease, and alacrima. Achalasia is a disorder that affects the ability to move food through the esophagus, the tube that carries food from the throat to the stomach. It can lead to severe feeding difficulties and low blood glucose (hypoglycemia). Addison disease, also known as primary adrenal insufficiency, is caused by abnormal function of the small hormone-producing glands on top of each kidney (adrenal glands). The main features of Addison disease include fatigue, loss of appetite, weight loss, low blood pressure, and darkening of the skin. The third major feature of triple A syndrome is a reduced or absent ability to secrete tears (alacrima). Most people with triple A syndrome have all three of these features, although some have only two.\n\nMany of the features of triple A syndrome are caused by dysfunction of the autonomic nervous system. This part of the nervous system controls involuntary body processes such as digestion, blood pressure, and body temperature. People with triple A syndrome often experience abnormal sweating, difficulty regulating blood pressure, unequal pupil size (anisocoria), and other signs and symptoms of autonomic nervous system dysfunction (dysautonomia).\n\nPeople with this condition may have other neurological abnormalities, such as developmental delay, intellectual disability, speech problems (dysarthria), and a small head size (microcephaly). In addition, affected individuals commonly experience muscle weakness, movement problems, and nerve abnormalities in their extremities (peripheral neuropathy). Some develop optic atrophy, which is the degeneration (atrophy) of the nerves that carry information from the eyes to the brain. Many of the neurological symptoms of triple A syndrome worsen over time.\n\nPeople with triple A syndrome frequently develop a thickening of the outer layer of skin (hyperkeratosis) on the palms of their hands and the soles of their feet. Other skin abnormalities may also be present in people with this condition.\n\nAlacrima is usually the first noticeable sign of triple A syndrome, as it becomes apparent early in life that affected children produce little or no tears while crying. They develop Addison disease and achalasia during childhood or adolescence, and most of the neurologic features of triple A syndrome begin during adulthood. The signs and symptoms of this condition vary among affected individuals, even among members of the same family.
Autosomal dominant optic atrophy classic form
MedGen UID:
137902
Concept ID:
C0338508
Disease or Syndrome
Optic atrophy type 1 (OPA1, or Kjer type optic atrophy) is characterized by bilateral and symmetric optic nerve pallor associated with insidious decrease in visual acuity (usually between ages 4 and 6 years), visual field defects, and color vision defects. Visual impairment is usually moderate (6/10 to 2/10), but ranges from mild or even insignificant to severe (legal blindness with acuity <1/20). The visual field defect is typically centrocecal, central, or paracentral; it is often large in those with severe disease. The color vision defect is often described as acquired blue-yellow loss (tritanopia). Other findings can include auditory neuropathy resulting in sensorineural hearing loss that ranges from severe and congenital to subclinical (i.e., identified by specific audiologic testing only). Visual evoked potentials are typically absent or delayed; pattern electroretinogram shows an abnormal N95:P50 ratio. Tritanopia is the classic feature of color vision defect, but more diffuse nonspecific dyschromatopsia is not uncommon. Ophthalmoscopic examination discloses temporal or diffuse pallor of the optic discs, sometimes associated with optic disc excavation. The neuroretinal rim shows some pallor in most cases, sometimes associated with a temporal pigmentary gray crescent.
Muscular atrophy, ataxia, retinitis pigmentosa, and diabetes mellitus
MedGen UID:
137966
Concept ID:
C0342281
Disease or Syndrome
A rare hereditary ataxia with characteristics of neurogenic muscular atrophy associated with signs of cerebellar ataxia, degeneration of the retina and diabetes mellitus. Onset of the disease is in adolescence and the course is slowly progressive.
Megaloblastic anemia, thiamine-responsive, with diabetes mellitus and sensorineural deafness
MedGen UID:
83338
Concept ID:
C0342287
Congenital Abnormality
Thiamine-responsive megaloblastic anemia syndrome (TRMA) is characterized by megaloblastic anemia, progressive sensorineural hearing loss, and diabetes mellitus. Onset of megaloblastic anemia occurs between infancy and adolescence. The anemia is corrected with thiamine treatment, but the red cells remain macrocytic and anemia can recur if treatment is withdrawn. Progressive sensorineural hearing loss often occurs early and can be detected in toddlers; hearing loss is irreversible and may not be prevented by thiamine treatment. The diabetes mellitus is non-type I in nature, with age of onset from infancy to adolescence. Thiamine treatment may reduce insulin requirement and delay onset of diabetes in some individuals.
Transcobalamin II deficiency
MedGen UID:
137976
Concept ID:
C0342701
Disease or Syndrome
Transcobalamin II deficiency (TCN2D) is an autosomal recessive disorder with onset in early infancy characterized by failure to thrive, megaloblastic anemia, and pancytopenia. Other features include methylmalonic aciduria, recurrent infections, and vomiting and diarrhea. Treatment with cobalamin results in clinical improvement, but the untreated disorder may result in mental retardation and neurologic abnormalities (summary by Haberle et al., 2009). Hall (1981) gave a clinically oriented review of congenital defects of vitamin B12 transport, and Frater-Schroder (1983) gave a genetically oriented review.
Congenital defect of folate absorption
MedGen UID:
83348
Concept ID:
C0342705
Disease or Syndrome
Hereditary folate malabsorption (HFM) is characterized by folate deficiency due to impaired intestinal folate absorption and impaired folate transport into the central nervous system. Findings include poor feeding, failure to thrive, and anemia. There can be leukopenia and thrombocytopenia, diarrhea and/or oral mucositis, hypoimmunoglobulinemia, and other immunologic dysfunction resulting in infections, most often Pneumocystis jirovecii pneumonia. Neurologic manifestations include developmental delays, cognitive and motor disorders, behavioral disorders, and seizures.
3-methylglutaconic aciduria type 1
MedGen UID:
90994
Concept ID:
C0342727
Disease or Syndrome
3-methylglutaconyl-CoA hydratase deficiency is an inherited condition that causes neurological problems. Beginning in infancy to early childhood, children with this condition often have delayed development of mental and motor skills (psychomotor delay), speech delay, involuntary muscle cramping (dystonia), and spasms and weakness of the arms and legs (spastic quadriparesis). Affected individuals can also have optic atrophy, which is the breakdown (atrophy) of nerve cells that carry visual information from the eyes to the brain.\n\nIn some cases, signs and symptoms of 3-methylglutaconyl-CoA hydratase deficiency begin in adulthood, often in a person's twenties or thirties. These individuals have damage to a type of brain tissue called white matter (leukoencephalopathy). This damage likely contributes to progressive problems with speech (dysarthria), difficulty coordinating movements (ataxia), stiffness (spasticity), optic atrophy, and a decline in intellectual function (dementia).\n\nAffected individuals who show symptoms of 3-methylglutaconyl-CoA hydratase deficiency in childhood often go on to develop leukoencephalopathy and other neurological problems in adulthood.\n\nAll people with 3-methylglutaconyl-CoA hydratase deficiency accumulate large amounts of a substance called 3-methylglutaconic acid in their body fluids. As a result, they have elevated levels of acid in their blood (metabolic acidosis) and excrete large amounts of acid in their urine (aciduria). 3-methylglutaconyl-CoA hydratase deficiency is one of a group of metabolic disorders that can be diagnosed by the presence of increased levels 3-methylglutaconic acid in urine (3-methylglutaconic aciduria). People with 3-methylglutaconyl-CoA hydratase deficiency also have high urine levels of another acid called 3-methylglutaric acid.
Beta-hydroxyisobutyryl-CoA deacylase deficiency
MedGen UID:
83349
Concept ID:
C0342738
Disease or Syndrome
3-Hydroxyisobutyryl-CoA hydrolase deficiency (HIBCHD) is an autosomal recessive inborn error of metabolism characterized by severely delayed psychomotor development, neurodegeneration, increased lactic acid, and brain lesions in the basal ganglia (summary by Ferdinandusse et al., 2013).
Deficiency of butyryl-CoA dehydrogenase
MedGen UID:
90998
Concept ID:
C0342783
Disease or Syndrome
Most infants with short-chain acyl-CoA dehydrogenase deficiency (SCADD) identified through newborn screening programs have remained well, and asymptomatic relatives who meet diagnostic criteria are reported. Thus, SCADD is now viewed as a biochemical phenotype rather than a disease. A broad range of clinical findings was originally reported in those with confirmed SCADD, including severe dysmorphic facial features, feeding difficulties / failure to thrive, metabolic acidosis, ketotic hypoglycemia, lethargy, developmental delay, seizures, hypotonia, dystonia, and myopathy. However, individuals with no symptoms were also reported. In a large series of affected individuals detected on metabolic evaluation for developmental delay, 20% had failure to thrive, feeding difficulties, and hypotonia; 22% had seizures; and 30% had hypotonia without seizures. In contrast, the majority of infants with SCADD have been detected by expanded newborn screening, and the great majority of these infants remain asymptomatic. As with other fatty acid oxidation deficiencies, characteristic biochemical findings of SCADD may be absent except during times of physiologic stress such as fasting and illness. A diagnosis of SCADD based on clinical findings should not preclude additional testing to look for other causes.
Flynn-Aird syndrome
MedGen UID:
91009
Concept ID:
C0343108
Disease or Syndrome
A rare genetic disease characterized by childhood onset of bilateral progressive sensorineural hearing loss, ocular anomalies (myopia, cataract, retinitis pigmentosa), central and peripheral nervous system features (dementia, epilepsy, ataxia, peripheral neuropathy), ectodermal features (skin atrophy, alopecia, dental caries), and skeletal anomalies (bone cysts, joint stiffness, scoliosis, kyphosis). Laboratory examination may reveal elevated cerebrospinal fluid protein.
Wernicke-Korsakoff syndrome
MedGen UID:
83883
Concept ID:
C0349464
Mental or Behavioral Dysfunction
A psychotic syndrome caused by damage to the brain by lack of thiamine (vitamin B1). Signs and symptoms include anterograde and retrograde amnesia, confabulation, apathy, ataxia, and coma.
PMM2-congenital disorder of glycosylation
MedGen UID:
138111
Concept ID:
C0349653
Disease or Syndrome
PMM2-CDG, the most common of a group of disorders of abnormal glycosylation of N-linked oligosaccharides, is divided into three clinical stages: infantile multisystem, late-infantile and childhood ataxia–intellectual disability, and adult stable disability. The clinical manifestations and course are highly variable, ranging from infants who die in the first year of life to mildly affected adults. Clinical findings tend to be similar in sibs. In the infantile multisystem presentation, infants show axial hypotonia, hyporeflexia, esotropia, and developmental delay. Feeding problems, vomiting, faltering growth, and developmental delay are frequently seen. Subcutaneous fat may be excessive over the buttocks and suprapubic region. Two distinct clinical courses are observed: (1) a nonfatal neurologic course with faltering growth, strabismus, developmental delay, cerebellar hypoplasia, and hepatopathy in infancy followed by neuropathy and retinitis pigmentosa in the first or second decade; and (2) a more severe neurologic-multivisceral course with approximately 20% mortality in the first year of life. The late-infantile and childhood ataxia–intellectual disability stage, which begins between ages three and ten years, is characterized by hypotonia, ataxia, severely delayed language and motor development, inability to walk, and IQ of 40 to 70; other findings include seizures, stroke-like episodes or transient unilateral loss of function, coagulopathy, retinitis pigmentosa, joint contractures, and skeletal deformities. In the adult stable disability stage, intellectual ability is stable; peripheral neuropathy is variable, progressive retinitis pigmentosa and myopia are seen, thoracic and spinal deformities with osteoporosis worsen, and premature aging is observed; females may lack secondary sexual development and males may exhibit decreased testicular volume. Hypogonadotropic hypogonadism and coagulopathy may occur. The risk for deep venous thrombosis is increased.
Myoclonic-astatic epilepsy
MedGen UID:
98284
Concept ID:
C0393702
Disease or Syndrome
A generalized myoclonic-atonic seizure is a type of generalized motor seizure characterized by a myoclonic jerk followed by an atonic motor component.
Glutathione synthetase deficiency with 5-oxoprolinuria
MedGen UID:
97988
Concept ID:
C0398746
Disease or Syndrome
Glutathione synthetase deficiency, or 5-oxoprolinuria, is an autosomal recessive disorder characterized, in its severe form, by massive urinary excretion of 5-oxoproline, metabolic acidosis, hemolytic anemia, and central nervous system damage. The metabolic defect results in decreased levels of cellular glutathione, which overstimulates the synthesis of gamma-glutamylcysteine and its subsequent conversion to 5-oxoproline (Larsson and Anderson, 2001).
Amelocerebrohypohidrotic syndrome
MedGen UID:
98036
Concept ID:
C0406740
Disease or Syndrome
Kohlschutter-Tonz syndrome (KTZS) is an autosomal recessive disorder characterized by severe global developmental delay, early-onset intractable seizures, spasticity, and amelogenesis imperfecta affecting both primary and secondary teeth and causing yellow or brown discoloration of the teeth. Although the phenotype is consistent, there is variability. Impaired intellectual development is related to the severity of seizures, and the disorder can thus be considered an epileptic encephalopathy. Some infants show normal development until seizure onset, whereas others are delayed from birth. The most severely affected individuals have profound mental retardation, never acquire speech, and become bedridden early in life (summary by Schossig et al., 2012 and Mory et al., 2012). See also Kohlschutter-Tonz syndrome-like (KTZSL; 619229), caused by heterozygous mutation in the SATB1 gene (602075) on chromosome 3p23.
Gillespie syndrome
MedGen UID:
96563
Concept ID:
C0431401
Disease or Syndrome
Gillespie syndrome (GLSP) is usually diagnosed in the first year of life by the presence of fixed dilated pupils in a hypotonic infant. Affected individuals have a characteristic form of iris hypoplasia in which the pupillary border of the iris exhibits a scalloped or 'festooned' edge, with iris strands extending onto the anterior lens surface at regular intervals. The key extraocular features of Gillespie syndrome are congenital hypotonia, progressive cerebellar hypoplasia, and ataxia, as well as variable cognitive impairment that is usually mild (summary by Gerber et al., 2016 and McEntagart et al., 2016).
Chiari type II malformation
MedGen UID:
108222
Concept ID:
C0555206
Congenital Abnormality
Chiari malformation type II (CM2), also known as the Arnold-Chiari malformation, consists of elongation and descent of the inferior cerebellar vermis, cerebellar hemispheres, pons, medulla, and fourth ventricle through the foramen magnum into the spinal canal. CM2 is uniquely associated with myelomeningocele (open spina bifida; see 182940) and is found only in this population (Stevenson, 2004). It is believed to be a disorder of neuroectodermal origin (Schijman, 2004). For a general phenotypic description of the different forms of Chiari malformations, see Chiari malformation type I (CM1; 118420).
Deficiency of guanidinoacetate methyltransferase
MedGen UID:
154356
Concept ID:
C0574080
Disease or Syndrome
The creatine deficiency disorders (CDDs), inborn errors of creatine metabolism and transport, comprise three disorders: the creatine biosynthesis disorders guanidinoacetate methyltransferase (GAMT) deficiency and L-arginine:glycine amidinotransferase (AGAT) deficiency; and creatine transporter (CRTR) deficiency. Developmental delay and cognitive dysfunction or intellectual disability and speech-language disorder are common to all three CDDs. Onset of clinical manifestations of GAMT deficiency (reported in ~130 individuals) is between ages three months and two years; in addition to developmental delays, the majority of individuals have epilepsy and develop a behavior disorder (e.g., hyperactivity, autism, or self-injurious behavior), and about 30% have movement disorder. AGAT deficiency has been reported in 16 individuals; none have had epilepsy or movement disorders. Clinical findings of CRTR deficiency in affected males (reported in ~130 individuals) in addition to developmental delays include epilepsy (variable seizure types and may be intractable) and behavior disorders (e.g., attention deficit and/or hyperactivity, autistic features, impulsivity, social anxiety), hypotonia, and (less commonly) a movement disorder. Poor weight gain with constipation and prolonged QTc on EKG have been reported. While mild-to-moderate intellectual disability is commonly observed up to age four years, the majority of adult males with CRTR deficiency have been reported to have severe intellectual disability. Females heterozygous for CRTR deficiency are typically either asymptomatic or have mild intellectual disability, although a more severe phenotype resembling the male phenotype has been reported.
3-Methylglutaconic aciduria type 3
MedGen UID:
108273
Concept ID:
C0574084
Disease or Syndrome
Costeff syndrome is characterized by optic atrophy and/or choreoathetoid movement disorder with onset before age ten years. Optic atrophy is associated with progressive decrease in visual acuity within the first years of life, sometimes associated with infantile-onset horizontal nystagmus. Most individuals have chorea, often severe enough to restrict ambulation. Some are confined to a wheelchair from an early age. Although most individuals develop spastic paraparesis, mild ataxia, and occasional mild cognitive deficit in their second decade, the course of the disease is relatively stable.
Cockayne syndrome type 2
MedGen UID:
155487
Concept ID:
C0751038
Disease or Syndrome
Cockayne syndrome (referred to as CS in this GeneReview) spans a continuous phenotypic spectrum that includes: CS type I, the "classic" or "moderate" form; CS type II, a more severe form with symptoms present at birth; this form overlaps with cerebrooculofacioskeletal (COFS) syndrome; CS type III, a milder and later-onset form; COFS syndrome, a fetal form of CS. CS type I is characterized by normal prenatal growth with the onset of growth and developmental abnormalities in the first two years. By the time the disease has become fully manifest, height, weight, and head circumference are far below the fifth percentile. Progressive impairment of vision, hearing, and central and peripheral nervous system function leads to severe disability; death typically occurs in the first or second decade. CS type II is characterized by growth failure at birth, with little or no postnatal neurologic development. Congenital cataracts or other structural anomalies of the eye may be present. Affected children have early postnatal contractures of the spine (kyphosis, scoliosis) and joints. Death usually occurs by age five years. CS type III is a phenotype in which major clinical features associated with CS only become apparent after age two years; growth and/or cognition exceeds the expectations for CS type I. COFS syndrome is characterized by very severe prenatal developmental anomalies (arthrogryposis and microphthalmia).
Cockayne syndrome type 1
MedGen UID:
155488
Concept ID:
C0751039
Disease or Syndrome
Cockayne syndrome (referred to as CS in this GeneReview) spans a continuous phenotypic spectrum that includes: CS type I, the "classic" or "moderate" form; CS type II, a more severe form with symptoms present at birth; this form overlaps with cerebrooculofacioskeletal (COFS) syndrome; CS type III, a milder and later-onset form; COFS syndrome, a fetal form of CS. CS type I is characterized by normal prenatal growth with the onset of growth and developmental abnormalities in the first two years. By the time the disease has become fully manifest, height, weight, and head circumference are far below the fifth percentile. Progressive impairment of vision, hearing, and central and peripheral nervous system function leads to severe disability; death typically occurs in the first or second decade. CS type II is characterized by growth failure at birth, with little or no postnatal neurologic development. Congenital cataracts or other structural anomalies of the eye may be present. Affected children have early postnatal contractures of the spine (kyphosis, scoliosis) and joints. Death usually occurs by age five years. CS type III is a phenotype in which major clinical features associated with CS only become apparent after age two years; growth and/or cognition exceeds the expectations for CS type I. COFS syndrome is characterized by very severe prenatal developmental anomalies (arthrogryposis and microphthalmia).
Severe myoclonic epilepsy in infancy
MedGen UID:
148243
Concept ID:
C0751122
Disease or Syndrome
SCN1A seizure disorders encompass a spectrum that ranges from simple febrile seizures and generalized epilepsy with febrile seizures plus (GEFS+) at the mild end to Dravet syndrome and intractable childhood epilepsy with generalized tonic-clonic seizures (ICE-GTC) at the severe end. Phenotypes with intractable seizures including Dravet syndrome are often associated with cognitive decline. Less commonly observed phenotypes include myoclonic astatic epilepsy (MAE), Lennox-Gastaut syndrome, infantile spasms, epilepsy with focal seizures, and vaccine-related encephalopathy and seizures. The phenotype of SCN1A seizure disorders can vary even within the same family.
Dentatorubral-pallidoluysian atrophy
MedGen UID:
155630
Concept ID:
C0751781
Disease or Syndrome
Dentatorubral-pallidoluysian atrophy (DRPLA) is a progressive disorder of ataxia, myoclonus, epilepsy, and progressive intellectual deterioration in children and ataxia, choreoathetosis, and dementia or character changes in adults. Onset ranges from before age one year to age 72 years; mean age of onset is 31.5 years. The clinical presentation varies depending on the age of onset. The cardinal features in adults are ataxia, choreoathetosis, and dementia. Cardinal features in children are progressive intellectual deterioration, behavioral changes, myoclonus, and epilepsy.
Unverricht-Lundborg syndrome
MedGen UID:
155923
Concept ID:
C0751785
Disease or Syndrome
Progressive myoclonic epilepsy type 1(EPM1) is a neurodegenerative disorder characterized by onset from age six to 15 years, stimulus-sensitive myoclonus, and tonic-clonic epileptic seizures. Some years after the onset, ataxia, incoordination, intentional tremor, and dysarthria develop. Individuals with EPM1 are cognitively mostly within the normal range, but show emotional lability and depression. The epileptic seizures are usually well controlled by anti-seizure medication, but the myoclonic jerks are progressive, action activated, and treatment resistant, and can be severely disabling.
Spinocerebellar ataxia type 2
MedGen UID:
155704
Concept ID:
C0752121
Disease or Syndrome
Spinocerebellar ataxia type 2 (SCA2) is characterized by progressive cerebellar ataxia, including nystagmus, slow saccadic eye movements, and in some individuals, ophthalmoparesis or parkinsonism. Pyramidal findings are present; deep tendon reflexes are brisk early on and absent later in the course. Age of onset is typically in the fourth decade with a ten- to 15-year disease duration.
Spinocerebellar ataxia type 5
MedGen UID:
155705
Concept ID:
C0752123
Disease or Syndrome
For a general discussion of autosomal dominant spinocerebellar ataxia (SCA), see SCA1 (164400).
Spinocerebellar ataxia type 6
MedGen UID:
148458
Concept ID:
C0752124
Disease or Syndrome
Spinocerebellar ataxia type 6 (SCA6) is characterized by adult-onset, slowly progressive cerebellar ataxia, dysarthria, and nystagmus. The age of onset ranges from 19 to 73 years; mean age of onset is between 43 and 52 years. Initial symptoms are gait unsteadiness, stumbling, and imbalance (in ~90%) and dysarthria (in ~10%). Eventually all persons have gait ataxia, upper-limb incoordination, intention tremor, and dysarthria. Dysphagia and choking are common. Visual disturbances may result from diplopia, difficulty fixating on moving objects, horizontal gaze-evoked nystagmus, and vertical nystagmus. Hyperreflexia and extensor plantar responses occur in up to 40%-50%. Basal ganglia signs, including dystonia and blepharospasm, occur in up to 25%. Mentation is generally preserved.
Allan-Herndon-Dudley syndrome
MedGen UID:
208645
Concept ID:
C0795889
Disease or Syndrome
Allan-Herndon-Dudley syndrome (AHDS), an X-linked disorder, is characterized in males by neurologic findings (hypotonia and feeding difficulties in infancy, developmental delay / intellectual disability ranging from mild to profound) and later-onset pyramidal signs, extrapyramidal findings (dystonia, choreoathetosis, paroxysmal movement disorder, hypokinesia, masked facies), and seizures, often with drug resistance. Additional findings can include dysthyroidism (manifest as poor weight gain, reduced muscle mass, and variable cold intolerance, sweating, elevated heart rate, and irritability) and pathognomonic thyroid test results. Most heterozygous females are not clinically affected but may have minor thyroid test abnormalities.
Gomez Lopez Hernandez syndrome
MedGen UID:
163201
Concept ID:
C0795959
Disease or Syndrome
Gomez-Lopez-Hernandez syndrome (GLHS), also known as cerebellotrigeminal dermal dysplasia, is a rare neurocutaneous syndrome classically characterized by the triad of rhombencephalosynapsis, trigeminal anesthesia, often giving rise to corneal opacities, and bilateral parietal or parietooccipital alopecia. However, trigeminal anesthesia is an inconsistent finding (summary by Sukhudyan et al., 2010).
Arts syndrome
MedGen UID:
163205
Concept ID:
C0796028
Disease or Syndrome
Arts syndrome, which is part of the spectrum of PRPS1-related disorders, is characterized by profound congenital sensorineural hearing impairment, early-onset hypotonia, delayed motor development, mild to moderate intellectual disability, ataxia, and increased risk of infection, all of which – with the exception of optic atrophy – present before age two years. Signs of peripheral neuropathy develop during early childhood. Twelve of 15 boys from the two Dutch families reported with Arts syndrome died before age six years of complications of infection. Carrier females can show late-onset (age >20 years) hearing impairment and other findings.
Ataxia - deafness - intellectual disability syndrome
MedGen UID:
208659
Concept ID:
C0796045
Disease or Syndrome
A rare genetic syndromic intellectual disability characterized by global developmental delay, intellectual disability, infantile or childhood onset of progressive ataxia, and bilateral sensorineural hearing impairment. Variable features include signs of upper and lower motor neuron disease, peripheral neuropathy, myopathic facies, lower limb muscle wasting, and heel contractures. There have been no further descriptions in the literature since 1993.
Myhre syndrome
MedGen UID:
167103
Concept ID:
C0796081
Disease or Syndrome
Myhre syndrome is a connective tissue disorder with multisystem involvement, progressive and proliferative fibrosis that may occur spontaneously or following trauma or surgery, mild-to-moderate intellectual disability, and in some instances, autistic-like behaviors. Organ systems primarily involved include: cardiovascular (congenital heart defects, long- and short-segment stenosis of the aorta and peripheral arteries, pericardial effusion, constrictive pericarditis, restrictive cardiomyopathy, and hypertension); respiratory (choanal stenosis, laryngotracheal narrowing, obstructive airway disease, or restrictive pulmonary disease), gastrointestinal (pyloric stenosis, duodenal strictures, severe constipation); and skin (thickened particularly on the hands and extensor surfaces). Additional findings include distinctive craniofacial features and skeletal involvement (intrauterine growth restriction, short stature, limited joint range of motion). To date, 55 individuals with molecularly confirmed Myhre syndrome have been reported.
Megalocornea-intellectual disability syndrome
MedGen UID:
162904
Concept ID:
C0796086
Disease or Syndrome
The cardinal findings of Neuhauser syndrome, also known as MMR syndrome, are impaired intellectual development or developmental delay, megalocornea, hypotonia, prominent forehead, micrognathia, prominent nasal bridge, and thin upper lip or carp-like mouth (Naritomi et al., 1997). Reviews Gutierrez-Amavizca et al. (2013) reviewed published reports and tabulated the clinical features of 35 patients with Neuhauser syndrome. Primary megalocornea and psychomotor delay were present in all patients. Characteristics observed in more than half of patients included hypotonia, growth retardation, abnormal electroencephalography (EEG) and/or seizures, micro- or macrocephaly, brain malformations such as cerebral atrophy and hypoplastic corpus callosum, craniofacial dysmorphisms, cardiac anomalies, osteoarticular abnormalities, and refractive errors. Additional features found at low frequency included primary hypothyroidism, recurrent infections, feeding difficulties, cerebral hypomyelination, dyslipidemia, sensorineural deafness, laryngomalacia, large fleshy and cup-shaped ears, obesity, and cryptorchidism. The authors stated that the classification suggested by Verloes et al. (1993) did not seem to be applicable, and proposed that the diagnosis of Neuhauser syndrome should be made in the presence of intellectual disability and megalocornea in the absence of elevated intraocular pressure, with at least 1 minor feature from among those observed in more than half of patients.
Primrose syndrome
MedGen UID:
162911
Concept ID:
C0796121
Disease or Syndrome
Primrose syndrome is characterized by macrocephaly, hypotonia, developmental delay, intellectual disability with expressive speech delay, behavioral issues, a recognizable facial phenotype, radiographic features, and altered glucose metabolism. Additional features seen in adults: sparse body hair, distal muscle wasting, and contractures. Characteristic craniofacial features include brachycephaly, high anterior hairline, deeply set eyes, ptosis, downslanted palpebral fissures, high palate with torus palatinus, broad jaw, and large ears with small or absent lobes. Radiographic features include calcification of the external ear cartilage, multiple Wormian bones, platybasia, bathrocephaly, slender bones with exaggerated metaphyseal flaring, mild epiphyseal dysplasia, and spondylar dysplasia. Additional features include hearing impairment, ocular anomalies, cryptorchidism, and nonspecific findings on brain MRI.
Cataract-ataxia-deafness syndrome
MedGen UID:
163216
Concept ID:
C0796123
Disease or Syndrome
A rare genetic disease characterized by mild intellectual deficit, congenital cataract, progressive sensorineural hearing impairment, ataxia, peripheral neuropathy, and short stature. There have been no further descriptions in the literature since 1991.
X-linked progressive cerebellar ataxia
MedGen UID:
163229
Concept ID:
C0796205
Disease or Syndrome
SCAX1 is an X-linked recessive neurologic disorder characterized by hypotonia at birth, delayed motor development, gait ataxia, difficulty standing, dysarthria, and slow eye movements. Brain MRI shows cerebellar ataxia (summary by Bertini et al., 2000). Genetic Heterogeneity of X-linked Spinocerebellar Ataxia X-linked recessive spinocerebellar ataxia (SCAX) is a clinically and genetically heterogeneous disorder. See also SCAX2 (302600), SCAX3 (301790), SCAX4 (301840), and SCAX5 (300703).
X-linked intellectual disability-psychosis-macroorchidism syndrome
MedGen UID:
163232
Concept ID:
C0796222
Disease or Syndrome
The spectrum of MECP2-related phenotypes in females ranges from classic Rett syndrome to variant Rett syndrome with a broader clinical phenotype (either milder or more severe than classic Rett syndrome) to mild learning disabilities; the spectrum in males ranges from severe neonatal encephalopathy to pyramidal signs, parkinsonism, and macroorchidism (PPM-X) syndrome to severe syndromic/nonsyndromic intellectual disability. Females: Classic Rett syndrome, a progressive neurodevelopmental disorder primarily affecting girls, is characterized by apparently normal psychomotor development during the first six to 18 months of life, followed by a short period of developmental stagnation, then rapid regression in language and motor skills, followed by long-term stability. During the phase of rapid regression, repetitive, stereotypic hand movements replace purposeful hand use. Additional findings include fits of screaming and inconsolable crying, autistic features, panic-like attacks, bruxism, episodic apnea and/or hyperpnea, gait ataxia and apraxia, tremors, seizures, and acquired microcephaly. Males: Severe neonatal-onset encephalopathy, the most common phenotype in affected males, is characterized by a relentless clinical course that follows a metabolic-degenerative type of pattern, abnormal tone, involuntary movements, severe seizures, and breathing abnormalities. Death often occurs before age two years.
Brown-Vialetto-van Laere syndrome 1
MedGen UID:
163239
Concept ID:
C0796274
Disease or Syndrome
Brown-Vialetto-Van Laere syndrome is a rare autosomal recessive neurologic disorder characterized by sensorineural hearing loss and a variety of cranial nerve palsies, usually involving the motor components of the seventh and ninth to twelfth (more rarely the third, fifth, and sixth) cranial nerves. Spinal motor nerves and, less commonly, upper motor neurons are sometimes affected, giving a picture resembling amyotrophic lateral sclerosis (ALS; 105400). The onset of the disease is usually in the second decade, but earlier and later onset have been reported. Hearing loss tends to precede the onset of neurologic signs, mostly progressive muscle weakness causing respiratory compromise. However, patients with very early onset may present with bulbar palsy and may not develop hearing loss until later. The symptoms, severity, and disease duration are variable (summary by Green et al., 2010). Genetic Heterogeneity of Brown-Vialetto-Van Laere Syndrome See also BVVLS2 (614707), caused by mutation in the SLC52A2 gene (607882) on chromosome 8q.
Oculodentodigital dysplasia
MedGen UID:
167236
Concept ID:
C0812437
Congenital Abnormality
Oculodentodigital syndrome is characterized by a typical facial appearance and variable involvement of the eyes, dentition, and fingers. Characteristic facial features include a narrow, pinched nose with hypoplastic alae nasi, prominent columella and thin anteverted nares together with a narrow nasal bridge, and prominent epicanthic folds giving the impression of hypertelorism. The teeth are usually small and carious. Typical eye findings include microphthalmia and microcornea. The characteristic digital malformation is complete syndactyly of the fourth and fifth fingers (syndactyly type III) but the third finger may be involved and associated camptodactyly is a common finding (summary by Judisch et al., 1979). Neurologic abnormalities are sometimes associated (Gutmann et al., 1991), and lymphedema has been reported in some patients with ODDD (Brice et al., 2013). See review by De Bock et al. (2013). Genetic Heterogeneity of Oculodentodigital Syndrome An autosomal recessive form of ODDD (257850) is also caused by mutation in the GJA1 gene, but the majority of cases are autosomal dominant.
6-Pyruvoyl-tetrahydrobiopterin synthase deficiency
MedGen UID:
209234
Concept ID:
C0878676
Disease or Syndrome
Tetrahydrobiopterin (BH4)-deficient hyperphenylalaninemia (HPA) comprises a genetically heterogeneous group of progressive neurologic disorders caused by autosomal recessive mutations in the genes encoding enzymes involved in the synthesis or regeneration of BH4. BH4 is a cofactor for phenylalanine hydroxylase (PAH; 612349), tyrosine hydroxylase (TH; 191290) and tryptophan hydroxylase (TPH1; 191060), the latter 2 of which are involved in neurotransmitter synthesis. The BH4-deficient HPAs are characterized phenotypically by hyperphenylalaninemia, depletion of the neurotransmitters dopamine and serotonin, and progressive cognitive and motor deficits (Dudesek et al., 2001). HPABH4A, caused by mutations in the PTS gene, represents the most common cause of BH4-deficient hyperphenylalaninemia (Dudesek et al., 2001). Other forms of BH4-deficient HPA include HPABH4B (233910), caused by mutation in the GCH1 gene (600225), HPABH4C (261630), caused by mutation in the QDPR gene (612676), and HPABH4D (264070), caused by mutation in the PCBD1 gene (126090). Niederwieser et al. (1982) noted that about 1 to 3% of patients with hyperphenylalaninemia have one of these BH4-deficient forms. These disorders are clinically and genetically distinct from classic phenylketonuria (PKU; 261600), caused by mutation in the PAH gene. Two additional disorders associated with BH4 deficiency and neurologic symptoms do not have overt hyperphenylalaninemia as a feature: dopa-responsive dystonia (612716), caused by mutation in the SPR gene (182125), and autosomal dominant dopa-responsive dystonia (DYT5; 128230), caused by mutation in the GCH1 gene. Patients with these disorders may develop hyperphenylalaninemia when stressed.
Deficiency of ferroxidase
MedGen UID:
168057
Concept ID:
C0878682
Disease or Syndrome
Aceruloplasminemia is characterized by iron accumulation in the brain and viscera. The clinical triad of retinal degeneration, diabetes mellitus (DM), and neurologic disease is seen in individuals ranging from age 30 years to older than 70 years. The neurologic findings of movement disorder (blepharospasm, grimacing, facial and neck dystonia, tremors, chorea) and ataxia (gait ataxia, dysarthria) correspond to regions of iron deposition in the brain. Individuals with aceruloplasminemia often present with anemia prior to onset of DM or obvious neurologic problems. Cognitive dysfunction including apathy and forgetfulness occurs in more than half of individuals with this condition.
Leber optic atrophy
MedGen UID:
182973
Concept ID:
C0917796
Disease or Syndrome
Leber hereditary optic neuropathy (LHON) typically presents in young adults as bilateral, painless, subacute visual failure. The peak age of onset in LHON is in the second and third decades of life, with 90% of those who lose their vision doing so before age 50 years. Very rarely, individuals first manifest LHON in the seventh and eighth decades of life. Males are four to five times more likely to be affected than females, but neither sex nor mutational status significantly influences the timing and severity of the initial visual loss. Neurologic abnormalities such as postural tremor, peripheral neuropathy, nonspecific myopathy, and movement disorders have been reported to be more common in individuals with LHON than in the general population. Some individuals with LHON, usually women, may also develop a multiple sclerosis-like illness.
Familial infantile myoclonic epilepsy
MedGen UID:
181488
Concept ID:
C0917800
Disease or Syndrome
TBC1D24-related disorders comprise a continuum of features that were originally described as distinct, recognized phenotypes: DOORS syndrome (deafness, onychodystrophy, osteodystrophy, mental retardation, and seizures). Profound sensorineural hearing loss, onychodystrophy, osteodystrophy, intellectual disability / developmental delay, and seizures. Familial infantile myoclonic epilepsy (FIME). Early-onset myoclonic seizures, focal epilepsy, dysarthria, and mild-to-moderate intellectual disability. Progressive myoclonus epilepsy (PME). Action myoclonus, tonic-clonic seizures, progressive neurologic decline, and ataxia. Early-infantile epileptic encephalopathy 16 (EIEE16). Epileptiform EEG abnormalities which themselves are believed to contribute to progressive disturbance in cerebral function. Autosomal recessive nonsyndromic hearing loss, DFNB86. Profound prelingual deafness. Autosomal dominant nonsyndromic hearing loss, DFNA65. Slowly progressive deafness with onset in the third decade, initially affecting the high frequencies.
Salla disease
MedGen UID:
203368
Concept ID:
C1096903
Disease or Syndrome
Free sialic acid storage disorders (FSASDs) are a spectrum of neurodegenerative disorders resulting from increased lysosomal storage of free sialic acid. Historically, FSASD was divided into separate allelic disorders: Salla disease, intermediate severe Salla disease, and infantile free sialic acid storage disease (ISSD). The mildest type was Salla disease, characterized by normal appearance and absence of neurologic findings at birth, followed by slowly progressive neurologic deterioration resulting in mild-to-moderate psychomotor delays, spasticity, athetosis, and epileptic seizures. Salla disease was named for a municipality in Finnish Lapland where a specific founder variant is relatively prevalent. However, the term Salla has been used in the literature to refer to less severe FSASD. More severe FSASD is historically referred to as ISSD, and is characterized by severe developmental delay, coarse facial features, hepatosplenomegaly, and cardiomegaly; death usually occurs in early childhood.
Dyskeratosis congenita, X-linked
MedGen UID:
216941
Concept ID:
C1148551
Disease or Syndrome
Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres. The phenotypic spectrum of telomere biology disorders is broad and includes individuals with classic dyskeratosis congenita (DC) as well as those with very short telomeres and an isolated physical finding. Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia, although this may not be present in all individuals. People with DC/TBD are at increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis. Other findings can include eye abnormalities (epiphora, blepharitis, sparse eyelashes, ectropion, entropion, trichiasis), taurodontism, liver disease, gastrointestinal telangiectasias, and avascular necrosis of the hips or shoulders. Although most persons with DC/TBD have normal psychomotor development and normal neurologic function, significant developmental delay is present in both forms; additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome) and bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome and Coats plus syndrome). Onset and progression of manifestations of DC/TBD vary: at the mild end of the spectrum are those who have only minimal physical findings with normal bone marrow function, and at the severe end are those who have the diagnostic triad and early-onset BMF.
Ichthyosis, cerebellar degeneration and hepatosplenomegaly
MedGen UID:
266150
Concept ID:
C1275088
Disease or Syndrome
Ichthyosis-hepatosplenomegaly-cerebellar degeneration syndrome is characterised by ichthyosis, hepatosplenomegaly and late-onset cerebellar ataxia. It has been described in two brothers. Transmission is either autosomal recessive or X-linked.
Deficiency of ribose-5-phosphate isomerase
MedGen UID:
220946
Concept ID:
C1291609
Disease or Syndrome
Ribose-5-P isomerase deficiency is an extremely rare, hereditary, disorder of pentose phosphate metabolism characterized by progressive leukoencephalopathy and a highly increased ribitol and D-arabitol levels in the brain and body fluids. Clinical presentation includes psychomotor delay, epilepsy, and childhood-onset slow neurological regression with ataxia, spasticity, optic atrophy and sensorimotor neuropathy.
Revesz syndrome
MedGen UID:
231230
Concept ID:
C1327916
Disease or Syndrome
Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres. The phenotypic spectrum of telomere biology disorders is broad and includes individuals with classic dyskeratosis congenita (DC) as well as those with very short telomeres and an isolated physical finding. Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia, although this may not be present in all individuals. People with DC/TBD are at increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis. Other findings can include eye abnormalities (epiphora, blepharitis, sparse eyelashes, ectropion, entropion, trichiasis), taurodontism, liver disease, gastrointestinal telangiectasias, and avascular necrosis of the hips or shoulders. Although most persons with DC/TBD have normal psychomotor development and normal neurologic function, significant developmental delay is present in both forms; additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome) and bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome and Coats plus syndrome). Onset and progression of manifestations of DC/TBD vary: at the mild end of the spectrum are those who have only minimal physical findings with normal bone marrow function, and at the severe end are those who have the diagnostic triad and early-onset BMF.
Ataxia-pancytopenia syndrome
MedGen UID:
230896
Concept ID:
C1327919
Disease or Syndrome
SAMD9L ataxia-pancytopenia (ATXPC) syndrome is characterized by cerebellar ataxia, variable hematologic cytopenias, and predisposition to marrow failure, myelodysplasia, and myeloid leukemia, sometimes associated with monosomy 7. The onset of hematologic abnormalities has been reported as early as age three months. The cytopenias in all cell lineages range from mild to very severe. Onset of neurologic impairment is variable. Nystagmus, dysmetria, increased deep tendon reflexes, and clonus are common. Gait impairment and other neurologic abnormalities are slowly progressive.
NARP syndrome
MedGen UID:
231285
Concept ID:
C1328349
Disease or Syndrome
Mitochondrial DNA (mtDNA)-associated Leigh syndrome and NARP (neurogenic muscle weakness, ataxia, and retinitis pigmentosa) are part of a continuum of progressive neurodegenerative disorders caused by abnormalities of mitochondrial energy generation. Leigh syndrome (or subacute necrotizing encephalomyelopathy) is characterized by onset of symptoms typically between ages three and 12 months, often following a viral infection. Decompensation (often with elevated lactate levels in blood and/or CSF) during an intercurrent illness is typically associated with psychomotor retardation or regression. Neurologic features include hypotonia, spasticity, movement disorders (including chorea), cerebellar ataxia, and peripheral neuropathy. Extraneurologic manifestations may include hypertrophic cardiomyopathy. About 50% of affected individuals die by age three years, most often as a result of respiratory or cardiac failure. NARP is characterized by proximal neurogenic muscle weakness with sensory neuropathy, ataxia, and pigmentary retinopathy. Onset of symptoms, particularly ataxia and learning difficulties, is often in early childhood. Individuals with NARP can be relatively stable for many years, but may suffer episodic deterioration, often in association with viral illnesses.
Hypogonadotropic hypogonadism 1 with or without anosmia
MedGen UID:
295872
Concept ID:
C1563719
Disease or Syndrome
Isolated gonadotropin-releasing hormone (GnRH) deficiency (IGD) is characterized by inappropriately low serum concentrations of the gonadotropins LH (luteinizing hormone) and FSH (follicle-stimulating hormone) in the presence of low circulating concentrations of sex steroids. IGD is associated with a normal sense of smell (normosmic IGD) in approximately 40% of affected individuals and an impaired sense of smell (Kallmann syndrome) in approximately 60%. IGD can first become apparent in infancy, adolescence, or adulthood. Infant boys with congenital IGD often have micropenis and cryptorchidism. Adolescents and adults with IGD have clinical evidence of hypogonadism and incomplete sexual maturation on physical examination. Adult males with IGD tend to have prepubertal testicular volume (i.e., <4 mL), absence of secondary sexual features (e.g., facial and axillary hair growth, deepening of the voice), decreased muscle mass, diminished libido, erectile dysfunction, and infertility. Adult females have little or no breast development and primary amenorrhea. Although skeletal maturation is delayed, the rate of linear growth is usually normal except for the absence of a distinct pubertal growth spurt.
Cerebellar ataxia-areflexia-pes cavus-optic atrophy-sensorineural hearing loss syndrome
MedGen UID:
318633
Concept ID:
C1832466
Disease or Syndrome
ATP1A3-related neurologic disorders represent a clinical continuum in which at least three distinct phenotypes have been delineated: rapid-onset dystonia-parkinsonism (RDP); alternating hemiplegia of childhood (ACH); and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS). However, some affected individuals have intermediate phenotypes or only a few features that do not fit well into one of these major phenotypes. RDP has been characterized by: abrupt onset of dystonia over days to weeks with parkinsonism (primarily bradykinesia and postural instability); common bulbar involvement; and absence or minimal response to an adequate trial of L-dopa therapy, with few exceptions. Often fever, physiologic stress, or alcoholic binges trigger the onset of symptoms. After their initial appearance, symptoms often stabilize with little improvement; occasionally second episodes occur with abrupt worsening of symptoms. Rarely, affected individuals have reported a more gradual onset of symptoms over weeks to months. Anxiety, depression, and seizures have been reported. Age of onset ranges from four to 55 years, although a childhood variation of RDP with onset between ages nine and 14 months has been reported. AHC is a complex neurodevelopmental syndrome most frequently manifesting in infancy or early childhood with paroxysmal episodic neurologic dysfunction including alternating hemiparesis or dystonia, quadriparesis, seizure-like episodes, and oculomotor abnormalities. Episodes can last for minutes, hours, days, or even weeks. Remission of symptoms occurs with sleep and immediately after awakening. Over time, persistent neurologic deficits including oculomotor apraxia, ataxia, choreoathetosis, dystonia, parkinsonism, and cognitive and behavioral dysfunction develop in the majority of those affected; more than 50% develop epilepsy in addition to their episodic movement disorder phenotype. CAPOS (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss) syndrome is characterized by episodes of ataxic encephalopathy and/or weakness during and after a febrile illness. Onset is between ages six months and four years. Some acute symptoms resolve; progression of sensory losses and severity vary.
Cayman type cerebellar ataxia
MedGen UID:
331319
Concept ID:
C1832585
Disease or Syndrome
Cayman cerebellar ataxia (ATCAY) is an autosomal recessive neurologic disorder characterized by hypotonia from birth, variable psychomotor retardation, and cerebellar dysfunction, including nystagmus, intention tremor, dysarthria, ataxic gait, and truncal ataxia. Although the disorder was initially believed to be restricted to an isolated region of Grand Cayman Island (summary by Nystuen et al., 1996; Bomar et al., 2003), one Pakistani family with the disorder and an ATCAY mutation has been reported, thus expanding the ethnic distribution (Manzoor et al., 2018).
Migraine, familial hemiplegic, 1
MedGen UID:
331388
Concept ID:
C1832884
Disease or Syndrome
Familial hemiplegic migraine (FHM) falls within the category of migraine with aura. In migraine with aura (including FHM) the neurologic symptoms of aura are unequivocally localizable to the cerebral cortex or brain stem and include visual disturbance (most common), sensory loss (e.g., numbness or paresthesias of the face or an extremity), and dysphasia (difficulty with speech). FHM must include motor involvement, such as hemiparesis (weakness of an extremity). Hemiparesis occurs with at least one other symptom during FHM aura. Neurologic deficits with FHM attacks can be prolonged for hours to days and may outlast the associated migrainous headache. FHM is often earlier in onset than typical migraine, frequently beginning in the first or second decade; the frequency of attacks tends to decrease with age. Approximately 40%-50% of families with CACNA1A-FHM have cerebellar signs ranging from nystagmus to progressive, usually late-onset mild ataxia.
Nystagmus, hereditary vertical
MedGen UID:
322336
Concept ID:
C1834078
Disease or Syndrome
Ceroid lipofuscinosis, neuronal, 4 (Kufs type)
MedGen UID:
320287
Concept ID:
C1834207
Disease or Syndrome
Neuronal ceroid lipofuscinosis-4 (CLN4) is an autosomal dominant neurodegenerative disorder characterized by onset of symptoms in adulthood. It belongs to a group of progressive neurodegenerative diseases characterized by accumulation of intracellular autofluorescent lipopigment storage material in the brain and other tissues. Several different forms have been described according to age of onset (see, e.g., CLN3, 204200). Individuals with the adult form, sometimes referred to as Kufs disease, develop psychiatric manifestations, seizures, cerebellar ataxia, and cognitive decline. Retinal degeneration is usually not present (summary by Benitez et al., 2011 and Velinov et al., 2012). For a general phenotypic description and a discussion of genetic heterogeneity of CLN, see CLN1 (256730).
Myoclonus-cerebellar ataxia-deafness syndrome
MedGen UID:
331780
Concept ID:
C1834579
Disease or Syndrome
This syndrome is characterised by the association of myoclonus, cerebellar ataxia and sensorineural hearing loss.
Autosomal recessive spinocerebellar ataxia 7
MedGen UID:
324520
Concept ID:
C1836474
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia is a neurologic disorder characterized by onset of progressive gait difficulties, eye movement abnormalities, and dysarthria in the first or second decade of life (summary by Dy et al., 2015).
Hereditary spastic paraplegia 26
MedGen UID:
373138
Concept ID:
C1836632
Disease or Syndrome
SPG26 is an autosomal recessive form of complicated spastic paraplegia characterized by onset in the first 2 decades of life of gait abnormalities due to lower limb spasticity and muscle weakness. Some patients have upper limb involvement. Additional features include intellectual disability, peripheral neuropathy, dysarthria, cerebellar signs, extrapyramidal signs, and cortical atrophy. The disorder is slowly progressive (summary by Boukhris et al., 2013). For a discussion of genetic heterogeneity of autosomal recessive SPG, see SPG5A (270800).
MPDU1-congenital disorder of glycosylation
MedGen UID:
322968
Concept ID:
C1836669
Disease or Syndrome
Congenital disorders of glycosylation (CDGs) are metabolic deficiencies in glycoprotein biosynthesis that usually cause severe mental and psychomotor retardation. Different forms of CDGs can be recognized by altered isoelectric focusing (IEF) patterns of serum transferrin. For a general discussion of CDGs, see CDG Ia (212065) and CDG Ib (602579).
PCWH syndrome
MedGen UID:
373160
Concept ID:
C1836727
Disease or Syndrome
PCWH syndrome is a complex neurocristopathy that includes features of 4 distinct syndromes: peripheral demyelinating neuropathy (see 118200), central dysmyelination, Waardenburg syndrome, and Hirschsprung disease (see 142623) (Inoue et al., 2004). Inoue et al. (2004) proposed the acronym PCWH for this disorder.
Neuronal ceroid lipofuscinosis 9
MedGen UID:
332304
Concept ID:
C1836841
Disease or Syndrome
The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The clinical course includes progressive dementia, seizures, and progressive visual failure (Mole et al., 2005). For a discussion of genetic heterogeneity of neuronal ceroid lipofuscinosis, see CLN1 (256730).
Posterior column ataxia-retinitis pigmentosa syndrome
MedGen UID:
324636
Concept ID:
C1836916
Disease or Syndrome
Posterior column ataxia with retinitis pigmentosa (AXPC1) is an autosomal recessive neurologic disorder characterized by childhood-onset retinitis pigmentosa and later onset of gait ataxia due to sensory loss (summary by Ishiura et al., 2011).
Hereditary cryohydrocytosis with reduced stomatin
MedGen UID:
332390
Concept ID:
C1837206
Disease or Syndrome
Stomatin-deficient cryohydrocytosis with neurologic defects is an autosomal dominant disorder characterized by delayed psychomotor development, seizures, cataracts, and pseudohyperkalemia resulting from defects in the red blood cell membrane. The disorder combines the neurologic features of Glut1 deficiency syndrome-1 (GLUT1DS1; 606777), resulting from impaired glucose transport at the blood-brain barrier, and hemolytic anemia/pseudohyperkalemia with stomatocytosis, resulting from a cation leak in erythrocytes (summary by Bawazir et al., 2012). For a discussion of clinical and genetic heterogeneity of red cell stomatocyte disorders, see 194380.
Hypomyelinating leukodystrophy 2
MedGen UID:
325157
Concept ID:
C1837355
Disease or Syndrome
Pelizaeus-Merzbacher-like disease 1 (PMLD1) is a slowly progressive leukodystrophy that typically presents during the neonatal or early-infantile period with nystagmus, commonly associated with hypotonia, delayed acquisition of motor milestones, speech delay, and dysarthria. Over time the hypotonia typically evolves into spasticity that affects the ability to walk and communicate. Cerebellar signs (gait ataxia, dysmetria, intention tremor, head titubation, and dysdiadochokinesia) frequently manifest during childhood. Some individuals develop extrapyramidal movement abnormalities (choreoathetosis and dystonia). Hearing loss and optic atrophy are observed in rare cases. Motor impairments can lead to swallowing difficulty and orthopedic complications, including hip dislocation and scoliosis. Most individuals have normal cognitive skills or mild intellectual disability – which, however, can be difficult to evaluate in the context of profound motor impairment.
Congenital disorder of glycosylation type 1E
MedGen UID:
324784
Concept ID:
C1837396
Disease or Syndrome
Congenital disorders of glycosylation (CDGs) are metabolic deficiencies in glycoprotein biosynthesis that usually cause severe mental and psychomotor retardation. Different forms of CDGs can be recognized by altered isoelectric focusing (IEF) patterns of serum transferrin. For a general discussion of CDGs, see CDG Ia (212065) and CDG Ib (602579).
Spinocerebellar ataxia type 25
MedGen UID:
373347
Concept ID:
C1837518
Disease or Syndrome
Spinocerebellar ataxia-25 (SCA25) is an autosomal dominant neurologic disorder characterized by the onset of lower limb ataxia resulting in gait difficulties in the first few decades of life, although later onset has been reported. Affected individuals often have upper limb involvement, dysarthria, scoliosis, abnormal eye movements, and sensory neuropathy with decreased reflexes. Some patients have sensorineural hearing loss. Brain imaging shows cerebellar atrophy. There is incomplete penetrance and variable expressivity, even within families (Barbier et al., 2022). For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (164400).
Joubert syndrome 3
MedGen UID:
332931
Concept ID:
C1837713
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Neuronal ceroid lipofuscinosis 8
MedGen UID:
374004
Concept ID:
C1838570
Disease or Syndrome
The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The lipopigment patterns observed most often in CLN8 comprise mixed combinations of 'granular,' 'curvilinear,' and 'fingerprint' profiles (Mole et al., 2005). For a general phenotypic description and a discussion of genetic heterogeneity of CLN, see CLN1 (256730).
Neuronal ceroid lipofuscinosis 7
MedGen UID:
325457
Concept ID:
C1838571
Disease or Syndrome
The neuronal ceroid lipofuscinoses (NCL, or CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally (summary by Mole et al., 2005). For a general phenotypic description and a discussion of genetic heterogeneity of CLN, see CLN1 (256730).
CARASIL syndrome
MedGen UID:
325051
Concept ID:
C1838577
Disease or Syndrome
HTRA1 disorder is a phenotypic spectrum in which some individuals have few to no symptoms and others manifest with the more severe CARASIL (cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy) phenotype. Those who have a heterozygous HTRA1 pathogenic variant may have mild neurologic findings (sometimes identified only on neuroimaging) or mild-to-moderate neurologic signs and symptoms of CARASIL. In this chapter, the term "classic CARASIL" refers to the more severe phenotype associated with biallelic pathogenic variants, and "HTRA1 cerebral small vessel disease" (HTRA1-CSVD) refers to the milder phenotype associated with a heterozygous HTRA1 pathogenic variant. Classic CARASIL is characterized by early-onset changes in the deep white matter of the brain observed on MRI, and associated neurologic findings. The most frequent initial symptom is gait disturbance from spasticity beginning between ages 20 and 40 years. Forty-four percent of affected individuals have stroke-like episodes before age 40 years. Mood changes (apathy and irritability), pseudobulbar palsy, and cognitive dysfunction begin between ages 20 and 50 years. The disease progresses slowly following the onset of neurologic symptoms. Scalp alopecia and acute mid- to lower-back pain (lumbago) before age 30 years are characteristic. The most frequent initial symptom in individuals with HTRA1-CSVD is slowly progressive gait disturbance after age 40 years, which may be followed by the development of mood changes and cognitive dysfunction. A majority of affected individuals have a stroke-like episode after age 40 years. Spondylosis and alopecia are seen in a minority of individuals with HTRA1-CSVD.
Mitochondrial complex I deficiency
MedGen UID:
374101
Concept ID:
C1838979
Disease or Syndrome
Isolated complex I deficiency is a rare inborn error of metabolism due to mutations in nuclear or mitochondrial genes encoding subunits or assembly factors of the human mitochondrial complex I (NADH: ubiquinone oxidoreductase) and is characterized by a wide range of manifestations including marked and often fatal lactic acidosis, cardiomyopathy, leukoencephalopathy, pure myopathy and hepatopathy with tubulopathy. Among the numerous clinical phenotypes observed are Leigh syndrome, Leber hereditary optic neuropathy and MELAS syndrome (see these terms).
Mitochondrial myopathy with diabetes
MedGen UID:
333236
Concept ID:
C1839028
Disease or Syndrome
A rare, genetic, mitochondrial DNA-related mitochondrial myopathy disorder characterized by slowly progressive muscular weakness (proximal greater than distal), predominantly involving the facial muscles and scapular girdle, associated with insulin-dependent diabetes mellitus. Neurological involvement and congenital myopathy may be variably observed.
Kallmann syndrome with spastic paraplegia
MedGen UID:
333437
Concept ID:
C1839911
Disease or Syndrome
Childhood onset GLUT1 deficiency syndrome 2
MedGen UID:
330866
Concept ID:
C1842534
Disease or Syndrome
The phenotypic spectrum of glucose transporter type 1 deficiency syndrome (Glut1 DS) is now known to be a continuum that includes the classic phenotype as well as paroxysmal exercise-induced dyskinesia and epilepsy (previously known as dystonia 18 [DYT18]) and paroxysmal choreoathetosis with spasticity (previously known as dystonia 9 [DYT9]), atypical childhood absence epilepsy, myoclonic astatic epilepsy, and paroxysmal non-epileptic findings including intermittent ataxia, choreoathetosis, dystonia, and alternating hemiplegia. The classic phenotype is characterized by infantile-onset seizures, delayed neurologic development, acquired microcephaly, and complex movement disorders. Seizures in classic early-onset Glut1 DS begin before age six months. Several seizure types occur: generalized tonic or clonic, focal, myoclonic, atypical absence, atonic, and unclassified. In some infants, apneic episodes and abnormal episodic eye-head movements similar to opsoclonus may precede the onset of seizures. The frequency, severity, and type of seizures vary among affected individuals and are not related to disease severity. Cognitive impairment, ranging from learning disabilities to severe intellectual disability, is typical. The complex movement disorder, characterized by ataxia, dystonia, and chorea, may occur in any combination and may be continuous, paroxysmal, or continual with fluctuations in severity influenced by environmental factors such as fasting or with infectious stress. Symptoms often improve substantially when a ketogenic diet is started.
Joubert syndrome 2
MedGen UID:
334114
Concept ID:
C1842577
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Infantile-onset autosomal recessive nonprogressive cerebellar ataxia
MedGen UID:
334220
Concept ID:
C1842676
Disease or Syndrome
A rare genetic autosomal recessive cerebellar ataxia disease with characteristics of nonprogressive cerebellar ataxia, with onset in infancy, manifesting with delayed motor and speech development, gait ataxia, dysmetria, hypotonia, increased deep tendon reflexes and dysarthria. Additional variable manifestations include moderate nystagmus on lateral gaze, mild spasticity, intention tremor, short stature and pes planus. Brain imaging reveals cerebellar vermis atrophy.
Epilepsy, familial adult myoclonic, 2
MedGen UID:
375031
Concept ID:
C1842852
Disease or Syndrome
Familial adult myoclonic epilepsy-2 (FAME2) is an autosomal dominant neurologic disorder characterized by onset of tremor affecting the fingers, hand, and voice in adolescence or young adulthood with somewhat later onset of rhythmic myoclonic jerks and generalized tonic-clonic seizures. Electrophysiologic studies are consistent with cortical reflex myoclonus. Some patients may show cognitive decline or migraines; photosensitivity is common (summary by De Fusco et al., 2014; Crompton et al., 2012). For a phenotypic description and a discussion of genetic heterogeneity of familial adult myoclonic epilepsy, see FAME1 (601068).
Niemann-Pick disease, type C2
MedGen UID:
335942
Concept ID:
C1843366
Disease or Syndrome
Niemann-Pick disease type C (NPC) is a slowly progressive lysosomal disorder whose principal manifestations are age dependent. The manifestations in the perinatal period and infancy are predominantly visceral, with hepatosplenomegaly, jaundice, and (in some instances) pulmonary infiltrates. From late infancy onward, the presentation is dominated by neurologic manifestations. The youngest children may present with hypotonia and developmental delay, with the subsequent emergence of ataxia, dysarthria, dysphagia, and, in some individuals, epileptic seizures, dystonia, and gelastic cataplexy. Although cognitive impairment may be subtle at first, it eventually becomes apparent that affected individuals have a progressive dementia. Older teenagers and young adults may present predominantly with apparent early-onset dementia or psychiatric manifestations; however, careful examination usually identifies typical neurologic signs.
Pontocerebellar hypoplasia type 1A
MedGen UID:
335969
Concept ID:
C1843504
Disease or Syndrome
Pontocerebellar hypoplasia (PCH) refers to a group of severe neurodegenerative disorders affecting growth and function of the brainstem and cerebellum, resulting in little or no development. Different types were classified based on the clinical picture and the spectrum of pathologic changes. PCH type 1 is characterized by central and peripheral motor dysfunction associated with anterior horn cell degeneration resembling infantile spinal muscular atrophy (SMA; see SMA1, 253300); death usually occurs early. Genetic Heterogeneity of Pontocerebellar Hypoplasia Also see PCH1B (614678), caused by mutation in the EXOSC3 gene (606489); PCH1C (616081), caused by mutation in the EXOSC8 gene (606019); PCH1D (618065), caused by mutation in the EXOSC9 gene (606180); PCH1E (619303), caused by mutation in the SLC25A46 gene (610826); PCH1F (619304), caused by mutation in the EXOSC1 gene (606493); PCH2A (277470), caused by mutation in the TSEN54 gene (608755); PCH2B (612389), caused by mutation in the TSEN2 gene (608753); PCH2C (612390), caused by mutation in the TSEN34 gene (608754); PCH2D (613811), caused by mutation in the SEPSECS gene (613009); PCH3 (608027), caused by mutation in the PCLO gene (604918); PCH4 (225753), caused by mutation in the TSEN54 gene; PCH5 (610204), caused by mutation in the TSEN54 gene; PCH6 (611523), caused by mutation in the RARS2 gene (611524); PCH7 (614969), caused by mutation in the TOE1 gene (613931); PCH8 (614961), caused by mutation in the CHMP1A gene (164010); PCH9 (615809), caused by mutation in the AMPD2 gene (102771); PCH10 (615803), caused by mutation in the CLP1 gene (608757); PCH11 (617695), caused by mutation in the TBC1D23 gene (617687); PCH12 (618266), caused by mutation in the COASY gene (609855); PCH13 (618606), caused by mutation in the VPS51 gene (615738); PCH14 (619301), caused by mutation in the PPIL1 gene (601301); PCH15 (619302), caused by mutation in the CDC40 gene (605585); PCH16 (619527), caused by mutation in the MINPP1 gene (605391); and PCH17 (619909), caused by mutation in the PRDM13 gene (616741) on chromosome 6q16.
Spastic paraplegia, ataxia, and intellectual disability
MedGen UID:
336010
Concept ID:
C1843661
Disease or Syndrome
Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis
MedGen UID:
375302
Concept ID:
C1843851
Disease or Syndrome
POLG-related disorders comprise a continuum of overlapping phenotypes that were clinically defined long before their molecular basis was known. Most affected individuals have some, but not all, of the features of a given phenotype; nonetheless, the following nomenclature can assist the clinician in diagnosis and management. Onset of the POLG-related disorders ranges from infancy to late adulthood. Alpers-Huttenlocher syndrome (AHS), one of the most severe phenotypes, is characterized by childhood-onset progressive and ultimately severe encephalopathy with intractable epilepsy and hepatic failure. Childhood myocerebrohepatopathy spectrum (MCHS) presents between the first few months of life and about age three years with developmental delay or dementia, lactic acidosis, and a myopathy with failure to thrive. Other findings can include liver failure, renal tubular acidosis, pancreatitis, cyclic vomiting, and hearing loss. Myoclonic epilepsy myopathy sensory ataxia (MEMSA) now describes the spectrum of disorders with epilepsy, myopathy, and ataxia without ophthalmoplegia. MEMSA now includes the disorders previously described as spinocerebellar ataxia with epilepsy (SCAE). The ataxia neuropathy spectrum (ANS) includes the phenotypes previously referred to as mitochondrial recessive ataxia syndrome (MIRAS) and sensory ataxia neuropathy dysarthria and ophthalmoplegia (SANDO). About 90% of persons in the ANS have ataxia and neuropathy as core features. Approximately two thirds develop seizures and almost one half develop ophthalmoplegia; clinical myopathy is rare. Autosomal recessive progressive external ophthalmoplegia (arPEO) is characterized by progressive weakness of the extraocular eye muscles resulting in ptosis and ophthalmoparesis (or paresis of the extraocular muscles) without associated systemic involvement; however, caution is advised because many individuals with apparently isolated arPEO at the onset develop other manifestations of POLG-related disorders over years or decades. Of note, in the ANS spectrum the neuropathy commonly precedes the onset of PEO by years to decades. Autosomal dominant progressive external ophthalmoplegia (adPEO) typically includes a generalized myopathy and often variable degrees of sensorineural hearing loss, axonal neuropathy, ataxia, depression, parkinsonism, hypogonadism, and cataracts (in what has been called "chronic progressive external ophthalmoplegia plus," or "CPEO+").
Spinocerebellar ataxia type 21
MedGen UID:
375311
Concept ID:
C1843891
Disease or Syndrome
Spinocerebellar ataxia-21 (SCA21) is an autosomal dominant neurologic disorder characterized by onset in the first decades of life of slowly progressive cerebellar ataxia, which is associated with cognitive impairment in most patients (summary by Delplanque et al., 2014). For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (164400).
Spinocerebellar ataxia, X-linked 2
MedGen UID:
375535
Concept ID:
C1844885
Disease or Syndrome
X-linked sideroblastic anemia with ataxia
MedGen UID:
335078
Concept ID:
C1845028
Disease or Syndrome
X-linked sideroblastic anemia and ataxia is a rare condition characterized by a blood disorder called sideroblastic anemia and movement problems known as ataxia. This condition occurs only in males.\n\nSideroblastic anemia results when developing red blood cells called erythroblasts do not make enough hemoglobin, which is the protein that carries oxygen in the blood. People with X-linked sideroblastic anemia and ataxia have mature red blood cells that are smaller than normal (microcytic) and appear pale (hypochromic) because of the shortage of hemoglobin. This disorder also leads to an abnormal accumulation of iron in red blood cells. The iron-loaded erythroblasts, which are present in bone marrow, are called ring sideroblasts. These abnormal cells give the condition its name. Unlike other forms of sideroblastic anemia, X-linked sideroblastic anemia and ataxia does not cause a potentially dangerous buildup of iron in the body. The anemia is typically mild and usually does not cause any symptoms.\n\nX-linked sideroblastic anemia and ataxia causes problems with balance and coordination that appear early in life. The ataxia primarily affects the trunk, making it difficult to sit, stand, and walk unassisted. In addition to ataxia, people with this condition often have trouble coordinating movements that involve judging distance or scale (dysmetria) and find it difficult to make rapid, alternating movements (dysdiadochokinesis). Mild speech difficulties (dysarthria), tremor, and abnormal eye movements have also been reported in some affected individuals.
Cataract, ataxia, short stature, and intellectual disability
MedGen UID:
375579
Concept ID:
C1845094
Disease or Syndrome
Syndromic X-linked intellectual disability Lubs type
MedGen UID:
337496
Concept ID:
C1846058
Disease or Syndrome
MECP2 duplication syndrome is a severe neurodevelopmental disorder characterized by early-onset hypotonia, feeding difficulty, gastrointestinal manifestations including gastroesophageal reflux and constipation, delayed psychomotor development leading to severe intellectual disability, poor speech development, progressive spasticity, recurrent respiratory infections (in ~75% of affected individuals), and seizures (in ~50%). MECP2 duplication syndrome is 100% penetrant in males. Occasionally females have been described with a MECP2 duplication and a range of findings from mild intellectual disability to a phenotype similar to that seen in males. In addition to the core features, autistic behaviors, nonspecific neuroradiologic findings on brain MRI, mottled skin, and urogenital anomalies have been observed in several affected boys.
Spondyloepimetaphyseal dysplasia, Bieganski type
MedGen UID:
335350
Concept ID:
C1846148
Disease or Syndrome
X-linked spondyloepimetaphyseal dysplasia with hypomyelinating leukodystrophy (SEMDHL) is an X-linked recessive developmental disorder characterized by slowly progressive skeletal and neurologic abnormalities, including short stature, large and deformed joints, significant motor impairment, visual defects, and sometimes cognitive deficits. Affected individuals typically have normal early development in the first year or so of life, followed by development regression and the development of symptoms. Brain imaging shows white matter abnormalities consistent with hypomyelinating leukodystrophy (summary by Miyake et al., 2017).
Autosomal recessive cerebellar ataxia-saccadic intrusion syndrome
MedGen UID:
335442
Concept ID:
C1846492
Disease or Syndrome
VPS13D movement disorder is a hyperkinetic movement disorder (dystonia, chorea, and/or ataxia) of variable age of onset that can be associated with developmental delay. Onset ranges from birth to adulthood. Individuals can present in childhood with motor delays and gait instability. Cognitive impairment ranging from mild intellectual disability to developmental delay has been reported, and several individuals have normal cognitive function. Individuals have also presented as young adults with gait difficulties caused by spastic ataxia or ataxia. In addition to gait ataxia, affected individuals had limb ataxia, dysarthria, and eye movement abnormalities (macro-saccadic oscillations, nystagmus, and saccadic pursuit). Additional features reported in some individuals include peripheral neuropathy and/or seizures. The disorder progresses to spastic ataxia or generalized dystonia, which can lead to loss of independent ambulation.
Spinocerebellar ataxia type 17
MedGen UID:
337637
Concept ID:
C1846707
Disease or Syndrome
Spinocerebellar ataxia type 17 (SCA17) is characterized by ataxia, dementia, and involuntary movements, including chorea and dystonia. Psychiatric symptoms, pyramidal signs, and rigidity are common. The age of onset ranges from three to 55 years. Individuals with full-penetrance alleles develop neurologic and/or psychiatric symptoms by age 50 years. Ataxia and psychiatric abnormalities are frequently the initial findings, followed by involuntary movement, parkinsonism, dementia, and pyramidal signs. Brain MRI shows variable atrophy of the cerebrum, brain stem, and cerebellum. The clinical features correlate with the length of the polyglutamine expansion but are not absolutely predictive of the clinical course.
Joubert syndrome with renal defect
MedGen UID:
335526
Concept ID:
C1846790
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Kufor-Rakeb syndrome
MedGen UID:
338281
Concept ID:
C1847640
Disease or Syndrome
Kufor-Rakeb syndrome is a rare autosomal recessive form of juvenile-onset atypical Parkinson disease (PARK9) associated with supranuclear gaze palsy, spasticity, and dementia. Some patients have neuroradiologic evidence of iron deposition in the basal ganglia, indicating that the pathogenesis of PARK9 can be considered among the syndromes of neurodegeneration with brain iron accumulation (NBIA; see 234200) (summary by Bruggemann et al., 2010). For a phenotypic description and a discussion of genetic heterogeneity of Parkinson disease (PD), see 168600. Biallelic mutation in the ATP13A2 gene also causes autosomal recessive spastic paraplegia-78 (SPG78; 617225), an adult-onset neurodegenerative disorder with overlapping features. Patients with SPG78 have later onset and prominent spasticity, but rarely parkinsonism. Loss of ATP13A2 function results in a multidimensional spectrum of neurologic features reflecting various regions of the brain and nervous system, including cortical, pyramidal, extrapyramidal, brainstem, cerebellar, and peripheral (summary by Estrada-Cuzcano et al., 2017).
Waardenburg syndrome type 4A
MedGen UID:
341244
Concept ID:
C1848519
Disease or Syndrome
Waardenburg syndrome type 4 (WS4), also known as Waardenburg-Shah syndrome, is an auditory-pigmentary syndrome characterized by pigmentary abnormalities of the hair, skin, and eyes, congenital sensorineural hearing loss, and Hirschsprung disease (reviews by Read and Newton, 1997 and Pingault et al., 2010). WS type 4A is caused by mutation in the EDNRB gene (131244). Clinical Variability of Waardenburg Syndrome Types 1-4 Waardenburg syndrome has been classified into 4 main phenotypes. Type I Waardenburg syndrome (WS1; 193500) is characterized by pigmentary abnormalities of the hair, including a white forelock and premature graying; pigmentary changes of the iris, such as heterochromia iridis and brilliant blue eyes; congenital sensorineural hearing loss; and 'dystopia canthorum.' WS type II (WS2) is distinguished from type I by the absence of dystopia canthorum. WS type III (WS3; 148820) has dystopia canthorum and is distinguished by the presence of upper limb abnormalities. WS type 4 has the additional feature of Hirschsprung disease (reviews by Read and Newton, 1997 and Pingault et al., 2010). Genetic Heterogeneity of Waardenburg Syndrome Type 4 Waardenburg syndrome type 4 is genetically heterogeneous. WS4B (613265) is caused by mutation in the EDN3 gene (131242) on chromosome 20q13, and WS4C (613266) is caused by mutation in the SOX10 gene (602229) on chromosome 22q13.
Familial isolated deficiency of vitamin E
MedGen UID:
341248
Concept ID:
C1848533
Disease or Syndrome
Ataxia with vitamin E deficiency (AVED) generally manifests in late childhood or early teens between ages five and 15 years. The first symptoms include progressive ataxia, clumsiness of the hands, loss of proprioception, and areflexia. Other features often observed are dysdiadochokinesia, dysarthria, positive Romberg sign, head titubation, decreased visual acuity, and positive Babinski sign. The phenotype and disease severity vary widely among families with different pathogenic variants; age of onset and disease course are more uniform within a given family, but symptoms and disease severity can vary even among sibs.
Thyrocerebrorenal syndrome
MedGen UID:
341311
Concept ID:
C1848813
Disease or Syndrome
A rare syndromic renal disorder characterized by renal, neurologic and thyroid disease, associated with thrombocytopenia. There have been no further descriptions in the literature since 1978.
Corneal-cerebellar syndrome
MedGen UID:
341379
Concept ID:
C1849087
Disease or Syndrome
Syndrome with the unusual combination of spinocerebellar degeneration and corneal dystrophy. Three sisters born to normal consanguineous parents have been reported, one of who had only minor spinocerebellar signs without ocular involvement. This autosomal recessive syndrome differs from the Mousa-Al-Din-Al-Nassar syndrome by the subnormal intellectual development and the epithelial (versus stromal) nature of the corneal dystrophy.
Autosomal recessive cerebellar ataxia-blindness-deafness syndrome
MedGen UID:
338611
Concept ID:
C1849094
Disease or Syndrome
A rare autosomal recessive syndromic cerebellar ataxia with the association of early-onset cerebellar ataxia, hearing loss and blindness. Patients may also present demyelinating peripheral motor neuropathy. Cerebral MRI shows alterations of the cerebellar white matter without cerebellar atrophy.
Infantile onset spinocerebellar ataxia
MedGen UID:
338613
Concept ID:
C1849096
Disease or Syndrome
Infantile-onset spinocerebellar ataxia (IOSCA) is a severe, progressive neurodegenerative disorder characterized by normal development until age one year, followed by onset of ataxia, muscle hypotonia, loss of deep-tendon reflexes, and athetosis. Ophthalmoplegia and sensorineural deafness develop by age seven years. By adolescence, affected individuals are profoundly deaf and no longer ambulatory; sensory axonal neuropathy, optic atrophy, autonomic nervous system dysfunction, and hypergonadotropic hypogonadism in females become evident. Epilepsy can develop into a serious and often fatal encephalopathy: myoclonic jerks or focal clonic seizures that progress to epilepsia partialis continua followed by status epilepticus with loss of consciousness.
Hereditary spastic paraplegia 15
MedGen UID:
341387
Concept ID:
C1849128
Disease or Syndrome
Spastic paraplegia 15 (SPG15), typically an early-onset complex hereditary spastic paraplegia, is characterized by progressive spasticity that begins in the lower extremities and is associated with several manifestations resulting from central and peripheral nervous system dysfunction. While onset of spasticity is typically in mid- to late childhood or adolescence (i.e., between ages 5 and 18 years), other manifestations, such as developmental delay or learning disability, may be present earlier, often preceding motor involvement. Individuals with adult onset have also been reported.
Charlevoix-Saguenay spastic ataxia
MedGen UID:
338620
Concept ID:
C1849140
Disease or Syndrome
Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is clinically characterized by a progressive cerebellar ataxia, peripheral neuropathy, and spasticity. Disease onset of classic ARSACS is often in early childhood, leading to delayed walking because of gait unsteadiness in very young toddlers, while an increasing number of individuals with disease onset in teenage or early-adult years are now being described. Typically the ataxia is followed by lower-limb spasticity and later by peripheral neuropathy – although pronounced peripheral neuropathy has been observed as a first sign of ARSACS. Oculomotor disturbances, dysarthria, and upper-limb ataxia develop with slower progression than the other findings. Brain imaging demonstrates atrophy of the superior vermis and the cerebellar hemisphere with additional findings on MRI, such as linear hypointensities in the pons and hyperintense rims around the thalami. Many affected individuals (though not all) have yellow streaks of hypermyelinated fibers radiating from the edges of the optic disc noted on ophthalmologic exam, and thickened retinal fibers can be demonstrated by optical coherence tomography. Mild intellectual disability, hearing loss, and urinary urgency and incontinence have been reported in some individuals.
Saldino-Mainzer syndrome
MedGen UID:
341455
Concept ID:
C1849437
Disease or Syndrome
Short-rib thoracic dysplasia (SRTD) with or without polydactyly refers to a group of autosomal recessive skeletal ciliopathies that are characterized by a constricted thoracic cage, short ribs, shortened tubular bones, and a 'trident' appearance of the acetabular roof. SRTD encompasses Ellis-van Creveld syndrome (EVC) and the disorders previously designated as Jeune syndrome or asphyxiating thoracic dystrophy (ATD), short rib-polydactyly syndrome (SRPS), and Mainzer-Saldino syndrome (MZSDS). Polydactyly is variably present, and there is phenotypic overlap in the various forms of SRTDs, which differ by visceral malformation and metaphyseal appearance. Nonskeletal involvement can include cleft lip/palate as well as anomalies of major organs such as the brain, eye, heart, kidneys, liver, pancreas, intestines, and genitalia. Some forms of SRTD are lethal in the neonatal period due to respiratory insufficiency secondary to a severely restricted thoracic cage, whereas others are compatible with life (summary by Huber and Cormier-Daire, 2012 and Schmidts et al., 2013). There is phenotypic overlap with the cranioectodermal dysplasias (Sensenbrenner syndrome; see CED1, 218330). For a discussion of genetic heterogeneity of short-rib thoracic dysplasia, see SRTD1 (208500).
Polymyoclonus, infantile
MedGen UID:
376647
Concept ID:
C1849731
Disease or Syndrome
Peripheral neuropathy, ataxia, focal necrotizing encephalopathy, and spongy degeneration of brain
MedGen UID:
342395
Concept ID:
C1850022
Disease or Syndrome
Mitochondrial DNA depletion syndrome 6 (hepatocerebral type)
MedGen UID:
338045
Concept ID:
C1850406
Disease or Syndrome
MPV17-related mitochondrial DNA (mtDNA) maintenance defect presents in the vast majority of affected individuals as an early-onset encephalohepatopathic (hepatocerebral) disease that is typically associated with mtDNA depletion, particularly in the liver. A later-onset neuromyopathic disease characterized by myopathy and neuropathy, and associated with multiple mtDNA deletions in muscle, has also rarely been described. MPV17-related mtDNA maintenance defect, encephalohepatopathic form is characterized by: Hepatic manifestations (liver dysfunction that typically progresses to liver failure, cholestasis, hepatomegaly, and steatosis); Neurologic involvement (developmental delay, hypotonia, microcephaly, and motor and sensory peripheral neuropathy); Gastrointestinal manifestations (gastrointestinal dysmotility, feeding difficulties, and failure to thrive); and Metabolic derangements (lactic acidosis and hypoglycemia). Less frequent manifestations include renal tubulopathy, nephrocalcinosis, and hypoparathyroidism. Progressive liver disease often leads to death in infancy or early childhood. Hepatocellular carcinoma has been reported.
Neuronal ceroid lipofuscinosis 5
MedGen UID:
376792
Concept ID:
C1850442
Disease or Syndrome
The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The lipopigment patterns observed most often in CLN5 comprise mixed combinations of 'granular,' 'curvilinear,' and 'fingerprint' profiles. The clinical course includes progressive dementia, seizures, and progressive visual failure (Mole et al., 2005). For a general phenotypic description and a discussion of genetic heterogeneity of CLN, see CLN1 (256730).
Neuronal ceroid lipofuscinosis 1
MedGen UID:
340540
Concept ID:
C1850451
Disease or Syndrome
The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The lipopigment pattern seen most often in CLN1 is referred to as granular osmiophilic deposits (GROD). The patterns most often observed in CLN2 and CLN3 are 'curvilinear' and 'fingerprint' profiles, respectively. CLN4, CLN5, CLN6, CLN7, and CLN8 show mixed combinations of granular, curvilinear, fingerprint, and rectilinear profiles. The clinical course includes progressive dementia, seizures, and progressive visual failure (Mole et al., 2005). Zeman and Dyken (1969) referred to these conditions as the 'neuronal ceroid lipofuscinoses.' Goebel (1995) provided a comprehensive review of the NCLs and noted that they are possibly the most common group of neurodegenerative diseases in children. Mole et al. (2005) provided a detailed clinical and genetic review of the neuronal ceroid lipofuscinoses. Genetic Heterogeneity of Neuronal Ceroid Lipofuscinosis See also CLN2 (204500), caused by mutation in the TPP1 gene (607998) on chromosome 11p15; CLN3 (204200), caused by mutation in the CLN3 gene (607042) on 16p12; CLN4 (162350), caused by mutation in the DNAJC5 gene (611203) on 20q13; CLN5 (256731), caused by mutation in the CLN5 gene (608102) on 13q22; CLN6A (601780) and CLN6B (204300), both caused by mutation in the CLN6 gene (606725) on 15q21; CLN7 (610951), caused by mutation in the MFSD8 gene (611124) on 4q28; CLN8 (600143) and the Northern epilepsy variant of CLN8 (610003), both caused by mutation in the CLN8 gene (607837) on 8p23; CLN10 (610127), caused by mutation in the CTSD gene (116840) on 11p15; CLN11 (614706), caused by mutation in the GRN gene (138945) on 17q21; CLN13 (615362), caused by mutation in the CTSF gene (603539) on 11q13; and CLN14 (611726), caused by mutation in the KCTD7 gene (611725) on 7q11. CLN9 (609055) has not been molecularly characterized. A disorder that was formerly designated neuronal ceroid lipofuscinosis-12 (CLN12) is now considered to be a variable form of Kufor-Rakeb syndrome (KRS; 606693).
Friedreich ataxia, so-called, with optic atrophy and sensorineural deafness
MedGen UID:
376920
Concept ID:
C1850982
Disease or Syndrome
Spinocerebellar ataxia type 34
MedGen UID:
338703
Concept ID:
C1851481
Disease or Syndrome
Spinocerebellar ataxia-34 is an autosomal dominant disorder characterized by slowly progressive cerebellar ataxia. The age at onset is usually during the young adult years, and most patients remain ambulatory until late in life. One family with SCA34 also had onset of erythema and hyperkeratosis in early childhood (Cadieux-Dion et al., 2014), whereas other families have additional neurologic signs, including ocular movement disturbances and pyramidal tract signs (Ozaki et al., 2015). For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (164400).
Joubert syndrome 6
MedGen UID:
342805
Concept ID:
C1853153
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Neuroferritinopathy
MedGen UID:
381211
Concept ID:
C1853578
Disease or Syndrome
Neuroferritinopathy is an adult-onset progressive movement disorder characterized by chorea or dystonia and speech and swallowing deficits. The movement disorder typically affects one or two limbs and progresses to become more generalized within 20 years of disease onset. When present, asymmetry in the movement abnormalities remains throughout the course of the disorder. Most individuals develop a characteristic orofacial action-specific dystonia related to speech that leads to dysarthrophonia. Frontalis overactivity and orolingual dyskinesia are common. Cognitive deficits and behavioral issues become major problems with time.
Megalencephaly with dysmyelination
MedGen UID:
344470
Concept ID:
C1855309
Disease or Syndrome
Pyruvate dehydrogenase E3-binding protein deficiency
MedGen UID:
343383
Concept ID:
C1855553
Disease or Syndrome
Pyruvate dehydrogenase deficiency is characterized by the buildup of a chemical called lactic acid in the body and a variety of neurological problems. Signs and symptoms of this condition usually first appear shortly after birth, and they can vary widely among affected individuals. The most common feature is a potentially life-threatening buildup of lactic acid (lactic acidosis), which can cause nausea, vomiting, severe breathing problems, and an abnormal heartbeat. People with pyruvate dehydrogenase deficiency usually have neurological problems as well. Most have delayed development of mental abilities and motor skills such as sitting and walking. Other neurological problems can include intellectual disability, seizures, weak muscle tone (hypotonia), poor coordination, and difficulty walking. Some affected individuals have abnormal brain structures, such as underdevelopment of the tissue connecting the left and right halves of the brain (corpus callosum), wasting away (atrophy) of the exterior part of the brain known as the cerebral cortex, or patches of damaged tissue (lesions) on some parts of the brain. Because of the severe health effects, many individuals with pyruvate dehydrogenase deficiency do not survive past childhood, although some may live into adolescence or adulthood.
Pyruvate dehydrogenase E2 deficiency
MedGen UID:
343386
Concept ID:
C1855565
Disease or Syndrome
Pyruvate dehydrogenase deficiency is characterized by the buildup of a chemical called lactic acid in the body and a variety of neurological problems. Signs and symptoms of this condition usually first appear shortly after birth, and they can vary widely among affected individuals. The most common feature is a potentially life-threatening buildup of lactic acid (lactic acidosis), which can cause nausea, vomiting, severe breathing problems, and an abnormal heartbeat. People with pyruvate dehydrogenase deficiency usually have neurological problems as well. Most have delayed development of mental abilities and motor skills such as sitting and walking. Other neurological problems can include intellectual disability, seizures, weak muscle tone (hypotonia), poor coordination, and difficulty walking. Some affected individuals have abnormal brain structures, such as underdevelopment of the tissue connecting the left and right halves of the brain (corpus callosum), wasting away (atrophy) of the exterior part of the brain known as the cerebral cortex, or patches of damaged tissue (lesions) on some parts of the brain. Because of the severe health effects, many individuals with pyruvate dehydrogenase deficiency do not survive past childhood, although some may live into adolescence or adulthood.
Joubert syndrome with oculorenal defect
MedGen UID:
340930
Concept ID:
C1855675
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
L-2-hydroxyglutaric aciduria
MedGen UID:
341029
Concept ID:
C1855995
Disease or Syndrome
2-hydroxyglutaric aciduria is a condition that causes progressive damage to the brain. The major types of this disorder are called D-2-hydroxyglutaric aciduria (D-2-HGA), L-2-hydroxyglutaric aciduria (L-2-HGA), and combined D,L-2-hydroxyglutaric aciduria (D,L-2-HGA).\n\nThe main features of D-2-HGA are delayed development, seizures, weak muscle tone (hypotonia), and abnormalities in the largest part of the brain (the cerebrum), which controls many important functions such as muscle movement, speech, vision, thinking, emotion, and memory. Researchers have described two subtypes of D-2-HGA, type I and type II. The two subtypes are distinguished by their genetic cause and pattern of inheritance, although they also have some differences in signs and symptoms. Type II tends to begin earlier and often causes more severe health problems than type I. Type II may also be associated with a weakened and enlarged heart (cardiomyopathy), a feature that is typically not found with type I.\n\nL-2-HGA particularly affects a region of the brain called the cerebellum, which is involved in coordinating movements. As a result, many affected individuals have problems with balance and muscle coordination (ataxia). Additional features of L-2-HGA can include delayed development, seizures, speech difficulties, and an unusually large head (macrocephaly). Typically, signs and symptoms of this disorder begin during infancy or early childhood. The disorder worsens over time, usually leading to severe disability by early adulthood.\n\nCombined D,L-2-HGA causes severe brain abnormalities that become apparent in early infancy. Affected infants have severe seizures, weak muscle tone (hypotonia), and breathing and feeding problems. They usually survive only into infancy or early childhood.
Friedreich ataxia 1
MedGen UID:
383962
Concept ID:
C1856689
Disease or Syndrome
Friedreich ataxia (FRDA) is characterized by slowly progressive ataxia with onset usually before age 25 years (mean age at onset: 10-15 yrs). FRDA is typically associated with dysarthria, muscle weakness, spasticity particularly in the lower limbs, scoliosis, bladder dysfunction, absent lower-limb reflexes, and loss of position and vibration sense. Approximately two thirds of individuals with FRDA have cardiomyopathy, up to 30% have diabetes mellitus, and approximately 25% have an "atypical" presentation with later onset or retained tendon reflexes.
Progressive encephalopathy with leukodystrophy due to DECR deficiency
MedGen UID:
346552
Concept ID:
C1857252
Disease or Syndrome
2,4-Dienoyl-CoA reductase deficiency (DECRD) is a rare autosomal recessive inborn error of metabolism resulting in mitochondrial dysfunction due to impaired production of NADPH, which is an essential cofactor for several mitochondrial enzymes. Affected individuals have a variable phenotype: some may have severe neurologic symptoms and metabolic dysfunction beginning in early infancy, whereas others may present with more subtle features, such as childhood-onset optic atrophy or intermittent muscle weakness. The variable severity is putatively dependent on the effect of the mutation on the NADK2 enzyme. Biochemical analysis typically shows hyperlysinemia, due to defective activity of the mitochondrial NADP(H)-dependent enzyme AASS (605113), which is usually a benign finding. More severe cases have increased C10:2-carnitine levels, due to defective activity of the enzyme DECR (DECR1; 222745) (summary by Houten et al., 2014 and Pomerantz et al., 2018).
Diaminopentanuria
MedGen UID:
347412
Concept ID:
C1857285
Disease or Syndrome
Congenital lactic acidosis, Saguenay-Lac-Saint-Jean type
MedGen UID:
387801
Concept ID:
C1857355
Disease or Syndrome
Mitochondrial complex IV deficiency nuclear type 5 (MC4DN5) is an autosomal recessive severe metabolic multisystemic disorder with onset in infancy. Features include delayed psychomotor development, impaired intellectual development with speech delay, mild dysmorphic facial features, hypotonia, ataxia, and seizures. There is increased serum lactate and episodic hypoglycemia. Some patients may have cardiomyopathy, abnormal breathing, or liver abnormalities, reflecting systemic involvement. Brain imaging shows lesions in the brainstem and basal ganglia, consistent with a diagnosis of Leigh syndrome (see 256000). Affected individuals tend to have episodic metabolic and/or neurologic crises in early childhood, which often lead to early death (summary by Debray et al., 2011). For a discussion of genetic heterogeneity of mitochondrial complex IV (cytochrome c oxidase) deficiency, see 220110.
3-methylglutaconic aciduria type 5
MedGen UID:
347542
Concept ID:
C1857776
Disease or Syndrome
3-Methylglutaconic aciduria type V (MGCA5) is an autosomal recessive disorder characterized by the onset of dilated or noncompaction cardiomyopathy in infancy or early childhood. Many patients die of cardiac failure. Other features include microcytic anemia, growth retardation, mild ataxia, mild muscle weakness, genital anomalies in males, and increased urinary excretion of 3-methylglutaconic acid. Some patients may have optic atrophy or delayed psychomotor development (summary by Davey et al., 2006 and Ojala et al., 2012). For a discussion of genetic heterogeneity of 3-methylglutaconic aciduria, see MGCA type I (250950).
Joubert syndrome 5
MedGen UID:
347545
Concept ID:
C1857780
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Huntington disease-like 3
MedGen UID:
347622
Concept ID:
C1858114
Disease or Syndrome
A rare Huntington disease-like syndrome with characteristics of childhood-onset progressive neurologic deterioration with pyramidal and extrapyramidal abnormalities, chorea, dystonia, ataxia, gait instability, spasticity, seizures, mutism, and (on brain MRI) progressive frontal cortical atrophy and bilateral caudate atrophy.
Hereditary spastic paraplegia 11
MedGen UID:
388073
Concept ID:
C1858479
Disease or Syndrome
Spastic paraplegia 11 (SPG11) is characterized by progressive spasticity and weakness of the lower limbs frequently associated with the following: mild intellectual disability with learning difficulties in childhood and/or progressive cognitive decline; peripheral neuropathy; pseudobulbar involvement; and increased reflexes in the upper limbs. Less frequent findings include: cerebellar signs (ataxia, nystagmus, saccadic pursuit); retinal degeneration; pes cavus; scoliosis; and parkinsonism with characteristic brain MRI features that include thinning of the corpus callosum. Onset occurs mainly during infancy or adolescence (range: age 1-31 years) and in rare cases as late as age 60 years. Most affected individuals become wheelchair bound one or two decades after disease onset.
Hereditary spastic paraplegia 10
MedGen UID:
349003
Concept ID:
C1858712
Disease or Syndrome
Spastic paraplegia-10 (SPG10) is an autosomal dominant neurologic disorder with variable manifestations. Some patients have onset of a 'pure' spastic paraplegia, with lower limb spasticity, hyperreflexia, extensor plantar responses, and variable involvement of the upper limbs beginning in childhood or young adulthood. Some patients show distal sensory impairment, which can be part of the 'pure' phenotype. However, some patients also show an axonal sensorimotor peripheral neuropathy with distal sensory impairment and distal muscle atrophy reminiscent of Charcot-Marie-Tooth disease type 2 (see, e.g., CMT2A, 118210). Rarely, patients with KIF5A mutations may have additional neurologic features, including parkinsonism or cognitive decline, consistent with a 'complicated' phenotype. Spastic paraplegia and peripheral neuropathy in isolation may represent extreme ends of the phenotypic spectrum of KIF5A mutations (summary by Goizet et al., 2009 and Crimella et al., 2012). For a general phenotypic description and a discussion of genetic heterogeneity of autosomal dominant spastic paraplegia, see SPG3A (182600).
Congenital cataracts-facial dysmorphism-neuropathy syndrome
MedGen UID:
346973
Concept ID:
C1858726
Congenital Abnormality
CTDP1-related congenital cataracts, facial dysmorphism, and neuropathy (CTDP1-CCFDN) is characterized by abnormalities of the eye (bilateral congenital cataracts, microcornea, microphthalmia, micropupils), mildly dysmorphic facial features apparent in late childhood, and a hypo-/demyelinating, symmetric, distal peripheral neuropathy. The neuropathy is predominantly motor at the onset and results in delays in early motor development, progressing to severe disability by the third decade of life. Secondary foot deformities and scoliosis are common. Sensory neuropathy develops after age ten years. Most affected individuals have a mild nonprogressive intellectual deficit and cerebellar involvement including ataxia, nystagmus, intention tremor, and dysmetria. All have short stature and most have subnormal weight. Adults have hypogonadotropic hypogonadism. Parainfectious rhabdomyolysis (profound muscle weakness, myoglobinuria, and excessively elevated serum concentration of creatine kinase usually following a viral infection) is a potentially life-threatening complication. To date all affected individuals and carriers identified have been from the Romani population.
Ataxia-hypogonadism-choroidal dystrophy syndrome
MedGen UID:
347798
Concept ID:
C1859093
Disease or Syndrome
PNPLA6 disorders span a phenotypic continuum characterized by variable combinations of cerebellar ataxia; upper motor neuron involvement manifesting as spasticity and/or brisk reflexes; chorioretinal dystrophy associated with variable degrees of reduced visual function; and hypogonadotropic hypogonadism (delayed puberty and lack of secondary sex characteristics). The hypogonadotropic hypogonadism occurs either in isolation or as part of anterior hypopituitarism (growth hormone, thyroid hormone, or gonadotropin deficiencies). Common but less frequent features are peripheral neuropathy (usually of axonal type manifesting as reduced distal reflexes, diminished vibratory sensation, and/or distal muscle wasting); hair anomalies (long eyelashes, bushy eyebrows, or scalp alopecia); short stature; and impaired cognitive functioning (learning disabilities in children; deficits in attention, visuospatial abilities, and recall in adults). Some of these features can occur in distinct clusters on the phenotypic continuum: Boucher-Neuhäuser syndrome (cerebellar ataxia, chorioretinal dystrophy, and hypogonadotropic hypogonadism); Gordon Holmes syndrome (cerebellar ataxia, hypogonadotropic hypogonadism, and – to a variable degree – brisk reflexes); Oliver-McFarlane syndrome (trichomegaly, chorioretinal dystrophy, short stature, intellectual disability, and hypopituitarism); Laurence-Moon syndrome; and spastic paraplegia type 39 (SPG39) (upper motor neuron involvement, peripheral neuropathy, and sometimes reduced cognitive functioning and/or cerebellar ataxia).
Autosomal recessive spinocerebellar ataxia 2
MedGen UID:
349134
Concept ID:
C1859298
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-2 is an neurologic disorder characterized by onset of impaired motor development and ataxic gait in early childhood. Additional features often include loss of fine motor skills, dysarthria, nystagmus, cerebellar signs, and delayed cognitive development with intellectual disability. Brain imaging shows cerebellar atrophy. Overall, the disorder is non- or slowly progressive, with survival into adulthood (summary by Jobling et al., 2015).
Cerebellar ataxia and neurosensory deafness
MedGen UID:
395224
Concept ID:
C1859304
Disease or Syndrome
Cerebellar ataxia-hypogonadism syndrome
MedGen UID:
349137
Concept ID:
C1859305
Disease or Syndrome
PNPLA6 disorders span a phenotypic continuum characterized by variable combinations of cerebellar ataxia; upper motor neuron involvement manifesting as spasticity and/or brisk reflexes; chorioretinal dystrophy associated with variable degrees of reduced visual function; and hypogonadotropic hypogonadism (delayed puberty and lack of secondary sex characteristics). The hypogonadotropic hypogonadism occurs either in isolation or as part of anterior hypopituitarism (growth hormone, thyroid hormone, or gonadotropin deficiencies). Common but less frequent features are peripheral neuropathy (usually of axonal type manifesting as reduced distal reflexes, diminished vibratory sensation, and/or distal muscle wasting); hair anomalies (long eyelashes, bushy eyebrows, or scalp alopecia); short stature; and impaired cognitive functioning (learning disabilities in children; deficits in attention, visuospatial abilities, and recall in adults). Some of these features can occur in distinct clusters on the phenotypic continuum: Boucher-Neuhäuser syndrome (cerebellar ataxia, chorioretinal dystrophy, and hypogonadotropic hypogonadism); Gordon Holmes syndrome (cerebellar ataxia, hypogonadotropic hypogonadism, and – to a variable degree – brisk reflexes); Oliver-McFarlane syndrome (trichomegaly, chorioretinal dystrophy, short stature, intellectual disability, and hypopituitarism); Laurence-Moon syndrome; and spastic paraplegia type 39 (SPG39) (upper motor neuron involvement, peripheral neuropathy, and sometimes reduced cognitive functioning and/or cerebellar ataxia).
Celiac disease, susceptibility to, 1
MedGen UID:
395227
Concept ID:
C1859310
Finding
Celiac disease is a systemic autoimmune disease that can be associated with gastrointestinal findings (diarrhea, malabsorption, abdominal pain and distension, bloating, vomiting, and weight loss) and/or highly variable non-gastrointestinal findings (dermatitis herpetiformis, chronic fatigue, joint pain/inflammation, iron deficiency anemia, migraines, depression, attention-deficit disorder, epilepsy, osteoporosis/osteopenia, infertility and/or recurrent fetal loss, vitamin deficiencies, short stature, failure to thrive, delayed puberty, dental enamel defects, and autoimmune disorders). Classic celiac disease, characterized by mild to severe gastrointestinal symptoms, is less common than non-classic celiac disease, characterized by absence of gastrointestinal symptoms.
Atonic-astatic syndrome of Foerster
MedGen UID:
395300
Concept ID:
C1859594
Disease or Syndrome
Ataxia, early-onset, with oculomotor apraxia and hypoalbuminemia
MedGen UID:
395301
Concept ID:
C1859598
Disease or Syndrome
Ataxia with oculomotor apraxia type 1 (AOA1) is characterized by childhood onset of slowly progressive cerebellar ataxia, followed by oculomotor apraxia and a severe primary motor peripheral axonal motor neuropathy. The first manifestation is progressive gait imbalance (mean age of onset: 4.3 years; range: 2-10 years), followed by dysarthria, then upper-limb dysmetria with mild intention tremor. Oculomotor apraxia, usually noticed a few years after the onset of ataxia, progresses to external ophthalmoplegia. All affected individuals have generalized areflexia followed by a peripheral neuropathy and quadriplegia with loss of ambulation about seven to ten years after onset. Hands and feet are short and atrophic. Chorea and upper-limb dystonia are common. Intellect remains normal in some individuals; in others, different degrees of cognitive impairment have been observed.
Ataxia, deafness, and cardiomyopathy
MedGen UID:
395312
Concept ID:
C1859645
Disease or Syndrome
Ataxia with myoclonic epilepsy and presenile dementia
MedGen UID:
347924
Concept ID:
C1859646
Disease or Syndrome
Angiomatosis, diffuse Corticomeningeal, of Divry and van Bogaert
MedGen UID:
347234
Concept ID:
C1859783
Disease or Syndrome
Amyotrophic lateral sclerosis type 2, juvenile
MedGen UID:
349246
Concept ID:
C1859807
Disease or Syndrome
ALS2-related disorder involves retrograde degeneration of the upper motor neurons of the pyramidal tracts and comprises a clinical continuum of the following three phenotypes: Infantile ascending hereditary spastic paraplegia (IAHSP), characterized by onset of spasticity with increased reflexes and sustained clonus of the lower limbs within the first two years of life, progressive weakness and spasticity of the upper limbs by age seven to eight years, and wheelchair dependence in the second decade with progression toward severe spastic tetraparesis and a pseudobulbar syndrome caused by progressive cranial nerve involvement. Juvenile primary lateral sclerosis (JPLS), characterized by upper motor neuron findings of pseudobulbar palsy and spastic quadriplegia without dementia or cerebellar, extrapyramidal, or sensory signs. Juvenile amyotrophic lateral sclerosis (JALS or ALS2), characterized by onset between ages three and 20 years. All affected individuals show a spastic pseudobulbar syndrome (spasticity of speech and swallowing) together with spastic paraplegia. Some individuals are bedridden by age 12 to 50 years.
Neuroectodermal melanolysosomal disease
MedGen UID:
348553
Concept ID:
C1860157
Disease or Syndrome
Elejalde neuroectodermal melanolysosomal syndrome is a rare autosomal recessive disorder characterized by silvery-gray hair and severe dysfunction of the central nervous system, present from infancy or early childhood and consisting of severe hypotonia, seizures, and impaired intellectual development. Skin may be hypopigmented with bronzing after sun exposure. Microscopy of hair reveals large granules of melanin unevenly distributed in the hair shaft. Abnormal melanocytes and melanosomes and abnormal inclusion bodies in fibroblasts may be present (Elejalde et al., 1979; Duran-McKinster et al., 1999). It has been proposed that, in at least some cases, Elejalde neuroectodermal melanolysosomal syndrome and Griscelli syndrome type 1 (GS1; 214450) represent the same entity; see below. GS1 is caused by mutation in the MYO5A gene (160777).
Tremor of intention, ataxia, and lipofuscinosis
MedGen UID:
396002
Concept ID:
C1860872
Disease or Syndrome
ADan amyloidosis
MedGen UID:
396208
Concept ID:
C1861735
Disease or Syndrome
ITM2B-related cerebral amyloid angiopathy-2, also known as familial Danish dementia (FDD), is an autosomal dominant neurodegenerative disorder characterized by the progressive development of cataracts and other ocular disorders including ocular hemorrhages, hearing impairment, varying neurologic symptoms, and dementia, usually associated with paranoid reactions and temporal disturbance of consciousness. Most patients die in the fifth to sixth decade of life. Neuropathologic findings include severe widespread cerebral amyloid angiopathy, hippocampal plaques, and neurofibrillary tangles, similar to Alzheimer disease (see 104300) (summary by Vidal et al., 2000).
Spinocerebellar ataxia type 31
MedGen UID:
348439
Concept ID:
C1861736
Disease or Syndrome
Spinocerebellar ataxia type 31 (SCA31) is a very rare disease with manifestation of late-onset of cerebral ataxia, dysarthria, and horizontal gaze nystagmus, and that is occasionally accompanied by pyramidal signs, tremor, decreased vibration sense, and hearing difficulties. The mean age of disease onset is 58 years but it can present between the ages of 8 to 83 years. SCA31 is due to non-coding pentanucleotide repeat expansions in the brain expressed, associated with NEDD4, 1 (BEAN1) gene (16q21). Inherited autosomal dominantly with incomplete penetrance.
Brachydactyly-nystagmus-cerebellar ataxia syndrome
MedGen UID:
350589
Concept ID:
C1862099
Disease or Syndrome
A rare multiple congenital anomalies/dysmorphic syndrome characterized by brachydactyly, nystagmus, and cerebellar ataxia. Intellectual deficit and strabismus have also been reported. There have been no further descriptions in the literature since 1934.
Ataxia with fasciculations
MedGen UID:
400052
Concept ID:
C1862440
Disease or Syndrome
Familial hemophagocytic lymphohistiocytosis 2
MedGen UID:
400366
Concept ID:
C1863727
Disease or Syndrome
Familial hemophagocytic lymphohistiocytosis-2 (FHL2) is an autosomal recessive disorder of immune dysregulation with onset in infancy or early childhood. It is characterized clinically by fever, edema, hepatosplenomegaly, and liver dysfunction. Neurologic impairment, seizures, and ataxia are frequent. Laboratory studies show pancytopenia, coagulation abnormalities, hypofibrinogenemia, and hypertriglyceridemia. There is increased production of cytokines, such as gamma-interferon (IFNG; 147570) and TNF-alpha (191160), by hyperactivation and proliferation of T cells and macrophages. Activity of cytotoxic T cells and NK cells is reduced, consistent with a defect in cellular cytotoxicity. Bone marrow, lymph nodes, spleen, and liver show features of hemophagocytosis. Chemotherapy and/or immunosuppressant therapy may result in symptomatic remission, but the disorder is fatal without bone marrow transplantation (summary by Dufourcq-Lagelouse et al., 1999, Stepp et al., 1999, and Molleran Lee et al., 2004). For a general phenotypic description and a discussion of genetic heterogeneity of FHL, see 267700.
Neuronal intranuclear inclusion disease
MedGen UID:
355075
Concept ID:
C1863843
Disease or Syndrome
Neuronal intranuclear inclusion disease (NIID) is an autosomal dominant, slowly progressive neurodegenerative disorder characterized by a wide range of clinical manifestations, including pyramidal and extrapyramidal symptoms, cerebellar ataxia, cognitive decline and dementia, peripheral neuropathy, and autonomic dysfunction. The age at onset varies, but most individuals present as adults between about 30 and 70 years of age. Pathologic investigation shows eosinophilic intranuclear inclusions in almost all cell types, including neurons, skin cells, fibroblasts, and skeletal muscle. Brain imaging shows a characteristic leukoencephalopathy with high intensity signals in the corticomedullary junction on diffusion-weighted imaging (DWI), as well as white matter abnormalities in subcortical and brainstem regions. Skin biopsy combined with brain imaging is useful for diagnosis (summary by Sone et al., 2016). The phenotype in some cases is suggestive of Parkinson disease (see 168600) and/or Alzheimer disease (see 104300), consistent with an evolving phenotypic spectrum of adult-onset NIID (summary by Tian et al., 2019).
Neuronal ceroid lipofuscinosis 10
MedGen UID:
350481
Concept ID:
C1864669
Disease or Syndrome
The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The clinical course includes progressive dementia, seizures, and progressive visual failure (Mole et al., 2005). For a discussion of genetic heterogeneity of neuronal ceroid lipofuscinosis, see CLN1 (256730).
Fatal mitochondrial disease due to combined oxidative phosphorylation defect type 3
MedGen UID:
355842
Concept ID:
C1864840
Disease or Syndrome
Combined oxidative phosphorylation deficiency type 3 is an extremely rare clinically heterogenous disorder described in about 5 patients to date. Clinical signs included hypotonia, lactic acidosis, and hepatic insufficiency, with progressive encephalomyopathy or hypertrophic cardiomyopathy.
Spondyloepimetaphyseal dysplasia, Genevieve type
MedGen UID:
355314
Concept ID:
C1864872
Disease or Syndrome
Spondyloepiphyseal dysplasia of the Genevieve type (SEMDG) is characterized by infantile-onset severe developmental delay and skeletal dysplasia, including short stature, premature carpal ossification, platyspondyly, longitudinal metaphyseal striations, and small epiphyses (summary by van Karnebeek et al., 2016).
Ethylmalonic encephalopathy
MedGen UID:
355966
Concept ID:
C1865349
Disease or Syndrome
Ethylmalonic encephalopathy (EE) is a severe, early-onset, progressive disorder characterized by developmental delay / mild-to-severe intellectual disability; generalized infantile hypotonia that evolves into hypertonia, spasticity, and (in some instances) dystonia; generalized tonic-clonic seizures; and generalized microvascular damage (diffuse and spontaneous relapsing petechial purpura, hemorrhagic suffusions of mucosal surfaces, and chronic hemorrhagic diarrhea). Infants sometimes have frequent vomiting and loss of social interaction. Speech is delayed and in some instances absent. Swallowing difficulties and failure to thrive are common. Children may be unable to walk without support and may be wheelchair bound. Neurologic deterioration accelerates following intercurrent infectious illness, and the majority of children die in the first decade.
Friedreich ataxia 2
MedGen UID:
356134
Concept ID:
C1865981
Disease or Syndrome
Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder characterized by progressive gait and limb ataxia with associated limb muscle weakness, absent lower limb reflexes, extensor plantar responses, dysarthria, and decreased vibratory sense and proprioception. Onset is usually in the first or second decade, before the end of puberty (summary by Delatycki et al., 2000). For a general phenotypic description of Friedreich ataxia (FRDA), see FRDA1 (229300), which is caused by mutation in the FXN gene (606829) on chromosome 9q13.
Episodic ataxia type 5
MedGen UID:
356142
Concept ID:
C1866039
Disease or Syndrome
An extremely rare form of hereditary episodic ataxia with characteristics of recurrent episodes of vertigo and ataxia lasting several hours.
Spinocerebellar ataxia with rigidity and peripheral neuropathy
MedGen UID:
401079
Concept ID:
C1866770
Disease or Syndrome
Posterior column ataxia
MedGen UID:
357379
Concept ID:
C1867923
Disease or Syndrome
Piebald trait-neurologic defects syndrome
MedGen UID:
358177
Concept ID:
C1868311
Disease or Syndrome
A rare genetic pigmentation anomaly of the skin syndrome with characteristics of ventral as well as dorsal leukoderma of the trunk and a congenital white forelock in association with cerebellar ataxia, impaired motor coordination, intellectual disability of variable severity and progressive, mild to profound, unilateral or bilateral sensorineural hearing loss. There have been no further descriptions in the literature since 1971.
Adult-onset autosomal dominant demyelinating leukodystrophy
MedGen UID:
356995
Concept ID:
C1868512
Disease or Syndrome
LMNB1-related autosomal dominant leukodystrophy (ADLD) is a slowly progressive disorder of central nervous system white matter characterized by onset of autonomic dysfunction in the fourth to fifth decade, followed by pyramidal and cerebellar abnormalities resulting in spasticity, ataxia, and tremor. Autonomic dysfunction can include bladder dysfunction, constipation, postural hypotension, erectile dysfunction, and (less often) impaired sweating. Pyramidal signs are often more prominent in the lower extremities (e.g., spastic weakness, hypertonia, clonus, brisk deep tendon reflexes, and bilateral Babinski signs). Cerebellar signs typically appear at the same time as the pyramidal signs and include gait ataxia, dysdiadochokinesia, intention tremor, dysmetria, and nystagmus. Many individuals have sensory deficits starting in the lower limbs. Pseudobulbar palsy with dysarthria, dysphagia, and forced crying and laughing may appear in the seventh or eighth decade. Although cognitive function is usually preserved or only mildly impaired early in the disease course, dementia and psychiatric manifestations can occur as late manifestations. Affected individuals may survive for decades after onset.
Neuronal ceroid lipofuscinosis 2
MedGen UID:
406281
Concept ID:
C1876161
Disease or Syndrome
The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The clinical course includes progressive dementia, seizures, and progressive visual failure. The lipopigment pattern seen most often in CLN2 consists of 'curvilinear' profiles (Mole et al., 2005). For a general phenotypic description and a discussion of genetic heterogeneity of CLN, see CLN1 (256730).
Mevalonic aciduria
MedGen UID:
368373
Concept ID:
C1959626
Disease or Syndrome
Mevalonic aciduria (MEVA), the first recognized defect in the biosynthesis of cholesterol and isoprenoids, is a consequence of a deficiency of mevalonate kinase (ATP:mevalonate 5-phosphotransferase; EC 2.7.1.36). Mevalonic acid accumulates because of failure of conversion to 5-phosphomevalonic acid, which is catalyzed by mevalonate kinase. Mevalonic acid is synthesized from 3-hydroxy-3-methylglutaryl-CoA, a reaction catalyzed by HMG-CoA reductase (142910). Mevalonic aciduria is characterized by dysmorphology, psychomotor retardation, progressive cerebellar ataxia, and recurrent febrile crises, usually manifesting in early infancy, accompanied by hepatosplenomegaly, lymphadenopathy, arthralgia, and skin rash. The febrile crises are similar to those observed in hyperimmunoglobulinemia D and to periodic fever syndrome (HIDS; 260920), which is also caused by mutation in the MVK gene (summary by Prietsch et al., 2003).
Joubert syndrome 7
MedGen UID:
369401
Concept ID:
C1969053
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Intellectual disability, autosomal dominant 1
MedGen UID:
409857
Concept ID:
C1969562
Mental or Behavioral Dysfunction
MBD5 haploinsufficiency is a neurodevelopmental disorder characterized by developmental delay, intellectual disability, severe speech impairment, seizures, sleep disturbances, and abnormal behaviors. Most children lack speech entirely or have single words, short phrases, or short sentences. Seizures are present in more than 80% of children; onset is usually around age two years. Sleep disturbances, present in about 90%, can result in excessive daytime drowsiness. Abnormal behaviors can include autistic-like behaviors (80%) and self-injury and aggression (>60%).
Spastic ataxia 3
MedGen UID:
370715
Concept ID:
C1969645
Disease or Syndrome
A rare genetic autosomal recessive spastic ataxia disease with characteristics of cerebellar ataxia, spasticity, cerebellar (and in some cases cerebral) atrophy, dystonia and leucoencephalopathy. Caused by homozygous or compound heterozygous complex genomic rearrangements involving the MARS2 gene on chromosome 2q33.
COG8-congenital disorder of glycosylation
MedGen UID:
409971
Concept ID:
C1970021
Disease or Syndrome
Syndrome with characteristics of severe psychomotor retardation, failure to thrive and intolerance to wheat and dairy products. So far, only two cases have been described. The disease is caused by mutations in the COG8 gene, which encodes a subunit of the COG complex. This complex is involved vesicle transport in the Golgi apparatus.
Leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome
MedGen UID:
370845
Concept ID:
C1970180
Disease or Syndrome
Leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation (LBSL) is characterized by slowly progressive cerebellar ataxia and spasticity with dorsal column dysfunction (decreased position and vibration sense) in most individuals. The neurologic dysfunction involves the legs more than the arms. The tendon reflexes are retained. Deterioration of motor skills usually starts in childhood or adolescence, but occasionally not until adulthood. Dysarthria develops over time. Occasional findings include epilepsy; learning problems; cognitive decline; and reduced consciousness, neurologic deterioration, and fever following minor head trauma. Individuals with neonatal or early-infantile onset have a severe disease course often associated with early death. Those with childhood onset have slow progression with wheelchair dependence in the teens or twenties. Adult onset is associated with slow progression and mild impairment.
Brain-lung-thyroid syndrome
MedGen UID:
369694
Concept ID:
C1970269
Disease or Syndrome
NKX2-1-related disorders range from benign hereditary chorea (BHC) to choreoathetosis, congenital hypothyroidism, and neonatal respiratory distress (also known as brain-lung-thyroid syndrome). Childhood-onset chorea, the hallmark of NKX2-1-related disorders, may or may not be associated with respiratory distress syndrome or congenital hypothyroidism. Chorea generally begins in early infancy or about age one year (most commonly) or in late childhood or adolescence, and progresses into the second decade after which it remains static or (rarely) remits. Pulmonary disease, the second most common manifestation, can include respiratory distress syndrome in neonates, interstitial lung disease in young children, and pulmonary fibrosis in older persons. The risk for pulmonary carcinoma is increased in young adults with an NKX2-1-related disorder. Thyroid dysfunction, the result of dysembryogenesis, can present as congenital hypothyroidism or compensated hypothyroidism. The risk for thyroid cancer is unknown and may not be increased. In one review, 50% of affected individuals had the full brain-lung-thyroid syndrome, 30% had involvement of brain and thyroid only, and 13% had isolated chorea only.
SLC35A1-congenital disorder of glycosylation
MedGen UID:
370234
Concept ID:
C1970344
Disease or Syndrome
An extremely rare form of carbohydrate deficient glycoprotein syndrome characterized clinically in the single reported case by repeated hemorrhagic incidents, including severe pulmonary hemorrhage.
Phosphoribosylpyrophosphate synthetase superactivity
MedGen UID:
370358
Concept ID:
C1970827
Disease or Syndrome
Phosphoribosylpyrophosphate synthetase (PRS) superactivity comprises two phenotypes, both characterized by hyperuricemia and hyperuricosuria. The mild phenotype (~75% of affected males) with onset in the second or third decade of life is typically limited to these biochemical findings, whereas the severe phenotype (~25% of affected males) with onset in the first decade of life has in addition to these biochemical findings variable combinations of developmental delay (DD) / intellectual disability (ID), sensorineural hearing loss, hypotonia, and ataxia. In the mild phenotype, uric acid crystalluria or a urinary stone is commonly the first clinical finding, followed later by gouty arthritis if serum urate concentration is not controlled.
Glycogen storage disease due to phosphoglycerate kinase 1 deficiency
MedGen UID:
410166
Concept ID:
C1970848
Disease or Syndrome
Phosphoglycerate kinase-1 deficiency is an X-linked recessive condition with a highly variable clinical phenotype that includes hemolytic anemia, myopathy, and neurologic involvement. Patients can express 1, 2, or all 3 of these manifestations (Shirakawa et al., 2006).
PHARC syndrome
MedGen UID:
436373
Concept ID:
C2675204
Disease or Syndrome
Fiskerstrand type peripheral neuropathy is a slowly-progressive Refsum-like disorder associating signs of peripheral neuropathy with late-onset hearing loss, cataract and pigmentary retinopathy that become evident during the third decade of life.
Leukoencephalopathy-ataxia-hypodontia-hypomyelination syndrome
MedGen UID:
390993
Concept ID:
C2676243
Disease or Syndrome
POLR3-related leukodystrophy, a hypomyelinating leukodystrophy with specific features on brain MRI, is characterized by varying combinations of four major clinical findings: Neurologic dysfunction, typically predominated by motor dysfunction (progressive cerebellar dysfunction, and to a lesser extent extrapyramidal [i.e., dystonia], pyramidal [i.e., spasticity] and cognitive dysfunctions). Abnormal dentition (delayed dentition, hypodontia, oligodontia, and abnormally placed or shaped teeth). Endocrine abnormalities such as short stature (in ~50% of individuals) with or without growth hormone deficiency, and more commonly, hypogonadotropic hypogonadism manifesting as delayed, arrested, or absent puberty. Ocular abnormality in the form of myopia, typically progressing over several years and becoming severe. POLR3-related leukodystrophy and 4H leukodystrophy are the two recognized terms for five previously described overlapping clinical phenotypes (initially described as distinct entities before their molecular basis was known). These include: Hypomyelination, hypodontia, hypogonadotropic hypogonadism (4H syndrome); Ataxia, delayed dentition, and hypomyelination (ADDH); Tremor-ataxia with central hypomyelination (TACH); Leukodystrophy with oligodontia (LO); Hypomyelination with cerebellar atrophy and hypoplasia of the corpus callosum (HCAHC). Age of onset is typically in early childhood but later-onset cases have also been reported. An infant with Wiedemann-Rautenstrauch syndrome (neonatal progeroid syndrome) was recently reported to have pathogenic variants in POLR3A on exome sequencing. Confirmation of this as a very severe form of POLR3-related leukodystrophy awaits replication in other individuals with a clinical diagnosis of Wiedemann-Rautenstrauch syndrome.
Hypomyelinating leukodystrophy 6
MedGen UID:
436642
Concept ID:
C2676244
Disease or Syndrome
TUBB4A-related leukodystrophy comprises a phenotypic spectrum in which the MRI findings range from hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC) at the severe end to isolated hypomyelination at the mild end. Progressive neurologic findings reflect involvement of the pyramidal tracts (spasticity, brisk deep tendon reflexes, and Babinski sign), extrapyramidal system (rigidity, dystonia, choreoathetosis, oculogyric crisis, and perioral dyskinesia), cerebellum (ataxia, intention tremor, dysmetria), and bulbar function (dysarthria, dysphonia, and swallowing). Cognition is variably affected, usually less severely than motor function. Typically, those with H-ABC present in early childhood (ages 1-3 years) and those with isolated hypomyelination in later childhood or adulthood. The rate of progression varies with disease severity.
Epilepsy, progressive myoclonic, 1B
MedGen UID:
394003
Concept ID:
C2676254
Disease or Syndrome
Individuals with biallelic PRICKLE1-related disorders typically present with progressive myoclonus epilepsy (PME) with ataxia characterized by myoclonic seizures (lightning-like jerks), generalized convulsive seizures, varying degrees of neurologic regression mainly presenting with ataxia, and mild cognitive impairment or normal cognition. Onset of symptoms is between ages five and ten years. Action myoclonus may affect the limbs or bulbar muscles, while spontaneous myoclonus may occasionally involve facial muscles. Dysarthria may also be an early feature of this condition. The main seizure types are myoclonic or tonic-clonic with frequent nocturnal occurrence. Individuals with heterozygous PRICKLE1 pathogenic variants have presented with non-PME seizures (isolated myoclonic seizures, juvenile myoclonic epilepsy), myoclonic epilepsy, developmental delay, intellectual disability, autism spectrum disorder, and/or central nervous system malformations.
Joubert syndrome 8
MedGen UID:
436772
Concept ID:
C2676771
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Hereditary spastic paraplegia 39
MedGen UID:
383142
Concept ID:
C2677586
Disease or Syndrome
PNPLA6 disorders span a phenotypic continuum characterized by variable combinations of cerebellar ataxia; upper motor neuron involvement manifesting as spasticity and/or brisk reflexes; chorioretinal dystrophy associated with variable degrees of reduced visual function; and hypogonadotropic hypogonadism (delayed puberty and lack of secondary sex characteristics). The hypogonadotropic hypogonadism occurs either in isolation or as part of anterior hypopituitarism (growth hormone, thyroid hormone, or gonadotropin deficiencies). Common but less frequent features are peripheral neuropathy (usually of axonal type manifesting as reduced distal reflexes, diminished vibratory sensation, and/or distal muscle wasting); hair anomalies (long eyelashes, bushy eyebrows, or scalp alopecia); short stature; and impaired cognitive functioning (learning disabilities in children; deficits in attention, visuospatial abilities, and recall in adults). Some of these features can occur in distinct clusters on the phenotypic continuum: Boucher-Neuhäuser syndrome (cerebellar ataxia, chorioretinal dystrophy, and hypogonadotropic hypogonadism); Gordon Holmes syndrome (cerebellar ataxia, hypogonadotropic hypogonadism, and – to a variable degree – brisk reflexes); Oliver-McFarlane syndrome (trichomegaly, chorioretinal dystrophy, short stature, intellectual disability, and hypopituitarism); Laurence-Moon syndrome; and spastic paraplegia type 39 (SPG39) (upper motor neuron involvement, peripheral neuropathy, and sometimes reduced cognitive functioning and/or cerebellar ataxia).
Autosomal recessive ataxia due to ubiquinone deficiency
MedGen UID:
436985
Concept ID:
C2677589
Disease or Syndrome
Primary coenzyme Q10 (CoQ10) deficiency is usually associated with multisystem involvement, including neurologic manifestations such as fatal neonatal encephalopathy with hypotonia; a late-onset slowly progressive multiple-system atrophy-like phenotype (neurodegeneration with autonomic failure and various combinations of parkinsonism and cerebellar ataxia, and pyramidal dysfunction); and dystonia, spasticity, seizures, and intellectual disability. Steroid-resistant nephrotic syndrome (SRNS), the hallmark renal manifestation, is often the initial manifestation either as isolated renal involvement that progresses to end-stage renal disease (ESRD), or associated with encephalopathy (seizures, stroke-like episodes, severe neurologic impairment) resulting in early death. Hypertrophic cardiomyopathy (HCM), retinopathy or optic atrophy, and sensorineural hearing loss can also be seen.
RFT1-congenital disorder of glycosylation
MedGen UID:
383145
Concept ID:
C2677590
Disease or Syndrome
Congenital disorders of glycosylation (CDGs) are a genetically heterogeneous group of autosomal recessive disorders caused by enzymatic defects in the synthesis and processing of asparagine (N)-linked glycans or oligosaccharides on glycoproteins. Type I CDGs comprise defects in the assembly of the dolichol lipid-linked oligosaccharide (LLO) chain and its transfer to the nascent protein. These disorders can be identified by a characteristic abnormal isoelectric focusing profile of plasma transferrin (Leroy, 2006). For a discussion of the classification of CDGs, see CDG1A (212065).
RIDDLE syndrome
MedGen UID:
394368
Concept ID:
C2677792
Disease or Syndrome
RIDDLE is an acronym for the major features of this syndrome: radiosensitivity, immunodeficiency, dysmorphic facies, and learning difficulties (Stewart et al., 2007).
X-linked non progressive cerebellar ataxia
MedGen UID:
394718
Concept ID:
C2678048
Disease or Syndrome
X-linked non progressive cerebellar ataxia is a rare hereditary ataxia characterized by delayed early motor development, severe neonatal hypotonia, non-progressive ataxia and slow eye movements, presenting normal cognitive abilities and absence of pyramidal signs. Frequently patients also manifest intention tremor, mild dysphagia, and dysarthria. Brain MRI reveals global cerebellar atrophy with absence of other malformations or degenerations of the central and peripheral nervous systems.
Christianson syndrome
MedGen UID:
394455
Concept ID:
C2678194
Disease or Syndrome
Christianson syndrome (referred to as CS in this GeneReview), an X-linked disorder, is characterized in males by cognitive dysfunction, behavioral disorder, and neurologic findings (e.g., seizures, ataxia, postnatal microcephaly, and eye movement abnormalities). Males with CS typically present with developmental delay, later meeting criteria for severe intellectual disability (ID). Behaviorally, autism spectrum disorder and hyperactivity are common, and may resemble the behaviors observed in Angelman syndrome. Hypotonia and oropharyngeal dysphagia in infancy may result in failure to thrive. Seizures, typically beginning before age three years, can include infantile spasms and tonic, tonic-clonic, myoclonic, and atonic seizures. Subsequently, regression (e.g., loss of ambulation and ability to feed independently) may occur. Manifestations in heterozygous females range from asymptomatic to mild ID and/or behavioral issues.
EAST syndrome
MedGen UID:
411243
Concept ID:
C2748572
Disease or Syndrome
Syndrome with characteristics of seizures, sensorineural deafness, ataxia, intellectual deficit, and electrolyte imbalance. It has been described in five patients from four families. The disease is caused by homozygous or compound heterozygous mutations in the KCNJ10 gene, encoding a potassium channel expressed in the brain, spinal cord, inner ear and kidneys. Transmission is autosomal recessive.
Peroxisome biogenesis disorder 9B
MedGen UID:
440765
Concept ID:
C2749346
Disease or Syndrome
Adult Refsum disease (ARD is associated with elevated plasma phytanic acid levels, late childhood-onset (or later) retinitis pigmentosa, and variable combinations of anosmia, polyneuropathy, deafness, ataxia, and ichthyosis. Onset of symptoms ranges from age seven months to older than age 50 years. Cardiac arrhythmia and heart failure caused by cardiomyopathy are potentially severe health problems that develop later in life.
Neuroblastoma, susceptibility to, 1
MedGen UID:
412713
Concept ID:
C2749485
Finding
Cerebellar ataxia, intellectual disability, and dysequilibrium syndrome 2
MedGen UID:
412914
Concept ID:
C2750234
Disease or Syndrome
Cerebellar ataxia, impaired intellectual development, and dysequilibrium syndrome (CAMRQ) is a genetically heterogeneous disorder characterized by congenital cerebellar ataxia and intellectual disability (summary by Gulsuner et al., 2011). For a discussion of genetic heterogeneity of CAMRQ, see CAMRQ1 (224050).
Cortical dysplasia-focal epilepsy syndrome
MedGen UID:
413258
Concept ID:
C2750246
Disease or Syndrome
Pitt-Hopkins-like syndrome-1 (PTHSL1) is an autosomal recessive neurodevelopmental disorder characterized by delayed psychomotor development, intellectual disability, severe speech impairment or regression, and behavioral abnormalities. Most patients have onset of seizures within the first years of life. Some patients may have cortical dysplasia on brain imaging (summary by Smogavec et al., 2016).
Cerebellar ataxia, intellectual disability, and dysequilibrium syndrome 3
MedGen UID:
442496
Concept ID:
C2750509
Disease or Syndrome
Cerebellar ataxia, impaired intellectual development, and dysequilibrium syndrome (CAMRQ) is a genetically heterogeneous disorder characterized by congenital cerebellar ataxia and mental retardation (summary by Gulsuner et al., 2011). For a discussion of genetic heterogeneity of CAMRQ, see CAMRQ1 (224050).
Hereditary spastic paraplegia 44
MedGen UID:
413042
Concept ID:
C2750784
Disease or Syndrome
A very rare, complex form of hereditary spastic paraplegia characterised by a late-onset, slowly progressive spastic paraplegia associated with mild ataxia and dysarthria, upper extremity involvement (i.e. loss of finger dexterity, dysmetria), and mild cognitive impairment, without the presence of nystagmus. A hypomyelinating leucodystrophy and thin corpus callosum is observed in all cases and psychomotor development is normal or near normal. Caused by mutations in the GJC2 gene (1q41-q42) encoding the gap junction gamma-2 protein.
Nijmegen breakage syndrome-like disorder
MedGen UID:
442700
Concept ID:
C2751318
Disease or Syndrome
Nijmegen breakage syndrome-like disorder (NBSLD) is an autosomal recessive disorder characterized by severe prenatal growth retardation and persistent postnatal growth restriction, congenital microcephaly, borderline to mildly impaired intellectual development, normal sexual development, and radioresistant DNA synthesis with no immunodeficiency, myelodysplasia, or early neurodegeneration (summary by Ragamin et al., 2020).
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 5
MedGen UID:
413981
Concept ID:
C2751319
Disease or Syndrome
Four phenotypes comprise the RRM2B mitochondrial DNA maintenance defects (RRM2B-MDMDs): RRM2B encephalomyopathic MDMD, the most severe phenotype, usually manifesting shortly after birth as hypotonia, poor feeding, and faltering growth requiring hospitalization. Subsequent assessments are likely to reveal multisystem involvement including sensorineural hearing loss, renal tubulopathy, and respiratory failure. Autosomal dominant progressive external ophthalmoplegia (adPEO), typically adult onset; other manifestations can include ptosis, bulbar dysfunction, fatigue, and muscle weakness. RRM2B autosomal recessive progressive external ophthalmoplegia (arPEO), a typically childhood-onset predominantly myopathic phenotype of PEO, ptosis, proximal muscle weakness, and bulbar dysfunction. RRM2B mitochondrial neurogastrointestinal encephalopathy (MNGIE)-like, characterized by progressive ptosis, ophthalmoplegia, gastrointestinal dysmotility, cachexia, and peripheral neuropathy. To date, 78 individuals from 52 families with a molecularly confirmed RRM2B-MDMD have been reported.
Familial amyloid neuropathy
MedGen UID:
414031
Concept ID:
C2751492
Disease or Syndrome
Hereditary transthyretin (ATTR) amyloidosis is characterized by a slowly progressive peripheral sensorimotor and/or autonomic neuropathy as well as non-neuropathic changes of cardiomyopathy, nephropathy, vitreous opacities, and CNS amyloidosis. The disease usually begins in the third to fifth decade in persons from endemic foci in Portugal and Japan; onset is later in persons from other areas. Typically, sensory neuropathy starts in the lower extremities with paresthesias and hypesthesias of the feet, followed within a few years by motor neuropathy. In some persons, particularly those with early-onset disease, autonomic neuropathy is the first manifestation of the condition; findings can include: orthostatic hypotension, constipation alternating with diarrhea, attacks of nausea and vomiting, delayed gastric emptying, sexual impotence, anhidrosis, and urinary retention or incontinence. Cardiac amyloidosis is mainly characterized by progressive cardiomyopathy. Individuals with leptomeningeal amyloidosis may have the following CNS findings: dementia, psychosis, visual impairment, headache, seizures, motor paresis, ataxia, myelopathy, hydrocephalus, or intracranial hemorrhage.
Cystic leukoencephalopathy without megalencephaly
MedGen UID:
416646
Concept ID:
C2751843
Disease or Syndrome
RNAse T2-deficient leukoencephalopathy is a disorder that affects the brain. People with RNAse T2-deficient leukoencephalopathy have neurological problems that become apparent during infancy; the problems generally do not worsen over time (progress). Most affected individuals have severe intellectual disability; muscle stiffness (spasticity); and a delay in developing motor skills such as sitting, crawling, and walking. Some do not learn to walk, and most do not develop the ability to speak. Other neurological features that can occur in RNAse T2-deficient leukoencephalopathy include hearing loss caused by abnormalities in the inner ear (sensorineural deafness), seizures, involuntary writhing movements of the hands (athetosis), uncontrolled muscle tensing (dystonia), and involuntary eye movements (nystagmus). In addition to the neurological problems associated with this disorder, some affected individuals have unusual facial features sometimes described as a "doll-like face."\n\nThe neurological problems in this disorder are caused by abnormalities in the brain. People with this condition have leukoencephalopathy, an abnormality of the brain's white matter that can be detected with medical imaging. White matter consists of nerve fibers covered by a fatty substance called myelin. Myelin insulates nerve fibers and promotes the rapid transmission of nerve impulses. In people with RNAse T2-deficient leukoencephalopathy, myelin is not made in sufficient amounts during development, leading to patchy white matter abnormalities (lesions) in the brain. In addition, individuals with RNAse T2-deficient leukoencephalopathy may have cysts in regions of the brain called the temporal lobes and enlargement of the fluid-filled cavities (ventricles) near the center of the brain. The white matter lesions are primarily concentrated around the cysts and the ventricles. An abnormally small head and brain size (microcephaly) often occurs in this disorder.
Hereditary spastic paraplegia 50
MedGen UID:
442869
Concept ID:
C2752008
Disease or Syndrome
AP-4-associated hereditary spastic paraplegia (HSP), also known as AP-4 deficiency syndrome, is a group of neurodegenerative disorders characterized by a progressive, complex spastic paraplegia with onset typically in infancy or early childhood. Early-onset hypotonia evolves into progressive lower-extremity spasticity. The majority of children become nonambulatory and usually wheelchair bound. Over time spasticity progresses to involve the upper extremities, resulting in a spastic tetraplegia. Associated complications include dysphagia, contractures, foot deformities, dysregulation of bladder and bowel function, and a pseudobulbar affect. About 50% of affected individuals have seizures. Postnatal microcephaly (usually in the -2SD to -3SD range) is common. All have developmental delay. Speech development is significantly impaired and many affected individuals remain nonverbal. Intellectual disability in older children is usually moderate to severe.
Maple syrup urine disease type 1A
MedGen UID:
443950
Concept ID:
C2930989
Disease or Syndrome
A maple syrup urine disease caused by mutations in BCKDHA.
ALG6-congenital disorder of glycosylation 1C
MedGen UID:
443952
Concept ID:
C2930997
Disease or Syndrome
Congenital disorders of glycosylation, previously called carbohydrate-deficient glycoprotein syndromes (CDGSs), are caused by defects in mannose addition during N-linked oligosaccharide assembly. CDGs can be divided into 2 types, depending on whether they impair lipid-linked oligosaccharide (LLO) assembly and transfer (CDG I), or affect trimming of the protein-bound oligosaccharide or the addition of sugars to it (CDG II) (Orlean, 2000). CDG Ic is characterized by psychomotor retardation with delayed walking and speech, hypotonia, seizures, and sometimes protein-losing enteropathy. It is the second largest subtype of CDG (summary by Sun et al., 2005). For a discussion of the classification of CDGs, see CDG1A (212065). Freeze and Aebi (1999) reviewed CDG Ib (602579) and CDG Ic.
Spinocerebellar ataxia type 30
MedGen UID:
424821
Concept ID:
C2936793
Disease or Syndrome
A rare disease with characteristics of slowly progressive and relatively pure ataxia described in 6 patients from one Australian family to date. The disease presents with oculomotor dysfunction, moderate dysarthria, and ataxia that progresses slowly and eventually leads to mobility impairment. Some patients have also reported mild hyperreflexia in the lower limbs. Rare manifestations include gaze-evoked nystagmus and dystonia. The causal gene has not yet been identified but it has been linked to chromosome 4q34.3-q35.1.
Bardet-Biedl syndrome 1
MedGen UID:
422452
Concept ID:
C2936862
Disease or Syndrome
Bardet-Biedl syndrome is an autosomal recessive and genetically heterogeneous ciliopathy characterized by retinitis pigmentosa, obesity, kidney dysfunction, polydactyly, behavioral dysfunction, and hypogonadism (summary by Beales et al., 1999). Eight proteins implicated in the disorder assemble to form the BBSome, a stable complex involved in signaling receptor trafficking to and from cilia (summary by Scheidecker et al., 2014). Genetic Heterogeneity of Bardet-Biedl Syndrome BBS2 (615981) is caused by mutation in a gene on 16q13 (606151); BBS3 (600151), by mutation in the ARL6 gene on 3q11 (608845); BBS4 (615982), by mutation in a gene on 15q22 (600374); BBS5 (615983), by mutation in a gene on 2q31 (603650); BBS6 (605231), by mutation in the MKKS gene on 20p12 (604896); BBS7 (615984), by mutation in a gene on 4q27 (607590); BBS8 (615985), by mutation in the TTC8 gene on 14q32 (608132); BBS9 (615986), by mutation in a gene on 7p14 (607968); BBS10 (615987), by mutation in a gene on 12q21 (610148); BBS11 (615988), by mutation in the TRIM32 gene on 9q33 (602290); BBS12 (615989), by mutation in a gene on 4q27 (610683); BBS13 (615990), by mutation in the MKS1 gene (609883) on 17q23; BBS14 (615991), by mutation in the CEP290 gene (610142) on 12q21, BBS15 (615992), by mutation in the WDPCP gene (613580) on 2p15; BBS16 (615993), by mutation in the SDCCAG8 gene (613524) on 1q43; BBS17 (615994), by mutation in the LZTFL1 gene (606568) on 3p21; BBS18 (615995), by mutation in the BBIP1 gene (613605) on 10q25; BBS19 (615996), by mutation in the IFT27 gene (615870) on 22q12; BBS20 (619471), by mutation in the IFT172 gene (607386) on 9p21; BBS21 (617406), by mutation in the CFAP418 gene (614477) on 8q22; and BBS22 (617119), by mutation in the IFT74 gene (608040) on 9p21. The CCDC28B gene (610162) modifies the expression of BBS phenotypes in patients who have mutations in other genes. Mutations in MKS1, MKS3 (TMEM67; 609884), and C2ORF86 also modify the expression of BBS phenotypes in patients who have mutations in other genes. Although BBS had originally been thought to be a recessive disorder, Katsanis et al. (2001) demonstrated that clinical manifestation of some forms of Bardet-Biedl syndrome requires recessive mutations in 1 of the 6 loci plus an additional mutation in a second locus. While Katsanis et al. (2001) called this 'triallelic inheritance,' Burghes et al. (2001) suggested the term 'recessive inheritance with a modifier of penetrance.' Mykytyn et al. (2002) found no evidence of involvement of the common BBS1 mutation in triallelic inheritance. However, Fan et al. (2004) found heterozygosity in a mutation of the BBS3 gene (608845.0002) as an apparent modifier of the expression of homozygosity of the met390-to-arg mutation in the BBS1 gene (209901.0001). Allelic disorders include nonsyndromic forms of retinitis pigmentosa: RP51 (613464), caused by TTC8 mutation, and RP55 (613575), caused by ARL6 mutation.
Microcephaly, seizures, and developmental delay
MedGen UID:
462017
Concept ID:
C3150667
Disease or Syndrome
Microcephaly, seizures, and developmental delay (MCSZ) is an autosomal recessive neurodevelopmental disorder with onset in infancy. There is a range of phenotypic severity: some patients develop refractory seizures in infancy, consistent with a developmental and epileptic encephalopathy (DEE), whereas others have more well-controlled seizures and a more protracted course associated with cerebellar atrophy and peripheral neuropathy (Shen et al., 2010 and Poulton et al., 2013). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Hemolytic anemia due to glucophosphate isomerase deficiency
MedGen UID:
462080
Concept ID:
C3150730
Disease or Syndrome
Glucose phosphate isomerase (GPI) deficiency is an inherited disorder that affects red blood cells, which carry oxygen to the body's tissues. People with this disorder have a condition known as chronic hemolytic anemia, in which red blood cells are broken down (undergo hemolysis) prematurely, resulting in a shortage of red blood cells (anemia). Chronic hemolytic anemia can lead to unusually pale skin (pallor), yellowing of the eyes and skin (jaundice), extreme tiredness (fatigue), shortness of breath (dyspnea), and a rapid heart rate (tachycardia). An enlarged spleen (splenomegaly), an excess of iron in the blood, and small pebble-like deposits in the gallbladder or bile ducts (gallstones) may also occur in this disorder.\n\nHemolytic anemia in GPI deficiency can range from mild to severe. In the most severe cases, affected individuals do not survive to birth. Individuals with milder disease can survive into adulthood. People with any level of severity of the disorder can have episodes of more severe hemolysis, called hemolytic crises, which can be triggered by bacterial or viral infections.\n\nA small percentage of individuals with GPI deficiency also have neurological problems, including intellectual disability and difficulty with coordinating movements (ataxia).
Combined oxidative phosphorylation defect type 7
MedGen UID:
462151
Concept ID:
C3150801
Disease or Syndrome
A rare mitochondrial disease due to a defect in mitochondrial protein synthesis with a variable phenotype that includes onset in infancy or early childhood of failure to thrive and psychomotor regression (after initial normal development), as well as ocular manifestations (such as ptosis, nystagmus, optic atrophy, ophthalmoplegia and reduced vision). Additional manifestations include bulbar paresis with facial weakness, hypotonia, difficulty chewing, dysphagia, mild dysarthria, ataxia, global muscle atrophy, and areflexia. It has a relatively slow disease progression with patients often living into the third decade of life.
Hereditary spastic paraplegia 48
MedGen UID:
462251
Concept ID:
C3150901
Disease or Syndrome
Spastic paraplegia-48 (SPG48) is an autosomal recessive neurologic disorder characterized by spasticity of the lower limbs resulting in gait difficulties. Most patients have onset in mid- or late-adulthood, although childhood onset has been reported in 1 patient. Additional features may include parkinsonism, urinary incontinence, neuropathy, and mild cognitive impairment (summary by Hirst et al., 2015). For a discussion of genetic heterogeneity of autosomal recessive SPG, see SPG5A (270800).
Mitochondrial DNA depletion syndrome 4b
MedGen UID:
462264
Concept ID:
C3150914
Disease or Syndrome
POLG-related disorders comprise a continuum of overlapping phenotypes that were clinically defined long before their molecular basis was known. Most affected individuals have some, but not all, of the features of a given phenotype; nonetheless, the following nomenclature can assist the clinician in diagnosis and management. Onset of the POLG-related disorders ranges from infancy to late adulthood. Alpers-Huttenlocher syndrome (AHS), one of the most severe phenotypes, is characterized by childhood-onset progressive and ultimately severe encephalopathy with intractable epilepsy and hepatic failure. Childhood myocerebrohepatopathy spectrum (MCHS) presents between the first few months of life and about age three years with developmental delay or dementia, lactic acidosis, and a myopathy with failure to thrive. Other findings can include liver failure, renal tubular acidosis, pancreatitis, cyclic vomiting, and hearing loss. Myoclonic epilepsy myopathy sensory ataxia (MEMSA) now describes the spectrum of disorders with epilepsy, myopathy, and ataxia without ophthalmoplegia. MEMSA now includes the disorders previously described as spinocerebellar ataxia with epilepsy (SCAE). The ataxia neuropathy spectrum (ANS) includes the phenotypes previously referred to as mitochondrial recessive ataxia syndrome (MIRAS) and sensory ataxia neuropathy dysarthria and ophthalmoplegia (SANDO). About 90% of persons in the ANS have ataxia and neuropathy as core features. Approximately two thirds develop seizures and almost one half develop ophthalmoplegia; clinical myopathy is rare. Autosomal recessive progressive external ophthalmoplegia (arPEO) is characterized by progressive weakness of the extraocular eye muscles resulting in ptosis and ophthalmoparesis (or paresis of the extraocular muscles) without associated systemic involvement; however, caution is advised because many individuals with apparently isolated arPEO at the onset develop other manifestations of POLG-related disorders over years or decades. Of note, in the ANS spectrum the neuropathy commonly precedes the onset of PEO by years to decades. Autosomal dominant progressive external ophthalmoplegia (adPEO) typically includes a generalized myopathy and often variable degrees of sensorineural hearing loss, axonal neuropathy, ataxia, depression, parkinsonism, hypogonadism, and cataracts (in what has been called "chronic progressive external ophthalmoplegia plus," or "CPEO+").
Constitutional megaloblastic anemia with severe neurologic disease
MedGen UID:
462555
Concept ID:
C3151205
Disease or Syndrome
Dihydrofolate reductase deficiency is an autosomal recessive metabolic disorder characterized by the hematologic findings of megaloblastic anemia and variable neurologic symptoms, ranging from severe developmental delay and generalized seizures in infancy (Banka et al., 2011) to childhood absence epilepsy with learning difficulties to lack of symptoms (Cario et al., 2011). Treatment with folinic acid can ameliorate some of the symptoms.
Spinocerebellar ataxia type 32
MedGen UID:
462693
Concept ID:
C3151343
Disease or Syndrome
Spinocerebellar ataxia-32 (SCA32) is an autosomal dominant neurologic disorder characterized by ataxia, variable mental impairment, and azoospermia in males (summary by Jiang et al., 2010). For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (164400).
Megalencephalic leukoencephalopathy with subcortical cysts 2A
MedGen UID:
462705
Concept ID:
C3151355
Disease or Syndrome
The classic phenotype of megalencephalic leukoencephalopathy with subcortical cysts (MLC) is characterized by early-onset macrocephaly, often in combination with mild gross motor developmental delay and seizures; gradual onset of ataxia, spasticity, and sometimes extrapyramidal findings; and usually late onset of mild mental deterioration. Macrocephaly, observed in virtually all individuals, may be present at birth but more frequently develops during the first year of life. The degree of macrocephaly is variable and can be as great as 4 to 6 SD above the mean in some individuals. After the first year of life, head growth rate normalizes and growth follows a line parallel to and usually several centimeters above the 98th centile. Initial mental and motor development is normal in most individuals. Walking is often unstable, followed by ataxia of the trunk and extremities, then minor signs of pyramidal dysfunction and brisk deep-tendon stretch reflexes. Almost all individuals have epilepsy from an early age. The epilepsy is typically well controlled with anti-seizure medication, but status epilepticus occurs relatively frequently. Mental deterioration is late and mild. Disease severity ranges from independent walking for a few years only to independent walking in the fifth decade. Some individuals have died in their teens or twenties; others are alive in their fifties. An improving phenotype has a similar initial presentation with delayed mental or motor development, followed by an improving clinical course: macrocephaly usually persists, but some children become normocephalic; motor function improves or normalizes; hypotonia and clumsiness may persist in some or neurologic examination may become normal. Some have intellectual disability that is stable, with or without autism. Epilepsy and status epilepticus may occur.
Dyskeratosis congenita, autosomal dominant 3
MedGen UID:
462795
Concept ID:
C3151445
Disease or Syndrome
Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres. The phenotypic spectrum of telomere biology disorders is broad and includes individuals with classic dyskeratosis congenita (DC) as well as those with very short telomeres and an isolated physical finding. Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia, although this may not be present in all individuals. People with DC/TBD are at increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis. Other findings can include eye abnormalities (epiphora, blepharitis, sparse eyelashes, ectropion, entropion, trichiasis), taurodontism, liver disease, gastrointestinal telangiectasias, and avascular necrosis of the hips or shoulders. Although most persons with DC/TBD have normal psychomotor development and normal neurologic function, significant developmental delay is present in both forms; additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome) and bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome and Coats plus syndrome). Onset and progression of manifestations of DC/TBD vary: at the mild end of the spectrum are those who have only minimal physical findings with normal bone marrow function, and at the severe end are those who have the diagnostic triad and early-onset BMF.
Proximal tubulopathy-diabetes mellitus-cerebellar ataxia syndrome
MedGen UID:
463309
Concept ID:
C3151959
Disease or Syndrome
Proximal tubulopathy-diabetes mellitus-cerebellar ataxia syndrome is characterized by onset of proximal tubulopathy in the first year of life, followed by progressive development during childhood of skin anomalies (erythrocyanosis and abnormal pigmentation), blindness, osteoporosis, cerebellar ataxia, mitochondrial myopathy, deafness and diabetes mellitus.
Niemann-Pick disease, type C1
MedGen UID:
465922
Concept ID:
C3179455
Disease or Syndrome
Niemann-Pick disease type C (NPC) is a slowly progressive lysosomal disorder whose principal manifestations are age dependent. The manifestations in the perinatal period and infancy are predominantly visceral, with hepatosplenomegaly, jaundice, and (in some instances) pulmonary infiltrates. From late infancy onward, the presentation is dominated by neurologic manifestations. The youngest children may present with hypotonia and developmental delay, with the subsequent emergence of ataxia, dysarthria, dysphagia, and, in some individuals, epileptic seizures, dystonia, and gelastic cataplexy. Although cognitive impairment may be subtle at first, it eventually becomes apparent that affected individuals have a progressive dementia. Older teenagers and young adults may present predominantly with apparent early-onset dementia or psychiatric manifestations; however, careful examination usually identifies typical neurologic signs.
Chromosome 15q11.2 deletion syndrome
MedGen UID:
467404
Concept ID:
C3180937
Disease or Syndrome
A heterozygous deletion of chromosome 15q11.2 may increase the susceptibility to neuropsychiatric or neurodevelopmental problems, including delayed psychomotor development, speech delay, autism spectrum disorder, attention deficit-hyperactivity disorder, obsessive-compulsive disorder, and possibly seizures (summary by Doornbos et al., 2009 and Burnside et al., 2011). See also chromosome 15q11.2 duplication syndrome (608636).
Syndromic X-linked intellectual disability Chudley-Schwartz type
MedGen UID:
477102
Concept ID:
C3275471
Mental or Behavioral Dysfunction
A syndromic X-linked intellectual disability characterized by moderate intellectual disability, seizures, dysmorphic facial features and in some older patients slowly progressive unsteady gait and progressive weakness that has material basis in variation in the chromosomal region Xq21.33-q23.
Optic atrophy with or without deafness, ophthalmoplegia, myopathy, ataxia, and neuropathy
MedGen UID:
478179
Concept ID:
C3276549
Disease or Syndrome
Syndromic optic atrophy, also known as DOA+ syndrome, is a neurologic disorder characterized most commonly by an insidious onset of visual loss and sensorineural hearing loss in childhood with variable presentation of other clinical manifestations including progressive external ophthalmoplegia (PEO), muscle cramps, hyperreflexia, and ataxia. There appears to be a wide range of intermediate phenotypes (Yu-Wai-Man et al., 2010).
Mitochondrial complex V (ATP synthase) deficiency nuclear type 2
MedGen UID:
481329
Concept ID:
C3279699
Disease or Syndrome
Mitochondrial encephalo-cardio-myopathy due to <i>TMEM70</i> mutation is characterized by early neonatal onset of hypotonia, hypetrophic cardiomyopathy and apneic spells within hours after birth accompanied by lactic acidosis, hyperammonemia and 3-methylglutaconic aciduria.
Hereditary sensory neuropathy-deafness-dementia syndrome
MedGen UID:
481515
Concept ID:
C3279885
Disease or Syndrome
DNMT1-related disorder is a degenerative disorder of the central and peripheral nervous systems comprising a phenotypic spectrum that includes hereditary sensory and autonomic neuropathy type 1E (HSAN1E) and autosomal dominant cerebellar ataxia, deafness, and narcolepsy (ADCA-DN). DNMT1 disorder is often characterized by moderate-to-severe sensorineural hearing loss beginning in the teens or early 20s, sensory impairment, sudomotor dysfunction (loss of sweating), and dementia usually beginning in the mid-40s. In some affected individuals, narcolepsy/cataplexy syndrome and ataxia are predominant findings.
Rafiq syndrome
MedGen UID:
481757
Concept ID:
C3280127
Disease or Syndrome
Rafiq syndrome (RAFQS) is an autosomal recessive disorder characterized by variably impaired intellectual and motor development, a characteristic facial dysmorphism, truncal obesity, and hypotonia. The facial dysmorphism comprises prominent eyebrows with lateral thinning, downward-slanting palpebral fissures, bulbous tip of the nose, large ears, and a thin upper lip. Behavioral problems, including overeating, verbal and physical aggression, have been reported in some cases. Serum transferrin isoelectric focusing shows a type 2 pattern (summary by Balasubramanian et al., 2019).
Neurodegeneration with brain iron accumulation 4
MedGen UID:
482001
Concept ID:
C3280371
Disease or Syndrome
Mitochondrial membrane protein-associated neurodegeneration (MPAN) is characterized initially by gait changes followed by progressive spastic paresis, progressive dystonia (which may be limited to the hands and feet or more generalized), neuropsychiatric abnormalities (emotional lability, depression, anxiety, impulsivity, compulsions, hallucinations, perseveration, inattention, and hyperactivity), and cognitive decline. Additional early findings can include dysphagia, dysarthria, optic atrophy, axonal neuropathy, parkinsonism, and bowel/bladder incontinence. Survival is usually well into adulthood. End-stage disease is characterized by severe dementia, spasticity, dystonia, and parkinsonism.
Multiple mitochondrial dysfunctions syndrome 2
MedGen UID:
482008
Concept ID:
C3280378
Disease or Syndrome
Multiple mitochondrial dysfunctions syndrome-2 (MMDS2) with hyperglycinemia is a severe autosomal recessive disorder characterized by developmental regression in infancy. Affected children have an encephalopathic disease course with seizures, spasticity, loss of head control, and abnormal movement. Additional more variable features include optic atrophy, cardiomyopathy, and leukodystrophy. Laboratory studies show increased serum glycine and lactate. Most patients die in childhood. The disorder represents a form of 'variant' nonketotic hyperglycinemia and is distinct from classic nonketotic hyperglycinemia (NKH, or GCE; 605899), which is characterized by significantly increased CSF glycine. Several forms of 'variant' NKH, including MMDS2, appear to result from defects of mitochondrial lipoate biosynthesis (summary by Baker et al., 2014). For a general description and a discussion of genetic heterogeneity of multiple mitochondrial dysfunctions syndrome, see MMDS1 (605711).
Cognitive impairment with or without cerebellar ataxia
MedGen UID:
482045
Concept ID:
C3280415
Disease or Syndrome
SCN8A-related epilepsy with encephalopathy is characterized by developmental delay, seizure onset in the first 18 months of life (mean 4 months), and intractable epilepsy characterized by multiple seizure types (generalized tonic-clonic seizures, infantile spasms, and absence and focal seizures). Epilepsy syndromes can include Lennox-Gastaut syndrome, West syndrome, and epileptic encephalopathies (e.g., Dravet syndrome). Hypotonia and movement disorders including dystonia, ataxia, and choreoathetosis are common. Psychomotor development varies from normal prior to seizure onset (with subsequent slowing or regression after seizure onset) to abnormal from birth. Intellectual disability, present in all, ranges from mild to severe (in ~50% of affected individuals). Autistic features are noted in some. Sudden unexpected death in epilepsy (SUDEP) of unknown cause has been reported in approximately 10% of published cases. To date SCN8A-related epilepsy with encephalopathy has been reported in the literature in about 50 individuals.
Alpha-methylacyl-CoA racemase deficiency
MedGen UID:
482058
Concept ID:
C3280428
Disease or Syndrome
AMACR deficiency is a rare autosomal recessive peroxisomal disorder characterized by adult onset of variable neurodegenerative symptoms affecting the central and peripheral nervous systems. Features may include seizures, visual failure, sensorimotor neuropathy, spasticity, migraine, and white matter hyperintensities on brain imaging. Serum pristanic acid and C27 bile acid intermediates are increased (summary by Smith et al., 2010).
Autosomal recessive spinocerebellar ataxia 12
MedGen UID:
482082
Concept ID:
C3280452
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-12 is a neurologic disorder characterized by onset of generalized seizures in infancy, delayed psychomotor development with mental retardation, and cerebellar ataxia. Some patients may also show spasticity (summary by Mallaret et al., 2014).
Hypomyelinating leukodystrophy 8 with or without oligodontia and-or hypogonadotropic hypogonadism
MedGen UID:
482274
Concept ID:
C3280644
Disease or Syndrome
POLR3-related leukodystrophy, a hypomyelinating leukodystrophy with specific features on brain MRI, is characterized by varying combinations of four major clinical findings: Neurologic dysfunction, typically predominated by motor dysfunction (progressive cerebellar dysfunction, and to a lesser extent extrapyramidal [i.e., dystonia], pyramidal [i.e., spasticity] and cognitive dysfunctions). Abnormal dentition (delayed dentition, hypodontia, oligodontia, and abnormally placed or shaped teeth). Endocrine abnormalities such as short stature (in ~50% of individuals) with or without growth hormone deficiency, and more commonly, hypogonadotropic hypogonadism manifesting as delayed, arrested, or absent puberty. Ocular abnormality in the form of myopia, typically progressing over several years and becoming severe. POLR3-related leukodystrophy and 4H leukodystrophy are the two recognized terms for five previously described overlapping clinical phenotypes (initially described as distinct entities before their molecular basis was known). These include: Hypomyelination, hypodontia, hypogonadotropic hypogonadism (4H syndrome); Ataxia, delayed dentition, and hypomyelination (ADDH); Tremor-ataxia with central hypomyelination (TACH); Leukodystrophy with oligodontia (LO); Hypomyelination with cerebellar atrophy and hypoplasia of the corpus callosum (HCAHC). Age of onset is typically in early childhood but later-onset cases have also been reported. An infant with Wiedemann-Rautenstrauch syndrome (neonatal progeroid syndrome) was recently reported to have pathogenic variants in POLR3A on exome sequencing. Confirmation of this as a very severe form of POLR3-related leukodystrophy awaits replication in other individuals with a clinical diagnosis of Wiedemann-Rautenstrauch syndrome.
Joubert syndrome 14
MedGen UID:
482396
Concept ID:
C3280766
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Childhood encephalopathy due to thiamine pyrophosphokinase deficiency
MedGen UID:
482496
Concept ID:
C3280866
Disease or Syndrome
Thiamine metabolism dysfunction syndrome-5 (THMD5) is an autosomal recessive metabolic disorder due to an inborn error of thiamine metabolism. The phenotype is highly variable, but in general, affected individuals have onset in early childhood of acute encephalopathic episodes associated with increased serum and CSF lactate. These episodes result in progressive neurologic dysfunction manifest as gait disturbances, ataxia, dystonia, and spasticity, which in some cases may result in loss of ability to walk. Cognitive function is usually preserved, although mildly delayed development has been reported. These episodes are usually associated with infection and metabolic decompensation. Some patients may have recovery of some neurologic deficits (Mayr et al., 2011). For a discussion of genetic heterogeneity of disorders due to thiamine metabolism dysfunction, see THMD1 (249270).
Joubert syndrome 15
MedGen UID:
482527
Concept ID:
C3280897
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Spastic ataxia 5
MedGen UID:
482607
Concept ID:
C3280977
Disease or Syndrome
Spastic ataxia-5 (SPAX5) is an autosomal recessive neurodegenerative disorder characterized by early-onset spasticity resulting in significantly impaired ambulation, cerebellar ataxia, oculomotor apraxia, dystonia, and myoclonic epilepsy (summary by Pierson et al., 2011). For a discussion of genetic heterogeneity of spastic ataxia, see SPAX1 (108600).
Infantile cerebellar-retinal degeneration
MedGen UID:
482822
Concept ID:
C3281192
Disease or Syndrome
Infantile cerebellar-retinal degeneration (ICRD) is a severe autosomal recessive neurodegenerative disorder characterized by onset between ages 2 and 6 months of truncal hypotonia, athetosis, seizures, and ophthalmologic abnormalities, particularly optic atrophy and retinal degeneration. Affected individuals show profound psychomotor retardation, with only some achieving rolling, sitting, or recognition of family. Brain MRI shows progressive cerebral and cerebellar degeneration (summary by Spiegel et al., 2012). A subset of patients may have a milder phenotype with variable features, including ataxia, developmental delay, and behavioral abnormalities (Blackburn et al., 2020). Mutation in the ACO2 gene also causes isolated optic atrophy (OPA9; 616289).
Leukoencephalopathy with calcifications and cysts
MedGen UID:
482830
Concept ID:
C3281200
Disease or Syndrome
Leukoencephalopathy, brain calcifications, and cysts (LCC), also known as Labrune syndrome, is characterized by a constellation of features restricted to the central nervous system, including leukoencephalopathy, brain calcifications, and cysts, resulting in spasticity, dystonia, seizures, and cognitive decline (summary by Labrune et al., 1996). See also cerebroretinal microangiopathy with calcifications and cysts (CRMCC; 612199), an autosomal recessive disorder caused by mutation in the CTC1 gene (613129) that shows phenotypic similarities to Labrune syndrome. CRMCC includes the neurologic findings of intracranial calcifications, leukodystrophy, and brain cysts, but also includes retinal vascular abnormalities and other systemic manifestations, such as osteopenia with poor bone healing, a high risk of gastrointestinal bleeding, hair, skin, and nail changes, and anemia and thrombocytopenia. Although Coats plus syndrome and Labrune syndrome were initially thought to be manifestations of the same disorder, namely CRMCC, molecular evidence has excluded mutations in the CTC1 gene in patients with Labrune syndrome, suggesting that the 2 disorders are not allelic (Anderson et al., 2012; Polvi et al., 2012).
Cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome
MedGen UID:
482853
Concept ID:
C3281223
Disease or Syndrome
Cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) is an autosomal recessive adult-onset, slowly progressive neurologic disorder characterized by imbalance due to cerebellar gait and limb ataxia, impaired vestibular function bilaterally, and non-length-dependent sensory neuropathy (summary by Szmulewicz et al., 2011).
Spinocerebellar ataxia type 36
MedGen UID:
483339
Concept ID:
C3472711
Disease or Syndrome
Spinocerebellar ataxia-36 (SCA36) is a slowly progressive neurodegenerative disorder characterized by adult-onset gait ataxia, eye movement abnormalities, tongue fasciculations, and variable upper motor neuron signs. Some affected individuals may develop hearing loss (summary by Garcia-Murias et al., 2012). For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (164400).
Hereditary spastic paraplegia 35
MedGen UID:
501249
Concept ID:
C3496228
Disease or Syndrome
Fatty acid hydroxylase-associated neurodegeneration (FAHN) is characterized early in the disease course by central nervous system involvement including corticospinal tract involvement (spasticity), mixed movement disorder (ataxia/dystonia), and eye findings (optic atrophy, oculomotor abnormalities), and later in the disease course by progressive intellectual impairment and seizures. With disease progression, dystonia and spasticity compromise the ability to ambulate, leading to wheelchair dependence. Life expectancy is variable. FAHN is considered to be a subtype of neurodegeneration with brain iron accumulation (NBIA).
Neuronal ceroid lipofuscinosis 11
MedGen UID:
761331
Concept ID:
C3539123
Disease or Syndrome
Neuronal ceroid lipofuscinosis-11 is an autosomal recessive neurologic disorder characterized by rapidly progressive visual loss due to retinal dystrophy, seizures, cerebellar ataxia, and cerebellar atrophy. Cognitive decline may also occur (summary by Smith et al., 2012). For a general phenotypic description and a discussion of genetic heterogeneity of CLN, see CLN1 (256730).
Myoclonus, familial, 1
MedGen UID:
761667
Concept ID:
C3539916
Disease or Syndrome
Familial myoclonus-1 is an autosomal dominant neurologic condition characterized by adult onset of cortical myoclonus manifest as involuntary jerks or movements affecting the face and limbs. Affected individuals can also experience falls without seizure activity or loss of consciousness (summary by Russell et al., 2012). Genetic Heterogeneity of Familial Myoclonus Also see MYOCL2 (618364), caused by mutation in the SCN8A gene (600702) on chromosome 12q13.
Pontine tegmental cap dysplasia
MedGen UID:
762040
Concept ID:
C3541340
Disease or Syndrome
Pontine tegmental cap dysplasia (PTCD) refers to a neurologic condition characterized by a distinct pattern of hindbrain malformations apparent on brain imaging. The abnormalities affect the pons, medulla, and cerebellum. In neuroradiologic studies, the ventral side of the pons is flattened, whereas there is vaulting ('capping') of the dorsal pontine border into the fourth ventricle. Affected individuals show a variety of neurologic deficits, most commonly sensorineural deafness, impaired cranial nerve function, and variable psychomotor retardation (summary by Barth et al., 2007).
Mitochondrial complex III deficiency nuclear type 1
MedGen UID:
762097
Concept ID:
C3541471
Disease or Syndrome
Autosomal recessive mitochondrial complex III deficiency is a severe multisystem disorder with onset at birth of lactic acidosis, hypotonia, hypoglycemia, failure to thrive, encephalopathy, and delayed psychomotor development. Visceral involvement, including hepatopathy and renal tubulopathy, may also occur. Many patients die in early childhood, but some may show longer survival (de Lonlay et al., 2001; De Meirleir et al., 2003). Genetic Heterogeneity of Mitochondrial Complex III Deficiency Mitochondrial complex III deficiency can be caused by mutation in several different nuclear-encoded genes. See MC3DN2 (615157), caused by mutation in the TTC19 gene (613814) on chromosome 17p12; MC3DN3 (615158), caused by mutation in the UQCRB gene (191330) on chromosome 8q; MC3DN4 (615159), caused by mutation in the UQCRQ gene (612080) on chromosome 5q31; MC3DN5 (615160), caused by mutation in the UQCRC2 gene (191329) on chromosome 16p12; MC3DN6 (615453), caused by mutation in the CYC1 gene (123980) on chromosome 8q24; MC3DN7 (615824), caused by mutation in the UQCC2 gene (614461) on chromosome 6p21; MC3DN8 (615838), caused by mutation in the LYRM7 gene (615831) on chromosome 5q23; MC3DN9 (616111), caused by mutation in the UQCC3 gene (616097) on chromosome 11q12; and MC3DN10 (618775), caused by mutation in the UQCRFS1 gene (191327) on chromosome 19q12. See also MTYCB (516020) for a discussion of a milder phenotype associated with isolated mitochondrial complex III deficiency and mutations in a mitochondrial-encoded gene.
Peroxisome biogenesis disorder 5B
MedGen UID:
762202
Concept ID:
C3542026
Disease or Syndrome
The overlapping phenotypes of neonatal adrenoleukodystrophy (NALD) and infantile Refsum disease (IRD) represent the milder manifestations of the Zellweger syndrome spectrum (ZSS) of peroxisome biogenesis disorders. The clinical course of patients with the NALD and IRD presentation is variable and may include developmental delay, hypotonia, liver dysfunction, sensorineural hearing loss, retinal dystrophy, and visual impairment. Children with the NALD presentation may reach their teens, and those with the IRD presentation may reach adulthood (summary by Waterham and Ebberink, 2012). For a complete phenotypic description and a discussion of genetic heterogeneity of PBD(NALD/IRD), see 601539. Individuals with mutations in the PEX2 gene have cells of complementation group 5 (CG5, equivalent to CG10 and CGF). For information on the history of PBD complementation groups, see 214100.
Peroxisome biogenesis disorder type 3B
MedGen UID:
763607
Concept ID:
C3550693
Disease or Syndrome
Zellweger spectrum disorder (ZSD) is a phenotypic continuum ranging from severe to mild. While individual phenotypes (e.g., Zellweger syndrome [ZS], neonatal adrenoleukodystrophy [NALD], and infantile Refsum disease [IRD]) were described in the past before the biochemical and molecular bases of this spectrum were fully determined, the term "ZSD" is now used to refer to all individuals with a defect in one of the ZSD-PEX genes regardless of phenotype. Individuals with ZSD usually come to clinical attention in the newborn period or later in childhood. Affected newborns are hypotonic and feed poorly. They have distinctive facies, congenital malformations (neuronal migration defects associated with neonatal-onset seizures, renal cysts, and bony stippling [chondrodysplasia punctata] of the patella[e] and the long bones), and liver disease that can be severe. Infants with severe ZSD are significantly impaired and typically die during the first year of life, usually having made no developmental progress. Individuals with intermediate/milder ZSD do not have congenital malformations, but rather progressive peroxisome dysfunction variably manifest as sensory loss (secondary to retinal dystrophy and sensorineural hearing loss), neurologic involvement (ataxia, polyneuropathy, and leukodystrophy), liver dysfunction, adrenal insufficiency, and renal oxalate stones. While hypotonia and developmental delays are typical, intellect can be normal. Some have osteopenia; almost all have ameleogenesis imperfecta in the secondary teeth.
Coenzyme Q10 deficiency, primary, 1
MedGen UID:
764868
Concept ID:
C3551954
Disease or Syndrome
Primary coenzyme Q10 (CoQ10) deficiency is usually associated with multisystem involvement, including neurologic manifestations such as fatal neonatal encephalopathy with hypotonia; a late-onset slowly progressive multiple-system atrophy-like phenotype (neurodegeneration with autonomic failure and various combinations of parkinsonism and cerebellar ataxia, and pyramidal dysfunction); and dystonia, spasticity, seizures, and intellectual disability. Steroid-resistant nephrotic syndrome (SRNS), the hallmark renal manifestation, is often the initial manifestation either as isolated renal involvement that progresses to end-stage renal disease (ESRD), or associated with encephalopathy (seizures, stroke-like episodes, severe neurologic impairment) resulting in early death. Hypertrophic cardiomyopathy (HCM), retinopathy or optic atrophy, and sensorineural hearing loss can also be seen.
Joubert syndrome 17
MedGen UID:
766178
Concept ID:
C3553264
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Brown-Vialetto-van Laere syndrome 2
MedGen UID:
766452
Concept ID:
C3553538
Disease or Syndrome
Brown-Vialetto-Van Laere syndrome-2 (BVVLS2) is an autosomal recessive progressive neurologic disorder characterized by early childhood onset of sensorineural deafness, bulbar dysfunction, and severe diffuse muscle weakness and wasting of the upper and lower limbs and axial muscles, resulting in respiratory insufficiency. Some patients may lose independent ambulation. Because it results from a defect in riboflavin metabolism, some patients may benefit from high-dose riboflavin supplementation (summary by Johnson et al., 2012; Foley et al., 2014). For discussion of genetic heterogeneity of Brown-Vialetto-Van Laere syndrome, see BVVLS1 (211530).
Cerebellar dysfunction with variable cognitive and behavioral abnormalities
MedGen UID:
766575
Concept ID:
C3553661
Disease or Syndrome
Cerebellar dysfunction with variable cognitive and behavioral abnormalities (CECBA) is an autosomal dominant neurologic disorder with significant phenotypic heterogeneity, even within families. The disorder is most often diagnosed through genetic analysis with retrospective clinical phenotyping. Symptom onset is usually in early childhood, although later onset, even in adulthood, has been reported. Most affected individuals show global developmental delay from early childhood, particularly of motor and language skills. Many have mild intellectual disability; behavioral and psychiatric abnormalities such as autism and obsessive-compulsive disorder are also often observed. The movement disorder is prominent and may include cerebellar signs such as ataxia, tremor, dysmetria, poor coordination, and dysarthria. Other abnormal movements including spasticity, myoclonus, and dystonia have been reported, thus widening the phenotypic spectrum. Brain imaging is usually normal, but may show cerebellar atrophy or nonspecific white matter lesions. Variable dysmorphic facial features may also be present (summary by Thevenon et al., 2012; Jacobs et al., 2021; Wijnen et al., 2020).
Alternating hemiplegia of childhood 2
MedGen UID:
766702
Concept ID:
C3553788
Disease or Syndrome
ATP1A3-related neurologic disorders represent a clinical continuum in which at least three distinct phenotypes have been delineated: rapid-onset dystonia-parkinsonism (RDP); alternating hemiplegia of childhood (ACH); and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS). However, some affected individuals have intermediate phenotypes or only a few features that do not fit well into one of these major phenotypes. RDP has been characterized by: abrupt onset of dystonia over days to weeks with parkinsonism (primarily bradykinesia and postural instability); common bulbar involvement; and absence or minimal response to an adequate trial of L-dopa therapy, with few exceptions. Often fever, physiologic stress, or alcoholic binges trigger the onset of symptoms. After their initial appearance, symptoms often stabilize with little improvement; occasionally second episodes occur with abrupt worsening of symptoms. Rarely, affected individuals have reported a more gradual onset of symptoms over weeks to months. Anxiety, depression, and seizures have been reported. Age of onset ranges from four to 55 years, although a childhood variation of RDP with onset between ages nine and 14 months has been reported. AHC is a complex neurodevelopmental syndrome most frequently manifesting in infancy or early childhood with paroxysmal episodic neurologic dysfunction including alternating hemiparesis or dystonia, quadriparesis, seizure-like episodes, and oculomotor abnormalities. Episodes can last for minutes, hours, days, or even weeks. Remission of symptoms occurs with sleep and immediately after awakening. Over time, persistent neurologic deficits including oculomotor apraxia, ataxia, choreoathetosis, dystonia, parkinsonism, and cognitive and behavioral dysfunction develop in the majority of those affected; more than 50% develop epilepsy in addition to their episodic movement disorder phenotype. CAPOS (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss) syndrome is characterized by episodes of ataxic encephalopathy and/or weakness during and after a febrile illness. Onset is between ages six months and four years. Some acute symptoms resolve; progression of sensory losses and severity vary.
Autosomal recessive spinocerebellar ataxia 13
MedGen UID:
766730
Concept ID:
C3553816
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-13 (SCAR13) is an autosomal recessive neurologic disorder characterized by delayed psychomotor development beginning in infancy. Affected individuals show mildly to profoundly impaired intellectual development with poor or absent speech as well as gait and stance ataxia and hyperreflexia. Most individuals also have eye movement abnormalities. Brain MRI shows cerebellar atrophy and ventriculomegaly (Guergueltcheva et al., 2012).
Peroxisome biogenesis disorder 4B
MedGen UID:
766851
Concept ID:
C3553937
Disease or Syndrome
Peroxisome biogenesis disorder-4B (PBD4B) includes the overlapping phenotypes of neonatal adrenoleukodystrophy (NALD) and infantile Refsum disease (IRD), which represent milder manifestations of the Zellweger syndrome spectrum (ZSS) of peroxisome biogenesis disorders (PBDs). The clinical course of patients with the NALD and IRD presentation is variable and may include developmental delay, hypotonia, liver dysfunction, sensorineural hearing loss, retinal dystrophy, and visual impairment. Children with the NALD presentation may reach their teens, and those with the IRD presentation may reach adulthood (summary by Waterham and Ebberink, 2012). For a complete phenotypic description and a discussion of genetic heterogeneity of PBD(NALD/IRD), see 601539. Individuals with mutations in the PEX6 gene have cells of complementation group 4 (CG4, equivalent to CG6 and CGC). For information on the history of PBD complementation groups, see 214100.
Peroxisome biogenesis disorder 6B
MedGen UID:
766862
Concept ID:
C3553948
Disease or Syndrome
The overlapping phenotypes of neonatal adrenoleukodystrophy (NALD) and infantile Refsum disease (IRD) represent the milder manifestations of the Zellweger syndrome spectrum (ZSS) of peroxisome biogenesis disorders. The clinical course of patients with the NALD and IRD presentation is variable and may include developmental delay, hypotonia, liver dysfunction, sensorineural hearing loss, retinal dystrophy, and visual impairment. Children with the NALD presentation may reach their teens, and those with the IRD presentation may reach adulthood. Some patients with PEX10 mutations have a milder disorder characterized by childhood-onset cerebellar ataxia and neuropathy without mental retardation (summary by Waterham and Ebberink, 2012). For a complete phenotypic description and a discussion of genetic heterogeneity of PBD(NALD/IRD), see 601539. Individuals with mutations in the PEX10 gene have cells of complementation group 7 (CG7, equivalent to CGB). For information on the history of PBD complementation groups, see 214100.
Peroxisome biogenesis disorder 8B
MedGen UID:
766874
Concept ID:
C3553960
Disease or Syndrome
The overlapping phenotypes of neonatal adrenoleukodystrophy (NALD) and infantile Refsum disease (IRD) represent the milder manifestations of the Zellweger syndrome spectrum (ZSS) of peroxisome biogenesis disorders. The clinical course of patients with the NALD and IRD presentation is variable and may include developmental delay, hypotonia, liver dysfunction, sensorineural hearing loss, retinal dystrophy, and visual impairment. Children with the NALD presentation may reach their teens, and those with the IRD presentation may reach adulthood (summary by Waterham and Ebberink, 2012). For a complete phenotypic description and a discussion of genetic heterogeneity of PBD(NALD/IRD), see 601539. Individuals with mutations in the PEX16 gene have cells of complementation group 9 (CG9, equivalent to CGD). For information on the history of PBD complementation groups, see 214100.
Pontocerebellar hypoplasia type 7
MedGen UID:
767140
Concept ID:
C3554226
Disease or Syndrome
Pontocerebellar hypoplasia type 7 (PCH7) is a severe neurologic condition characterized by delayed psychomotor development, hypotonia, breathing abnormalities, and gonadal abnormalities (summary by Anderson et al., 2011). For a general phenotypic description and a discussion of genetic heterogeneity of PCH, see PCH1 (607596).
Mitochondrial complex III deficiency nuclear type 2
MedGen UID:
767519
Concept ID:
C3554605
Disease or Syndrome
Mitochondrial complex III deficiency nuclear type 2 is an autosomal recessive severe neurodegenerative disorder that usually presents in childhood, but may show later onset, even in adulthood. Affected individuals have motor disability, with ataxia, apraxia, dystonia, and dysarthria, associated with necrotic lesions throughout the brain. Most patients also have cognitive impairment and axonal neuropathy and become severely disabled later in life (summary by Ghezzi et al., 2011). The disorder may present clinically as spinocerebellar ataxia or Leigh syndrome, or with psychiatric disturbances (Morino et al., 2014; Atwal, 2014; Nogueira et al., 2013). For a discussion of genetic heterogeneity of mitochondrial complex III deficiency, see MC3DN1 (124000).
Mitochondrial complex III deficiency nuclear type 4
MedGen UID:
767521
Concept ID:
C3554607
Disease or Syndrome
Mitochondrial complex III deficiency can be fatal in childhood, although individuals with mild signs and symptoms can survive into adolescence or adulthood.\n\nMost people with mitochondrial complex III deficiency have a buildup of a chemical called lactic acid in the body (lactic acidosis). Some affected individuals also have buildup of molecules called ketones (ketoacidosis) or high blood glucose levels (hyperglycemia). Abnormally high levels of these chemicals in the body can be life-threatening.\n\nThe severity of mitochondrial complex III deficiency varies widely among affected individuals. People who are mildly affected tend to have muscle weakness (myopathy) and extreme tiredness (fatigue), particularly during exercise (exercise intolerance). More severely affected individuals have problems with multiple body systems, such as liver disease that can lead to liver failure, kidney abnormalities (tubulopathy), and brain dysfunction (encephalopathy). Encephalopathy can cause delayed development of mental and motor skills (psychomotor delay), movement problems, weak muscle tone (hypotonia), and difficulty with communication. Some affected individuals have a form of heart disease called cardiomyopathy, which can lead to heart failure. \n\nMitochondrial complex III deficiency is a genetic condition that can affect several parts of the body, including the brain, kidneys, liver, heart, and the muscles used for movement (skeletal muscles). Signs and symptoms of mitochondrial complex III deficiency usually begin in infancy but can appear later.
Ataxia with oculomotor apraxia type 3
MedGen UID:
767604
Concept ID:
C3554690
Disease or Syndrome
AOA3 is an autosomal recessive progressive neurologic disorder with onset in the second decade of life (Al Tassan et al., 2012). For a discussion of genetic heterogeneity of ataxia-oculomotor apraxia, see AOA1 (208920).
Multiple system atrophy 1, susceptibility to
MedGen UID:
811503
Concept ID:
C3714927
Finding
Multiple system atrophy (MSA) is a distinct clinicopathologic entity that manifests as a progressive adult-onset neurodegenerative disorder causing parkinsonism, cerebellar ataxia, and autonomic, urogenital, and pyramidal dysfunction in various combinations. Two main subtypes are recognized: 'subtype C,' characterized predominantly by cerebellar ataxia, and 'subtype P,' characterized predominantly by parkinsonism. MSA is characterized pathologically by the degeneration of striatonigral and olivopontocerebellar structures and glial cytoplasmic inclusions (GCIs) that consist of abnormally phosphorylated alpha-synuclein (SNCA; 163890) or tau (MAPT; 157140) (Gilman et al., 1998; Gilman et al., 2008; Scholz et al., 2009). 'Subtype C' of MSA has been reported to be more prevalent than 'subtype P' in the Japanese population (65-67% vs 33-35%), whereas 'subtype P' has been reported to be more prevalent than 'subtype C' in Europe (63% vs 34%) and North America (60% vs 13%, with 27% of cases unclassified) (summary by The Multiple-System Atrophy Research Collaboration, 2013). MSA is similar clinically and pathologically to Parkinson disease (PD; 168600) and Lewy body dementia (127750). See also PARK1 (168601), which is specifically caused by mutation in the SNCA gene. Pure autonomic failure manifests as orthostatic hypotension and other autonomic abnormalities without other neurologic involvement. Although there is some phenotypic overlap, the relationship of pure autonomic failure to MSA is unclear (Vanderhaeghen et al., 1970; Schatz, 1996).
Neuronal ceroid lipofuscinosis 13
MedGen UID:
811566
Concept ID:
C3715049
Disease or Syndrome
Neuronal ceroid lipofuscinosis-13 (CLN13) is an autosomal recessive neurodegenerative disorder characterized by adult onset of progressive cognitive decline and motor dysfunction leading to dementia and often early death. Some patients develop seizures. Neurons show abnormal accumulation of autofluorescent material (summary by Smith et al., 2013). Adult-onset neuronal ceroid lipofuscinosis is sometimes referred to as Kufs disease (see 204300). In a review of the classification of CLN disease, Gardner and Mole (2021) noted that the CLN13 phenotype corresponds to 'Kufs type B', which is characterized by dementia and a variety of motor signs (Smith et al., 2013). For a discussion of genetic heterogeneity of neuronal ceroid lipofuscinosis (CLN), see CLN1 (256730).
X-linked intellectual disability, Cantagrel type
MedGen UID:
813060
Concept ID:
C3806730
Disease or Syndrome
X-linked intellectual developmental disorder-98 (XLID98) is a neurodevelopmental disorder characterized by delayed psychomotor development, poor speech, behavioral abnormalities, poor overall growth, dysmorphic facial features, and often early-onset seizures. Some carrier females are unaffected, whereas other females with mutations are affected; males tend to be more severely affected than females. It is believed that the phenotypic variability and disease manifestations in female carriers results from skewed X-inactivation or cellular mosaicism (summary by de Lange et al., 2016).
Autosomal dominant cerebellar ataxia, deafness and narcolepsy
MedGen UID:
813625
Concept ID:
C3807295
Disease or Syndrome
ADCADN is an autosomal dominant neurologic disorder characterized by adult onset of progressive cerebellar ataxia, narcolepsy/cataplexy, sensorineural deafness, and dementia. More variable features include optic atrophy, sensory neuropathy, psychosis, and depression (summary by Winkelmann et al., 2012).
Muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A14
MedGen UID:
815546
Concept ID:
C3809216
Disease or Syndrome
Multiple congenital anomalies-hypotonia-seizures syndrome 3
MedGen UID:
815686
Concept ID:
C3809356
Disease or Syndrome
Multiple congenital anomalies-hypotonia-seizures syndrome is an autosomal recessive disorder characterized by neonatal hypotonia, lack of psychomotor development, seizures, dysmorphic features, and variable congenital anomalies involving the cardiac, urinary, and gastrointestinal systems. Most affected individuals die before 3 years of age (summary by Maydan et al., 2011). The disorder is caused by a defect in glycosylphosphatidylinositol (GPI) biosynthesis. For a discussion of genetic heterogeneity of MCAHS, see MCAHS1 (614080). For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293).
Mitochondrial DNA depletion syndrome 13
MedGen UID:
815922
Concept ID:
C3809592
Disease or Syndrome
FBXL4-related encephalomyopathic mitochondrial DNA (mtDNA) depletion syndrome is a multi-system disorder characterized primarily by congenital or early-onset lactic acidosis and growth failure, feeding difficulty, hypotonia, and developmental delay. Other neurologic manifestations can include seizures, movement disorders, ataxia, autonomic dysfunction, and stroke-like episodes. All affected individuals alive at the time they were reported (median age: 3.5 years) demonstrated significant developmental delay. Other findings can involve the heart (hypertrophic cardiomyopathy, congenital heart malformations, arrhythmias), liver (mildly elevated transaminases), eyes (cataract, strabismus, nystagmus, optic atrophy), hearing (sensorineural hearing loss), and bone marrow (neutropenia, lymphopenia). Survival varies; the median age of reported deaths was two years (range 2 days – 75 months), although surviving individuals as old as 36 years have been reported. To date FBXL4-related mtDNA depletion syndrome has been reported in 50 individuals.
Early-onset progressive neurodegeneration-blindness-ataxia-spasticity syndrome
MedGen UID:
815995
Concept ID:
C3809665
Disease or Syndrome
Spastic paraplegia-79B (SPG79B) is an autosomal recessive progressive neurologic disorder characterized by onset of spastic paraplegia and optic atrophy in the first decade of life. Additional features are variable, but may include peripheral neuropathy, cerebellar ataxia, and cognitive impairment (summary by Rydning et al., 2017). For a discussion of genetic heterogeneity of autosomal recessive spastic paraplegia, see SPG5A (270800).
Hereditary spastic paraplegia 72
MedGen UID:
816490
Concept ID:
C3810160
Disease or Syndrome
Hereditary spastic paraplegia-72A (SPG72A) is a pure form of spastic paraplegia with onset of difficulty walking and stiff legs associated with hyperreflexia and extensor plantar responses in early childhood. The disorder is slowly progressive, and some patients develop the need for assistance in walking. Some patients may have pes cavus or sphincter disturbances. Cognition, speech, and ocular function are normal (summary by Esteves et al., 2014). For a discussion of genetic heterogeneity of autosomal dominant spastic paraplegia, see SPG3A (182600).
Joubert syndrome 21
MedGen UID:
816542
Concept ID:
C3810212
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Proximal myopathy with extrapyramidal signs
MedGen UID:
816615
Concept ID:
C3810285
Disease or Syndrome
Myopathy with extrapyramidal signs is an autosomal recessive disorder characterized by early childhood onset of proximal muscle weakness and learning disabilities. While the muscle weakness is static, most patients develop progressive extrapyramidal signs that may become disabling (summary by Logan et al., 2014). Brain MRI in 1 patient showed congenital malformations, including polymicrogyria and cerebellar dysplasia (Wilton et al., 2020).
Autosomal recessive spinocerebellar ataxia 15
MedGen UID:
816656
Concept ID:
C3810326
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-15 (SCAR15) is characterized by early-onset ataxia, cognitive impairment, dysarthria, and developmental delay. Variable features include seizures, nystagmus, and abnormal reflexes (Seidahmed et al., 2020).
Vasculitis due to ADA2 deficiency
MedGen UID:
854497
Concept ID:
C3887654
Disease or Syndrome
Adenosine deaminase 2 deficiency (DADA2) is a complex systemic autoinflammatory disorder in which vasculopathy/vasculitis, dysregulated immune function, and/or hematologic abnormalities may predominate. Inflammatory features include intermittent fevers, rash (often livedo racemosa/reticularis), and musculoskeletal involvement (myalgia/arthralgia, arthritis, myositis). Vasculitis, which usually begins before age ten years, may manifest as early-onset ischemic (lacunar) and/or hemorrhagic strokes, or as cutaneous or systemic polyarteritis nodosa. Hypertension and hepatosplenomegaly are often found. More severe involvement may lead to progressive central neurologic deficits (dysarthria, ataxia, cranial nerve palsies, cognitive impairment) or to ischemic injury to the kidney, intestine, and/or digits. Dysregulation of immune function can lead to immunodeficiency or autoimmunity of varying severity; lymphadenopathy may be present and some affected individuals have had lymphoproliferative disease. Hematologic disorders may begin early in life or in late adulthood, and can include lymphopenia, neutropenia, pure red cell aplasia, thrombocytopenia, or pancytopenia. Of note, both interfamilial and intrafamilial phenotypic variability (e.g., in age of onset, frequency and severity of manifestations) can be observed; also, individuals with biallelic ADA2 pathogenic variants may remain asymptomatic until adulthood or may never develop clinical manifestations of DADA2.
Spinocerebellar ataxia type 35
MedGen UID:
854733
Concept ID:
C3888031
Disease or Syndrome
Spinocerebellar ataxia-35 (SCA35) is an autosomal dominant adult-onset neurologic disorder characterized by difficulty walking due to cerebellar ataxia. The age at onset ranges from teenage years to late adulthood, and the disorder is slowly progressive. Additional features may include hand tremor, dysarthria, hyperreflexia, and saccadic eye movements (summary by Guo et al., 2014). For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (164400).
Spinocerebellar ataxia type 37
MedGen UID:
855217
Concept ID:
C3889636
Disease or Syndrome
Spinocerebellar ataxia type 37 (SCA37) is characterized by adult onset, dysarthria, slowly progressive gait and limb ataxia with severe dysmetria in the lower extremities, mild dysmetria in the upper extremities, dysphagia, and abnormal ocular movements (dysmetric vertical saccades, irregular and slow vertical smooth pursuit, slow vertical optokinetic nystagmus, and oscillopsia (visual disturbance in which objects appear to oscillate). In most individuals, the initial signs/symptoms include falls, dysarthria, or clumsiness followed by a complete cerebellar syndrome. A distinctive clinical feature is the presence of altered vertical eye movements in early stages of the disease, even preceding ataxia symptoms. Clinical progression is slow and affected individuals usually become wheelchair bound between ten and 33 years after disease onset.
Ataxia-telangiectasia-like disorder 1
MedGen UID:
861227
Concept ID:
C4012790
Disease or Syndrome
Ataxia-telangiectasia-like disorder-1 is an autosomal recessive disorder characterized clinically by progressive cerebellar degeneration resulting in ataxia and oculomotor apraxia. Laboratory studies of patient cells showed increased susceptibility to radiation, consistent with a defect in DNA repair. The disorder shares some phenotypic features of ataxia-telangiectasia (AT; 208900), but telangiectases and immune deficiency are not present in ATLD1 (summary by Hernandez et al., 1993 and Stewart et al., 1999). Genetic Heterogeneity of Ataxia-Telangiectasia-Like Disorder See also ATLD2 (615919), caused by mutation in the PCNA gene (176740) on chromosome 20p12.
Complex cortical dysplasia with other brain malformations 6
MedGen UID:
862720
Concept ID:
C4014283
Disease or Syndrome
Any complex cortical dysplasia with other brain malformations in which the cause of the disease is a mutation in the TUBB gene.
Immunodeficiency 23
MedGen UID:
862808
Concept ID:
C4014371
Disease or Syndrome
IMD23 is an autosomal recessive primary immunodeficiency syndrome characterized by onset of recurrent infections, usually respiratory or cutaneous, in early childhood. Immune workup usually shows neutropenia, lymphopenia, eosinophilia, and increased serum IgE or IgA. Neutrophil chemotactic defects have also been reported. Infectious agents include bacteria, viruses, and fungi. Many patients develop atopic dermatitis, eczema, and other signs of autoinflammation. Affected individuals may also show developmental delay or cognitive impairment of varying severity (summary by Bjorksten and Lundmark, 1976 and Zhang et al., 2014).
Mitochondrial complex III deficiency nuclear type 8
MedGen UID:
862877
Concept ID:
C4014440
Disease or Syndrome
Mitochondrial complex III deficiency, nuclear type 8, is an autosomal recessive disorder characterized by progressive neurodegeneration with onset in childhood. Affected individuals may have normal or delayed early development, and often have episodic acute neurologic decompensation and regression associated with febrile illnesses. The developmental regression results in variable intellectual disability and motor deficits, such as hypotonia, axial hypertonia, and spasticity; some patients may lose the ability to walk independently. Laboratory studies show increased serum lactate and isolated deficiency of mitochondrial complex III in skeletal muscle and fibroblasts. Brain imaging shows a characteristic pattern of multifocal small cystic lesions in the periventricular and deep cerebral white matter (summary by Dallabona et al., 2016). For a discussion of genetic heterogeneity of mitochondrial complex III deficiency, see MC3DN1 (124000).
Developmental and epileptic encephalopathy, 24
MedGen UID:
862968
Concept ID:
C4014531
Disease or Syndrome
Developmental and epileptic encephalopathy-24 (DEE24) is a neurologic disorder characterized by onset of refractory seizures in infancy, severely impaired global development, intellectual disability, and behavioral abnormalities. Most patients have onset of variable types of seizures between 4 and 13 months of age, but earlier onset in the first days of life has also been reported. Seizures are often triggered by fever, at least initially; status epilepticus may occur (summary by Nava et al., 2014 and Marini et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Leukoencephalopathy, progressive, with ovarian failure
MedGen UID:
863025
Concept ID:
C4014588
Disease or Syndrome
Progressive leukoencephalopathy with ovarian failure is an autosomal recessive neurodegenerative disorder characterized by loss of motor and cognitive skills, usually with onset in young adulthood. Some patients may have a history of delayed motor development or learning difficulties in early childhood. Neurologic decline is severe, usually resulting in gait difficulties, ataxia, spasticity, and cognitive decline and dementia. Most patients lose speech and become wheelchair-bound or bedridden. Brain MRI shows progressive white matter signal abnormalities in the deep white matter. Affected females develop premature ovarian failure (summary by Dallabona et al., 2014).
Developmental and epileptic encephalopathy, 25
MedGen UID:
863058
Concept ID:
C4014621
Disease or Syndrome
Developmental and epileptic encephalopathy-25 with amelogenesis imperfecta (DEE25) is an autosomal recessive neurologic disorder characterized by the onset of refractory seizures in early infancy. Most patients present with seizures in the neonatal period, which is often associated with status epilepticus. However, there is phenotypic variability, and some patients have onset of seizures later in infancy. Affected individuals show global developmental delay with intellectual disability and poor speech and communication. The seizures may remit somewhat with age, but there are persistent neurologic symptoms, including ataxia, spasticity, and abnormal involuntary movements. In addition to neurologic deficits, patients also have dental anomalies with amelogenesis imperfecta (summary by Thevenon et al., 2014 and Schossig et al., 2017). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Frontotemporal dementia and/or amyotrophic lateral sclerosis 2
MedGen UID:
863085
Concept ID:
C4014648
Disease or Syndrome
CHCHD10-related disorders are characterized by a spectrum of adult-onset neurologic phenotypes that can include: Mitochondrial myopathy (may also be early onset): weakness, amyotrophy, exercise intolerance. Amyotrophic lateral sclerosis (ALS): progressive degeneration of upper motor neurons and lower motor neurons. Frontotemporal dementia (FTD): slowly progressive behavioral changes, language disturbances, cognitive decline, extrapyramidal signs. Late-onset spinal motor neuronopathy (SMA, Jokela type): weakness, cramps, and/or fasciculations; areflexia. Axonal Charcot-Marie-Tooth neuropathy: slowly progressive lower-leg muscle weakness and atrophy, small hand muscle weakness, loss of tendon reflexes, sensory abnormalities. Cerebellar ataxia: gait ataxia, kinetic ataxia (progressive loss of coordination of lower- and upper-limb movements), dysarthria/dysphagia, nystagmus, cerebellar oculomotor disorder. Because of the recent discovery of CHCHD10-related disorders and the limited number of affected individuals reported to date, the natural history of these disorders (except for SMAJ caused by the p.Gly66Val pathogenic variant) is largely unknown.
Combined oxidative phosphorylation defect type 20
MedGen UID:
863097
Concept ID:
C4014660
Disease or Syndrome
Combined oxidative phosphorylation defect type 20 is a rare mitochondrial oxidative phosphorylation disorder characterized by variable combination of psychomotor delay, hypotonia, muscle weakness, seizures, microcephaly, cardiomyopathy and mild dysmorphic facial features. Variable types of structural brain anomalies have also been reported. Biochemical studies typically show decreased activity of mitochondrial complexes (mainly complex I).
Ataxia-telangiectasia-like disorder 2
MedGen UID:
863113
Concept ID:
C4014676
Disease or Syndrome
Ataxia-telangiectasia-like disorder-2 is an autosomal recessive syndrome resulting from defects in DNA excision repair. Affected individuals have a neurodegenerative phenotype characterized by developmental delay, ataxia, and sensorineural hearing loss. Other features include short stature, cutaneous and ocular telangiectasia, and photosensitivity (summary by Baple et al., 2014). For a discussion of genetic heterogeneity of ATLD, see ATLD1 (604391).
Severe neurodegenerative syndrome with lipodystrophy
MedGen UID:
863137
Concept ID:
C4014700
Disease or Syndrome
The spectrum of BSCL2-related neurologic disorders includes Silver syndrome and variants of Charcot-Marie-Tooth neuropathy type 2, distal hereditary motor neuropathy (dHMN) type V, and spastic paraplegia 17. Features of these disorders include onset of symptoms ranging from the first to the seventh decade, slow disease progression, upper motor neuron involvement (gait disturbance with pyramidal signs ranging from mild to severe spasticity with hyperreflexia in the lower limbs and variable extensor plantar responses), lower motor neuron involvement (amyotrophy of the peroneal muscles and small muscles of the hand), and pes cavus and other foot deformities. Disease severity is variable among and within families.
Episodic ataxia type 8
MedGen UID:
863545
Concept ID:
C4015108
Disease or Syndrome
A rare hereditary ataxia characterized by recurrent episodes of ataxia with variable frequency and duration, associated with slurred speech, generalized muscle weakness and balance disturbance. Other symptoms may occur between episodes, including intention tremor, gait ataxia, mild dysarthria, myokymia, migraine and nystagmus.
Congenital sideroblastic anemia-B-cell immunodeficiency-periodic fever-developmental delay syndrome
MedGen UID:
863609
Concept ID:
C4015172
Disease or Syndrome
Sideroblastic anemia with B-cell immunodeficiency, periodic fevers, and developmental delay (SIFD) is an autosomal recessive syndromic disorder characterized by onset of severe sideroblastic anemia in the neonatal period or infancy. Affected individuals show delayed psychomotor development with variable neurodegeneration. Recurrent periodic fevers without an infectious etiology occur throughout infancy and childhood; immunologic work-up shows B-cell lymphopenia and hypogammaglobulinemia. Other more variable features include sensorineural hearing loss, retinitis pigmentosa, nephrocalcinosis, and cardiomyopathy. Death in the first decade may occur (summary by Wiseman et al., 2013).
Polyendocrine-polyneuropathy syndrome
MedGen UID:
863698
Concept ID:
C4015261
Disease or Syndrome
A rare genetic disease with characteristics of childhood onset of multiple endocrine manifestations in combination with central and peripheral nervous system abnormalities. Reported signs and symptoms include postnatal growth retardation, moderate intellectual disability, hypogonadotropic hypogonadism, insulin-dependent diabetes mellitus, central hypothyroidism, demyelinating sensorimotor polyneuropathy, cerebellar and pyramidal signs. Progressive hearing loss and a hypoplastic pituitary gland have also been described. Brain imaging shows moderate white matter abnormalities.
Intellectual disability, autosomal recessive 46
MedGen UID:
863720
Concept ID:
C4015283
Mental or Behavioral Dysfunction
Any autosomal recessive non-syndromic intellectual disability in which the cause of the disease is a mutation in the NDST1 gene.
Autosomal recessive spinocerebellar ataxia 17
MedGen UID:
863738
Concept ID:
C4015301
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-17 (SCAR17) is a neurologic disorder characterized by onset of gait ataxia and cerebellar signs in early childhood. Patients also have variably impaired intellectual development (summary by Evers et al., 2016).
Perrault syndrome 5
MedGen UID:
863744
Concept ID:
C4015307
Disease or Syndrome
Perrault syndrome is characterized by sensorineural hearing loss (SNHL) in males and females and ovarian dysfunction in females. SNHL is bilateral and ranges from profound with prelingual (congenital) onset to moderate with early-childhood onset. When onset is in early childhood, hearing loss can be progressive. Ovarian dysfunction ranges from gonadal dysgenesis (absent or streak gonads) manifesting as primary amenorrhea to primary ovarian insufficiency (POI) defined as cessation of menses before age 40 years. Fertility in affected males is reported as normal (although the number of reported males is limited). Neurologic features described in some individuals with Perrault syndrome include learning difficulties and developmental delay, cerebellar ataxia, and motor and sensory peripheral neuropathy.
Hypomyelinating leukodystrophy 9
MedGen UID:
863760
Concept ID:
C4015323
Disease or Syndrome
Hypomyelinating leukodystrophy-9 is an autosomal recessive neurologic disorder characterized by onset of delayed psychomotor development, spasticity, and nystagmus in the first year of life. Additional neurologic features such as ataxia and abnormal movements may also occur. Brain imaging shows diffuse hypomyelination affecting all regions of the brain (summary by Wolf et al., 2014). For a general phenotypic description and a discussion of genetic heterogeneity of HLD, see 312080.
Progressive myoclonic epilepsy type 7
MedGen UID:
863857
Concept ID:
C4015420
Disease or Syndrome
Progressive myoclonic epilepsy-7 (EPM7) is a neurologic disorder characterized by onset of severe progressive myoclonus and infrequent tonic-clonic seizures in the first or second decades of life. Most patients become wheelchair-bound; some patients may have cognitive decline (summary by Muona et al., 2015). For a discussion of genetic heterogeneity of progressive myoclonic epilepsy, see EPM1A (254800).
Autosomal recessive spinocerebellar ataxia 18
MedGen UID:
863942
Concept ID:
C4015505
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-18 is a neurologic disorder characterized by delayed psychomotor development, severely impaired gait due to cerebellar ataxia, ocular movement abnormalities, and intellectual disability. Brain imaging shows progressive cerebellar atrophy (summary by Hills et al., 2013).
Developmental and epileptic encephalopathy, 28
MedGen UID:
863956
Concept ID:
C4015519
Disease or Syndrome
Developmental and epileptic encephalopathy-28 (DEE28) is an autosomal recessive severe neurologic disorder characterized by the onset of refractory seizures in the first months of life. Affected individuals have severe axial hypotonia and profoundly impaired psychomotor development. More severely affected patients have acquired microcephaly, poor or absent visual contact, and retinal degeneration; early death may occur (summary by Mignot et al., 2015). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Neurologic, endocrine, and pancreatic disease, multisystem, infantile-onset 1
MedGen UID:
864165
Concept ID:
C4015728
Disease or Syndrome
Infantile-onset multisystem neurologic, endocrine, and pancreatic disease-1 (IMNEPD1) is an autosomal recessive multisystemic disorder with variable expressivity. The core features usually include global developmental delay with impaired intellectual development and speech delay, ataxia, sensorineural hearing loss, and pancreatic insufficiency. Additional features may include peripheral neuropathy, postnatal microcephaly, dysmorphic facial features, and cerebellar atrophy. However, some patients may not display all features (summary by Picker-Minh et al., 2016, Sharkia et al., 2017). Genetic Heterogeneity of Infantile-Onset Multisystem Neurologic, Endocrine, and Pancreatic Disease See also IMNEPD2 (619418), caused by mutation in the YARS1 gene (603623) on chromosome 1p35.
Congenital hyperammonemia, type I
MedGen UID:
907954
Concept ID:
C4082171
Disease or Syndrome
Carbamoyl phosphate synthetase I deficiency is an autosomal recessive inborn error of metabolism of the urea cycle which causes hyperammonemia. There are 2 main forms: a lethal neonatal type and a less severe, delayed-onset type (summary by Klaus et al., 2009). Urea cycle disorders are characterized by the triad of hyperammonemia, encephalopathy, and respiratory alkalosis. Five disorders involving different defects in the biosynthesis of the enzymes of the urea cycle have been described: ornithine transcarbamylase deficiency (311250), carbamyl phosphate synthetase deficiency, argininosuccinate synthetase deficiency, or citrullinemia (215700), argininosuccinate lyase deficiency (207900), and arginase deficiency (207800).
Joubert syndrome 24
MedGen UID:
905319
Concept ID:
C4084841
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Joubert syndrome 25
MedGen UID:
895764
Concept ID:
C4084842
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Spinocerebellar ataxia type 41
MedGen UID:
908281
Concept ID:
C4225158
Disease or Syndrome
A rare autosomal dominant cerebellar ataxia type III disorder with characteristics of adult-onset progressive imbalance and loss of coordination associated with an ataxic gait. Mild atrophy of the cerebellar vermis has been reported on brain magnetic resonance imaging.
Hypomyelinating leukodystrophy 13
MedGen UID:
896545
Concept ID:
C4225170
Disease or Syndrome
Hypomyelinating leukodystrophy-13 is an autosomal recessive neurodegenerative disorder characterized by infantile onset of delayed psychomotor development, axial hypotonia, and spasticity associated with delayed myelination and periventricular white matter abnormalities on brain imaging. More variable neurologic deficits, such as visual impairment, may also occur. Some patients may experience cardiac failure during acute illness (summary by Edvardson et al., 2016). For a general phenotypic description and a discussion of genetic heterogeneity of HLD, see 312080.
Severe intellectual disability-corpus callosum agenesis-facial dysmorphism-cerebellar ataxia syndrome
MedGen UID:
902346
Concept ID:
C4225193
Disease or Syndrome
A rare genetic neurological disorder with characteristics of congenital microcephaly, severe intellectual disability, hypertonia at birth lessening with age, ataxia and specific dysmorphic facial features including hirsutism, low anterior hairline and bitemporal narrowing arched thick and medially sparse eyebrows, long eyelashes, lateral upper eyelids swelling and a skin fold partially covering the inferior eyelids, low-set posteriorly rotated protruding ears, anteverted nares and a full lower lip. Brain imaging shows partial to almost complete agenesis of the corpus callosum and variable degrees of cerebellar hypoplasia. Caused by homozygous mutation in the FRMD4A gene on chromosome 10p13.
Spinocerebellar ataxia type 42
MedGen UID:
902592
Concept ID:
C4225205
Disease or Syndrome
Spinocerebellar ataxia-42 (SCA42) is an autosomal dominant neurologic disorder characterized predominantly by gait instability and additional cerebellar signs such as dysarthria, nystagmus, and saccadic pursuits. The age at onset and severity of the disorder is highly variable. The disorder is slowly progressive (Coutelier et al., 2015). For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (164400).
Cardiac anomalies - developmental delay - facial dysmorphism syndrome
MedGen UID:
900924
Concept ID:
C4225208
Disease or Syndrome
Impaired intellectual development and distinctive facial features with or without cardiac defects (MRFACD) is an autosomal dominant, complex syndromic neurodevelopmental disorder characterized by delayed psychomotor development, poor speech acquisition, distinctive dysmorphic facial features, including frontal bossing, upslanting palpebral fissures, depressed nasal bridge with bulbous tip, and macrostomia. There is variable penetrance of cardiac malformations, ranging from no malformations to patent foramen ovale to septal defects and/or transposition of the great arteries (summary by Adegbola et al., 2015).
Spastic paraplegia-severe developmental delay-epilepsy syndrome
MedGen UID:
897828
Concept ID:
C4225215
Disease or Syndrome
Spastic paraplegia and psychomotor retardation with or without seizures is an autosomal recessive complex neurodevelopmental disorder with onset in infancy. Affected children show hypotonia followed by severely impaired global development and significant motor disability. Most develop seizures in childhood and have speech delay. Other features, such as ocular abnormalities, foot deformities, hypoplasia of the corpus callosum, and decreased white matter, are more variable (summary by Hollstein et al., 2015).
Macrothrombocytopenia-lymphedema-developmental delay-facial dysmorphism-camptodactyly syndrome
MedGen UID:
906646
Concept ID:
C4225222
Disease or Syndrome
Takenouchi-Kosaki syndrome is a highly heterogeneous autosomal dominant complex congenital developmental disorder affecting multiple organ systems. The core phenotype includes delayed psychomotor development with variable intellectual disability, dysmorphic facial features, and cardiac, genitourinary, and hematologic or lymphatic defects, including thrombocytopenia and lymphedema. Additional features may include abnormalities on brain imaging, skeletal anomalies, and recurrent infections. Some patients have a milder disease course reminiscent of Noonan syndrome (see, e.g., NS1, 163950) (summary by Martinelli et al., 2018).
Optic atrophy 10 with or without ataxia, intellectual disability, and seizures
MedGen UID:
905727
Concept ID:
C4225227
Disease or Syndrome
Charcot-Marie-Tooth disease type 4K
MedGen UID:
895560
Concept ID:
C4225246
Disease or Syndrome
Charcot-Marie-Tooth disease type 4K is an autosomal recessive demyelinating peripheral neuropathy characterized by onset in the first decade of distal muscle weakness and atrophy associated with impaired distal sensation. Both upper and lower limbs are affected. Affected individuals may also have nystagmus and late-onset cerebellar ataxia. Laboratory studies show increased serum lactate and isolated mitochondrial complex IV deficiency (summary by Echaniz-Laguna et al., 2013). For a phenotypic description and a discussion of genetic heterogeneity of autosomal recessive demyelinating Charcot-Marie-Tooth disease, see CMT4A (214400).
Early-onset Lafora body disease
MedGen UID:
907932
Concept ID:
C4225258
Disease or Syndrome
Progressive myoclonic epilepsy-10 (EPM10) is an autosomal recessive neurodegenerative disorder characterized by onset of progressive myoclonus, ataxia, spasticity, dysarthria, and cognitive decline in the first decade of life. The severity is variable, but some patients may become mute and bedridden with psychosis (summary by Turnbull et al., 2012). For a general phenotypic description and a discussion of genetic heterogeneity of progressive myoclonic epilepsy, see EPM1A (254800).
Short stature, microcephaly, and endocrine dysfunction
MedGen UID:
895448
Concept ID:
C4225288
Disease or Syndrome
In patients with SSMED, short stature and microcephaly are apparent at birth, and there is progressive postnatal growth failure. Endocrine dysfunction, including hypergonadotropic hypogonadism, multinodular goiter, and diabetes mellitus, is present in affected adults. Progressive ataxia has been reported in some patients, with onset ranging from the second to fifth decade of life. In addition, a few patients have developed tumors, suggesting that there may be a predisposition to tumorigenesis. In contrast to syndromes involving defects in other components of the nonhomologous end-joining (NHEJ) complex (see, e.g., 606593), no clinically overt immunodeficiency has been observed in SSMED, although laboratory analysis has revealed lymphopenia or borderline leukopenia in some patients (Murray et al., 2015; Bee et al., 2015; de Bruin et al., 2015; Guo et al., 2015).
Neuropathy, hereditary motor and sensory, type 6B
MedGen UID:
895482
Concept ID:
C4225302
Disease or Syndrome
Hereditary motor and sensory neuropathy type VIB is an autosomal recessive complex progressive neurologic disorder characterized mainly by early-onset optic atrophy resulting in progressive visual loss and peripheral axonal sensorimotor neuropathy with highly variable age at onset and severity. Affected individuals may also have cerebellar or pontocerebellar atrophy on brain imaging, and they may show abnormal movements such as ataxia, dysmetria, and myoclonus (summary by Abrams et al., 2015). For a general phenotypic description and a discussion of genetic heterogeneity of HMSN6, see HMSN6A (601152).
Hypomyelinating leukodystrophy 11
MedGen UID:
897960
Concept ID:
C4225305
Disease or Syndrome
POLR3-related leukodystrophy, a hypomyelinating leukodystrophy with specific features on brain MRI, is characterized by varying combinations of four major clinical findings: Neurologic dysfunction, typically predominated by motor dysfunction (progressive cerebellar dysfunction, and to a lesser extent extrapyramidal [i.e., dystonia], pyramidal [i.e., spasticity] and cognitive dysfunctions). Abnormal dentition (delayed dentition, hypodontia, oligodontia, and abnormally placed or shaped teeth). Endocrine abnormalities such as short stature (in ~50% of individuals) with or without growth hormone deficiency, and more commonly, hypogonadotropic hypogonadism manifesting as delayed, arrested, or absent puberty. Ocular abnormality in the form of myopia, typically progressing over several years and becoming severe. POLR3-related leukodystrophy and 4H leukodystrophy are the two recognized terms for five previously described overlapping clinical phenotypes (initially described as distinct entities before their molecular basis was known). These include: Hypomyelination, hypodontia, hypogonadotropic hypogonadism (4H syndrome); Ataxia, delayed dentition, and hypomyelination (ADDH); Tremor-ataxia with central hypomyelination (TACH); Leukodystrophy with oligodontia (LO); Hypomyelination with cerebellar atrophy and hypoplasia of the corpus callosum (HCAHC). Age of onset is typically in early childhood but later-onset cases have also been reported. An infant with Wiedemann-Rautenstrauch syndrome (neonatal progeroid syndrome) was recently reported to have pathogenic variants in POLR3A on exome sequencing. Confirmation of this as a very severe form of POLR3-related leukodystrophy awaits replication in other individuals with a clinical diagnosis of Wiedemann-Rautenstrauch syndrome.
Microcephaly 15, primary, autosomal recessive
MedGen UID:
895496
Concept ID:
C4225310
Disease or Syndrome
Neurodevelopmental disorder with progressive microcephaly, spasticity, and brain imaging abnormalities (NEDMISBA) is an autosomal recessive disorder characterized by a spectrum of neurologic abnormalities apparent from early infancy. Affected individuals have impaired intellectual development with poor speech, progressive microcephaly, and appendicular spasticity. Brain imaging usually shows abnormalities, including enlarged ventricles, white matter defects, and atrophy or hypoplasia of brain tissue. Some patients have a more severe phenotype with seizures, lack of developmental milestones, and early death (summary by Harel et al., 2018).
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 2
MedGen UID:
901897
Concept ID:
C4225312
Disease or Syndrome
Autosomal recessive progressive external ophthalmoplegia with mitochondrial DNA deletions-2 (PEOB2) is a mitochondrial disorder characterized by adult onset of progressive external ophthalmoplegia, exercise intolerance, muscle weakness, and signs and symptoms of spinocerebellar ataxia, such as impaired gait and dysarthria. Some patients may have respiratory insufficiency. Laboratory studies are consistent with a defect in mtDNA replication (summary by Reyes et al., 2015). For a discussion of genetic heterogeneity of autosomal recessive PEO, see PEOB1 (258450).
Intellectual disability, autosomal dominant 38
MedGen UID:
895359
Concept ID:
C4225343
Mental or Behavioral Dysfunction
Any autosomal dominant non-syndromic intellectual disability in which the cause of the disease is a mutation in the EEF1A2 gene.
Developmental and epileptic encephalopathy, 32
MedGen UID:
909501
Concept ID:
C4225350
Disease or Syndrome
Developmental and epileptic encephalopathy-32 (DEE32) is a neurologic disorder characterized by the onset of various seizure types, including febrile and myoclonic seizures, between about 5 and 17 months of age after normal early development. Thereafter, patients manifest global developmental delay or developmental regression with impaired intellectual development and poor or absent speech. Some may be able to attend special schools. Other features include ataxia with difficulty walking, deficient fine motor skills, tremor, and dysarthria. The seizures are initially refractory in some cases, but may remit later during childhood; however, neurologic deficits persist (summary by Syrbe et al., 2015). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Dyskeratosis congenita, autosomal recessive 6
MedGen UID:
905452
Concept ID:
C4225356
Disease or Syndrome
Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres. The phenotypic spectrum of telomere biology disorders is broad and includes individuals with classic dyskeratosis congenita (DC) as well as those with very short telomeres and an isolated physical finding. Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia, although this may not be present in all individuals. People with DC/TBD are at increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis. Other findings can include eye abnormalities (epiphora, blepharitis, sparse eyelashes, ectropion, entropion, trichiasis), taurodontism, liver disease, gastrointestinal telangiectasias, and avascular necrosis of the hips or shoulders. Although most persons with DC/TBD have normal psychomotor development and normal neurologic function, significant developmental delay is present in both forms; additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome) and bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome and Coats plus syndrome). Onset and progression of manifestations of DC/TBD vary: at the mild end of the spectrum are those who have only minimal physical findings with normal bone marrow function, and at the severe end are those who have the diagnostic triad and early-onset BMF.
Congenital myasthenic syndrome 18
MedGen UID:
906793
Concept ID:
C4225364
Disease or Syndrome
Congenital myasthenic syndrome-18 (CMS18) is an autosomal dominant presynaptic neuromuscular disorder characterized by early-onset muscle weakness and easy fatigability associated with delayed psychomotor development and ataxia (summary by Shen et al., 2014). For a discussion of genetic heterogeneity of CMS, see CMS1A (601462).
Lichtenstein-Knorr syndrome
MedGen UID:
898996
Concept ID:
C4225383
Disease or Syndrome
Lichtenstein-Knorr syndrome is an autosomal recessive neurologic disorder characterized by postnatal onset of severe progressive sensorineural hearing loss and progressive cerebellar ataxia. Features usually develop in childhood or young adulthood (summary by Guissart et al., 2015). Some patients with SLC9A1 mutations may not have deafness (Iwama et al., 2018)
Ataxia - oculomotor apraxia type 4
MedGen UID:
902323
Concept ID:
C4225397
Disease or Syndrome
Ataxia-oculomotor apraxia-4 (AOA4) is an autosomal recessive neurologic disorder characterized by onset of dystonia and ataxia in the first decade. Additional features include oculomotor apraxia and peripheral neuropathy. Some patients may show cognitive impairment. The disorder is progressive, and most patients become wheelchair-bound in the second or third decade (summary by Bras et al., 2015). For a discussion of genetic heterogeneity of ataxia-oculomotor apraxia, see AOA1 (208920).
Syndromic X-linked intellectual disability 34
MedGen UID:
902184
Concept ID:
C4225417
Mental or Behavioral Dysfunction
X-linked syndromic intellectual developmental disorder-34 (MRXS34) is an X-linked recessive neurodevelopmental disorder characterized by delayed psychomotor development, intellectual disability with poor speech, dysmorphic facial features, and mild structural brain abnormalities, including thickening of the corpus callosum (summary by Mircsof et al., 2015).
Intellectual disability, X-linked, syndromic 33
MedGen UID:
895979
Concept ID:
C4225418
Disease or Syndrome
X-linked syndromic intellectual developmental disorder-33 (MRXS33) is an X-linked recessive neurodevelopmental disorder characterized by delayed psychomotor development, intellectual disability, and characteristic facial features (summary by O'Rawe et al., 2015).
COG4-congenital disorder of glycosylation
MedGen UID:
929221
Concept ID:
C4303552
Disease or Syndrome
An extremely rare form of carbohydrate deficient glycoprotein syndrome with, in the single reported case to date, seizures, some dysmorphic features, axial hypotonia, slight peripheral hypertonia and hyperreflexia.
Lissencephaly due to TUBA1A mutation
MedGen UID:
930822
Concept ID:
C4305153
Congenital Abnormality
A congenital cortical development anomaly due to abnormal neuronal migration involving neocortical and hippocampal lamination, corpus callosum, cerebellum and brainstem. A large clinical spectrum can be observed, from children with severe epilepsy and intellectual and motor deficit to cases with severe cerebral dysgenesis in the antenatal period leading to pregnancy termination due to the severity of the prognosis.
Hypotonia, ataxia, and delayed development syndrome
MedGen UID:
934585
Concept ID:
C4310618
Disease or Syndrome
EBF3 neurodevelopmental disorder (EBF3-NDD) is associated with developmental delay (DD) / intellectual disability (ID), speech delay, gait or truncal ataxia, hypotonia, behavioral problems, and facial dysmorphism. Variability between individuals with EBF3-NDD is significant. Although all affected children have DD noted in early infancy, intellect generally ranges from mild to severe ID, with two individuals functioning in the low normal range. Less common issues can include genitourinary abnormalities and gastrointestinal and/or musculoskeletal involvement. To date, 42 symptomatic individuals from 39 families have been reported.
Congenital bile acid synthesis defect 6
MedGen UID:
934591
Concept ID:
C4310624
Disease or Syndrome
Congenital bile acid synthesis defect-6 (CBAS6) is characterized by persistent hypertransaminasemia and accumulation of C27 bile acids (summary by Alonso-Pena et al., 2022). For a general phenotypic description and a discussion of genetic heterogeneity of congenital bile acid synthesis defects, see CBAS1 (607765).
Optic atrophy 11
MedGen UID:
934595
Concept ID:
C4310628
Disease or Syndrome
Optic atrophy-11 (OPA11) is an autosomal recessive disorder characterized by delayed psychomotor development, intellectual disability, ataxia, optic atrophy, and leukoencephalopathy on brain imaging. Laboratory studies are consistent with mitochondrial dysfunction (summary by Hartmann et al., 2016). For a discussion of genetic heterogeneity of optic atrophy, see OPA1 (165500).
Dystonia, childhood-onset, with optic atrophy and basal ganglia abnormalities
MedGen UID:
934601
Concept ID:
C4310634
Disease or Syndrome
MECR-related neurologic disorder is characterized by a progressive childhood-onset movement disorder and optic atrophy; intellect is often – but not always – preserved. The movement disorder typically presents between ages one and 6.5 years and is mainly dystonia that can be accompanied by chorea and/or ataxia. Over time some affected individuals require assistive devices for mobility. Speech fluency and intelligibility are progressively impaired due to dysarthria. Optic atrophy typically develops between ages four and 12 years and manifests as reduced visual acuity, which can include functional blindness (also known as legal blindness) in adulthood. Because only 13 affected individuals are known to the authors, and because nearly half of them were diagnosed retrospectively as adults, the natural history of disease progression and other aspects of the phenotype have not yet been completely defined.
Encephalopathy, progressive, with amyotrophy and optic atrophy
MedGen UID:
934634
Concept ID:
C4310667
Disease or Syndrome
Progressive encephalopathy with amyotrophy and optic atrophy (PEAMO) is a severe autosomal recessive neurodegenerative disorder characterized by delayed development with hypotonia apparent in infancy and subsequent motor regression. Most affected individuals are unable to or lose the ability to sit and show distal amyotrophy and weakness of all 4 limbs. The patients are cognitively impaired and unable to speak or have severe dysarthria. Additional features include optic atrophy, thin corpus callosum, and cerebellar atrophy (Sferra et al., 2016).
Periventricular nodular heterotopia 7
MedGen UID:
934636
Concept ID:
C4310669
Disease or Syndrome
Periventricular nodular heterotopia-7 (PVNH7) is a neurologic disorder characterized by abnormal neuronal migration during brain development resulting in delayed psychomotor development and intellectual disability; some patients develop seizures. Other features include cleft palate and 2-3 toe syndactyly (summary by Broix et al., 2016). For a phenotypic description and a discussion of genetic heterogeneity of periventricular heterotopia, see 300049.
Early-onset progressive diffuse brain atrophy-microcephaly-muscle weakness-optic atrophy syndrome
MedGen UID:
934638
Concept ID:
C4310671
Disease or Syndrome
PEBAT is an autosomal recessive neurodevelopmental disorder characterized by severely delayed psychomotor development apparent soon after birth or in infancy, profound intellectual disability, poor or absent speech, and seizures. Most patients are never able to walk due to hypotonia or spasticity. Brain imaging shows cerebral and cerebellar atrophy, thin corpus callosum, and secondary hypomyelination. The disorder shows progressive features, including microcephaly, consistent with a neurodegenerative process (summary by Miyake et al., 2016; Flex et al., 2016).
Encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy, 1
MedGen UID:
934642
Concept ID:
C4310675
Disease or Syndrome
Early-onset progressive encephalopathy with brain edema and/or leukoencephalopathy-1 (PEBEL1) is an autosomal recessive severe neurometabolic disorder characterized by rapidly progressive neurologic deterioration that is usually associated with a febrile illness. Affected infants tend to show normal early development followed by acute psychomotor regression with ataxia, hypotonia, respiratory insufficiency, and seizures, resulting in coma and death in the first years of life. Brain imaging shows multiple abnormalities, including brain edema and signal abnormalities in the cortical and subcortical regions (summary by Kremer et al., 2016). Genetic Heterogeneity of PEBEL See also PEBEL2 (618321), caused by mutation in the NAXD gene (615910) on chromosome 13q34.
Harel-Yoon syndrome
MedGen UID:
934644
Concept ID:
C4310677
Disease or Syndrome
Harel-Yoon syndrome is a syndromic neurodevelopmental disorder characterized by delayed psychomotor development, intellectual disability, truncal hypotonia, spasticity, and peripheral neuropathy. Other more variable features such as optic atrophy may also occur. Laboratory studies in some patients show evidence of mitochondrial dysfunction (summary by Harel et al., 2016).
Developmental and epileptic encephalopathy, 47
MedGen UID:
934652
Concept ID:
C4310685
Disease or Syndrome
Developmental and epileptic encephalopathy-47 (DEE47) is a neurologic disorder characterized by onset of intractable seizures in the first days or weeks of life. EEG shows background slowing and multifocal epileptic spikes, and may show hypsarrhythmia. Most patients have developmental regression after seizure onset and show persistent intellectual disability and neurologic impairment, although the severity is variable. Treatment with phenytoin, a voltage-gated sodium channel blocker, may be beneficial (summary by Guella et al., 2016). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Short stature, rhizomelic, with microcephaly, micrognathia, and developmental delay
MedGen UID:
934653
Concept ID:
C4310686
Disease or Syndrome
The core features of short stature-micrognathia syndrome (SSMG) are intrauterine growth restriction (IUGR), postnatal short stature that is often rhizomelic, and micrognathia. Other common features include preterm birth, microcephaly, developmental delay, and genitourinary malformations in males. Transient liver dysfunction and glycosylation abnormalities during illness, giant cell hepatitis, hepatoblastoma, and cataracts have also been observed. Inter- and intrafamilial phenotypic severity varies greatly, from a relatively mild disorder to intrauterine death or stillbirth (Ritter et al., 2022).
Developmental and epileptic encephalopathy, 45
MedGen UID:
934658
Concept ID:
C4310691
Disease or Syndrome
Developmental and epileptic encephalopathy-45 (DEE45) is a neurologic disorder characterized by global developmental delay apparent in infancy or early childhood and onset of seizures within the first 12 months of life. Affected individuals have severely impaired intellectual development, hypotonia, and other persistent neurologic deficits (summary by Burgess et al., 2019). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Neurodegeneration with ataxia, dystonia, and gaze palsy, childhood-onset
MedGen UID:
934660
Concept ID:
C4310693
Disease or Syndrome
Childhood-onset neurodegeneration with ataxia, dystonia, and gaze palsy (NADGP) is an autosomal recessive progressive disorder characterized by onset of gait ataxia, cognitive decline, and gaze palsy in the first or second decades. Additional features include dysarthria, dystonia, and athetoid movements. Some patients may become wheelchair-bound as young adults (summary by Haack et al., 2016).
Joubert syndrome 28
MedGen UID:
934672
Concept ID:
C4310705
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Joubert syndrome 27
MedGen UID:
934673
Concept ID:
C4310706
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Developmental and epileptic encephalopathy, 43
MedGen UID:
934679
Concept ID:
C4310712
Disease or Syndrome
Developmental and epileptic encephalopathy-43 (DEE43) is a neurologic disorder characterized by the onset of various types of seizures usually in the first year of life. The age at onset is highly variable, ranging from the neonatal period to about 12 months of age. Later onset may rarely occur. Seizure types include febrile, infantile spasms, focal, tonic-clonic, and myoclonic; they tend to be refractory to treatment. Affected individuals show global developmental delay with mild to moderate intellectual disability, although some may have normal early development before the onset of seizures. EEG shows focal, multifocal, or generalized sharp waves associated with seizures, sometimes with hypsarrhythmia. Additional more variable features include tube feeding, hypotonia, peripheral hypertonia, ataxia, dyskinesia, and behavioral difficulties, including aggression, ADHD, stereotypic, and impulsive behavior (summary by the Epi4K Consortium, 2016). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Developmental and epileptic encephalopathy, 42
MedGen UID:
934683
Concept ID:
C4310716
Disease or Syndrome
Developmental and epileptic encephalopathy-42 (DEE42) is a neurologic disorder characterized by the onset of various types of seizures in the first hours or days of life, although rare patients may have onset in the first weeks of life. The seizures tend to be refractory and associated with EEG abnormalities, including multifocal spikes and generalized spike-wave complexes. Affected infants show global developmental delay with severely impaired intellectual development. Other features may include axial hypotonia, peripheral hypertonia with hyperreflexia, tremor, ataxia, and abnormal eye movements (summary by the Epi4K Consortium, 2016). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Okur-Chung neurodevelopmental syndrome
MedGen UID:
934706
Concept ID:
C4310739
Disease or Syndrome
Individuals with Okur-Chung neurodevelopmental syndrome (OCNDS) frequently have nonspecific clinical features, delayed language development, motor delay, intellectual disability (typically in the mild-to-moderate range), generalized hypotonia starting in infancy, difficulty feeding, and nonspecific dysmorphic facial features. Developmental delay affects all areas of development, but language is more impaired than gross motor skills in most individuals. Intellectual disability has been reported in about three quarters of individuals. Less common findings may include kyphoscoliosis, postnatal short stature, disrupted circadian rhythm leading to sleep disturbance, seizures, and poor coordination.
Developmental and epileptic encephalopathy, 38
MedGen UID:
934729
Concept ID:
C4310762
Disease or Syndrome
Developmental and epileptic encephalopathy-38 (DEE38) is an autosomal recessive neurologic and neurodegenerative disorder characterized by the onset of various type of seizures usually between about 4 and 7 months of age. Prior to the onset of seizures, most infants show severely impaired global development, hypotonia with poor head control, and visual inattention with roving eye movements and nystagmus. Seizures are usually refractory to treatment and associated with status epilepticus. Patients have little or no development with inability to walk or speak, spasticity or abnormal movements, and often cortical blindness. There is failure to thrive, and many require tube-feeding. Death in early childhood due to aspiration or intractable epilepsy may occur. The disorder is associated with a defect in GPI-anchoring of membrane-bound proteins (summary by Palmer et al., 2016; Davids et al., 2020). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350. For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293).
Spinocerebellar ataxia 43
MedGen UID:
934730
Concept ID:
C4310763
Disease or Syndrome
Spinocerebellar ataxia-43 is an autosomal dominant, slowly progressive neurologic disorder characterized by adult-onset gait and limb ataxia and often associated with peripheral neuropathy mainly affecting the motor system, although some patients may have distal sensory impairment (summary by Depondt et al., 2016). For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (164400).
Intellectual disability, autosomal dominant 43
MedGen UID:
934738
Concept ID:
C4310771
Mental or Behavioral Dysfunction
HIVEP2-related intellectual disability is a neurological disorder characterized by moderate to severe developmental delay and intellectual disability and mild physical abnormalities (dysmorphic features). Early symptoms of the condition include weak muscle tone (hypotonia) and delayed development of motor skills, such as sitting, standing, and walking. After learning to walk, many affected individuals continue to have difficulty with this activity; their walking style (gait) is often unbalanced and wide-based. Speech is also delayed, and some people with this condition never learn to talk. Most people with HIVEP2-related intellectual disability also have unusual physical features, such as widely spaced eyes (hypertelorism), a broad nasal bridge, or fingers with tapered ends, although there is no characteristic pattern of such features among affected individuals. Many people with the condition exhibit neurodevelopmental disorders, such as hyperactivity, attention deficit disorder, aggression, anxiety, and autism spectrum disorder, which is a group of developmental disorders characterized by impaired communication and social interaction.\n\nOther features of HIVEP2-related intellectual disability include mild abnormalities in the structure of the brain and an abnormally small brain and head size (microcephaly). Less common health problems include seizures; recurrent ear infections; and eye disorders, such as eyes that do not look in the same direction (strabismus), "lazy eye" (amblyopia), and farsightedness (hyperopia). Some people with HIVEP2-related intellectual disability have gastrointestinal problems, which can include backflow of acidic stomach contents into the esophagus (gastroesophageal reflux) and constipation.
TELO2-related intellectual disability-neurodevelopmental disorder
MedGen UID:
934745
Concept ID:
C4310778
Disease or Syndrome
A rare genetic multiple congenital anomalies/dysmorphic syndrome with characteristics of global developmental delay and intellectual disability, infantile hypotonia, microcephaly, movement disorder and impaired balance. Variable manifestations include hearing loss, cortical visual impairment, abnormalities of fingers and/or toes, congenital cardiac anomalies, kyphoscoliosis, dysmorphic facial features, abnormal sleep pattern and seizures.
Spinocerebellar ataxia, autosomal recessive 22
MedGen UID:
934748
Concept ID:
C4310781
Disease or Syndrome
Any autosomal recessive cerebellar ataxia in which the cause of the disease is a mutation in the VWA3B gene.
Intellectual disability, autosomal recessive 53
MedGen UID:
934761
Concept ID:
C4310794
Disease or Syndrome
Neurodevelopmental disorder with or without hypotonia, seizures, and cerebellar atrophy (NEDHSCA) is an autosomal recessive disorder characterized by severely delayed psychomotor development, hypotonia apparent since infancy, and early-onset seizures in most patients. Some patients may have additional features, such as cerebellar atrophy, ataxia, and nonspecific dysmorphic features. NEDHSCA is one of a group of similar neurologic disorders resulting from biochemical defects in the glycosylphosphatidylinositol (GPI) biosynthetic pathway. Some patients with NEDHSCA may have the Emm-null blood group phenotype (see 619812) (summary by Makrythanasis et al., 2016; Duval et al., 2021). For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293).
Intellectual disability, X-linked, syndromic, Bain type
MedGen UID:
934781
Concept ID:
C4310814
Disease or Syndrome
Most individuals with HNRNPH2-related neurodevelopmental disorder (HNRNPH2-NDD) have symptoms early in life, before age 12 months. The major features of HNRNPH2-NDD are developmental delay / intellectual disability, motor and language delays, behavioral and psychiatric disorders, and growth and musculoskeletal abnormalities. Minor features include dysmorphic facies, gastrointestinal disturbances, epilepsy, and visual defects. Although HNRNPH2-NDD is an X-linked condition, there is not enough information on affected females versus affected males to make any generalizations about phenotypic differences between the two sexes.
Intellectual disability, X-linked 104
MedGen UID:
934784
Concept ID:
C4310817
Disease or Syndrome
Any non-syndromic X-linked intellectual disability in which the cause of the disease is a mutation in the FRMPD4 gene.
Intellectual disability, X-linked, syndromic, 35
MedGen UID:
1392054
Concept ID:
C4478383
Disease or Syndrome
Cerebroretinal microangiopathy with calcifications and cysts 2
MedGen UID:
1390862
Concept ID:
C4479220
Disease or Syndrome
Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres. The phenotypic spectrum of telomere biology disorders is broad and includes individuals with classic dyskeratosis congenita (DC) as well as those with very short telomeres and an isolated physical finding. Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia, although this may not be present in all individuals. People with DC/TBD are at increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis. Other findings can include eye abnormalities (epiphora, blepharitis, sparse eyelashes, ectropion, entropion, trichiasis), taurodontism, liver disease, gastrointestinal telangiectasias, and avascular necrosis of the hips or shoulders. Although most persons with DC/TBD have normal psychomotor development and normal neurologic function, significant developmental delay is present in both forms; additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome) and bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome and Coats plus syndrome). Onset and progression of manifestations of DC/TBD vary: at the mild end of the spectrum are those who have only minimal physical findings with normal bone marrow function, and at the severe end are those who have the diagnostic triad and early-onset BMF.
Autosomal recessive limb-girdle muscular dystrophy type R18
MedGen UID:
1385598
Concept ID:
C4517996
Disease or Syndrome
Autosomal recessive limb-girdle muscular dystrophy-18 (LGMD18) is characterized by childhood-onset of proximal muscle weakness resulting in gait abnormalities and scapular winging. Serum creatine kinase is increased. A subset of patients may show a hyperkinetic movement disorder with chorea, ataxia, or dystonia and global developmental delay (summary by Bogershausen et al., 2013). Additional more variable features include alacrima, achalasia, cataracts, or hepatic steatosis (Liang et al., 2015; Koehler et al., 2017). For a discussion of genetic heterogeneity of autosomal recessive limb-girdle muscular dystrophy, see LGMDR1 (253600).
Spinocerebellar ataxia type 40
MedGen UID:
1385103
Concept ID:
C4518336
Disease or Syndrome
A very rare disease with characteristics of adult-onset unsteady gait and dysarthria, followed by wide-based gait, gait ataxia, ocular dysmetria, intention tremor, scanning speech, hyperreflexia and dysdiadochokinesis.
Spinocerebellar ataxia type 38
MedGen UID:
1379865
Concept ID:
C4518337
Disease or Syndrome
Spinocerebellar ataxia type 38 (SCA38) is characterized as a pure cerebellar ataxia with symptoms typically manifesting in the fourth decade of life. The most common presenting features are nystagmus and slowly progressive gait ataxia. As the disease progresses, cerebellar symptoms (limb ataxia, dysarthria, dysphagia, diplopia on the horizontal line) may emerge, and affected individuals may experience sensory loss. In the later stages of the condition, ophthalmoparesis followed by ophthalmoplegia may occur. Features that distinguish SCA38 from other spinocerebellar ataxias include pes cavus without paresis, hyposmia, hearing loss, and anxiety disorder. Dementia and extrapyramidal signs are not common features of SCA38. Brain imaging typically demonstrates cerebellar atrophy mainly affecting the vermis without atrophy of the cerebral cortex and a normal appearance of the brain stem. With disease progression, nerve conduction velocities and electromyography demonstrate a sensory and motor axonal polyneuropathy in all four extremities. Life span is apparently not decreased.
Spinocerebellar ataxia 44
MedGen UID:
1611168
Concept ID:
C4521563
Disease or Syndrome
Meckel syndrome 13
MedGen UID:
1627793
Concept ID:
C4539714
Disease or Syndrome
Orofaciodigital syndrome 16
MedGen UID:
1620071
Concept ID:
C4539729
Disease or Syndrome
Spinocerebellar ataxia, autosomal recessive 25
MedGen UID:
1618081
Concept ID:
C4539808
Disease or Syndrome
Developmental and epileptic encephalopathy, 56
MedGen UID:
1621755
Concept ID:
C4540034
Disease or Syndrome
Developmental and epileptic encephalopathy-56 (DEE56) is a neurodevelopmental disorder characterized by early-onset seizures in most patients, followed by impaired intellectual development, variable behavioral abnormalities, and sometimes additional neurologic features, such as ataxia (summary by Guella et al., 2017). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Childhood-onset motor and cognitive regression syndrome with extrapyramidal movement disorder
MedGen UID:
1626007
Concept ID:
C4540086
Disease or Syndrome
Childhood-onset neurodegeneration with brain atrophy (CONDBA) is a severe progressive neurodegenerative disorder characterized by loss of motor and cognitive skills between ages 2 and 7 years. Affected individuals may have normal development or mild developmental delay, but all eventually lose all motor skills, resulting in inability to walk, absence of language, and profound intellectual disability. Brain imaging shows progressive cerebral and cerebellar atrophy (summary by Edvardson et al., 2017).
Mitochondrial myopathy-cerebellar ataxia-pigmentary retinopathy syndrome
MedGen UID:
1620960
Concept ID:
C4540096
Disease or Syndrome
Mitochondrial myopathy and ataxia (MMYAT) is an autosomal recessive mtDNA depletion disorder characterized by cerebellar ataxia, congenital muscle involvement with histologic findings ranging from myopathic to dystrophic, and pigmentary retinopathy (summary by Donkervoort et al., 2019).
Pontocerebellar hypoplasia, type 11
MedGen UID:
1627627
Concept ID:
C4540164
Congenital Abnormality
Pontocerebellar hypoplasia type 11 (PCH11) is an autosomal recessive neurodevelopmental disorder characterized by severely delayed psychomotor development with impaired intellectual development and poor speech, microcephaly, dysmorphic features, and pontocerebellar hypoplasia on brain imaging. Additional features are more variable (summary by Marin-Valencia et al., 2017). For a general phenotypic description and a discussion of genetic heterogeneity of PCH, see PCH1 (607596).
Neurodevelopmental disorder with microcephaly, ataxia, and seizures
MedGen UID:
1613354
Concept ID:
C4540188
Disease or Syndrome
Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) is an autosomal recessive disorder characterized by global developmental delay and early-onset seizures. More variable features may include deafness, cardiomyopathy, and severe febrile decompensations (summary by Ravel et al., 2021).
Neurodevelopmental disorder, mitochondrial, with abnormal movements and lactic acidosis, with or without seizures
MedGen UID:
1619876
Concept ID:
C4540192
Disease or Syndrome
NEMMLAS is an autosomal recessive multisystemic disorder characterized by delayed psychomotor development, intellectual disability, and abnormal motor function, including hypotonia, dystonia, ataxia, and spasticity. Patient tissues may show deficiencies in one or more of the mitochondrial oxidative phosphorylation (OXPHOS) enzymes, but this is not a constant finding (summary by Wortmann et al., 2017).
Galloway-Mowat syndrome 5
MedGen UID:
1617227
Concept ID:
C4540274
Disease or Syndrome
Galloway-Mowat syndrome is a renal-neurologic disease characterized by early-onset nephrotic syndrome associated with microcephaly, gyral abnormalities, and delayed psychomotor development. Most patients have dysmorphic facial features, often including hypertelorism and ear abnormalities. Other features, such as arachnodactyly and visual or hearing impairment, are more variable. Most patients die in the first years of life (summary by Braun et al., 2017). For a general phenotypic description and a discussion of genetic heterogeneity of GAMOS, see GAMOS1 (251300).
Joubert syndrome 32
MedGen UID:
1626697
Concept ID:
C4540342
Disease or Syndrome
Joubert syndrome-32 (JBTS32) is an autosomal recessive developmental disorder characterized by delayed psychomotor development, intellectual disability, dysmorphic facial features, and postaxial polydactyly. Brain imaging shows cerebellar abnormalities consistent with the molar tooth sign (MTS) (summary by De Mori et al., 2017). For discussion of genetic heterogeneity of Joubert syndrome, see JBTS1 (213300).
Joubert syndrome 33
MedGen UID:
1615779
Concept ID:
C4540389
Disease or Syndrome
Joubert syndrome (JBTS) represents a classic ciliopathy characterized by hypotonia, ataxia, cognitive impairment, and a distinctive brain malformation, the 'molar tooth sign.' In addition, retinal dystrophy, cystic kidney disease, liver fibrosis, and polydactyly occur in a subset of patients (summary by Wheway et al., 2015). For a discussion of genetic heterogeneity of Joubert syndrome, see JBTS1 (213300).
Intellectual disability, autosomal dominant 54
MedGen UID:
1614787
Concept ID:
C4540484
Mental or Behavioral Dysfunction
Neurodevelopmental disorder with severe motor impairment and absent language
MedGen UID:
1622162
Concept ID:
C4540496
Mental or Behavioral Dysfunction
NEDMIAL is a neurodevelopmental disorder characterized by delayed psychomotor development and hypotonia apparent from early infancy, resulting in feeding difficulties, ataxic gait or inability to walk, delayed or absent speech development, and impaired intellectual development, sometimes with behavioral abnormalities, such as hand-flapping. Additional common features may include sleep disorder, nonspecific dysmorphic facial features, and joint hyperlaxity (summary by Lessel et al., 2017 and Mannucci et al., 2021).
Nephrotic syndrome 14
MedGen UID:
1617660
Concept ID:
C4540559
Disease or Syndrome
Sphingosine phosphate lyase insufficiency syndrome (SPLIS) is characterized by varying combinations of steroid-resistant nephrotic syndrome (ranging from nonimmune fetal hydrops to adolescent onset), primary adrenal insufficiency (with or without mineralocorticoid deficiency), testicular insufficiency, hypothyroidism, ichthyosis, lymphopenia/immunodeficiency, and neurologic abnormalities that can include developmental delay, regression / progressive neurologic involvement, cranial nerve deficits, and peripheral motor and sensory neuropathy.
Familial hemophagocytic lymphohistiocytosis type 1
MedGen UID:
1642840
Concept ID:
C4551514
Disease or Syndrome
Familial Hemophagocytic lymphohistiocytosis (FHL) is a rare primary immunodeficiency characterized by a macrophage activation syndrome with an onset usually occurring within a few months or less common several years after birth.
Joubert syndrome 1
MedGen UID:
1644883
Concept ID:
C4551568
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Wolfram syndrome 1
MedGen UID:
1641635
Concept ID:
C4551693
Disease or Syndrome
WFS1 Wolfram syndrome spectrum disorder (WFS1-WSSD) is a progressive neurodegenerative disorder characterized by onset of diabetes mellitus (DM) and optic atrophy (OA) before age 16 years, and typically associated with other endocrine abnormalities, sensorineural hearing loss, and progressive neurologic abnormalities (cerebellar ataxia, peripheral neuropathy, dementia, psychiatric illness, and urinary tract atony). Although DM is mostly insulin-dependent, overall the course is milder (with lower prevalence of microvascular disease) than that seen in isolated DM. OA typically results in significantly reduced visual acuity in the first decade. Sensorineural hearing impairment ranges from congenital deafness to milder, sometimes progressive, hearing impairment.
Perrault syndrome 1
MedGen UID:
1640257
Concept ID:
C4551721
Disease or Syndrome
Perrault syndrome is characterized by sensorineural hearing loss (SNHL) in males and females and ovarian dysfunction in females. SNHL is bilateral and ranges from profound with prelingual (congenital) onset to moderate with early-childhood onset. When onset is in early childhood, hearing loss can be progressive. Ovarian dysfunction ranges from gonadal dysgenesis (absent or streak gonads) manifesting as primary amenorrhea to primary ovarian insufficiency (POI) defined as cessation of menses before age 40 years. Fertility in affected males is reported as normal (although the number of reported males is limited). Neurologic features described in some individuals with Perrault syndrome include learning difficulties and developmental delay, cerebellar ataxia, and motor and sensory peripheral neuropathy.
Galloway-Mowat syndrome 1
MedGen UID:
1634188
Concept ID:
C4551772
Disease or Syndrome
Knobloch syndrome 1
MedGen UID:
1642123
Concept ID:
C4551775
Disease or Syndrome
Knobloch syndrome-1 (KNO1) is an autosomal recessive developmental disorder primarily characterized by typical eye abnormalities, including high myopia, cataracts, dislocated lens, vitreoretinal degeneration, and retinal detachment, with occipital skull defects, which can range from occipital encephalocele to occult cutis aplasia (summary by Aldahmesh et al., 2011). Genetic Heterogeneity of Knobloch Syndrome KNO2 (618458) is caused by mutation in the PAK2 gene (605022) on chromosome 3q29.
Encephalopathy due to GLUT1 deficiency
MedGen UID:
1645412
Concept ID:
C4551966
Disease or Syndrome
The phenotypic spectrum of glucose transporter type 1 deficiency syndrome (Glut1 DS) is now known to be a continuum that includes the classic phenotype as well as paroxysmal exercise-induced dyskinesia and epilepsy (previously known as dystonia 18 [DYT18]) and paroxysmal choreoathetosis with spasticity (previously known as dystonia 9 [DYT9]), atypical childhood absence epilepsy, myoclonic astatic epilepsy, and paroxysmal non-epileptic findings including intermittent ataxia, choreoathetosis, dystonia, and alternating hemiplegia. The classic phenotype is characterized by infantile-onset seizures, delayed neurologic development, acquired microcephaly, and complex movement disorders. Seizures in classic early-onset Glut1 DS begin before age six months. Several seizure types occur: generalized tonic or clonic, focal, myoclonic, atypical absence, atonic, and unclassified. In some infants, apneic episodes and abnormal episodic eye-head movements similar to opsoclonus may precede the onset of seizures. The frequency, severity, and type of seizures vary among affected individuals and are not related to disease severity. Cognitive impairment, ranging from learning disabilities to severe intellectual disability, is typical. The complex movement disorder, characterized by ataxia, dystonia, and chorea, may occur in any combination and may be continuous, paroxysmal, or continual with fluctuations in severity influenced by environmental factors such as fasting or with infectious stress. Symptoms often improve substantially when a ketogenic diet is started.
Lissencephaly type 1 due to doublecortin gene mutation
MedGen UID:
1644310
Concept ID:
C4551968
Disease or Syndrome
DCX-related disorders include the neuronal migration disorders: Classic thick lissencephaly (more severe anteriorly), usually in males. Subcortical band heterotopia (SBH), primarily in females. Males with classic DCX-related lissencephaly typically have early and profound cognitive and language impairment, cerebral palsy, and epileptic seizures. The clinical phenotype in females with SBH varies widely with cognitive abilities that range from average or mild cognitive impairment to severe intellectual disability and language impairment. Seizures, which frequently are refractory to anti-seizure medication, may be either focal or generalized and behavioral problems may also be observed. In DCX-related lissencephaly and SBH the severity of the clinical manifestation correlates roughly with the degree of the underlying brain malformation as observed in cerebral imaging.
Dyskeratosis congenita, autosomal dominant 1
MedGen UID:
1645250
Concept ID:
C4551974
Disease or Syndrome
Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres. The phenotypic spectrum of telomere biology disorders is broad and includes individuals with classic dyskeratosis congenita (DC) as well as those with very short telomeres and an isolated physical finding. Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia, although this may not be present in all individuals. People with DC/TBD are at increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis. Other findings can include eye abnormalities (epiphora, blepharitis, sparse eyelashes, ectropion, entropion, trichiasis), taurodontism, liver disease, gastrointestinal telangiectasias, and avascular necrosis of the hips or shoulders. Although most persons with DC/TBD have normal psychomotor development and normal neurologic function, significant developmental delay is present in both forms; additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome) and bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome and Coats plus syndrome). Onset and progression of manifestations of DC/TBD vary: at the mild end of the spectrum are those who have only minimal physical findings with normal bone marrow function, and at the severe end are those who have the diagnostic triad and early-onset BMF.
Familial hypobetalipoproteinemia 1
MedGen UID:
1639219
Concept ID:
C4551990
Disease or Syndrome
Individuals with biallelic APOB-related familial hypobetalipoproteinemia (APOB-FHBL) may present from infancy through to adulthood with a range of clinical symptoms including deficiency of fat-soluble vitamins and gastrointestinal and neurologic dysfunction. Affected individuals typically have plasma total cholesterol, LDL cholesterol, and apo B levels below the fifth centile for age and sex. Acanthocytosis, elevated liver enzymes, and hyperbilirubinemia may also be found. The most common clinical findings are hepatomegaly, steatorrhea, and failure to thrive / growth deficiency. In the absence of treatment, affected individuals can develop atypical pigmentation of the retina; progressive loss of deep tendon reflexes, vibratory sense, and proprioception; muscle pain or weakness; dysarthria; ataxia; tremors; and steatohepatitis, fibrosis, and rarely, cirrhosis of the liver. Individuals with a heterozygous, typically truncating pathogenic variant in APOB are usually asymptomatic with mild liver dysfunction and hepatic steatosis. However, about 5%-10% of individuals with heterozygous APOB-FHBL develop relatively more severe nonalcoholic steatohepatitis requiring medical attention and occasionally progressing to cirrhosis, albeit very rarely.
Cerebroretinal microangiopathy with calcifications and cysts 1
MedGen UID:
1636142
Concept ID:
C4552029
Disease or Syndrome
Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres. The phenotypic spectrum of telomere biology disorders is broad and includes individuals with classic dyskeratosis congenita (DC) as well as those with very short telomeres and an isolated physical finding. Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia, although this may not be present in all individuals. People with DC/TBD are at increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis. Other findings can include eye abnormalities (epiphora, blepharitis, sparse eyelashes, ectropion, entropion, trichiasis), taurodontism, liver disease, gastrointestinal telangiectasias, and avascular necrosis of the hips or shoulders. Although most persons with DC/TBD have normal psychomotor development and normal neurologic function, significant developmental delay is present in both forms; additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome) and bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome and Coats plus syndrome). Onset and progression of manifestations of DC/TBD vary: at the mild end of the spectrum are those who have only minimal physical findings with normal bone marrow function, and at the severe end are those who have the diagnostic triad and early-onset BMF.
Fanconi anemia, complementation group S
MedGen UID:
1632414
Concept ID:
C4554406
Disease or Syndrome
Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.
Epileptic encephalopathy, infantile or early childhood, 2
MedGen UID:
1638319
Concept ID:
C4693362
Disease or Syndrome
Developmental and epileptic encephalopathy-92 (DEE92) is characterized in most patients by onset of seizures in infancy or childhood and associated with global developmental delay and variable impairment of intellectual development. The seizure type and severity varies, and seizures may be intractable in some patients. Some patients are severely affected, unable to walk or speak, whereas others show some development. Additional neurologic features, including cortical blindness, dystonia, and spasticity, may occur. Mutations occur de novo (summary by Hamdan et al., 2017). For a discussion of genetic heterogeneity of DEE, see 308350.
Intellectual disability, autosomal dominant 55, with seizures
MedGen UID:
1635938
Concept ID:
C4693371
Disease or Syndrome
Developmental delay and seizures with or without movement abnormalities
MedGen UID:
1641343
Concept ID:
C4693376
Disease or Syndrome
DEDSM is a neurodevelopmental disorder characterized by global developmental delay, variable intellectual disability, and early-onset seizures with a myoclonic component. Most patients have delayed motor development and show abnormal movements, including ataxia, dystonia, and tremor (summary by Hamdan et al., 2017).
Intellectual disability, autosomal dominant 56
MedGen UID:
1638835
Concept ID:
C4693389
Mental or Behavioral Dysfunction
Neurodevelopmental disorder with movement abnormalities, abnormal gait, and autistic features
MedGen UID:
1647077
Concept ID:
C4693405
Disease or Syndrome
Neurodevelopmental disorder with movement abnormalities, abnormal gait, and autistic features (NEDMAGA) is characterized by infantile-onset global developmental delay with severe to profound intellectual disability, mildly delayed walking with broad-based and unsteady gait, and absence of meaningful language. Patients have features of autism, with repetitive behaviors and poor communication, but usually are socially reactive and have a happy demeanor. More variable neurologic features include mild seizures, spasticity, and peripheral neuropathy (summary by Palmer et al., 2017).
Charcot-Marie-Tooth disease, dominant intermediate G
MedGen UID:
1642893
Concept ID:
C4693509
Disease or Syndrome
CMTDIG is an autosomal dominant neurologic disorder with a highly variable phenotype. Most affected individuals have onset in the first or second decades of slowly progressive distal motor weakness and atrophy, resulting in gait instability and distal upper limb impairment, as well as distal sensory impairment. More severely affected individuals may have pes cavus and claw hands and become wheelchair-bound, whereas other affected individuals have later onset with a milder disease course. Electrophysiologic studies tend to show median motor nerve conduction velocities (NCV) in the 'intermediate' range, between 25 and 45 m/s (summary by Berciano et al., 2017). In a review of intermediate CMT, Berciano et al. (2017) noted that advanced axonal degeneration may induce secondary demyelinating changes resulting in decreased NCV and attenuated compound muscle action potential (CMAP) in median nerve conduction studies. They thus suggested that testing the upper arm, axilla to elbow, may provide more accurate assessment of NCV and CMAP and reveal an intermediate phenotype (review by Berciano et al., 2017). For a discussion of genetic heterogeneity of CMTDI, see 606482.
Developmental and epileptic encephalopathy, 59
MedGen UID:
1633749
Concept ID:
C4693550
Disease or Syndrome
Developmental and epileptic encephalopathy-59 (DEE59) is characterized by severe global developmental delay apparent in infancy with onset of various types of seizures in the first months of life (range 3 to 11 months). The seizures are usually refractory and are often associated with hypsarrhythmia on EEG, although brain imaging is usually normal. More severely affected individuals may be unable to speak or walk, have poor interaction, and require a feeding tube (summary by the EuroEPINOMICS-RES Consortium et al., 2014). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Hypotonia, ataxia, developmental delay, and tooth enamel defect syndrome
MedGen UID:
1647427
Concept ID:
C4693578
Disease or Syndrome
An autosomal dominant condition caused by mutations(s) in the CTBP1 gene, encoding C-terminal-binding protein 1. It is characterized by hypotonia, ataxia, developmental delay, and tooth enamel defects.
Neurodegeneration with brain iron accumulation 7
MedGen UID:
1647672
Concept ID:
C4693583
Disease or Syndrome
Neurodegeneration with brain iron accumulation-7 (NBIA7) is characterized by iron accumulation in the basal ganglia and manifests as a progressive extrapyramidal syndrome with dystonia, rigidity, and choreoathetosis. Severity and rate of progression are variable (Drecourt et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of NBIA, see NBIA1 (234200).
Neurodegeneration with brain iron accumulation 8
MedGen UID:
1645224
Concept ID:
C4693587
Disease or Syndrome
Neurodegeneration with brain iron accumulation-8 (NBIA8) is characterized by iron accumulation in the basal ganglia and manifests as a progressive extrapyramidal syndrome with dystonia, rigidity, and choreoathetosis (Drecourt et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of NBIA, see NBIA1 (234200).
Chromosome 1p35 deletion syndrome
MedGen UID:
1632676
Concept ID:
C4693669
Disease or Syndrome
Spinocerebellar ataxia 47
MedGen UID:
1636349
Concept ID:
C4693672
Disease or Syndrome
Spinocerebellar ataxia-47 (SCA47) is an autosomal dominant neurologic disorder characterized by slowly progressive gait ataxia. Additional features usually include diplopia, dysarthria, and dysmetria. Brain imaging shows atrophy of the cerebellar vermis. The age at onset is variable: affected members in 1 reported family developed symptoms as adults in their thirties or forties, whereas 1 unrelated girl had onset in the first decade (Gennarino et al., 2018). For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (164400).
Leukodystrophy, hypomyelinating, 15
MedGen UID:
1633653
Concept ID:
C4693733
Disease or Syndrome
Hypomyelinating leukodystrophy-15 is an autosomal recessive neurodegenerative disorder characterized by onset of motor and cognitive impairment in the first or second decade of life. Features include dystonia, ataxia, spasticity, and dysphagia. Most patients develop severe optic atrophy, and some have hearing loss. Brain imaging shows hypomyelinating leukodystrophy with thin corpus callosum. The severity of the disorder is variable (summary by Mendes et al., 2018) For a discussion of genetic heterogeneity of HLD, see 312080.
Multiple mitochondrial dysfunctions syndrome 6
MedGen UID:
1643082
Concept ID:
C4693741
Disease or Syndrome
Multiple mitochondrial dysfunctions syndrome-6 is an autosomal recessive severe neurodegenerative disorder with onset in early childhood. Affected individuals may have initial normal development, but show neurologic regression in the first year of life. They have hypotonia, inability to walk, poor speech, intellectual disability, and motor abnormalities, such as ataxia, dystonia, and spasticity. Some patients may die in childhood. Laboratory evidence indicates that the disorder results from mitochondrial dysfunction (summary by Vogtle et al., 2018). For a general description and a discussion of genetic heterogeneity of multiple mitochondrial dysfunctions syndrome, see MMDS1 (605711).
Combined oxidative phosphorylation defect type 15
MedGen UID:
1646555
Concept ID:
C4706313
Disease or Syndrome
A rare mitochondrial disease due to a defect in mitochondrial protein synthesis with onset in infancy or early childhood of muscular hypotonia, gait ataxia, mild bilateral pyramidal tract signs, developmental delay (affecting mostly speech and coordination) and subsequent intellectual disability. Short stature, obesity, microcephaly, strabismus, nystagmus, reduced visual acuity, lactic acidosis, and a brain neuropathology consistent with Leigh syndrome are also reported. Caused by homozygous or compound heterozygous mutation in the MTFMT gene on chromosome 15q22.
Alacrima, achalasia, and intellectual disability syndrome
MedGen UID:
1640947
Concept ID:
C4706563
Disease or Syndrome
Alacrima, achalasia, and impaired intellectual development syndrome (AAMR) is an autosomal recessive disorder characterized by onset of these 3 main features at birth or in early infancy. More variable features include hypotonia, gait abnormalities, anisocoria, and visual or hearing deficits. The disorder shows similarity to the triple A syndrome (231550), but patients with AAMR do not have adrenal insufficiency (summary by Koehler et al., 2013). See also 300858 for a phenotypically similar disorder that shows X-linked inheritance.
Citrullinemia type I
MedGen UID:
1648491
Concept ID:
C4721769
Disease or Syndrome
Citrullinemia type I (CTLN1) presents as a spectrum that includes a neonatal acute form (the "classic" form), a milder late-onset form (the "non-classic" form), a form in which women have onset of symptoms at pregnancy or post partum, and a form without symptoms or hyperammonemia. Distinction between the forms is based primarily on clinical findings, although emerging evidence suggests that measurement of residual argininosuccinate synthase enzyme activity may help to predict those who are likely to have a severe phenotype and those who are likely to have an attenuated phenotype. Infants with the acute neonatal form appear normal at birth. Shortly thereafter, they develop hyperammonemia and become progressively lethargic, feed poorly, often vomit, and may develop signs of increased intracranial pressure (ICP). Without prompt intervention, hyperammonemia and the accumulation of other toxic metabolites (e.g., glutamine) result in increased ICP, increased neuromuscular tone, spasticity, ankle clonus, seizures, loss of consciousness, and death. Children with the severe form who are treated promptly may survive for an indeterminate period of time, but usually with significant neurologic deficits. Even with chronic protein restriction and scavenger therapy, long-term complications such as liver failure and other (rarely reported) organ system manifestations are possible. The late-onset form may be milder than that seen in the acute neonatal form, but commences later in life for reasons that are not completely understood. The episodes of hyperammonemia are similar to those seen in the acute neonatal form, but the initial neurologic findings may be more subtle because of the older age of the affected individuals. Women with onset of severe symptoms including acute hepatic decompensation during pregnancy or in the postpartum period have been reported. Furthermore, previously asymptomatic and non-pregnant individuals have been described who remained asymptomatic up to at least age ten years, with the possibility that they could remain asymptomatic lifelong.
Mitochondrial complex 1 deficiency, nuclear type 12
MedGen UID:
1648278
Concept ID:
C4746984
Disease or Syndrome
Parkinsonism-dystonia, infantile, 2
MedGen UID:
1648382
Concept ID:
C4747991
Disease or Syndrome
Infantile-onset parkinsonism-dystonia-2 (PKDYS2) is an autosomal recessive complex infantile-onset neurologic disorder characterized by abnormal movements, including parkinsonism, dystonia, and poor fine motor skills, as well as autonomic dysfunction, including abnormal sweating, cold extremities, and poor sleep. Some patients have variable degrees of developmental delay. Features of the disorder are consistent with decreased levels of monoamine neurotransmitters, although levels of these in the spinal fluid are normal (summary by Rilstone et al., 2013). For a discussion of genetic heterogeneity of PKDYS, see 613135.
Intellectual developmental disorder with or without epilepsy or cerebellar ataxia
MedGen UID:
1648354
Concept ID:
C4748041
Disease or Syndrome
Neurodevelopmental disorder with spasticity and poor growth
MedGen UID:
1648309
Concept ID:
C4748081
Disease or Syndrome
Neurodevelopmental disorder with spasticity and poor growth (NEDSG) is an autosomal recessive disorder characterized by severe early-onset encephalopathy with progressive microcephaly (Nahorski et al., 2018).
Spinocerebellar ataxia 42, early-onset, severe, with neurodevelopmental deficits
MedGen UID:
1648308
Concept ID:
C4748120
Disease or Syndrome
Neurodevelopmental disorder with regression, abnormal movements, loss of speech, and seizures
MedGen UID:
1648345
Concept ID:
C4748127
Disease or Syndrome
Spinocerebellar ataxia 48
MedGen UID:
1648409
Concept ID:
C4748158
Disease or Syndrome
SCA48 is an autosomal dominant neurodegenerative disorder characterized by onset of gait ataxia and/or cognitive-affective symptoms in midadulthood. Patients may present with involvement of either system, but most eventually develop impairment in both. Features include gait ataxia, dysarthria, and dysphagia, as well as cognitive decline, deficits in executive function, and psychiatric or affective manifestations, such as depression, anxiety, and apathy. Additional more variable features may include movement abnormalities, such as parkinsonism, tremor, chorea, dystonia, and dysmetria; spasticity is not observed. Brain imaging shows selective atrophy of the posterior areas of the cerebellar vermis, often with bilateral T2-weighted hyperintensities in the dentate nuclei (the 'crab sign'), and diffusion tensor imaging (DTI) may show paucity of cerebellar connections to the brainstem and cerebrum. The presentation is consistent with a clinical diagnosis of cerebellar cognitive-affective syndrome (CCAS). The phenotype shows both inter- and intrafamilial variability as well as some clinical overlap with SCAR16, suggesting that mutations in the STUB1 gene result in a spectrum of neurodegenerative manifestations (summary by Genis et al., 2018; Cocozza et al., 2020; Palvadeau et al., 2020; Ravel et al., 2021). Magri et al. (2022) found evidence that heterozygous STUB1 variants alone do not cause disease but require a concurrent expanded repeat allele of the TBP gene (600075) for disease manifestation; see MOLECULAR GENETICS.
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 5
MedGen UID:
1648331
Concept ID:
C4748184
Disease or Syndrome
Peripheral neuropathy, autosomal recessive, with or without impaired intellectual development
MedGen UID:
1648480
Concept ID:
C4748283
Disease or Syndrome
Autosomal recessive peripheral neuropathy with or without impaired intellectual development is an early childhood-onset neurologic disorder characterized by slowly progressive distal motor impairment resulting in gait difficulties, often with loss of ambulation, and difficulties using the hands in most patients. Most affected individuals also have impaired intellectual development, although some have normal cognition. Electrophysiologic testing and sural nerve biopsy are most compatible with an axonal motor neuropathy; some patients may show signs of demyelination. Additional features may include eye movement abnormalities, claw hands, foot deformities, and scoliosis (summary by Ylikallio et al., 2017).
Glycosylphosphatidylinositol biosynthesis defect 18
MedGen UID:
1648478
Concept ID:
C4748357
Disease or Syndrome
DEE95 is a severe autosomal recessive developmental disorder characterized by severely impaired global development, hypotonia, weakness, ataxia, coarse facial features, and intractable seizures. More variable features may include abnormalities of the hands and feet, inguinal hernia, and feeding difficulties. The disorder is part of a group of similar neurologic disorders resulting from biochemical defects in the glycosylphosphatidylinositol (GPI) biosynthetic pathway (summary by Nguyen et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350. For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293).
Joubert syndrome 35
MedGen UID:
1648453
Concept ID:
C4748442
Disease or Syndrome
Joubert syndrome-35 (JBTS35) is an autosomal recessive disorder characterized by brain malformations that result in developmental delay, oculomotor apraxia, and hypotonia. Some patients have renal and retinal involvement (Alkanderi et al., 2018). For a discussion of genetic heterogeneity of Joubert syndrome, see JBTS1 (213300).
Neurodegeneration, childhood-onset, stress-induced, with variable ataxia and seizures
MedGen UID:
1648391
Concept ID:
C4748527
Disease or Syndrome
Stress-induced childhood-onset neurodegeneration with variable ataxia and seizures (CONDSIAS) is an autosomal recessive neurodegenerative disorder with onset in the first years of life following normal early development. Patient have cyclic episodic deterioration in response to stress, such as infection or febrile illness. The severity is highly variable: some patients develop seizures early in life that are associated with loss of developmental milestones and early sudden death in childhood, whereas others present at a later age with muscle weakness, gait ataxia, impaired speech, more subtle clinical deterioration, and cognitive decline. Neurologic involvement includes gait ataxia, cerebellar signs associated with cerebellar atrophy, generalized brain atrophy, impaired intellectual development, hearing loss, and peripheral neuropathy (summary by Ghosh et al., 2018).
Cortical dysplasia, complex, with other brain malformations 9
MedGen UID:
1648399
Concept ID:
C4748540
Disease or Syndrome
Complex cortical dysplasia with other brain malformations-9 is a severe autosomal recessive disorder characterized by profoundly impaired motor and cognitive development apparent from early infancy. Affected individuals develop intractable seizures and are unable to speak or ambulate. Brain imaging shows pachygyria as well as hypogenesis of the corpus callosum and other variable brain abnormalities. The phenotype results from impaired cortical neuronal migration (summary by Schaffer et al., 2018). For a discussion of genetic heterogeneity of CDCBM, see CDCBM1 (614039).
Infantile hypotonia-oculomotor anomalies-hyperkinetic movements-developmental delay syndrome
MedGen UID:
1648431
Concept ID:
C4748715
Disease or Syndrome
Baker-Gordon syndrome (BAGOS) is a neurodevelopmental disorder characterized by infantile hypotonia, ophthalmic abnormalities, moderate to profound global developmental delay, poor or absent speech, behavioral abnormalities, hyperkinetic movements, and EEG abnormalities in the absence of overt seizures (summary by Baker et al., 2018).
Mitochondrial complex 1 deficiency, nuclear type 3
MedGen UID:
1648346
Concept ID:
C4748752
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 4
MedGen UID:
1648324
Concept ID:
C4748753
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 5
MedGen UID:
1648292
Concept ID:
C4748754
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 6
MedGen UID:
1648496
Concept ID:
C4748759
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 10
MedGen UID:
1648426
Concept ID:
C4748768
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 17
MedGen UID:
1648418
Concept ID:
C4748786
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 21
MedGen UID:
1648383
Concept ID:
C4748792
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 27
MedGen UID:
1648481
Concept ID:
C4748826
Disease or Syndrome
Neurodegeneration, childhood-onset, with cerebellar atrophy
MedGen UID:
1648286
Concept ID:
C4748934
Disease or Syndrome
Childhood-onset neurodegeneration with cerebellar atrophy (CONDCA) is a severe autosomal recessive neurodevelopmental disorder affecting the central and peripheral nervous system. Patients present in the first year of life with global developmental delay, impaired intellectual development, poor or absent speech, and motor abnormalities. Brain imaging shows cerebellar atrophy. The severity is variable, but death in childhood may occur (Shashi et al., 2018).
Spinocerebellar ataxia, autosomal recessive 23
MedGen UID:
1667331
Concept ID:
C4750914
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-23 is a neurologic disorder characterized by epilepsy, intellectual disability, and gait ataxia (summary by Gomez-Herreros et al., 2014).
Ferro-cerebro-cutaneous syndrome
MedGen UID:
1658844
Concept ID:
C4751570
Disease or Syndrome
A rare genetic metabolic liver disease with characteristics of progressive neurodegeneration, cutaneous abnormalities including varying degrees of ichthyosis or seborrheic dermatitis, and systemic iron overload. Patients manifest with infantile-onset seizures, encephalopathy, abnormal eye movements, axial hypotonia with peripheral hypertonia, brisk reflexes, cortical blindness and deafness, myoclonus and hepato/splenomegaly, as well as oral manifestations including microdontia, widely spaced and pointed teeth with delayed eruption and gingival overgrowth.
Hypomyelination with brain stem and spinal cord involvement and leg spasticity
MedGen UID:
1667792
Concept ID:
C4755254
Disease or Syndrome
Hypomyelination with brainstem and spinal cord involvement and leg spasticity is an autosomal recessive leukoencephalopathy characterized by onset in the first year of life of severe spasticity, mainly affecting the lower limbs and resulting in an inability to achieve independent ambulation. Affected individuals show delayed motor development and nystagmus; some may have mild mental retardation. Brain MRI shows hypomyelination and white matter lesions in the cerebrum, brainstem, cerebellum, and spinal cord (summary by Taft et al., 2013).
Spinocerebellar ataxia, autosomal recessive, with axonal neuropathy 1
MedGen UID:
1683470
Concept ID:
C4759870
Disease or Syndrome
Spinocerebellar ataxia with axonal neuropathy type 1 (SCAN1) is characterized by late-childhood-onset slowly progressive cerebellar ataxia and distal sensorimotor axonal neuropathy. Gaze nystagmus and dysarthria usually develop after the onset of ataxic gait. As the disease advances, pain and touch sensation in the hands and feet become impaired; vibration sense is lost in hands and lower thighs. Individuals with advanced disease develop a steppage gait and pes cavus and eventually become wheelchair dependent. Cognitive dysfunction – present in some – manifests as mild intellectual disability and poor executive function. To date only seven affected individuals have been described from three apparently unrelated consanguineous families (one from Saudi Arabia and two from Oman); therefore, it is likely that the full phenotypic spectrum of this disorder is not yet known.
Autosomal recessive spinocerebellar ataxia 20
MedGen UID:
1684324
Concept ID:
C5190595
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-20 is a neurodevelopmental disorder characterized by severely delayed psychomotor development with poor or absent speech, wide-based or absent gait, coarse facies, and cerebellar atrophy (summary by Thomas et al., 2014).
Autosomal recessive spinocerebellar ataxia 11
MedGen UID:
1681191
Concept ID:
C5190803
Disease or Syndrome
A rare hereditary cerebellar ataxia disorder with characteristics of late-onset spinocerebellar ataxia, manifesting with slowly progressive gait disturbances, dysarthria, limb and truncal ataxia and smooth-pursuit eye movement disturbance, associated with a history of psychomotor delay from childhood. Mild atrophy of the cerebellar vermis and hemispheres is observed on brain imaging. There is evidence the disease is caused by homozygous mutation in the SYT14 gene on chromosome 1q32.
Progressive myoclonic epilepsy type 6
MedGen UID:
1681379
Concept ID:
C5190805
Disease or Syndrome
Progressive myoclonic epilepsy-6 (EPM6) is an autosomal recessive neurologic disorder characterized by onset of ataxia in the first years of life, followed by action myoclonus and seizures later in childhood, and loss of independent ambulation in the second decade. Cognition is not usually affected, although mild memory difficulties may occur in the third decade (summary by Corbett et al., 2011). For a discussion of genetic heterogeneity of progressive myoclonic epilepsy, see EPM1A (254800).
Basal ganglia calcification, idiopathic, 7, autosomal recessive
MedGen UID:
1683911
Concept ID:
C5193025
Disease or Syndrome
Autosomal recessive idiopathic basal ganglia calcification-7 is a neurologic disorder characterized by onset of symptoms in adulthood. Patients present with dysarthria, gait abnormalities, various movement abnormalities, and often cognitive decline. Brain imaging shows abnormal accumulation of calcium deposits in deep brain regions, including the basal ganglia, thalamus, dentate nuclei, cerebellum, and sometimes other areas of the brain and spinal cord. Some patients with brain imaging abnormalities may be clinically asymptomatic (summary by Yao et al., 2018). For a detailed phenotypic description and a discussion of genetic heterogeneity of IBGC, see IBGC1 (213600).
NAD(P)HX dehydratase deficiency
MedGen UID:
1681210
Concept ID:
C5193026
Disease or Syndrome
Early-onset progressive encephalopathy with brain edema and/or leukoencephalopathy-2 (PEBEL2) is an autosomal recessive severe neurometabolic disorder characterized by rapidly progressive neurologic deterioration that is usually associated with a febrile illness. Affected infants tend to show normal early development followed by acute psychomotor regression with ataxia, hypotonia, and sometimes seizures, resulting in death in the first years of life. Brain imaging shows multiple abnormalities, including brain edema and signal abnormalities in the cortical and subcortical regions (summary by Van Bergen et al., 2019). For a discussion of genetic heterogeneity of PEBEL, see PEBEL1 (617186).
Neurodevelopmental disorder with central and peripheral motor dysfunction
MedGen UID:
1674767
Concept ID:
C5193049
Disease or Syndrome
Neurodevelopmental disorder with central and peripheral motor dysfunction (NEDCPMD) is an autosomal recessive neurologic disorder with a highly variable phenotype. At the severe end of the spectrum, patients may have hypotonia apparent from birth, necessitating mechanical respiration and tube-feeding, and global developmental delay with absence of reaction to touch and no eye contact. At the mild end of the spectrum, patients may present with infantile-onset progressive ataxia and demyelinating peripheral neuropathy. The disorder is caused by mutation in the NFASC gene, which has several neuronal- and glial-specific transcripts. The variable clinical phenotype may be caused by several factors, including the severity of the mutation, the selective involvement of distinct isoforms by pathogenic variants, and the presence of genetic modifiers (summary by Monfrini et al., 2019).
Intellectual developmental disorder, autosomal recessive 69
MedGen UID:
1676539
Concept ID:
C5193067
Disease or Syndrome
Leukoencephalopathy, acute reversible, with increased urinary alpha-ketoglutarate
MedGen UID:
1677730
Concept ID:
C5193068
Disease or Syndrome
Acute reversible leukoencephalopathy with increased urinary alpha-ketoglutarate (ARLIAK) is an autosomal recessive disorder characterized by acute reversible neurologic deterioration in the context of a febrile illness. The disorder is associated with transient leukoencephalopathy on brain imaging concurrent with the acute episode, as well as persistently increased excretion of dicarboxylic acids, particularly alpha-ketoglutarate (summary by Dewulf et al., 2019).
Spinocerebellar ataxia, autosomal recessive, with axonal neuropathy 3
MedGen UID:
1673607
Concept ID:
C5193070
Disease or Syndrome
Spinocerebellar ataxia with axonal neuropathy-3 (SCAN3) is an autosomal recessive neuromuscular disorder characterized by onset in the first decade of slowly progressive distal muscle weakness and atrophy and distal sensory impairment due to an axonal peripheral neuropathy. Affected individuals have gait disturbances and sometimes manual dexterity difficulties, as well as cerebellar ataxia associated with cerebellar atrophy on brain imaging. Additional features usually include dysarthria, hyporeflexia, and increased serum creatine kinase. Some patients may have impaired intellectual development (summary by Higuchi et al., 2018). For a discussion of genetic heterogeneity of SCAN, see SCAN1 (607250).
Metabolic crises, recurrent, with variable encephalomyopathic features and neurologic regression
MedGen UID:
1681269
Concept ID:
C5193083
Disease or Syndrome
Recurrent metabolic crises with variable encephalomyopathic features and neurologic regression (MECREN) is an autosomal recessive metabolic disorder with a highly variable phenotype. Most affected individuals present in the first years of life with episodic lactic acidosis associated with illness or stress, resulting in transient or permanent neurologic dysfunction. Some patients may recover, whereas others show subsequent variable developmental regression of motor and cognitive skills. Other features may include dystonia, hypotonia with inability to sit or walk, seizures, and abnormal signals in the basal ganglia. There is significant phenotypic heterogeneity, even among patients with the same mutation (summary by Almannai et al., 2018).
Neurodevelopmental disorder with impaired speech and hyperkinetic movements
MedGen UID:
1681181
Concept ID:
C5193088
Disease or Syndrome
Neurodevelopmental disorder with impaired speech and hyperkinetic movements (NEDISHM) is an autosomal recessive disorder characterized by global developmental delay apparent in infancy. Most patients have mildly delayed walking, speech and language delay, and a hyperkinetic movement disorder with dystonia, tremor, ataxia, or chorea. Some may develop seizures that tend to abate (summary by Khan et al., 2019).
Encephalopathy, acute, infection-induced, susceptibility to, 9
MedGen UID:
1673394
Concept ID:
C5193089
Finding
Susceptibility to acute infection-induced encephalopathy-9 (IIAE9) is an autosomal recessive disorder characterized by episodic acute neurodegeneration and developmental regression associated with infections and febrile illness. Patients present in the first months or years of life, often after normal or only mildly delayed early development. Some patients may have partial recovery between episodes, such as transient ataxia, but the overall disease course is progressive, resulting in global developmental delay, abnormal movements, refractory seizures, microcephaly, and cerebellar atrophy (summary by Fichtman et al., 2019). For a discussion of genetic heterogeneity of susceptibility to acute infection-induced encephalopathy, see 610551.
Developmental delay with variable intellectual impairment and behavioral abnormalities
MedGen UID:
1676192
Concept ID:
C5193092
Disease or Syndrome
Developmental delay with variable intellectual impairment and behavioral abnormalities (DDVIBA) is an autosomal dominant neurodevelopmental disorder. Most patients have impaired intellectual development with speech difficulties, and many have behavioral abnormalities, most commonly autism spectrum disorder (ASD), defects in attention, and/or hyperactivity. Many patients have dysmorphic features, although there is not a consistent gestalt. Additional more variable features may include hypotonia, somatic overgrowth with macrocephaly, mild distal skeletal anomalies, sleep disturbances, movement disorders, and gastrointestinal issues, such as constipation. The phenotype is highly variable (summary by Vetrini et al., 2019 and Torti et al., 2019).
Spastic ataxia 9, autosomal recessive
MedGen UID:
1680026
Concept ID:
C5193100
Disease or Syndrome
Neurodevelopmental disorder with or without variable brain abnormalities; NEDBA
MedGen UID:
1675664
Concept ID:
C5193102
Disease or Syndrome
Neurodevelopmental disorder with or without variable brain abnormalities (NEDBA) is characterized by global developmental delay apparent from infancy or early childhood, resulting in mildly delayed walking, variably impaired intellectual development, and poor or absent speech. Additional features may include hypotonia, spasticity, or ataxia. About half of patients have abnormal findings on brain imaging, including cerebral or cerebellar atrophy, loss of white matter volume, thin corpus callosum, and perisylvian polymicrogyria. Seizures are not a prominent finding, and although some patients may have nonspecific dysmorphic facial features, there is no common or consistent gestalt (summary by Platzer et al., 2019).
Brain abnormalities, neurodegeneration, and dysosteosclerosis
MedGen UID:
1678789
Concept ID:
C5193117
Disease or Syndrome
Brain abnormalities, neurodegeneration, and dysosteosclerosis (BANDDOS) is an autosomal recessive disorder characterized by brain abnormalities, progressive neurologic deterioration, and sclerotic bone dysplasia similar to dysosteosclerosis (DOS). The age at onset is highly variable: some patients may present in infancy with hydrocephalus, global developmental delay, and hypotonia, whereas others may have onset of symptoms in the late teens or early twenties after normal development. Neurologic features include loss of previous motor and language skills, cognitive impairment, spasticity, and focal seizures. Brain imaging shows periventricular white matter abnormalities and calcifications, large cisterna magna or Dandy-Walker malformation, and sometimes agenesis of the corpus callosum (summary by Guo et al., 2019).
Cerebellar atrophy with seizures and variable developmental delay
MedGen UID:
1683734
Concept ID:
C5193132
Disease or Syndrome
Cerebellar atrophy with seizures and variable developmental delay (CASVDD) is an autosomal recessive neurologic disorder characterized by cerebellar ataxia associated with atrophy of the cerebellar vermis on brain imaging. Most patients also have onset of severe refractory seizures in the first year of life and show global developmental delay, compatible with epileptic encephalopathy (summary by Edvardson et al., 2013). However, at least 1 patient with normal cognitive development and only 1 febrile seizure has been reported (Valence et al., 2019), suggesting significant clinical variability of this disorder.
Ichthyotic keratoderma, spasticity, hypomyelination, and dysmorphic facial features
MedGen UID:
1682428
Concept ID:
C5193147
Disease or Syndrome
Ichthyotic keratoderma, spasticity, hypomyelination, and dysmorphic features (IKSHD) is characterized by epidermal hyperproliferation and increased keratinization, resulting in ichthyosis; hypomyelination of central white matter, causing spastic paraplegia and central nystagmus; and optic atrophy, resulting in reduction of peripheral vision and visual acuity (Mueller et al., 2019). In addition, patients exhibit mild facial dysmorphism (Kutkowska-Kazmierczak et al., 2018).
Oculopharyngodistal myopathy 1
MedGen UID:
1684682
Concept ID:
C5231388
Disease or Syndrome
Oculopharyngodistal myopathy-1 (OPDM1) is an autosomal dominant disorder characterized by adult-onset ptosis, external ophthalmoplegia, facial muscle weakness, distal limb muscle weakness and atrophy, and pharyngeal involvement, resulting in dysphagia and dysarthria. Skeletal muscle biopsy shows myopathic changes with rimmed vacuoles. There are variable manifestations of the disorder regarding muscle involvement and severity (summary by Ishiura et al., 2019). Genetic Heterogeneity of Oculopharyngodistal Myopathy See also OPDM2 (618940), caused by trinucleotide repeat expansion in the GIPC1 gene (605072) on chromosome 19p13; OPDM3 (619473), caused by trinucleotide repeat expansion in the NOTCH2NLC gene (618025) on chromosome 1q21; and OPDM4 (619790), caused by trinucleotide repeat expansion in the RILPL1 gene (614092) on chromosome 12q24. Oculopharyngeal muscular dystrophy (OPMD; 164300) is a similar disorder with overlapping features. It is caused by a similar heterozygous trinucleotide repeat expansion in the PABPN1 gene (602279) (summary by Durmus et al., 2011).
Congenital cerebellar hypoplasia
MedGen UID:
1695950
Concept ID:
C5231391
Disease or Syndrome
Cerebellar hypoplasia/atrophy, epilepsy, and global developmental delay is an autosomal recessive neurodevelopmental disorder characterized by infantile onset of hypotonia and developmental delay with subsequent impaired intellectual development and severe speech delay. In childhood, affected individuals show delayed walking and develop epilepsy that is usually controlled by medication. Brain imaging shows cerebellar hypoplasia/atrophy (summary by Wang et al., 2019).
Neurodevelopmental disorder with visual defects and brain anomalies
MedGen UID:
1684774
Concept ID:
C5231404
Disease or Syndrome
Neurodevelopmental disorder with visual defects and brain anomalies (NEDVIBA) is characterized by global developmental delay with impaired intellectual development and speech delay, variable visual defects, including retinitis pigmentosa and optic atrophy, hypotonia or hypertonia, and variable structural brain abnormalities. Other nonspecific features may be found (summary by Okur et al., 2019).
Spastic tetraplegia and axial hypotonia, progressive
MedGen UID:
1684731
Concept ID:
C5231422
Disease or Syndrome
Progressive spastic tetraplegia and axial hypotonia (STAHP) is an autosomal recessive neurologic disorder characterized by onset of severe and progressive motor dysfunction in the first year of life. Affected individuals have severe axial hypotonia combined with spastic tetraplegia, hyperekplexia, hypertonia, and myokymia, reflecting upper motor neuron involvement. Cognitive development may be affected, but only 2 unrelated patients have been reported (Andersen et al., 2019; Park et al., 2019).
Oculopharyngeal myopathy with leukoencephalopathy 1
MedGen UID:
1684701
Concept ID:
C5231436
Disease or Syndrome
Mitochondrial complex 5 (ATP synthase) deficiency, nuclear type 6
MedGen UID:
1684729
Concept ID:
C5231461
Disease or Syndrome
Mitochondrial complex V (ATP synthase) deficiency nuclear type 6 (MC5DN6) is an autosomal recessive progressive and degenerative disorder characterized by episodic regression of gross motor skills beginning in early childhood. The episodes are associated with metabolic stress, including fever, illness, and general anesthesia. Patients develop gait difficulties or loss of ambulation, as well as other variable abnormalities, including abnormal movements, hemiplegia, and persistent lethargy. Brain imaging shows degenerative features in the basal ganglia and brainstem consistent with a diagnosis of Leigh syndrome (see 256000) (summary by Barca et al., 2018). For a discussion of genetic heterogeneity of mitochondrial complex V deficiency, see MC5DN1 (604273).
Leukodystrophy, hypomyelinating, 19, transient infantile
MedGen UID:
1684698
Concept ID:
C5231463
Disease or Syndrome
Transient infantile hypomyelinating leukodystrophy-19 (HLD19) is a disorder characterized by onset of transient neurologic abnormalities in early infancy, with resolution within the first or second decades. Affected individuals typically present in the newborn period or in early infancy with nystagmus and motor deficits associated with marked hypomyelination on brain imaging. Both neurologic impairment and abnormal brain imaging spontaneously resolve during childhood. Most patients have normal cognition and can attend regular schools, although some may have persistent neurologic deficits, such as gait ataxia, speech pronunciation defects, and/or mild cognitive impairment (summary by Yan et al., 2019). For a discussion of genetic heterogeneity of HLD, see 312080.
Neurodevelopmental disorder with nonspecific brain abnormalities and with or without seizures
MedGen UID:
1684757
Concept ID:
C5231470
Disease or Syndrome
Neurodevelopmental disorder with nonspecific brain abnormalities is a highly variable syndrome characterized by impaired intellectual development and behavioral abnormalities associated with structural changes on brain imaging. Some patients have seizures, hypotonia, and scoliosis/kyphosis. Cognitive function ranges from severely impaired to the ability to attend schools with special assistance (summary by Fischer-Zirnsak et al., 2019).
Liang-Wang syndrome
MedGen UID:
1684847
Concept ID:
C5231479
Disease or Syndrome
Liang-Wang syndrome (LIWAS) is a polymalformation syndrome apparent from birth that shows large phenotypic variability and severity. However, all patients have some degree of neurologic dysfunction. The most severely affected individuals have severe global developmental delay with impaired intellectual development and poor or absent speech, marked craniofacial dysmorphism, and visceral and connective tissue abnormalities affecting the bones and vessels. The least severely affected individuals lack seizures, significant dysmorphism, and visceral involvement; they come to attention for neurologic signs and symptoms, including developmental delay with speech delay, strabismus, and/or ataxia. About half of patients have brain imaging anomalies, notably cerebral and cerebellar atrophy and thin corpus callosum, whereas the other half have normal brain imaging (summary by Liang et al., 2019).
Hereditary spastic paraplegia 30
MedGen UID:
1710020
Concept ID:
C5235139
Disease or Syndrome
Spastic paraplegia-30 (SPG30) is a neurologic disorder characterized by onset of slowly progressive spastic paraplegia in the first or second decades of life. Affected individuals have unsteady spastic gait and hyperreflexia of the lower limbs. Some patients have a 'pure' form of the disorder, limited to spastic paraplegia, whereas others may have a 'complicated' form that includes cognitive dysfunction, learning disabilities, or behavioral abnormalities, peripheral sensorimotor neuropathy, urinary sphincter problems, and/or cerebellar atrophy with thin corpus callosum on brain imaging. The phenotypic features represent a spectrum of abnormalities of the central, peripheral, and autonomic nervous system (summary by Pennings et al., 2020). For a discussion of genetic heterogeneity of autosomal dominant spastic paraplegia, see SPG3A (182600). For a discussion of genetic heterogeneity of autosomal recessive spastic paraplegia, see SPG5A (270800).
Intellectual disability, autosomal dominant 9
MedGen UID:
1714250
Concept ID:
C5393830
Disease or Syndrome
NESCAV syndrome (NESCAVS) is a neurodegenerative disorder characterized by onset of features in infancy or early childhood. Affected individuals show global developmental delay with delayed walking or difficulty walking due to progressive spasticity mainly affecting the lower limbs and often leading to loss of independent ambulation. There is variably impaired intellectual development, speech delay, and learning disabilities and/or behavioral abnormalities. Additional features may include cortical visual impairment, often associated with optic atrophy, axonal peripheral neuropathy, seizures, dysautonomia, ataxia, and dystonia. Brain imaging often shows progressive cerebellar atrophy and thin corpus callosum. Some patients may show developmental regression, particularly of motor skills. The phenotype and presentation are highly variable (summary by Nemani et al., 2020).
Epilepsy, progressive myoclonic, 11
MedGen UID:
1716712
Concept ID:
C5394362
Disease or Syndrome
Progressive myoclonic epilepsy-11 (EPM11) is a neurodegenerative disorder characterized by onset of developmental regression and various types of seizures around 2 years of age after relatively normal early development. The seizures are usually refractory to treatment and are associated with multiple abnormalities on EEG. During the first and second decades, affected individuals develop additional neurologic signs and symptoms, including pyramidal, extrapyramidal, and cerebellar signs such as spasticity, loss of independent ambulation, myoclonus, tremor, and ataxia. Cognitive impairment is severe, and patients can speak only a few words or are non-verbal (summary by Hamanaka et al., 2020). For discussion of genetic heterogeneity of progressive myoclonic epilepsy, see EPM1A (254800).
Neurodevelopmental disorder with hypotonia and cerebellar atrophy, with or without seizures
MedGen UID:
1710849
Concept ID:
C5394372
Disease or Syndrome
Neurodevelopmental disorder with hypotonia and cerebellar atrophy, with or without seizures (NEDHCAS) is an autosomal recessive neurodevelopmental disorder characterized by global developmental delay with variably impaired intellectual development, delayed motor skills, and poor or absent speech. Most patients develop early-onset seizures and demonstrate cerebellar ataxia or dysmetria associated with progressive cerebellar atrophy on brain imaging. The disorder is caused by a defect in glycosylphosphatidylinositol (GPI) biosynthesis (summary by Nguyen et al., 2020). For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293).
COACH syndrome 1
MedGen UID:
1769861
Concept ID:
C5435651
Disease or Syndrome
Any COACH syndrome in which the cause of the disease is a variation in the TMEM67 gene.
Mitochondrial complex IV deficiency, nuclear type 1
MedGen UID:
1750917
Concept ID:
C5435656
Disease or Syndrome
Mitochondrial complex IV deficiency nuclear type 1 (MC4DN1) is an autosomal recessive metabolic disorder characterized by rapidly progressive neurodegeneration and encephalopathy with loss of motor and cognitive skills between about 5 and 18 months of age after normal early development. Affected individuals show hypotonia, failure to thrive, loss of the ability to sit or walk, poor communication, and poor eye contact. Other features may include oculomotor abnormalities, including slow saccades, strabismus, ophthalmoplegia, and nystagmus, as well as deafness, apneic episodes, ataxia, tremor, and brisk tendon reflexes. Brain imaging shows bilateral symmetric lesions in the basal ganglia, consistent with a clinical diagnosis of Leigh syndrome (see 256000). Some patients may also have abnormalities in the brainstem and cerebellum. Laboratory studies usually show increased serum and CSF lactate and decreased levels and activity of mitochondrial respiratory complex IV in patient tissues. There is phenotypic variability, but death in childhood, often due to central respiratory failure, is common (summary by Tiranti et al., 1998; Tiranti et al., 1999; Teraoka et al., 1999; Poyau et al., 2000) Genetic Heterogeneity of Mitochondrial Complex IV Deficiency Most isolated COX deficiencies are inherited as autosomal recessive disorders caused by mutations in nuclear-encoded genes; mutations in the mtDNA-encoded COX subunit genes are relatively rare (Shoubridge, 2001; Sacconi et al., 2003). Mitochondrial complex IV deficiency caused by mutation in nuclear-encoded genes, in addition to MC4DN1, include MC4DN2 (604377), caused by mutation in the SCO2 gene (604272); MC4DN3 (619046), caused by mutation in the COX10 gene (602125); MC4DN4 (619048), caused by mutation in the SCO1 gene (603664); MC4DN5 (220111), caused by mutation in the LRPPRC gene (607544); MC4DN6 (615119), caused by mutation in the COX15 gene (603646); MC4DN7 (619051), caused by mutation in the COX6B1 gene (124089); MC4DN8 (619052), caused by mutation in the TACO1 gene (612958); MC4DN9 (616500), caused by mutation in the COA5 gene (613920); MC4DN10 (619053), caused by mutation in the COX14 gene (614478); MC4DN11 (619054), caused by mutation in the COX20 gene (614698); MC4DN12 (619055), caused by mutation in the PET100 gene (614770); MC4DN13 (616501), caused by mutation in the COA6 gene (614772); MC4DN14 (619058), caused by mutation in the COA3 gene (614775); MC4DN15 (619059), caused by mutation in the COX8A gene (123870); MC4DN16 (619060), caused by mutation in the COX4I1 gene (123864); MC4DN17 (619061), caused by mutation in the APOPT1 gene (616003); MC4DN18 (619062), caused by mutation in the COX6A2 gene (602009); MC4DN19 (619063), caused by mutation in the PET117 gene (614771); MC4DN20 (619064), caused by mutation in the COX5A gene (603773); MC4DN21 (619065), caused by mutation in the COXFA4 gene (603883); MC4DN22 (619355), caused by mutation in the COX16 gene (618064); and MC4DN23 (620275), caused by mutation in the COX11 gene (603648). Mitochondrial complex IV deficiency has been associated with mutations in several mitochondrial genes, including MTCO1 (516030), MTCO2 (516040), MTCO3 (516050), MTTS1 (590080), MTTL1 (590050), and MTTN (590010).
Combined oxidative phosphorylation deficiency 45
MedGen UID:
1731010
Concept ID:
C5436461
Disease or Syndrome
Combined oxidative phosphorylation deficiency-45 (COXPD45) is an autosomal recessive multisystem disorder characterized by poor overall growth apparent from infancy, global developmental delay, seizures, and acute progressive neurologic deterioration with loss of skills. Other features may include dysmorphic facies and lesions on brain imaging. Laboratory studies show increased serum lactate and COXPD in patient tissues, consistent with a mitochondrial defect (summary by Serre et al., 2013). For discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060).
Cone-rod synaptic disorder syndrome, congenital nonprogressive
MedGen UID:
1773574
Concept ID:
C5436505
Disease or Syndrome
Congenital nonprogressive cone-rod synaptic disorder syndrome (CRSDS) is characterized by retinal and neurodevelopmental disease as well as occasional anomalies of glucose homeostasis. Patients exhibit low vision, photophobia, and nystagmus, and show an electronegative waveform in response to bright flash under dark adaptation on electroretinography, with severely reduced and delayed light-adapted responses. Neurodevelopmental features include poor to no language and autistic behaviors (Mechaussier et al., 2020).
Coenzyme q10 deficiency, primary, 9
MedGen UID:
1740444
Concept ID:
C5436638
Disease or Syndrome
Coenzyme Q10 deficiency-9 (COQ10D9) is an autosomal recessive disorder characterized by onset of cerebellar ataxia associated with cerebellar atrophy in the first decade of life. Some patients may have additional neurologic signs and symptoms, including intellectual disability and seizures. Treatment with CoQ10 may offer clinical benefit (summary by Malicdan et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of primary coenzyme Q10 deficiency, see COQ10D1 (607426).
Mitochondrial complex 4 deficiency, nuclear type 3
MedGen UID:
1764816
Concept ID:
C5436682
Disease or Syndrome
Mitochondrial complex IV deficiency nuclear type 3 (MC4DN3) is an autosomal recessive multisystem metabolic disorder with a highly variable phenotype. Some patients present with encephalomyopathic features in early infancy, whereas others may present later in infancy or the first years of life after normal early development. Affected individuals show hypotonia, failure to thrive, and developmental delay or regression with poor eye contact and loss of motor skills with ataxia. Additional features observed in some patients include proximal renal tubulopathy, macrocytic anemia, sensorineural hearing loss, nystagmus, and hypertrophic cardiomyopathy, consistent with systemic involvement. Brain imaging in most patients shows lesions consistent with Leigh syndrome (see 256000). Laboratory studies show increased serum lactate and decreased levels and activity of mitochondrial respiratory complex IV. Most patients die in infancy (summary by Valnot et al., 2000 and Antonicka et al., 2003). For a discussion of genetic heterogeneity of mitochondrial complex IV (cytochrome c oxidase) deficiency, see 220110.
Mitochondrial complex 4 deficiency, nuclear type 11
MedGen UID:
1760275
Concept ID:
C5436694
Disease or Syndrome
Mitochondrial complex IV deficiency nuclear type 11 (MC4DN11) is an autosomal recessive metabolic disorder characterized by a childhood-onset sensory neuronopathy and additional features which may include hypotonia, cerebellar ataxia, tremor, dystonia, choreoathetosis, and/or dysarthria. Patients may have variable motor delay, speech delay, or impaired intellectual development (summary by Doss et al., 2014; Otero et al., 2019; Xu et al., 2019; Dong et al., 2021). For a discussion of genetic heterogeneity of mitochondrial complex IV (cytochrome c oxidase) deficiency, see 220110.
Mitochondrial complex 4 deficiency, nuclear type 17
MedGen UID:
1730423
Concept ID:
C5436718
Disease or Syndrome
Mitochondrial complex IV deficiency nuclear type 17 (MC4DN17) is an autosomal recessive neurometabolic disorder with somewhat variable clinical manifestations and severity. Most affected individuals present in early childhood with motor and gait difficulties after normal early development. These motor abnormalities progress to spastic tetraparesis, sometimes resulting in loss of ambulation. Many patients also show episodic developmental regression: some have impaired cognition and dysarthria, although others have normal speech and cognition. More variable features include seizures and sensorimotor polyneuropathy. The clinical features tend to stabilize over time. Brain imaging shows a cavitating leukodystrophy, and laboratory studies show variably decreased levels and activity of mitochondrial respiratory complex IV in patient tissues (Melchionda et al., 2014). For a discussion of genetic heterogeneity of mitochondrial complex IV (cytochrome c oxidase) deficiency, see 220110.
Mitochondrial complex 4 deficiency, nuclear type 21
MedGen UID:
1732562
Concept ID:
C5436727
Disease or Syndrome
Mitochondrial complex IV deficiency nuclear type 21 (MC4DN21) is an autosomal recessive multisystem metabolic disorder characterized by the onset of symptoms in infancy. Affected individuals present with congenital lactic acidosis and later show global developmental delay with delayed speech and learning disabilities. Additional features include motor dysfunction manifest as spasticity, dystonia, and pyramidal tract signs. Ataxia, peripheral neuropathy, and seizures may also occur. Brain imaging shows T2-weighted hyperintensities in subcortical regions, consistent with a clinical diagnosis of Leigh syndrome (see 256000). Patient tissues show variably decreased levels and activity of mitochondrial respiratory complex IV (Pitceathly et al., 2013). For a discussion of genetic heterogeneity of mitochondrial complex IV (cytochrome c oxidase) deficiency, see 220110.
Neurodevelopmental disorder with microcephaly, impaired language, epilepsy, and gait abnormalities
MedGen UID:
1764121
Concept ID:
C5436788
Disease or Syndrome
Neurodevelopmental disorder with microcephaly, impaired language, epilepsy, and gait abnormalities (NEDMILEG) is characterized by global developmental delay apparent in infancy. Affected individuals have delayed walking with variable gait abnormalities, including ataxia and spasticity, impaired intellectual development with poor or absent speech and language, and progressive microcephaly. Dysmorphic facial features may also be observed. Most patients have early-onset seizures; some may develop a demyelinating peripheral neuropathy. The clinical features suggest involvement of both the central and peripheral nervous systems (Manole et al., 2020).
Intellectual developmental disorder with speech delay and axonal peripheral neuropathy
MedGen UID:
1754849
Concept ID:
C5436813
Disease or Syndrome
Intellectual developmental disorder with speech delay and axonal peripheral neuropathy (IDDSAPN) is an autosomal recessive neurologic disorder characterized by mild global developmental delay with motor impairment and severe speech delay apparent in the first years of life. Affected individuals begin to walk independently between 3 and 4 years of age, but often have an unsteady or ataxic gait. Most patients have progressive distal muscle weakness and atrophy of the lower limbs, foot or hand deformities, and dysarthria, consistent with a peripheral neuropathy. There is mildly impaired intellectual development. Some patients may have behavioral anomalies, such as autistic features or attention deficit-hyperactivity disorder (ADHD), and some can attend special schools. The overall clinical features indicate involvement of both the central and peripheral nervous systems (summary by Martin et al., 2020 and Ahmed et al., 2021)
COACH syndrome 3
MedGen UID:
1755565
Concept ID:
C5436841
Disease or Syndrome
COACH syndrome is classically defined as Cerebellar vermis hypoplasia, Oligophrenia, Ataxia, Colobomas, and Hepatic fibrosis (Verloes and Lambotte, 1989). Brain MRI demonstrates the molar tooth sign, which is a feature of Joubert syndrome. The disorder has been described as a Joubert syndrome-related disorder with liver disease (summary by Doherty et al., 2010). For a general phenotypic description and a discussion of genetic heterogeneity of COACH syndrome, see 216360.
Intellectual developmental disorder with paroxysmal dyskinesia or seizures
MedGen UID:
1727046
Concept ID:
C5436894
Disease or Syndrome
Intellectual developmental disorder with paroxysmal dyskinesia or seizures (IDDPADS) is an autosomal recessive complex neurologic disorder characterized by global developmental delay with impaired intellectual development and language delay. In addition, most patients develop a paroxysmal hyperkinetic movement disorder in the first months or years of life manifest as sudden falls or backward propulsion, eye or head deviation, and dystonic limb posturing followed by chorea and dyskinetic movements. The episodes are pharmacoresistant to anticonvulsant medication. EEG may show interictal abnormalities, but are usually not consistent with epilepsy. However, some patients may also develop epileptic seizures or only have seizures without a movement disorder (summary by Doummar et al., 2020).
Mitochondrial complex 2 deficiency, nuclear type 3
MedGen UID:
1751884
Concept ID:
C5436934
Disease or Syndrome
Mitochondrial complex II deficiency nuclear type 3 (MC2DN3) is an autosomal recessive multisystemic metabolic disorder with a highly variable phenotype. Some patients may have an encephalomyopathic picture with episodic developmental regression, loss of motor skills, hypotonia, ataxia, dystonia, and seizures or myoclonus. Other patients present in infancy with hypertrophic cardiomyopathy, which may be fatal. Laboratory studies show increased serum lactate and mitochondrial complex II deficiency in muscle and fibroblasts (summary by Jackson et al., 2014 and Alston et al., 2015). For a discussion of genetic heterogeneity of MC2DN, see MC2DN1 (252011).
Epilepsy, progressive myoclonic, 12
MedGen UID:
1778162
Concept ID:
C5543069
Disease or Syndrome
Progressive myoclonic epilepsy-12 (EPM12) is an autosomal recessive neurologic disorder characterized by onset of tonic-clonic seizures and/or myoclonus in the second decade of life. Affected individuals develop cerebellar ataxia associated with progressive cerebral and cerebellar atrophy on brain imaging. Most patients lose ambulation and become wheelchair-bound. Additional more variable features include mild cognitive dysfunction or psychiatric manifestations, such as depression or anxiety (summary by Mazzola et al., 2021). For a discussion of genetic heterogeneity of progressive myoclonic epilepsy, see EPM1A (254800).
Deafness, congenital, and adult-onset progressive leukoencephalopathy
MedGen UID:
1784506
Concept ID:
C5543087
Disease or Syndrome
Congenital deafness and adult-onset progressive leukoencephalopathy (DEAPLE) is an autosomal recessive complex neurodegenerative disorder characterized by congenital neurosensory deafness followed by onset of neurodegenerative symptoms, including pyramidal signs and cognitive decline, in young adulthood. Some patients may have mild developmental delay or learning difficulties in childhood, but most can function independently. The onset of motor and cognitive decline in adulthood can be rapid and may result in early death. Brain imaging shows diffuse white matter abnormalities affecting various brain regions, consistent with a progressive leukoencephalopathy. More variable additional features may include visual impairment and axonal peripheral neuropathy (summary by Scheidecker et al., 2019).
Mitochondrial complex 2 deficiency, nuclear type 4
MedGen UID:
1782861
Concept ID:
C5543176
Disease or Syndrome
Mitochondrial complex II deficiency nuclear type 4 (MC2DN4) is a severe autosomal recessive disorder characterized by early-onset progressive neurodegeneration with leukoencephalopathy. Acute episodes of neurodegeneration are often triggered by catabolic stress such as infection or fasting.
Developmental delay with dysmorphic facies and dental anomalies
MedGen UID:
1785587
Concept ID:
C5543197
Disease or Syndrome
Developmental delay with dysmorphic facies and dental anomalies (DEFDA) is characterized by generally mild global developmental delay with variably impaired intellectual development, walking by 2 to 3 years, and slow language acquisition. The severity of the disorder ranges from moderate cognitive deficits to mild learning difficulties or behavioral abnormalities. Most patients have dysmorphic facial features, often with abnormal dentition and nonspecific visual defects, such as myopia, astigmatism, and strabismus. Although rare, involvement of other systems, such as skeletal, cardiac, and gastrointestinal, may be present (summary by den Hoed et al., 2021).
Kohlschutter-Tonz syndrome-like
MedGen UID:
1781649
Concept ID:
C5543202
Disease or Syndrome
Den Hoed-de Boer-Voisin syndrome (DHDBV) is characterized by global developmental delay with moderately to severely impaired intellectual development, poor or absent speech, and delayed motor skills. Although the severity of the disorder varies, many patients are nonverbal and have hypotonia with inability to sit or walk. Early-onset epilepsy is common and may be refractory to treatment, leading to epileptic encephalopathy and further interruption of developmental progress. Most patients have feeding difficulties with poor overall growth and dysmorphic facial features, as well as significant dental anomalies resembling amelogenesis imperfecta. The phenotype is reminiscent of Kohlschutter-Tonz syndrome (KTZS; 226750). More variable features of DHDBV include visual defects, behavioral abnormalities, and nonspecific involvement of other organ systems (summary by den Hoed et al., 2021).
Neurodegeneration with ataxia and late-onset optic atrophy
MedGen UID:
1779901
Concept ID:
C5543254
Disease or Syndrome
Neurodegeneration with ataxia and late-onset optic atrophy (NDAXOA) is an autosomal dominant disorder with somewhat variable manifestations. Most affected individuals present in mid-adulthood with slowly progressive cerebellar and gait ataxia, optic atrophy, and myopathy or myalgia. Some patients may have a childhood history of neurologic features, including limited extraocular movements. Additional features can include cardiomyopathy, psychiatric disturbances, and peripheral sensory impairment (summary by Taylor et al., 1996 and Courage et al., 2017).
Spondyloepiphyseal dysplasia, sensorineural hearing loss, impaired intellectual development, and leber congenital amaurosis
MedGen UID:
1780157
Concept ID:
C5543257
Disease or Syndrome
SHILCA is characterized by early-onset retinal degeneration in association with sensorineural hearing loss, short stature, vertebral anomalies, and epiphyseal dysplasia, as well as motor and intellectual delay. Delayed myelination, leukoencephalopathy, and hypoplasia of the corpus callosum and cerebellum have been observed on brain MRI (Bedoni et al., 2020).
Cerebellar hypoplasia-intellectual disability-congenital microcephaly-dystonia-anemia-growth retardation syndrome
MedGen UID:
1780242
Concept ID:
C5543287
Disease or Syndrome
CIMDAG syndrome (CIMDAG) is a multisystemic disorder characterized by severely impaired psychomotor development and hematologic abnormalities apparent from early infancy. Affected individuals show poor overall growth with microcephaly, impaired intellectual development, poor or absent speech, poor eye contact, and motor problems, such as inability to walk, hypotonia, and spasticity. Brain imaging typically shows cerebral and cerebellar atrophy, thin corpus callosum, and delayed myelination. The associated hematologic abnormalities are variable, but are mostly consistent with congenital dyserythropoietic anemia (CDA) (summary by Rodger et al., 2020 and Seu et al., 2020).
Leukodystrophy, hypomyelinating, 21
MedGen UID:
1778269
Concept ID:
C5543334
Disease or Syndrome
Hypomyelinating leukodystrophy-21 (HLD21) is an autosomal recessive neurodegenerative disorder characterized by global developmental delay apparent from infancy with loss of motor, speech, and cognitive milestones in the first decades of life. Affected individuals show cerebellar and pyramidal signs, including nystagmus, ataxia, dystonia, and spasticity, resulting in the loss of ambulation. Other more variable features include feeding difficulties, poor overall growth with microcephaly, optic atrophy, and seizures. Brain imaging shows diffuse hypomyelination of the white matter and atrophy of the cerebellum and corpus callosum. The disorder is progressive and may lead to premature death (summary by Dorboz et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of HLD, see 312080.
Radio-Tartaglia syndrome
MedGen UID:
1778557
Concept ID:
C5543339
Disease or Syndrome
Radio-Tartaglia syndrome (RATARS) is a neurodevelopmental disorder characterized by global developmental delay with impaired intellectual development, speech delay, and variable behavioral abnormalities. Affected individuals show hypotonia, mild motor difficulties, and craniofacial dysmorphism. Brain imaging may show nonspecific defects; rare patients have seizures or pyramidal signs. A subset of individuals may have congenital heart defects, precocious puberty, and obesity in females. Some of the features are similar to those observed in patients with chromosome 1p36 deletion syndrome (607872) (summary by Radio et al., 2021).
Developmental and epileptic encephalopathy 6B
MedGen UID:
1779648
Concept ID:
C5543353
Disease or Syndrome
SCN1A seizure disorders encompass a spectrum that ranges from simple febrile seizures and generalized epilepsy with febrile seizures plus (GEFS+) at the mild end to Dravet syndrome and intractable childhood epilepsy with generalized tonic-clonic seizures (ICE-GTC) at the severe end. Phenotypes with intractable seizures including Dravet syndrome are often associated with cognitive decline. Less commonly observed phenotypes include myoclonic astatic epilepsy (MAE), Lennox-Gastaut syndrome, infantile spasms, epilepsy with focal seizures, and vaccine-related encephalopathy and seizures. The phenotype of SCN1A seizure disorders can vary even within the same family.
Intellectual developmental disorder, autosomal dominant 65
MedGen UID:
1787923
Concept ID:
C5543371
Disease or Syndrome
Autosomal dominant intellectual developmental disorder-65 (MRD65) is characterized by delayed motor and speech acquisition, variably impaired intellectual development, and behavioral abnormalities. Affected individuals also have dysmorphic facial features. Brain imaging may be normal or may show abnormalities, including cerebellar hypoplasia, poor development of the corpus callosum, dysmorphic hippocampus, and polymicrogyria. Feeding difficulties, hypotonia, and seizures may also be observed (Duncan et al., 2020).
Neurodevelopmental disorder with cerebellar atrophy and motor dysfunction
MedGen UID:
1781936
Concept ID:
C5543427
Disease or Syndrome
Neurodevelopmental disorder with cerebellar atrophy and motor dysfunction (NEDCAM) is an autosomal recessive disorder characterized by global developmental delay with prominent motor abnormalities, mainly axial hypotonia, gait ataxia, and appendicular spasticity. Affected individuals have cognitive impairment and speech delay; brain imaging shows cerebellar atrophy. The severity is variable (summary by Kour et al., 2021).
Ataxia, intention tremor, and hypotonia syndrome, childhood-onset
MedGen UID:
1787902
Concept ID:
C5543478
Disease or Syndrome
Childhood-onset ataxia, intention tremor, and hypotonia syndrome (ATITHS) is a neurodevelopmental disorder characterized by delayed walking due to ataxia, intention tremor, and hypotonia apparent from early childhood. Affected individuals have global developmental delay with mildly impaired intellectual development and speech delay or learning disabilities. Eye movement abnormalities may also be present. Brain imaging shows cerebellar atrophy in some patients (summary by Webb et al., 2021).
Spinocerebellar ataxia, autosomal recessive 29
MedGen UID:
1788435
Concept ID:
C5543595
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-29 (SCAR29) is a progressive neurodegenerative disorder characterized by delayed motor development in early infancy followed by difficulty walking due to an ataxic gait or inability to walk, hypotonia, and variably impaired intellectual development. Other features include dysarthria, nystagmus, peripheral spasticity, nystagmus, and visual impairment. Brain imaging typically shows atrophy of the cerebellar vermis, but other abnormalities may also be present. Some patients are wheelchair-bound and/or nonverbal (summary by Sanderson et al., 2021) In a review of the pathogenesis of disorders with prominent dystonia as a feature, Monfrini et al. (2021) classified SCAR29 as belonging to a group of neurologic disorders termed 'HOPS-associated neurologic disorders' (HOPSANDs), which are caused by mutations in genes encoding various components of the autophagic/endolysosomal system, including VPS41.
Spinocerebellar ataxia, autosomal recessive 30
MedGen UID:
1778853
Concept ID:
C5543620
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-30 (SCAR30) is a progressive neurologic disorder characterized by childhood-onset global developmental delay with variably impaired intellectual development, motor dysfunction, and cerebellar ataxia. Affected individuals may also have psychiatric abnormalities, such as obsessive behavior, psychotic episodes, or hallucinations. Brain imaging usually shows cerebellar atrophy, although this may be an age-dependent feature (summary by Langer et al., 2018).
Hypokalemic tubulopathy and deafness
MedGen UID:
1785163
Concept ID:
C5543621
Disease or Syndrome
Hypokalemic tubulopathy and deafness (HKTD) is an autosomal recessive disorder characterized by hypokalemic tubulopathy with renal salt wasting, disturbed acid-base homeostasis, and sensorineural deafness (Schlingmann et al., 2021).
Spinocerebellar ataxia, autosomal recessive 31
MedGen UID:
1786855
Concept ID:
C5543627
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-31 (SCAR31) is a complex neurodevelopmental disorder characterized by global developmental delay with hypotonia and variably impaired intellectual and language development. Affected individuals have an ataxic gait, tremor, and dysarthria; more severely affected patients also have spasticity with inability to walk. Most have optic atrophy. Brain imaging shows cerebellar hypoplasia, enlarged ventricles, and atrophy of the posterior corpus callosum. Additional features may include retinitis pigmentosa, sensorineural deafness, dysmorphic facial features, and possibly endocrine dysfunction (summary by Collier et al., 2021).
Mitochondrial dna depletion syndrome 16B (neuroophthalmic type)
MedGen UID:
1780329
Concept ID:
C5543632
Disease or Syndrome
Mitochondrial DNA depletion syndrome-16B (MTDPS16B) is an autosomal recessive childhood-onset and progressive neuroophthalmic mtDNA depletion disorder characterized by optic atrophy, mixed polyneuropathy, spinal and cerebellar ataxia, and generalized chorea (Dosekova et al., 2020).
Ceroid lipofuscinosis, neuronal, 6B (Kufs type)
MedGen UID:
1794137
Concept ID:
C5561927
Disease or Syndrome
Neuronal ceroid lipofuscinosis-6B (CLN6B) is an autosomal recessive form of 'Kufs disease,' which refers in general to adult-onset neuronal ceroid lipofuscinosis without retinal involvement. CLN6B is a neurodegenerative disorder with a mean onset of symptoms at around age 28 years, although onset in the teens and later adulthood may also occur. Patients typically present with progressive myoclonus epilepsy, ataxia, loss of motor function, dysarthria, progressive dementia, and progressive cerebral and cerebellar atrophy on brain imaging. Ultrastructural examination typically shows fingerprint profiles and granular osmiophilic deposits in some tissues, including brain samples (summary by Arsov et al., 2011 and Berkovic et al., 2019). However, pathologic findings in peripheral tissues in adults is not as accurate for diagnosis as it is in children with the disease (Cherian et al., 2021). For a general phenotypic description and a discussion of genetic heterogeneity of CLN, see CLN1 (256730).
Focal segmental glomerulosclerosis and neurodevelopmental syndrome
MedGen UID:
1794148
Concept ID:
C5561938
Disease or Syndrome
Focal segmental glomerulosclerosis and neurodevelopmental syndrome (FSGSNEDS) is characterized by global developmental delay and renal dysfunction manifest as proteinuria and nephrotic syndrome apparent from infancy or early childhood. Some patients present with renal disease, whereas others present with developmental delay and develop renal disease later in childhood. Renal biopsy shows focal segmental glomerulosclerosis (FSGS), but the course of the disease is variable: some patients have transient proteinuria and others require renal transplant. Neurodevelopmental features are also variable, with some patients having only mildly impaired intellectual development, and others having a severe developmental disorder associated with early-onset refractory seizures or epileptic encephalopathy. Additional features, including feeding difficulties, poor overall growth, and nonspecific dysmorphic facial features, are commonly observed (summary by Assoum et al., 2018 and Weng et al., 2021).
Ritscher-Schinzel syndrome 4
MedGen UID:
1794149
Concept ID:
C5561939
Disease or Syndrome
Ritscher-Schinzel syndrome-4 (RTSC4) is characterized by a constellation of congenital anomalies, including dysmorphic craniofacial features and structural brain anomalies, such as Dandy-Walker malformation (220200), hindbrain malformations, or agenesis of the corpus callosum, associated with global developmental delay and impaired intellectual development. Congenital cardiac defects have been reported in 1 family (summary by Ritscher et al., 1987 and Jeanne et al., 2021). For a discussion of genetic heterogeneity of Ritscher-Schinzel syndrome, see RTSC1 (220210).
Oculopharyngodistal myopathy 3
MedGen UID:
1794166
Concept ID:
C5561956
Disease or Syndrome
Oculopharyngodistal myopathy-3 (OPDM3) is a neuromyodegenerative disease characterized by progressive muscle weakness with ocular, facial, pharyngeal, and distal limb involvement, resulting in dysarthria and gait difficulties. The onset of the disorder is usually in adulthood, although childhood onset has rarely been reported. Additional features include hyporeflexia, proximal muscle weakness, neck muscle weakness, dysarthria, dysphagia, and ptosis. Some patients may develop pigmentary retinopathy, peripheral neuropathy, or hearing loss. Cognition is usually not affected, but there may be deficits or psychiatric manifestations. Brain imaging tends to show a leukoencephalopathy, often with a characteristic linear signal along the corticomedullary junction on brain imaging. Skin and muscle biopsy show intranuclear inclusions and rimmed vacuoles. Many of the clinical features are reminiscent of NIID, suggesting that these disorders likely fall within a broad phenotypic spectrum of diseases with neuromyodegenerative features associated with abnormal repeat expansions in this gene (summary by Ogasawara et al., 2020 and Yu et al., 2021). For a discussion of genetic heterogeneity of OPDM, see OPDM1 (164310).
Developmental delay, impaired speech, and behavioral abnormalities
MedGen UID:
1794167
Concept ID:
C5561957
Disease or Syndrome
Developmental delay, impaired speech, and behavioral abnormalities (DDISBA) is characterized by global developmental delay apparent from early childhood. Intellectual disability can range from mild to severe. Additional variable features may include dysmorphic facial features, seizures, hypotonia, motor abnormalities such as Tourette syndrome or dystonia, and hearing loss (summary by Cousin et al., 2021).
Intellectual developmental disorder with hypotonia, impaired speech, and dysmorphic facies
MedGen UID:
1794207
Concept ID:
C5561997
Disease or Syndrome
Intellectual developmental disorder with hypotonia, impaired speech, and dysmorphic facies (IDDHISD) is characterized by global developmental delay with impaired intellectual development and poor or absent speech, hypotonia, ophthalmologic abnormalities, and nonspecific dysmorphic features. Some affected individuals have seizures, and a few have involvement of other organ systems (Goodman et al., 2021).
Cerebellar ataxia, brain abnormalities, and cardiac conduction defects
MedGen UID:
1794215
Concept ID:
C5562005
Disease or Syndrome
Cerebellar ataxia, brain abnormalities, and cardiac conduction defects (CABAC) is an autosomal recessive primarily neurologic disorder with variable manifestations. Common features included infantile-onset hypotonia, poor motor development, poor feeding and overall growth, and ataxic gait due to cerebellar ataxia. Other features include dysarthria, nystagmus, variable ocular anomalies, spasticity, hyperreflexia, and nonspecific dysmorphic features. Most, but not all, patients have global developmental delay with impaired intellectual development and speech delay. Brain imaging shows cerebellar hypoplasia, often with brainstem hypoplasia, enlarged ventricles, delayed myelination, and thin corpus callosum. A significant number of patients develop cardiac conduction defects in childhood or adolescence, often requiring pacemaker placement (summary by Slavotinek et al., 2020).
Neurodevelopmental disorder with impaired language and ataxia and with or without seizures
MedGen UID:
1794216
Concept ID:
C5562006
Disease or Syndrome
Neurodevelopmental disorder with impaired language and ataxia and with or without seizures (NEDLAS) is characterized by axial hypotonia and global developmental delay apparent in early infancy. Affected individuals have delayed walking with gait ataxia and poor language development. Behavioral abnormalities also commonly occur. The severity is highly variable: a subset of patients have a more severe phenotype with early-onset seizures resembling epileptic encephalopathy, inability to walk or speak, and hypomyelination on brain imaging (summary by Stolz et al., 2021).
Trichothiodystrophy 9, nonphotosensitive
MedGen UID:
1794268
Concept ID:
C5562058
Disease or Syndrome
Nonphotosensitive trichothiodystrophy-9 (TTD9) is characterized by brittle hair and nails and scaly skin, accompanied by failure to thrive, microcephaly, and neuromotor developmental delay. Hair analysis shows low sulfur content, and skin fibroblasts demonstrate normal DNA repair efficiency after UV irradiation (Botta et al., 2021). For a general phenotypic description and discussion of genetic heterogeneity of trichothiodystrophy, see TTD1 (601675).
Yoon-Bellen neurodevelopmental syndrome
MedGen UID:
1794276
Concept ID:
C5562066
Disease or Syndrome
Yoon-Bellen neurodevelopmental syndrome (YOBELN) is an autosomal recessive disorder characterized mainly by global developmental delay with variably impaired intellectual development. The manifestations and severity of the phenotype are highly variable. Additional neurologic features may include hypotonia, spasticity, ataxia, hearing loss, visual problems, seizures, and nonspecific anomalies on brain imaging (summary by Yap et al., 2021).
Leukodystrophy, hypomyelinating, 23, with ataxia, deafness, liver dysfunction, and dilated cardiomyopathy
MedGen UID:
1794284
Concept ID:
C5562074
Disease or Syndrome
Hypomyelinating leukodystrophy-23 with ataxia, deafness, liver dysfunction, and dilated cardiomyopathy (HLD23) is an autosomal recessive neurodegenerative disorder with systemic manifestations. Affected individuals show delayed motor development and ataxic gait in early childhood that progresses to spastic paraplegia with loss of ambulation in the first decades of life. Additional features include progressive sensorineural hearing loss resulting in deafness, hepatic dysfunction with elevated liver enzymes, and dilated cardiomyopathy that ultimately results in death in the first or second decades. Brain imaging shows hypomyelination, diffuse white matter abnormalities consistent with leukodystrophy, and thin corpus callosum (summary by Sferra et al., 2021). For a general phenotypic description and a discussion of genetic heterogeneity of HLD, see 312080.
Autosomal recessive spastic paraplegia type 76
MedGen UID:
1798906
Concept ID:
C5567483
Disease or Syndrome
Spastic paraplegia-76 is an autosomal recessive neurologic disorder characterized by young-adult onset of slowly progressive spasticity of the lower limbs resulting in gait difficulties. Most affected individuals have upper limb involvement and additional features such as foot deformities and dysarthria. Cognition is unaffected (summary by Gan-Or et al., 2016). For a general phenotypic description and a discussion of genetic heterogeneity of autosomal recessive spastic paraplegia, see SPG5A (270800).
Recurrent metabolic encephalomyopathic crises-rhabdomyolysis-cardiac arrhythmia-intellectual disability syndrome
MedGen UID:
1798947
Concept ID:
C5567524
Disease or Syndrome
Individuals with TANGO2-related metabolic encephalopathy and arrhythmias can present in acute metabolic crisis (hypoglycemia, elevated lactate, mild hyperammonemia) or with developmental delay, regression, and/or seizures. The acute presentation varies from profound muscle weakness, ataxia, and/or disorientation to a comatose state. Individuals can present with intermittent acute episodes of rhabdomyolysis. The first episode of myoglobinuria has been known to occur as early as age five months. Acute renal tubular damage due to myoglobinuria can result in acute kidney injury and renal failure. During acute illness, transient electrocardiogram changes can be seen; the most common is QT prolongation. Life-threatening recurrent ventricular tachycardia or torsade de pointes occurs primarily during times of acute illness. Individuals who do not present in metabolic crises may present with gait incoordination, progressively unsteady gait, difficulty with speech, or clumsiness. Intellectual disability of variable severity is observed in almost all individuals. Seizures are observed outside the periods of crises in more than 75% of individuals. Hypothyroidism has been reported in more than one third of individuals.
Autosomal recessive spastic paraplegia type 78
MedGen UID:
1799316
Concept ID:
C5567893
Disease or Syndrome
Autosomal recessive spastic paraplegia-78 is an adult-onset neurodegenerative disorder characterized predominantly by spasticity and muscle weakness of the lower limbs, resulting in gait difficulties and loss of ambulation in some patients. Affected individuals also have cerebellar signs, such as dysarthria, oculomotor disturbances, and limb and gait ataxia; brain imaging shows cerebellar atrophy. Some patients may have mild cognitive impairment or frank dementia. The phenotype is highly variable (summary by Estrada-Cuzcano et al., 2017). Biallelic mutation in the ATP13A2 gene also causes Kufor-Rakeb syndrome (KRS; 606693), a neurodegenerative disorder with overlapping features. Patients with KRS have earlier onset and prominent parkinsonism. Loss of ATP13A2 function results in a multidimensional spectrum of neurologic features reflecting various regions of the brain and nervous system, including cortical, pyramidal, extrapyramidal, brainstem, cerebellar, and peripheral (summary by Estrada-Cuzcano et al., 2017).
DYRK1A-related intellectual disability syndrome
MedGen UID:
1799566
Concept ID:
C5568143
Mental or Behavioral Dysfunction
DYRK1A syndrome is characterized by intellectual disability including impaired speech development, autism spectrum disorder including anxious and/or stereotypic behavior problems, and microcephaly. Affected individuals often have a clinically recognizable phenotype including a typical facial gestalt, feeding problems, seizures, hypertonia, gait disturbances, and foot anomalies. The majority of affected individuals function in the moderate-to-severe range of intellectual disability; however, individuals with mild intellectual disability have also been reported. Other medical concerns relate to febrile seizures in infancy; the development of epilepsy with seizures of the atonic, absence, and generalized myoclonic types; short stature; and gastrointestinal problems. Ophthalmologic, urogenital, cardiac, and/or dental anomalies have been reported.
Charcot-Marie-Tooth disease axonal type 2Z
MedGen UID:
1800448
Concept ID:
C5569025
Disease or Syndrome
Charcot-Marie-Tooth disease type 2Z (CMT2Z) is an autosomal dominant axonal peripheral neuropathy characterized by onset, usually in the first decade, of distal lower limb muscle weakness and sensory impairment. The disorder is progressive, and affected individuals tend to develop upper limb and proximal muscle involvement in an asymmetric pattern, resulting in severe disability late in adulthood. Rare occurrence of global developmental delay with impaired intellectual development or learning difficulties has been observed. In some instances, the same mutation may result in different phenotypic manifestations (CMT2Z or DIGFAN), which highlights the clinical spectrum associated with MORC2 mutations and may render the classification of patients into one or the other disorder challenging (summary by Sevilla et al., 2016, Ando et al., 2017, Guillen Sacoto et al., 2020). For a phenotypic description and a discussion of genetic heterogeneity of axonal CMT, see CMT2A1 (118210).
Pyruvate dehydrogenase E3 deficiency
MedGen UID:
1805500
Concept ID:
C5574660
Disease or Syndrome
The phenotypes of dihydrolipoamide dehydrogenase (DLD) deficiency are an overlapping continuum that ranges from early-onset neurologic manifestations to adult-onset liver involvement and, rarely, a myopathic presentation. Early-onset DLD deficiency typically manifests in infancy as hypotonia with lactic acidosis. Affected infants frequently do not survive their initial metabolic decompensation, or die within the first few years of life during a recurrent metabolic decompensation. Children who live beyond the first two to three years frequently exhibit growth deficiencies and residual neurologic deficits (intellectual disability, spasticity, ataxia, and seizures). In contrast, isolated liver involvement can present as early as the neonatal period and as late as the third decade. Evidence of liver injury/failure is preceded by nausea and emesis and frequently associated with encephalopathy and/or coagulopathy. Acute metabolic episodes are frequently associated with lactate elevations, hyperammonemia, and hepatomegaly. With resolution of the acute episodes affected individuals frequently return to baseline with no residual neurologic deficit or intellectual disability. Liver failure can result in death, even in those with late-onset disease. Individuals with the myopathic presentation may experience muscle cramps, weakness, and an elevated creatine kinase.
3-methylglutaconic aciduria, type VIIB
MedGen UID:
1810214
Concept ID:
C5676893
Disease or Syndrome
CLPB (caseinolytic peptidase B) deficiency is characterized by neurologic involvement and neutropenia, which can range from severe to mild. In severe CLPB deficiency, death usually occurs at a few months of age due to significant neonatal neurologic involvement (hyperekplexia or absence of voluntary movements, hypotonia or hypertonia, swallowing problems, respiratory insufficiency, and epilepsy) and severe neutropenia associated with life-threatening infections. Individuals with moderate CLPB deficiency present with neurologic abnormalities in infancy including hypotonia and feeding problems, and develop spasticity, a progressive movement disorder (ataxia, dystonia, and/or dyskinesia), epilepsy, and intellectual disability. Neutropenia is variable, but not life threatening. In those with mild CLPB deficiency there is no neurologic involvement, intellect is normal, neutropenia is mild and intermittent, and life expectancy is normal.
Gastrointestinal defects and immunodeficiency syndrome 2
MedGen UID:
1811526
Concept ID:
C5676901
Disease or Syndrome
PI4KA-related disorder is a clinically variable disorder characterized primarily by neurologic dysfunction (limb spasticity, developmental delay, intellectual disability, seizures, ataxia, nystagmus), gastrointestinal manifestations (multiple intestinal atresia, inflammatory bowel disease), and combined immunodeficiency (leukopenia, variable immunoglobulin defects). Age of onset is typically antenatal or in early childhood; individuals can present with any combination of these features. Rare individuals present with later-onset hereditary spastic paraplegia. Brain MRI findings can include hypomyelinating leukodystrophy, cerebellar hypoplasia/atrophy, thin or dysplastic corpus callosum, and/or perisylvian polymicrogyria.
Neurodevelopmental disorder with or without variable movement or behavioral abnormalities
MedGen UID:
1802087
Concept ID:
C5676908
Disease or Syndrome
Neurodevelopmental disorder with or without variable movement or behavioral abnormalities (NEDMAB) is an autosomal dominant disorder characterized by mildly to severely impaired intellectual development and, in some patients, movement abnormalities consisting of tremors, cerebellar ataxia, or extrapyramidal symptoms. Movement abnormalities have onset in childhood or adolescence. Other variable features include autism spectrum disorder or autistic features and epilepsy.
Spastic paraplegia 86, autosomal recessive
MedGen UID:
1801286
Concept ID:
C5676910
Disease or Syndrome
Autosomal recessive spastic paraplegia-86 (SPG86) is a complex neurologic disorder characterized by global developmental delay apparent from early childhood combined with early-onset progressive spasticity mainly affecting the lower limbs, but also affecting the upper limbs. Affected individuals have hyperreflexia, extensor plantar responses, pyramidal signs, and difficulty walking or inability to walk. Some may have joint contractures and foot or ankle deformities. Patients with SPG86 have impaired intellectual development with poor or absent speech, often with behavioral abnormalities. Brain imaging shows thin corpus callosum and white matter abnormalities. Rare patients may have seizures. The disorder is thus a complicated form of SPG (summary by Yahia et al., 2021, Miyake et al., 2022). For a discussion of genetic heterogeneity of autosomal recessive spastic paraplegia, see SPG5A (270800).
Parkinsonism-dystonia 3, childhood-onset
MedGen UID:
1808365
Concept ID:
C5676913
Disease or Syndrome
Childhood-onset parkinsonism-dystonia-3 (PKDYS3) is an autosomal recessive neurodegenerative disorder with onset in infancy or early childhood. Affected individuals present with progressive movement abnormalities, including parkinsonism with tremor, dystonia, myoclonus ataxia, and hyperkinetic movements such as ballismus. The parkinsonism features may be responsive to treatment with levodopa, although many patients develop levodopa-induced dyskinesia. Some patients may have mild cognitive impairment or psychiatric disturbances (summary by Burke et al., 2018 and Skorvanek et al., 2022). For a discussion of genetic heterogeneity of PKDYS, see 613135.
Charcot-Marie-Tooth disease, demyelinating, IIA 1I
MedGen UID:
1811493
Concept ID:
C5676914
Disease or Syndrome
Demyelinating Charcot-Marie-Tooth disease type 1I (CMT1I) is a neurologic disorder characterized predominantly by delayed motor development in the first years of life associated with gait abnormalities, sensory ataxia, hyporeflexia, and distal sensory impairment due to a sensorimotor peripheral neuropathy that mainly affects the lower limbs. The disorder is progressive, and some may have upper limb involvement. A subset of patients has central nervous system involvement that manifests as global developmental delay with impaired intellectual development and speech difficulties. Other features may include spasticity, hyperreflexia, tremor, dysmetria, seizures, or cerebellar findings. Brain imaging may be normal or show nonspecific abnormalities, such as white matter signal changes and delayed myelination (summary by Djordjevic et al., 2021). For a discussion of genetic heterogeneity of autosomal dominant Charcot-Marie-Tooth disease type 1, see CMT1B (118200).
Spinocerebellar ataxia 49
MedGen UID:
1805601
Concept ID:
C5676950
Disease or Syndrome
Spinocerebellar ataxia-49 (SCA49) is an autosomal dominant neurologic disorder characterized initially by gait abnormalities, gaze-evoked nystagmus, and hyperreflexia. The age at onset is highly variable, ranging from the second to seventh decades, even within the same family. The disorder is slowly progressive, and later features may include dysarthria, dysmetria, diplopia, pyramidal signs, and axonal peripheral neuropathy. Brain imaging shows cerebellar atrophy and myelination defects (Corral-Juan et al., 2022).
Neurodevelopmental disorder with neuromuscular and skeletal abnormalities
MedGen UID:
1803456
Concept ID:
C5676965
Disease or Syndrome
Neurodevelopmental disorder with neuromuscular and skeletal abnormalities (NEDNMS) is an autosomal recessive disorder characterized by global developmental delay apparent from infancy or early childhood. The severity of the disorder is highly variable. Affected individuals show impaired intellectual development and motor delay associated with either severe hypotonia or hypertonia and spasticity. Most affected individuals have skeletal defects and dysmorphic facial features. Some may have ocular or auditory problems, peripheral neuropathy, behavioral abnormalities, and nonspecific findings on brain imaging (Kurolap et al., 2022).
Developmental and epileptic encephalopathy 103
MedGen UID:
1809962
Concept ID:
C5677002
Disease or Syndrome
Developmental and epileptic encephalopathy-103 (DEE103) is characterized by onset of various types of seizures in the first year of life, most of which are refractory to treatment. Affected individuals show global developmental delay with impaired intellectual development ranging from mild to severe. Additional features may include hypotonia, ataxia, and behavioral abnormalities, including autism and hyperactivity (Schwarz et al., 2022). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Mitochondrial complex II deficiency, nuclear type 1
MedGen UID:
1814582
Concept ID:
C5700310
Disease or Syndrome
Mitochondrial complex II deficiency is an autosomal recessive multisystemic metabolic disorder with a highly variable phenotype. Some patients have multisystem involvement of the brain, heart, and muscle with onset in infancy, whereas others have only isolated cardiac or muscle involvement. Measurement of complex II activity in muscle is the most reliable means of diagnosis; however, there is no clear correlation between residual complex II activity and severity or clinical outcome. In some cases, treatment with riboflavin may have clinical benefit (summary by Jain-Ghai et al., 2013). Complex II, also known as succinate dehydrogenase, is part of the mitochondrial respiratory chain. Genetic Heterogeneity of Mitochondrial Complex II Deficiency See MC2DN2 (619166), caused by mutation in the SDHAF1 gene (612848) on chromosome 19q13; MC2DN3 (619167), caused by mutation in the SDHD gene (602690) on chromosome 11q23; and MC2DN4 (619224), caused by mutation in the SDHB gene (185470) on chromosome 1p36. Fullerton et al. (2020) reviewed the genetic basis of isolated mitochondrial complex II deficiency.
Neurodevelopmental disorder with epilepsy and brain atrophy
MedGen UID:
1823957
Concept ID:
C5774184
Disease or Syndrome
Neurodevelopmental disorder with epilepsy and brain atrophy (NEDEBA) is an autosomal recessive disorder characterized by early-onset progressive myoclonus epilepsy with ataxia (summary by Bott et al., 2021).
Intellectual developmental disorder with muscle tone abnormalities and distal skeletal defects
MedGen UID:
1823972
Concept ID:
C5774199
Disease or Syndrome
Intellectual developmental disorder with muscle tone abnormalities and distal skeletal defects (IDDMDS) is an autosomal recessive disorder characterized by global developmental delay apparent in infancy manifest as speech delay and late walking by a few years. Affected individuals have hypertonia or, more rarely, hypotonia; a notable common feature is facial myokymia with corresponding EMG findings. Additional features include distal skeletal defects such as joint contractures, hypo- or areflexia, and hernia (Marafi et al., 2022).
Developmental delay, hypotonia, and impaired language
MedGen UID:
1823975
Concept ID:
C5774202
Disease or Syndrome
Developmental delay, hypotonia, and impaired language (DEDHIL) is a neurodevelopmental disorder characterized by variably impaired intellectual development usually with hypotonia, mild motor delay, and language difficulties. Affected individuals may also have nonspecific dysmorphic facial features, gastrointestinal problems, and abnormalities on brain imaging (Stephenson et al., 2022).
Microcephaly 29, primary, autosomal recessive
MedGen UID:
1823993
Concept ID:
C5774220
Disease or Syndrome
Autosomal recessive primary microcephaly-29 (MCPH29) is characterized by small head circumference apparent at birth and associated with global developmental delay, impaired intellectual development, speech delay, and behavioral abnormalities. Affected individuals also have poor overall growth with short stature, mild dysmorphic facial features, and seizures (Khan et al., 2020). For a discussion of genetic heterogeneity of primary microcephaly, see MCPH1 (251200).
Neurodevelopmental disorder with craniofacial dysmorphism and skeletal defects
MedGen UID:
1824008
Concept ID:
C5774235
Disease or Syndrome
Neurodevelopmental disorder with craniofacial dysmorphism and skeletal defects (NEDCDS) is characterized by global developmental delay, severely impaired intellectual development with poor or absent speech, characteristic facial features, and variable skeletal abnormalities. Additional features include feeding difficulties, inability to walk or walking with an abnormal gait, and cerebellar or other abnormalities on brain imaging (Reichert et al., 2020).
Neurodegeneration, childhood-onset, with multisystem involvement due to mitochondrial dysfunction
MedGen UID:
1824013
Concept ID:
C5774240
Disease or Syndrome
Childhood-onset neurodegeneration with multisystem involvement due to mitochondrial dysfunction (CONDMIM) is an autosomal recessive syndromic disorder characterized primarily by neurologic deficits. Patients show global developmental delay and variably impaired intellectual development with speech delay apparent from infancy. Affected individuals have hypotonia, poor feeding, poor overall growth, and respiratory distress early in life. Other features include visual impairment due to optic atrophy, sensorineural hearing loss, and neuromuscular abnormalities. The severity is highly variable. The disorder is progressive; about half of patients show developmental regression with loss of previous skills. Features suggestive of a mitochondrial disorder include cataracts, cardiomyopathy, diabetes mellitus, combined oxidative phosphorylation deficiency, and increased lactate. Some patients develop seizures, some have dysmorphic facial features, and some have nonspecific abnormalities on brain imaging. Death in childhood may occur (Kaiyrzhanov et al., 2022).
Neurodevelopmental disorder with eye movement abnormalities and ataxia
MedGen UID:
1824014
Concept ID:
C5774241
Disease or Syndrome
Neurodevelopmental disorder with eye movement abnormalities and ataxia (NEDEMA) is characterized by global developmental delay apparent from infancy. Affected individuals show delayed walking with an unsteady gait, variably impaired intellectual development, learning disabilities, and speech difficulties. Abnormal eye movements, which are often noted in early childhood, include opsoclonus, nystagmus, and strabismus. Some patients have seizures, which may be refractory (Lu et al., 2022).
Spinocerebellar ataxia 50
MedGen UID:
1824045
Concept ID:
C5774272
Disease or Syndrome
Spinocerebellar ataxia-50 (SCA50) is an autosomal dominant neurologic disorder characterized by cerebellar ataxia, oculomotor apraxia and other eye movement abnormalities, and cerebellar atrophy on brain imaging. Most patients develop symptoms as adults, although childhood onset has rarely been reported. Additional more variable features may include tremor, dysarthria, dysphagia, and cognitive impairment with executive dysfunction (Coutelier et al., 2022; Schoggl et al., 2022).
Muscular dystrophy, congenital, with or without seizures
MedGen UID:
1824047
Concept ID:
C5774274
Disease or Syndrome
Congenital muscular dystrophy with or without seizures (MYOS) is an autosomal recessive disorder characterized by severe muscle hypotonia apparent from birth, as well as developmental delay. Laboratory studies show increased serum creatine kinase and muscle biopsy shows nonspecific dystrophic features. Most patients develop seizures or have abnormal epileptiform findings on EEG studies; other variable findings may include feeding difficulties, nystagmus, myopathic facies, areflexia, and brain atrophy on MRI (summary by Larson et al., 2018 and Henige et al., 2021).
Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities
MedGen UID:
1824058
Concept ID:
C5774285
Disease or Syndrome
Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities (NEDHFS) is an autosomal recessive disorder characterized by severe global developmental delay with impaired intellectual development and poor or absent speech. Affected individuals have dysmorphic facies, including large abnormally shaped ears and strabismus, hypotonia, and dry skin with keratosis pilaris. Some patients develop seizures. Metabolic studies are unremarkable (Morava et al., 2021).
Tessadori-Van Haaften neurodevelopmental syndrome 3
MedGen UID:
1824083
Concept ID:
C5774310
Disease or Syndrome
Tessadori-Bicknell-van Haaften neurodevelopmental syndrome-3 (TEBIVANED3) is characterized by global developmental delay with poor overall growth, impaired intellectual development, and speech difficulties. More variable features include hypotonia, microcephaly, and dysmorphic facies. The severity and manifestations of the disorder are highly variable (Tessadori et al., 2022). For a discussion of genetic heterogeneity of Tessadori-Bicknell-van Haaften neurodevelopmental disorder, see TEBIVANED1 (619758).
Megalencephalic leukoencephalopathy with subcortical cysts 1
MedGen UID:
1826136
Concept ID:
C5779875
Disease or Syndrome
The classic phenotype of megalencephalic leukoencephalopathy with subcortical cysts (MLC) is characterized by early-onset macrocephaly, often in combination with mild gross motor developmental delay and seizures; gradual onset of ataxia, spasticity, and sometimes extrapyramidal findings; and usually late onset of mild mental deterioration. Macrocephaly, observed in virtually all individuals, may be present at birth but more frequently develops during the first year of life. The degree of macrocephaly is variable and can be as great as 4 to 6 SD above the mean in some individuals. After the first year of life, head growth rate normalizes and growth follows a line parallel to and usually several centimeters above the 98th centile. Initial mental and motor development is normal in most individuals. Walking is often unstable, followed by ataxia of the trunk and extremities, then minor signs of pyramidal dysfunction and brisk deep-tendon stretch reflexes. Almost all individuals have epilepsy from an early age. The epilepsy is typically well controlled with anti-seizure medication, but status epilepticus occurs relatively frequently. Mental deterioration is late and mild. Disease severity ranges from independent walking for a few years only to independent walking in the fifth decade. Some individuals have died in their teens or twenties; others are alive in their fifties. An improving phenotype has a similar initial presentation with delayed mental or motor development, followed by an improving clinical course: macrocephaly usually persists, but some children become normocephalic; motor function improves or normalizes; hypotonia and clumsiness may persist in some or neurologic examination may become normal. Some have intellectual disability that is stable, with or without autism. Epilepsy and status epilepticus may occur.
Neurodevelopmental disorder with absent speech and movement and behavioral abnormalities
MedGen UID:
1840955
Concept ID:
C5830319
Mental or Behavioral Dysfunction
Neurodevelopmental disorder with absent speech and movement and behavioral abnormalities (NEDSMB) is an autosomal recessive disorder characterized by global developmental delay and severely impaired intellectual development with aggressive behavior. Mild dysmorphic features and hypodontia are also present (Faqeih et al., 2023).
Neurodevelopmental disorder with microcephaly and speech delay, with or without brain abnormalities
MedGen UID:
1841049
Concept ID:
C5830413
Disease or Syndrome
Neurodevelopmental disorder with microcephaly and speech delay, with or without brain abnormalities (NEDMSBA) is an autosomal recessive disorder characterized by global developmental delay, hypotonia, delayed or absent walking, impaired intellectual development, and poor or absent speech, apparent from early infancy. Affected individuals have postnatal progressive microcephaly and may show poor overall growth and dysmorphic facial features. Additional more variable features include cortical visual impairment, seizures, hypotonia, spasticity, and sensorineural deafness. Brain imaging is abnormal in most patients, showing myelination defects, cortical atrophy, or thin corpus callosum. There is phenotypic variability, even within families (Bogershausen et al., 2022; Lin et al., 2022).
Spastic paraplegia 89, autosomal recessive
MedGen UID:
1841167
Concept ID:
C5830531
Disease or Syndrome
Autosomal recessive spastic paraplegia-89 (SPG89) is characterized by symptom onset in the first years of life. Affected individuals show delayed motor development with abnormal spastic gait and hyperreflexia of the lower limbs. Some patients may have mildly impaired intellectual development or learning difficulties (Deng et al., 2023). For a discussion of genetic heterogeneity of autosomal recessive SPG, see SPG5A (270800).
Dystonia 37, early-onset, with striatal lesions
MedGen UID:
1841228
Concept ID:
C5830592
Disease or Syndrome
Early-onset dystonia-37 with striatal lesions (DYT37) is an autosomal recessive neurologic movement disorder characterized by the onset of progressive dystonia, dysphagia, and choreoathetosis in the first months or years of life. Affected individuals show delayed motor development and may have impaired intellectual development. The disorder is severely disabling; patients lose ambulation and require tube-feeding. Brain imaging shows hyperintense lesions affecting the basal ganglia and striatum (Harrer et al., 2023).
Combined oxidative phosphorylation deficiency 58
MedGen UID:
1841277
Concept ID:
C5830641
Disease or Syndrome
Combined oxidative phosphorylation deficiency-58 (COXPD58) is an autosomal recessive disorder characterized by a wide range of clinical presentations including neonatal lactic acidosis, epileptic encephalopathy, developmental delay and impaired intellectual development with nonspecific changes on brain MRI, or mitochondrial myopathy with a treatable neuromuscular transmission defect (Van Haute et al., 2023). For a discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060).

Professional guidelines

PubMed

Pedroso JL, Vale TC, Braga-Neto P, Dutra LA, França MC Jr, Teive HAG, Barsottini OGP
Arq Neuropsiquiatr 2019 Mar;77(3):184-193. doi: 10.1590/0004-282X20190020. PMID: 30970132
Levin J, Kurz A, Arzberger T, Giese A, Höglinger GU
Dtsch Arztebl Int 2016 Feb 5;113(5):61-9. doi: 10.3238/arztebl.2016.0061. PMID: 26900156Free PMC Article
Marquer A, Barbieri G, Pérennou D
Ann Phys Rehabil Med 2014 Mar;57(2):67-78. Epub 2014 Feb 6 doi: 10.1016/j.rehab.2014.01.002. PMID: 24582474

Recent clinical studies

Etiology

Yildirim M, Gocmen R, Konuskan B, Parlak S, Yalnizoglu D, Anlar B
J Child Neurol 2020 May;35(6):380-388. Epub 2020 Mar 12 doi: 10.1177/0883073820901407. PMID: 32160830
Pedroso JL, Vale TC, Braga-Neto P, Dutra LA, França MC Jr, Teive HAG, Barsottini OGP
Arq Neuropsiquiatr 2019 Mar;77(3):184-193. doi: 10.1590/0004-282X20190020. PMID: 30970132
Joubert B, Rostásy K, Honnorat J
Handb Clin Neurol 2018;155:313-332. doi: 10.1016/B978-0-444-64189-2.00021-4. PMID: 29891069
Buckley E, Mazzà C, McNeill A
Gait Posture 2018 Feb;60:154-163. Epub 2017 Dec 1 doi: 10.1016/j.gaitpost.2017.11.024. PMID: 29220753
Miyai I, Ito M, Hattori N, Mihara M, Hatakenaka M, Yagura H, Sobue G, Nishizawa M; Cerebellar Ataxia Rehabilitation Trialists Collaboration
Neurorehabil Neural Repair 2012 Jun;26(5):515-22. Epub 2011 Dec 2 doi: 10.1177/1545968311425918. PMID: 22140200