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Intellectual disability, profound

MedGen UID:
892508
Concept ID:
C3161330
Mental or Behavioral Dysfunction
Synonyms: IQ less than 20; Mental retardation, profound; Profound mental retardation
 
HPO: HP:0002187

Definition

Profound mental retardation is defined as an intelligence quotient (IQ) below 20. [from HPO]

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVIntellectual disability, profound

Conditions with this feature

Mucopolysaccharidosis, MPS-II
MedGen UID:
7734
Concept ID:
C0026705
Disease or Syndrome
Mucopolysaccharidosis type II (MPS II; also known as Hunter syndrome) is an X-linked multisystem disorder characterized by glycosaminoglycan (GAG) accumulation. The vast majority of affected individuals are male; on rare occasion heterozygous females manifest findings. Age of onset, disease severity, and rate of progression vary significantly among affected males. In those with early progressive disease, CNS involvement (manifest primarily by progressive cognitive deterioration), progressive airway disease, and cardiac disease usually result in death in the first or second decade of life. In those with slowly progressive disease, the CNS is not (or is minimally) affected, although the effect of GAG accumulation on other organ systems may be early progressive to the same degree as in those who have progressive cognitive decline. Survival into the early adult years with normal intelligence is common in the slowly progressing form of the disease. Additional findings in both forms of MPS II include: short stature; macrocephaly with or without communicating hydrocephalus; macroglossia; hoarse voice; conductive and sensorineural hearing loss; hepatosplenomegaly; dysostosis multiplex; spinal stenosis; and carpal tunnel syndrome.
Rett syndrome
MedGen UID:
48441
Concept ID:
C0035372
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.
Aicardi syndrome
MedGen UID:
61236
Concept ID:
C0175713
Disease or Syndrome
Aicardi syndrome is a neurodevelopmental disorder that affects primarily females. Initially it was characterized by a typical triad of agenesis of the corpus callosum, central chorioretinal lacunae, and infantile spasms. As more affected individuals have been ascertained, it has become clear that not all affected girls have all three features of the classic triad and that other neurologic and systemic defects are common, including other brain malformations, optic nerve abnormalities, other seizure types, intellectual disability of varying severity, and scoliosis.
Cerebrooculofacioskeletal syndrome 1
MedGen UID:
66320
Concept ID:
C0220722
Disease or Syndrome
An autosomal recessive subtype of cerebrooculofacioskeletal syndrome caused by mutation(s) in the ERCC6 gene, encoding DNA excision repair protein ERCC-6.
Pallister-Killian syndrome
MedGen UID:
120540
Concept ID:
C0265449
Disease or Syndrome
Pallister-Killian syndrome (PKS) is a dysmorphic condition involving most organ systems, but is also characterized by a tissue-limited mosaicism; most fibroblasts have 47 chromosomes with an extra small metacentric chromosome, whereas the karyotype of lymphocytes is normal. The extra metacentric chromosome is an isochromosome for part of the short arm of chromosome 12: i(12)(p10) (Peltomaki et al., 1987; Warburton et al., 1987).
Fumarase deficiency
MedGen UID:
87458
Concept ID:
C0342770
Disease or Syndrome
Fumarate hydratase (FH) deficiency results in severe neonatal and early infantile encephalopathy that is characterized by poor feeding, failure to thrive, hypotonia, lethargy, and seizures. Dysmorphic facial features include frontal bossing, depressed nasal bridge, and widely spaced eyes. Many affected individuals are microcephalic. A spectrum of brain abnormalities are seen on magnetic resonance imaging, including cerebral atrophy, enlarged ventricles and generous extra-axial cerebral spinal fluid (CSF) spaces, delayed myelination for age, thinning of the corpus callosum, and an abnormally small brain stem. Brain malformations including bilateral polymicrogyria and absence of the corpus callosum can also be observed. Development is severely affected: most affected individuals are nonverbal and nonambulatory, and many die during early childhood. Less severely affected individuals with moderate cognitive impairment and long-term survival have been reported.
Aicardi-Goutieres syndrome 1
MedGen UID:
162912
Concept ID:
C0796126
Disease or Syndrome
Most characteristically, Aicardi-Goutières syndrome (AGS) manifests as an early-onset encephalopathy that usually, but not always, results in severe intellectual and physical disability. A subgroup of infants with AGS present at birth with abnormal neurologic findings, hepatosplenomegaly, elevated liver enzymes, and thrombocytopenia, a picture highly suggestive of congenital infection. Otherwise, most affected infants present at variable times after the first few weeks of life, frequently after a period of apparently normal development. Typically, they demonstrate the subacute onset of a severe encephalopathy characterized by extreme irritability, intermittent sterile pyrexias, loss of skills, and slowing of head growth. Over time, as many as 40% develop chilblain skin lesions on the fingers, toes, and ears. It is becoming apparent that atypical, sometimes milder, cases of AGS exist, and thus the true extent of the phenotype associated with pathogenic variants in the AGS-related genes is not yet known.
Bohring-Opitz syndrome
MedGen UID:
208678
Concept ID:
C0796232
Disease or Syndrome
Bohring-Opitz syndrome (BOS) is characterized by distinctive facial features and posture, growth failure, variable but usually severe intellectual disability, and variable anomalies. The facial features may include microcephaly or trigonocephaly / prominent (but not fused) metopic ridge, hypotonic facies with full cheeks, synophrys, glabellar and eyelid nevus flammeus (simplex), prominent globes, widely set eyes, palate anomalies, and micrognathia. The BOS posture, which is most striking in early childhood and often becomes less apparent with age, is characterized by flexion at the elbows with ulnar deviation and flexion of the wrists and metacarpophalangeal joints. Feeding difficulties in early childhood, including cyclic vomiting, have a significant impact on overall health; feeding tends to improve with age. Seizures are common and typically responsive to standard epileptic medications. Minor cardiac anomalies and transient bradycardia and apnea may be present. Affected individuals may experience recurrent infections, which also tend to improve with age. Isolated case reports suggest that individuals with BOS are at greater risk for Wilms tumor than the general population, but large-scale epidemiologic studies have not been conducted.
Pettigrew syndrome
MedGen UID:
162924
Concept ID:
C0796254
Disease or Syndrome
X-linked Dandy-Walker malformation with intellectual disability, basal ganglia disease and seizures (XDIBS), or Pettigrew syndrome is a central nervous system malformation characterized by severe intellectual deficit, early hypotonia with progression to spasticity and contractures, choreoathetosis, seizures, dysmorphic face (long face with prominent forehead), and brain imaging abnormalities such as Dandy-Walker malformation, and iron deposition. (From Mondo:0010574)
Matthew-Wood syndrome
MedGen UID:
318679
Concept ID:
C1832661
Disease or Syndrome
Syndromic microphthalmia-9 (MCOPS9), also referred to as pulmonary hypoplasia-diaphragmatic hernia-anophthalmia-cardiac defect, is characterized by bilateral clinical anophthalmia, pulmonary hypoplasia/aplasia, cardiac malformations, and diaphragmatic defects. The phenotype is variable, ranging from isolated clinical anophthalmia or microphthalmia to complex presentations involving the cardiac, pulmonary, diaphragmatic, and renal systems. At its most severe, infants are born without pulmonary structures and die soon after birth (Marcadier et al., 2015).
Isolated cleft palate
MedGen UID:
332392
Concept ID:
C1837218
Congenital Abnormality
Cleft palate as an isolated malformation behaves as an entity distinct from cleft lip with or without cleft palate (see 119530). Dominantly inherited cleft soft palate in 4 generations has been reported (Jenkins and Stady, 1980); see 119570.
Muscular dystrophy-dystroglycanopathy type B6
MedGen UID:
373284
Concept ID:
C1837229
Disease or Syndrome
MDDGB6 is an autosomal recessive congenital muscular dystrophy with impaired intellectual development and structural brain abnormalities (Longman et al., 2003). It is part of a group of similar disorders resulting from defective glycosylation of alpha-dystroglycan (DAG1; 128239), collectively known as 'dystroglycanopathies' (Mercuri et al., 2009). For a discussion of genetic heterogeneity of congenital muscular dystrophy-dystroglycanopathy type B, see MDDGB1 (613155).
AICA-ribosiduria
MedGen UID:
332474
Concept ID:
C1837530
Disease or Syndrome
AICA-ribosiduria is characterized by severe to profound global neurodevelopmental impairment, severe visual impairment due to chorioretinal atrophy, ante-postnatal growth impairment, and severe scoliosis. Dysmorphic features include coarse facies and upturned nose. Early-onset epilepsy may occur. Less common features may include aortic coarctation, chronic hepatic cytolysis, minor genital malformations, and nephrocalcinosis (Ramond et al., 2020).
X-linked intellectual disability, Stocco dos Santos type
MedGen UID:
335202
Concept ID:
C1845530
Disease or Syndrome
X-linked intellectual disability, Stocco Dos Santos type is characterised by severe intellectual deficit with hyperactivity, language delay, congenital hip luxation, short stature, kyphosis and recurrent respiratory infections. Aggressive behaviour and frequent epileptic seizures may also be present. The syndrome has been described in four boys from the same family. Transmission is X-linked and is caused by mutations in the <i>KIAA1202</i> gene, localised to the Xp11.2 region.
Ulna hypoplasia-intellectual disability syndrome
MedGen UID:
341275
Concept ID:
C1848650
Disease or Syndrome
Ulna hypoplasia - intellectual deficit is a very rare syndrome characterized by mesomelic shortness of the forearms, bilateral clubfeet, aplasia or hypoplasia of all nails and severe psychomotor retardation.
PEHO syndrome
MedGen UID:
342404
Concept ID:
C1850055
Disease or Syndrome
PEHO is a severe autosomal recessive neurodevelopmental disorder characterized by extreme cerebellar atrophy due to almost total loss of granule neurons. Affected individuals present in early infancy with hypotonia, profoundly delayed psychomotor development, optic atrophy, progressive atrophy of the cerebellum and brainstem, and dysmyelination. Most patients also develop infantile seizures that are often associated with hypsarrhythmia on EEG, and many have peripheral edema (summary by Anttonen et al., 2017).
PEHO-like syndrome
MedGen UID:
337956
Concept ID:
C1850056
Disease or Syndrome
A rare genetic neurological disease characterized by progressive encephalopathy, early-onset seizures with a hypsarrhythmic pattern, facial and limb edema, severe hypotonia, early arrest of psychomotor development and craniofacial dysmorphism (evolving microcephaly, narrow forehead, short nose, prominent auricles, open mouth, micrognathia), in the absence of neuro-ophthalmic or neuroradiologic findings. Poor visual responsiveness, growth failure and tapering fingers are also associated. There is evidence the disease is caused by homozygous mutation in the CCDC88A gene on chromosome 2p16.
Mosaic variegated aneuploidy syndrome 1
MedGen UID:
338026
Concept ID:
C1850343
Disease or Syndrome
Mosaic variegated aneuploidy (MVA) syndrome is a rare disorder in which some cells in the body have an abnormal number of chromosomes instead of the usual 46 chromosomes, a situation known as aneuploidy. Most commonly, cells have an extra chromosome, which is called trisomy, or are missing a chromosome, which is known as monosomy. In MVA syndrome, some cells are aneuploid and others have the normal number of chromosomes, which is a phenomenon known as mosaicism. Typically, at least one-quarter of cells in affected individuals have an abnormal number of chromosomes. Because the additional or missing chromosomes vary among the abnormal cells, the aneuploidy is described as variegated.\n\nThere are at least three types of MVA syndrome, each with a different genetic cause. Type 1 is the most common and displays the classic signs and symptoms described above. Type 2 appears to have slightly different signs and symptoms than type 1, although the small number of affected individuals makes it difficult to define its characteristic features. Individuals with MVA syndrome type 2 grow slowly before and after birth; however, their head size is typically normal. Some people with MVA syndrome type 2 have unusually short arms. Individuals with MVA syndrome type 2 do not seem to have an increased risk of cancer. Another form of MVA syndrome is characterized by a high risk of developing Wilms tumor. Individuals with this form may also have other signs and symptoms typical of MVA syndrome type 1.\n\nIn MVA syndrome, growth before birth is slow (intrauterine growth restriction). After birth, affected individuals continue to grow at a slow rate and are shorter than average. In addition, they typically have an unusually small head size (microcephaly). Another common feature of MVA syndrome is an increased risk of developing cancer in childhood. Cancers that occur most frequently in affected individuals include a cancer of muscle tissue called rhabdomyosarcoma, a form of kidney cancer known as Wilms tumor, and a cancer of the blood-forming tissue known as leukemia.\n\nLess commonly, people with MVA syndrome have eye abnormalities or distinctive facial features, such as a broad nasal bridge and low-set ears. Some affected individuals have brain abnormalities, the most common of which is called Dandy-Walker malformation. Intellectual disability, seizures, and other health problems can also occur in people with MVA syndrome.
Thanatophoric dysplasia type 1
MedGen UID:
358383
Concept ID:
C1868678
Disease or Syndrome
Thanatophoric dysplasia (TD) is a short-limb skeletal dysplasia that is usually lethal in the perinatal period. TD is divided into subtypes: TD type I is characterized by micromelia with bowed femurs and, uncommonly, the presence of craniosynostosis of varying severity. TD type II is characterized by micromelia with straight femurs and uniform presence of moderate-to-severe craniosynostosis with cloverleaf skull deformity. Other features common to type I and type II include: short ribs, narrow thorax, relative macrocephaly, distinctive facial features, brachydactyly, hypotonia, and redundant skin folds along the limbs. Most affected infants die of respiratory insufficiency shortly after birth. Rare long-term survivors have been reported.
Severe achondroplasia-developmental delay-acanthosis nigricans syndrome
MedGen UID:
393098
Concept ID:
C2674173
Congenital Abnormality
SADDAN dysplasia (severe achondroplasia with developmental delay and acanthosis nigricans) is a very rare skeletal dysplasia characterized by the constellation of these features. Radiology reveals 'ram's horn' shaped clavicles and reverse bowing of lower limbs. Approximately half of patients die before the fourth week of life secondary to respiratory failure (summary by Zankl et al., 2008).
Hypomyelinating leukodystrophy 4
MedGen UID:
383026
Concept ID:
C2677109
Disease or Syndrome
Any leukodystrophy in which the cause of the disease is a mutation in the HSPD1 gene.
Developmental and epileptic encephalopathy, 4
MedGen UID:
436917
Concept ID:
C2677326
Disease or Syndrome
STXBP1 encephalopathy with epilepsy is characterized by early-onset encephalopathy with epilepsy (i.e., moderate-to-severe intellectual disability, refractory seizures, and ongoing epileptiform activity). The median age of onset of seizures is six weeks (range 1 day to 13 years). Seizure types can include infantile spasms; generalized tonic-clonic, clonic, or tonic seizures; and myoclonic, focal, atonic, and absence seizures. Epilepsy syndromes can include Ohtahara syndrome, West syndrome, Lennox-Gaustaut syndrome, and Dravet syndrome (not SCN1A-related), classic Rett syndrome (not MECP2-related), and atypical Rett syndrome (not CDKL5-related). The EEG is characterized by focal epileptic activity, burst suppression, hypsarrhythmia, or generalized spike-and-slow waves. Other findings can include abnormal tone, movement disorders (especially ataxia and dystonia), and behavior disorders (including autism spectrum disorder). Feeding difficulties are common.
Joubert syndrome 10
MedGen UID:
440688
Concept ID:
C2749019
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.
Muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A2
MedGen UID:
461761
Concept ID:
C3150411
Disease or Syndrome
Congenital muscular dystrophy-dystroglycanopathy with brain and eye anomalies (type A), which includes both the more severe Walker-Warburg syndrome (WWS) and the slightly less severe muscle-eye-brain disease (MEB), is an autosomal recessive disorder with characteristic brain and eye malformations, profound mental retardation, congenital muscular dystrophy, and death usually in the first years of life. It represents the most severe end of a phenotypic spectrum of similar disorders resulting from defective glycosylation of DAG1 (128239), collectively known as 'dystroglycanopathies' (van Reeuwijk et al., 2005). For a general phenotypic description and a discussion of genetic heterogeneity of muscular dystrophy-dystroglycanopathy type A, see MDDGA1 (236670).
Muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A5
MedGen UID:
461763
Concept ID:
C3150413
Disease or Syndrome
Congenital muscular dystrophy-dystroglycanopathy with brain and eye anomalies (type A), which includes both the more severe Walker-Warburg syndrome (WWS) and the slightly less severe muscle-eye-brain disease (MEB), is an autosomal recessive disorder with characteristic brain and eye malformations, profound mental retardation, congenital muscular dystrophy, and death usually in the first years of life. It represents the most severe end of a phenotypic spectrum of similar disorders resulting from defective glycosylation of DAG1 (128239), collectively known as 'dystroglycanopathies' (Beltran-Valero de Bernabe et al., 2004). For a general phenotypic description and a discussion of genetic heterogeneity of muscular dystrophy-dystroglycanopathy type A, see MDDGA1 (236670).
Developmental and epileptic encephalopathy, 5
MedGen UID:
462081
Concept ID:
C3150731
Disease or Syndrome
Developmental and epileptic encephalopathy-5 (DEE5) is a neurologic disorder characterized by global developmental delay and the onset of tonic seizures or infantile spasms in the first months of life. The seizures tend to be refractory to treatment, and EEG shows hypsarrhythmia, consistent with a clinical diagnosis of West syndrome. Affected individuals have severely impaired psychomotor development with lack of visual attention, poor head control, feeding difficulties, microcephaly, and spastic quadriplegia. Brain imaging may show cerebral atrophy and hypomyelination (summary by Saitsu et al., 2010). For a general phenotypic description and a discussion of genetic heterogeneity of developmental and epileptic encephalopathy, see 308350.
Pontocerebellar hypoplasia type 2D
MedGen UID:
462490
Concept ID:
C3151140
Disease or Syndrome
PCH2D is an autosomal recessive disorder characterized by progressive microcephaly, postnatal onset of progressive atrophy of the cerebrum and cerebellum, profound mental retardation, spasticity, and variable seizures (summary by Ben-Zeev et al., 2003). For a general phenotypic description and a discussion of genetic heterogeneity of pontocerebellar hypoplasia type 2, see PCH2A (277470).
Lissencephaly 4
MedGen UID:
462811
Concept ID:
C3151461
Disease or Syndrome
Lissencephaly-4 (LIS4) is an autosomal recessive neurodevelopmental disorder characterized by lissencephaly, severe brain atrophy, extreme microcephaly (head circumference of more than 10 standard deviations (SD) below the mean), and profound mental retardation. It has also been referred to as 'microlissencephaly' (summary by Bakircioglu et al., 2011 and Alkuraya et al., 2011). For a general phenotypic description and a discussion of genetic heterogeneity of lissencephaly, see LIS1 (607432).
Muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A3
MedGen UID:
462869
Concept ID:
C3151519
Disease or Syndrome
An autosomal recessive muscular dystrophy caused by mutations in the POMGNT1 gene. It is associated with characteristic brain and eye malformations, profound mental retardation, and death usually in the first years of life.
Warburg micro syndrome 3
MedGen UID:
481833
Concept ID:
C3280203
Disease or Syndrome
RAB18 deficiency is the molecular deficit underlying both Warburg micro syndrome (characterized by eye, nervous system, and endocrine abnormalities) and Martsolf syndrome (characterized by similar – but milder – findings). To date Warburg micro syndrome comprises >96% of reported individuals with genetically defined RAB18 deficiency. The hallmark ophthalmologic findings are bilateral congenital cataracts, usually accompanied by microphthalmia, microcornea (diameter <10), and small atonic pupils. Poor vision despite early cataract surgery likely results from progressive optic atrophy and cortical visual impairment. Individuals with Warburg micro syndrome have severe to profound intellectual disability (ID); those with Martsolf syndrome have mild to moderate ID. Some individuals with RAB18 deficiency also have epilepsy. In Warburg micro syndrome, a progressive ascending spastic paraplegia typically begins with spastic diplegia and contractures during the first year, followed by upper-limb involvement leading to spastic quadriplegia after about age five years, often eventually causing breathing difficulties. In Martsolf syndrome infantile hypotonia is followed primarily by slowly progressive lower-limb spasticity. Hypogonadism – when present – manifests in both syndromes, in males as micropenis and/or cryptorchidism and in females as hypoplastic labia minora, clitoral hypoplasia, and small introitus.
Microcephaly, epilepsy, and diabetes syndrome
MedGen UID:
481870
Concept ID:
C3280240
Disease or Syndrome
Primary microcephaly-epilepsy-permanent neonatal diabetes syndrome is a rare, genetic, neurologic disease characterized by congenital microcephaly, severe, early-onset epileptic encephalopathy (manifesting as intractable, myoclonic and/or tonic-clonic seizures), permanent, neonatal, insulin-dependent diabetes mellitus, and severe global developmental delay. Muscular hypotonia, skeletal abnormalities, feeding difficulties, and dysmorphic facial features (including narrow forehead, anteverted nares, small mouth with deep philtrum, tented upper lip vermilion) are frequently associated. Brain MRI reveals cerebral atrophy with cortical gyral simplification and aplasia/hypoplasia of the corpus callosum.
Intellectual disability, autosomal recessive 18
MedGen UID:
481895
Concept ID:
C3280265
Mental or Behavioral Dysfunction
MRT18 is an autosomal recessive disorder characterized by impaired intellectual development with or without epilepsy. Other features may include spasticity, congenital heart disease, brain abnormalities, and atypical electroencephalography (summary by Trehan et al., 2015).
Microcephaly-cerebellar hypoplasia-cardiac conduction defect syndrome
MedGen UID:
482322
Concept ID:
C3280692
Disease or Syndrome
The Zaki-Gleeson syndrome is an autosomal recessive neurodevelopmental disorder characterized by profound mental retardation, severe microcephaly, poor growth, cerebellar hypoplasia, and second-degree cardiac conduction defects (Zaki et al., 2011).
Congenital ichthyosis-intellectual disability-spastic quadriplegia syndrome
MedGen UID:
482486
Concept ID:
C3280856
Disease or Syndrome
ISQMR is a severe autosomal recessive disorder characterized by ichthyosis apparent from birth, profound psychomotor retardation with essentially no development, spastic quadriplegia, and seizures (summary by Aldahmesh et al., 2011).
Developmental and epileptic encephalopathy, 13
MedGen UID:
482821
Concept ID:
C3281191
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.
X-linked intellectual disability-cardiomegaly-congestive heart failure syndrome
MedGen UID:
763827
Concept ID:
C3550913
Disease or Syndrome
X-linked intellectual disability-cardiomegaly-congestive heart failure syndrome is a rare X-linked syndromic intellectual disability disorder characterized by profound intellectual disability, global developmental delay with absent speech, seizures, large joint contractures, abnormal position of thumbs and middle-age onset of cardiomegaly and atrioventricular valve abnormalities, resulting in subsequent congestive heart failure. Additional features include variable facial dysmorphism (notably large ears with overfolded helix) and large testes.
Muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A, 7
MedGen UID:
766244
Concept ID:
C3553330
Disease or Syndrome
Congenital muscular dystrophy-dystroglycanopathy with brain and eye anomalies (type A), which includes both the more severe Walker-Warburg syndrome (WWS) and the slightly less severe muscle-eye-brain disease (MEB), is an autosomal recessive disorder with characteristic brain and eye malformations, profound mental retardation, congenital muscular dystrophy, and death usually in the first years of life. It represents the most severe end of a phenotypic spectrum of similar disorders resulting from defective glycosylation of alpha-dystroglycan (DAG1; 128239), collectively known as 'dystroglycanopathies' (summary by Roscioli et al., 2012). For a general phenotypic description and a discussion of genetic heterogeneity of muscular dystrophy-dystroglycanopathy type A, see MDDGA1 (236670).
Developmental and epileptic encephalopathy, 15
MedGen UID:
767230
Concept ID:
C3554316
Disease or Syndrome
Warburg micro syndrome 4
MedGen UID:
816595
Concept ID:
C3810265
Disease or Syndrome
RAB18 deficiency is the molecular deficit underlying both Warburg micro syndrome (characterized by eye, nervous system, and endocrine abnormalities) and Martsolf syndrome (characterized by similar – but milder – findings). To date Warburg micro syndrome comprises >96% of reported individuals with genetically defined RAB18 deficiency. The hallmark ophthalmologic findings are bilateral congenital cataracts, usually accompanied by microphthalmia, microcornea (diameter <10), and small atonic pupils. Poor vision despite early cataract surgery likely results from progressive optic atrophy and cortical visual impairment. Individuals with Warburg micro syndrome have severe to profound intellectual disability (ID); those with Martsolf syndrome have mild to moderate ID. Some individuals with RAB18 deficiency also have epilepsy. In Warburg micro syndrome, a progressive ascending spastic paraplegia typically begins with spastic diplegia and contractures during the first year, followed by upper-limb involvement leading to spastic quadriplegia after about age five years, often eventually causing breathing difficulties. In Martsolf syndrome infantile hypotonia is followed primarily by slowly progressive lower-limb spasticity. Hypogonadism – when present – manifests in both syndromes, in males as micropenis and/or cryptorchidism and in females as hypoplastic labia minora, clitoral hypoplasia, and small introitus.
Megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome 1
MedGen UID:
861164
Concept ID:
C4012727
Disease or Syndrome
MPPH (megalencephaly-postaxial polydactyly-polymicrogyria-hydrocephalus) syndrome is a developmental brain disorder characterized by megalencephaly (brain overgrowth) with the cortical malformation bilateral perisylvian polymicrogyria (BPP). At birth the occipital frontal circumference (OFC) ranges from normal to 6 standard deviations (SD) above the mean for age, sex, and gestational age; in older individuals the range is from 3 to 10 SD above the mean. A variable degree of ventriculomegaly is seen in almost all children with MPPH syndrome; nearly 50% of individuals have frank hydrocephalus. Neurologic problems associated with BPP include oromotor dysfunction (100%), epilepsy (50%), and mild-to-severe intellectual disability (100%). Postaxial hexadactyly occurs in 50% of individuals with MPPH syndrome.
Intellectual disability, autosomal recessive 43
MedGen UID:
862823
Concept ID:
C4014386
Mental or Behavioral Dysfunction
Autosomal recessive intellectual developmental disorder-43 (MRT43) is characterized by impaired intellectual development, poor language skills, short stature, and dysmorphic features. Some patients may have significant motor delays (summary by Gangfuss et al., 2022).
Pontocerebellar hypoplasia type 2E
MedGen UID:
862925
Concept ID:
C4014488
Disease or Syndrome
Pontocerebellar hypoplasia type 2E is an autosomal recessive neurodegenerative disorder characterized by profound mental retardation, progressive microcephaly, spasticity, and early-onset epilepsy (summary by Feinstein et al., 2014). For a general phenotypic description and a discussion of genetic heterogeneity of pontocerebellar hypoplasia type 2, see PCH2A (277470).
Fatty acyl-CoA reductase 1 deficiency
MedGen UID:
863781
Concept ID:
C4015344
Disease or Syndrome
Peroxisomal fatty acyl-CoA reductase-1 disorder (PFCRD) is an autosomal recessive disorder characterized by onset in infancy of severely delayed psychomotor development, growth retardation with microcephaly, and seizures. Some patients may have congenital cataracts and develop spasticity later in childhood. Biochemical studies tend to show decreased plasmalogen, consistent with a peroxisomal defect. The disorder is reminiscent of rhizomelic chondrodysplasia punctata (see, e.g., RCDP1, 215100), although the characteristic skeletal abnormalities observed in RCDP are absent (Buchert et al., 2014).
Glucocorticoid deficiency 2
MedGen UID:
891117
Concept ID:
C4049714
Disease or Syndrome
Familial glucocorticoid deficiency is an autosomal recessive disorder resulting from resistance to the action of adrenocorticotropin (ACTH) on the adrenal cortex, which stimulates glucocorticoid production. Affected individuals are deficient in cortisol and, if untreated, are likely to succumb to hypoglycemia or overwhelming infection in infancy or childhood (summary by Metherell et al., 2005). For a general phenotypic description and a discussion of genetic heterogeneity of familial glucocorticoid deficiency, see GCCD1 (202200).
Hypotonia, infantile, with psychomotor retardation and characteristic facies 2
MedGen UID:
907651
Concept ID:
C4225203
Disease or Syndrome
UNC80 deficiency is characterized by hypotonia, strabismus, oral motor dysfunction, postnatal growth deficiency, and developmental delay. The majority of individuals do not learn to walk. All individuals lack expressive language; however, many have expressive body language, and a few have used signs to communicate. Seizures may develop during infancy or childhood. Additional features can include nystagmus, extremity hypertonia, a high-pitched cry, repetitive and self-stimulatory behaviors, constipation, clubfeet, joint contractures, and scoliosis. For most individuals the UNC80 deficiency syndrome is not progressive. Individuals have slow acquisition of skills and do not have a loss of skills suggestive of neurodegeneration.
SLC39A8-CDG
MedGen UID:
899837
Concept ID:
C4225234
Disease or Syndrome
Congenital disorder of glycosylation type IIn (CDG2N) is an autosomal recessive severe multisystem developmental disorder characterized by delayed psychomotor development apparent from infancy, hypotonia, and variable additional features, such as short stature, seizures, visual impairment, and cerebellar atrophy. Serum transferrin analysis shows a CDG type II pattern (summary by Boycott et al., 2015 and Park et al., 2015). For a discussion of genetic heterogeneity of CDG type II, see CDG2A (212066).
Trichothiodystrophy 5, nonphotosensitive
MedGen UID:
899675
Concept ID:
C4225420
Disease or Syndrome
Trichothiodystrophy-5 (TTD5) is an X-linked disorder characterized by sparse and brittle hair, facial dysmorphism, global developmental delays, growth deficiency, hypogonadism, and structural brain abnormalities (summary by Mendelsohn et al., 2020). For a general phenotypic description and a discussion of genetic heterogeneity of trichothiodystrophy, see TTD1 (601675).
Muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A1
MedGen UID:
924974
Concept ID:
C4284790
Disease or Syndrome
Congenital muscular dystrophy-dystroglycanopathy with brain and eye anomalies (type A), which includes both the more severe Walker-Warburg syndrome (WWS) and the slightly less severe muscle-eye-brain disease (MEB), is a genetically heterogeneous autosomal recessive disorder with characteristic brain and eye malformations, profound mental retardation, congenital muscular dystrophy, and early death. The phenotype commonly includes cobblestone (type II) lissencephaly, cerebellar malformations, and retinal malformations. More variable features include macrocephaly or microcephaly, hypoplasia of midline brain structures, ventricular dilatation, microphthalmia, cleft lip/palate, and congenital contractures (Dobyns et al., 1989). Those with a more severe phenotype characterized as Walker-Warburg syndrome often die within the first year of life, whereas those characterized as having muscle-eye-brain disease may rarely acquire the ability to walk and to speak a few words. These are part of a group of disorders resulting from defective glycosylation of DAG1 (128239), collectively known as 'dystroglycanopathies' (Godfrey et al., 2007). Genetic Heterogeneity of Congenital Muscular Dystrophy-Dystroglycanopathy with Brain and Eye Anomalies (Type A) Muscular dystrophy-dystroglycanopathy with brain and eye anomalies (type A) is genetically heterogeneous and can be caused by mutation in other genes involved in DAG1 glycosylation: see MDDGA2 (613150), caused by mutation in the POMT2 gene (607439); MDDGA3 (253280), caused by mutation in the POMGNT1 gene (606822); MDDGA4 (253800), caused by mutation in the FKTN gene (607440); MDDGA5 (613153), caused by mutation in the FKRP gene (606596); MDDGA6 (613154), caused by mutation in the LARGE gene (603590); MDDGA7 (614643), caused by mutation in the ISPD gene (CRPPA; 614631); MDDGA8 (614830) caused by mutation in the GTDC2 gene (POMGNT2; 614828); MDDGA9 (616538), caused by mutation in the DAG1 gene (128239); MDDGA10 (615041), caused by mutation in the TMEM5 gene (RXYLT1; 605862); MDDGA11 (615181), caused by mutation in the B3GALNT2 gene (610194); MDDGA12 (615249), caused by mutation in the SGK196 gene (POMK; 615247); MDDGA13 (615287), caused by mutation in the B3GNT1 gene (B4GAT1; 605517); and MDDGA14 (615350), caused by mutation in the GMPPB gene (615320).
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.
Developmental and epileptic encephalopathy, 41
MedGen UID:
934684
Concept ID:
C4310717
Disease or Syndrome
Developmental and epileptic encephalopathy-41 (DEE41) is a neurologic disorder characterized by the onset of seizures in the first days or weeks of life. Affected infants show severely impaired psychomotor development with hypotonia, spasticity, lack of speech, poor visual fixation, feeding difficulties sometimes necessitating tube feeding, poor overall growth and microcephaly, and contractures. Brain imaging may show delayed myelination, thin corpus callosum, and cerebral atrophy (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, 40
MedGen UID:
934704
Concept ID:
C4310737
Disease or Syndrome
Developmental and epileptic encephalopathy-40 (DEE40) is an autosomal recessive neurologic disorder characterized by the onset of refractory infantile spasms within the first 6 months of life. Affected infants may have normal or mildly delayed development before the onset of seizures, but thereafter show developmental stagnation and severe neurologic impairment. EEG typically shows hypsarrhythmia, consistent with a clinical diagnosis of West syndrome. Additional features include poor feeding, axial hypotonia with peripheral spasticity, limited eye contact, profoundly impaired intellectual development with absent language, and poor fine motor skills (summary by Alfaiz et al., 2016). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Severe growth deficiency-strabismus-extensive dermal melanocytosis-intellectual disability syndrome
MedGen UID:
934712
Concept ID:
C4310745
Disease or Syndrome
Neurodevelopmental disorder with microcephaly and gray sclerae (NEDMIGS) is a severe autosomal recessive disorder characterized by impaired global development with hypotonia often precluding independent ambulation, profoundly impaired intellectual development with poor or absent language, mild microcephaly, and abnormal visual fixation. Patients also have gray sclerae and may have coarse facial features. Most affected individuals have seizures; some may have brain imaging abnormalities (summary by Shaheen et al., 2016 and Froukh et al., 2020).
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).
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).
Developmental and epileptic encephalopathy, 53
MedGen UID:
1374886
Concept ID:
C4479313
Disease or Syndrome
Developmental and epileptic encephalopathy-53 (DEE53) is a severe autosomal recessive neurodegenerative disorder characterized by onset of intractable seizures in infancy. Affected individuals show hypotonia and very poor or absent global development, resulting in severe intellectual disability and spastic quadriplegia. Some patients may die in childhood (summary by Hardies et al., 2016). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Neurodevelopmental disorder with microcephaly, hypotonia, and variable brain anomalies
MedGen UID:
1380860
Concept ID:
C4479566
Disease or Syndrome
NMIHBA is a severe autosomal recessive neurodevelopmental and neurodegenerative disorder characterized by global developmental delay apparent from infancy and profoundly impaired intellectual development. Affected individuals have microcephaly with accompanying dysmorphic features, truncal hypotonia, peripheral spasticity, and lack of independent ambulation or speech acquisition. Brain imaging shows variable abnormalities, including cortical atrophy, thin corpus callosum, cerebellar hypoplasia, and delayed myelination (summary by Zollo et al., 2017).
Diencephalic-mesencephalic junction dysplasia syndrome 1
MedGen UID:
1615973
Concept ID:
C4538630
Disease or Syndrome
Diencephalic-mesencephalic junction dysplasia syndrome-1 (DMJDS1) is an autosomal recessive neurodevelopmental disorder characterized by progressive microcephaly, severely delayed or even absent psychomotor development with profound intellectual disability, and spasticity or dystonia. Some patients may have seizures and/or visual impairment. Brain imaging shows a characteristic developmental malformation of the midbrain; subtle intracranial calcifications may also be present (summary by Aran et al., 2016 and Guemez-Gamboa et al., 2018). Genetic Heterogeneity of Diencephalic-Mesencephalic Junction Dysplasia Syndrome See also DMJDS2 (618646), caused by mutation in the GSX2 gene (616253) on chromosome 4q12.
Developmental and epileptic encephalopathy, 55
MedGen UID:
1622363
Concept ID:
C4539843
Disease or Syndrome
Developmental and epileptic encephalopathy-55 (DEE55) is an autosomal recessive neurologic disorder characterized by onset of refractory seizures in the first weeks or months of life. Affected individuals have an extremely poor outcome, with profoundly impaired intellectual development, absent speech, spastic quadriplegia, and dyskinetic movements. Most have cortical visual impairment and require a feeding tube. Brain imaging shows nonspecific abnormalities, including cerebral atrophy, thin corpus callosum, and abnormal signals in the white matter. Death in childhood may occur. Biochemically, the disorder is associated with impaired synthesis of GPI-anchored proteins (summary by Vetro 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).
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).
Neurodevelopmental disorder with microcephaly, seizures, and cortical atrophy
MedGen UID:
1615361
Concept ID:
C4540493
Disease or Syndrome
Neurodevelopmental disorder with microcephaly, seizures, and cortical atrophy (NDMSCA) is an autosomal recessive disorder characterized by severe global developmental delay with poor motor and intellectual function apparent soon after birth, as well as postnatal progressive microcephaly. Most patients develop early-onset, frequent, and often intractable seizures, compatible with an epileptic encephalopathy. Other features include poor feeding, poor overall growth, absent speech, poor or absent eye contact, inability to achieve walking, hypotonia, and peripheral spasticity. Brain imaging usually shows progressive cerebral atrophy, thin corpus callosum, and abnormalities in myelination. Death in childhood may occur (summary by Siekierska et al., 2019).
Pseudo-TORCH syndrome 1
MedGen UID:
1639355
Concept ID:
C4552078
Disease or Syndrome
Developmental and epileptic encephalopathy, 60
MedGen UID:
1638894
Concept ID:
C4693663
Disease or Syndrome
Developmental and epileptic encephalopathy-60 (DEE60) is an autosomal recessive neurologic disorder characterized by the onset of infantile spasms, seizures, or myoclonus in the first months of life. EEG typically shows hypsarrhythmia, consistent with a clinical diagnosis of West syndrome. Affected individuals have severe global developmental delay with inability to sit, walk, or speak. Brain imaging may show brain atrophy and hippocampal malrotation (summary by Mutoh et al., 2018). For a discussion of genetic heterogeneity of DEE, see 308350.
Developmental and epileptic encephalopathy, 61
MedGen UID:
1639392
Concept ID:
C4693688
Disease or Syndrome
Developmental and epileptic encephalopathy-61 (DEE61) is an autosomal recessive neurologic disorder characterized by the onset of refractory seizures in the first months or years of life. There is profound global developmental delay with intellectual disability, inability to walk, poor voluntary movements, spasticity, microcephaly, cerebral atrophy, and dysmorphic facial features (summary by Muona et al., 2016). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Neurodevelopmental disorder with spastic quadriplegia and brain abnormalities with or without seizures
MedGen UID:
1633724
Concept ID:
C4693816
Disease or Syndrome
El-Hattab-Alkuraya syndrome is characterized by microcephaly (often early onset and progressive); severe-to-profound developmental delay; refractory and early-onset seizures; spastic quadriplegia with axial hypotonia; and growth deficiency with poor weight gain and short stature. Characteristic findings on brain imaging include cerebral atrophy that is disproportionately most prominent in the frontal lobes; ex vacuo ventricular dilatation with notable posterior horn predominance; brain stem volume loss with flattening of the belly of the pons; and symmetric under-opercularization. Neurologic involvement is progressive, with significant morbidity and mortality.
Leukodystrophy, hypomyelinating, 17
MedGen UID:
1644557
Concept ID:
C4693912
Disease or Syndrome
Hypomyelinating leukodystrophy-17 is an autosomal recessive neurodevelopmental disorder characterized by poor, if any, development apparent from infancy. Affected individuals never learn to walk or speak, and have early-onset multifocal seizures, spasticity, poor overall growth, and microcephaly (up to -10 SD). Brain imaging shows multiple abnormalities, including cerebral and cerebellar atrophy, thin corpus callosum, abnormal signals in the basal ganglia, and features suggesting hypo- or demyelination. Some patients may die in childhood (summary by Shukla et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of hypomyelinating leukodystrophy, see 312080.
Developmental and epileptic encephalopathy, 2
MedGen UID:
1663579
Concept ID:
C4750718
Disease or Syndrome
Developmental and epileptic encephalopathy-2 (DEE2) is an X-linked dominant severe neurologic disorder characterized by onset of seizures in the first months of life and severe global developmental delay resulting in impaired intellectual development and poor motor control. Other features include lack of speech development, subtle dysmorphic facial features, sleep disturbances, gastrointestinal problems, and stereotypic hand movements. There is some phenotypic overlap with Rett syndrome (312750), but DEE2 is considered to be a distinct entity (summary by Fehr et al., 2013). For a discussion of genetic heterogeneity of DEE, see 308350.
Galloway-Mowat syndrome 8
MedGen UID:
1675829
Concept ID:
C5193045
Disease or Syndrome
Galloway-Mowat syndrome-8 is an autosomal recessive disorder characterized by impaired psychomotor development, poor overall growth with microcephaly, and early-onset progressive nephrotic syndrome associated with focal segmental glomerulosclerosis on renal biopsy. Some patients may have seizures, and some may die in childhood (summary by Fujita et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of GAMOS, see GAMOS1 (251300).
Developmental and epileptic encephalopathy, 73
MedGen UID:
1681654
Concept ID:
C5193065
Disease or Syndrome
Developmental and epileptic encephalopathy-73 (DEE73) is a neurologic disorder characterized by the onset of refractory seizures in the first months of life. Affected individuals meet almost no developmental milestones: they have hypotonia and are unable to walk, speak, or feed properly. They have poor overall growth with small head circumference and dysmorphic facial features. Additional manifestations include cortical visual impairment with roving eye movements and variable hearing loss (summary by Edvardson et al., 2019). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Hypotonia, hypoventilation, impaired intellectual development, dysautonomia, epilepsy, and eye abnormalities
MedGen UID:
1672905
Concept ID:
C5193124
Disease or Syndrome
Hypotonia, hypoventilation, impaired intellectual development, dysautonomia, epilepsy, and eye abnormalities (HIDEA) is an autosomal recessive neurodevelopmental syndrome characterized by global developmental delay, poor or absent speech, hypotonia, variable ocular movement and visual abnormalities, and respiratory difficulties, including hypoventilation, and sleep apnea. Patients may have significant breathing problems during respiratory infections that may lead to early death (summary by Rahikkala et al., 2019).
Glycosylphosphatidylinositol biosynthesis defect 21
MedGen UID:
1684749
Concept ID:
C5231419
Disease or Syndrome
Neurodevelopmental disorder with brain anomalies, seizures, and scoliosis (NEDBSS) is an autosomal recessive disorder characterized by severely impaired psychomotor development, hypotonia, seizures, and structural brain anomalies, including thin corpus callosum and cerebellar atrophy. Other features include scoliosis, dysmorphic facies, and visual impairment. Affected individuals are usually unable to walk or speak and may require tube feeding in severe cases. The disorder is caused by a defect in glycosylphosphatidylinositol (GPI) biosynthesis (summary by Knaus et al., 2019). For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293).
Developmental and epileptic encephalopathy, 81
MedGen UID:
1684681
Concept ID:
C5231450
Disease or Syndrome
Developmental and epileptic encephalopathy-81 (DEE81) is an autosomal recessive neurodevelopmental disorder typically characterized by onset of severe refractory seizures soon after birth or in the first months of life. Affected individuals show little developmental progress with no eye contact and no motor or cognitive development. Other features may include facial dysmorphism, such as hypotonic facies and epicanthal folds, as well as sensorineural hearing loss and peripheral neuropathy. Brain imaging shows cerebral atrophy, impaired myelination, thin corpus callosum, and progressive leukoencephalopathy (summary by Esposito et al., 2019; Maddirevula et al., 2019). For a discussion of genetic heterogeneity of DEE, see 308350.
Developmental and epileptic encephalopathy, 83
MedGen UID:
1684784
Concept ID:
C5231487
Disease or Syndrome
Developmental and epileptic encephalopathy-83 (DEE83) is a severe autosomal recessive neurodevelopmental disorder characterized by onset of frequent seizures in the first days to months of life that are usually refractory to medical treatment and are associated with significant EEG abnormalities. Affected individuals have profoundly impaired development, with no motor or language skill acquisition, poor or absent visual tracking, and poor oromotor function necessitating tube feeding. Many patients die in the first years of life (summary by Perenthaler et al., 2020). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Neurodevelopmental disorder with epilepsy, spasticity, and brain atrophy
MedGen UID:
1717952
Concept ID:
C5394027
Disease or Syndrome
Neurodevelopmental disorder with epilepsy, spasticity, and brain atrophy (NEDESBA) is an autosomal recessive disorder characterized by severely impaired global development apparent soon after birth. Affected individuals develop seizures in the first year of life and achieve almost no psychomotor progress, resulting in feeding difficulties and an inability to walk or speak. Other features include hypotonia, peripheral spasticity with contractures, cortical visual impairment, and dysmorphic features, including microcephaly. Death in childhood may occur (summary by Van Bergen et al., 2020). Van Bergen et al. (2020) noted that the molecular mechanism of this disorder can be classified into a group of similar phenotypes resulting from mutations in genes associated with transport protein particles, sometimes referred to as 'TRAPPopathies' (review by Sacher et al., 2019).
Intellectual developmental disorder with seizures and language delay
MedGen UID:
1740295
Concept ID:
C5436574
Disease or Syndrome
SETD1B-related neurodevelopmental disorder (SETD1B-NDD) is characterized by developmental delay (mainly affecting speech and language), intellectual disability, seizures, autism spectrum disorder or autism-like behaviors, and additional behavioral concerns. Speech delay and/or language disorder has been reported in most affected individuals. Delay in gross motor skills and mild-to-moderate intellectual disability are common. Most affected individuals have seizures with variable onset and seizure type. Behavioral issues including hyperactivity, aggression, anxiety, and sleep disorders have been reported in approximately half of individuals. Less common features include ophthalmologic manifestations and feeding issues.
Developmental and epileptic encephalopathy 89
MedGen UID:
1761611
Concept ID:
C5436853
Disease or Syndrome
Developmental and epileptic encephalopathy-89 (DEE89) is a severe autosomal recessive disorder characterized by profound global developmental delay with impaired intellectual development, absent speech, inability to sit or walk due to axial hypotonia and spastic quadriparesis, and onset of seizures in the first days or months of life. EEG shows suppression-burst pattern or hypsarrhythmia, consistent with DEE or a clinical diagnosis of West syndrome. More variable features include joint contractures with foot deformities, dysmorphic facial features with cleft palate, and omphalocele. Affected individuals have poor motor skills, poor eye contact, and lack of language development; some die in infancy or early childhood. Brain imaging may be normal or show nonspecific abnormalities (summary by Chatron et al., 2020).
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.
Developmental and epileptic encephalopathy 96
MedGen UID:
1780167
Concept ID:
C5543446
Disease or Syndrome
Developmental and epileptic encephalopathy-96 (DEE96) is characterized by onset of seizures in the first days or weeks of life. Affected infants have tonic or myoclonic seizures associated with burst-suppression pattern on EEG. They also have hypotonia with respiratory insufficiency that may result in premature death. Those that survive have profound developmental delay and persistent seizures (summary by Suzuki et al., 2019). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
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).
Developmental and epileptic encephalopathy-107
MedGen UID:
1823988
Concept ID:
C5774215
Disease or Syndrome
Developmental and epileptic encephalopathy-107 (DEE107) is a severe autosomal recessive neurologic disorder characterized by onset of seizures in the first months of life and severe global developmental delay, profound intellectual disability, progressive microcephaly, and hypotonia (Conroy et al., 2016). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Neurodevelopmental disorder with short stature, prominent forehead, and feeding difficulties
MedGen UID:
1824001
Concept ID:
C5774228
Disease or Syndrome
Neurodevelopmental disorder with short stature, prominent forehead, and feeding difficulties (NEDSFF) is an autosomal recessive disorder characterized by distinct craniofacial features, multisystem dysfunction, profound neurodevelopmental delays, and neonatal death (Shankar et al., 2022).
Developmental and epileptic encephalopathy 110
MedGen UID:
1824038
Concept ID:
C5774265
Disease or Syndrome
Developmental and epileptic encephalopathy-110 (DEE110) is an autosomal recessive disorder characterized by profound global developmental delay and hypotonia apparent in infancy followed by onset of seizures in the first months or years of life. Affected individuals achieve almost no developmental milestones and show impaired intellectual development, poor or absent speech, inability to walk or grasp objects, peripheral spasticity, and poor eye contact. Brain imaging shows hypoplastic corpus callosum and cortical atrophy (Dahimene et al., 2022). For a discussion of genetic heterogeneity of DEE, see 308350.

Professional guidelines

PubMed

D'Onofrio G, Accogli A, Severino M, Caliskan H, Kokotović T, Blazekovic A, Jercic KG, Markovic S, Zigman T, Goran K, Barišić N, Duranovic V, Ban A, Borovecki F, Ramadža DP, Barić I, Fazeli W, Herkenrath P, Marini C, Vittorini R, Gowda V, Bouman A, Rocca C, Alkhawaja IA, Murtaza BN, Rehman MMU, Al Alam C, Nader G, Mancardi MM, Giacomini T, Srivastava S, Alvi JR, Tomoum H, Matricardi S, Iacomino M, Riva A, Scala M, Madia F, Pistorio A, Salpietro V, Minetti C, Rivière JB, Srour M, Efthymiou S, Maroofian R, Houlden H, Vernes SC, Zara F, Striano P, Nagy V
Hum Genet 2023 Jul;142(7):909-925. Epub 2023 May 14 doi: 10.1007/s00439-023-02552-2. PMID: 37183190Free PMC Article
Cook CB, Armstrong L, Boerkoel CF, Clarke LA, du Souich C, Demos MK, Gibson WT, Gill H, Lopez E, Patel MS, Selby K, Abu-Sharar Z; CAUSES Study, Elliott AM, Friedman JM
Cold Spring Harb Mol Case Stud 2021 Dec;7(6) Epub 2021 Dec 9 doi: 10.1101/mcs.a006125. PMID: 34697084Free PMC Article
Borlot F, de Almeida BI, Combe SL, Andrade DM, Filloux FM, Myers KA
Epilepsia 2019 Aug;60(8):1661-1669. Epub 2019 Jul 5 doi: 10.1111/epi.16273. PMID: 31273778

Recent clinical studies

Etiology

Cook CB, Armstrong L, Boerkoel CF, Clarke LA, du Souich C, Demos MK, Gibson WT, Gill H, Lopez E, Patel MS, Selby K, Abu-Sharar Z; CAUSES Study, Elliott AM, Friedman JM
Cold Spring Harb Mol Case Stud 2021 Dec;7(6) Epub 2021 Dec 9 doi: 10.1101/mcs.a006125. PMID: 34697084Free PMC Article
McKenna B, Koomar T, Vervier K, Kremsreiter J, Michaelson JJ
Cold Spring Harb Mol Case Stud 2018 Dec;4(6) Epub 2018 Dec 17 doi: 10.1101/mcs.a003285. PMID: 30559312Free PMC Article

Diagnosis

Ramadesikan S, Hickey S, De Los Reyes E, Patel AD, Franklin SJ, Brennan P, Crist E, Lee K, White P, McBride KL, Koboldt DC, Wilson RK
Cold Spring Harb Mol Case Stud 2022 Feb;8(2) Epub 2022 Mar 24 doi: 10.1101/mcs.a006165. PMID: 35091508Free PMC Article
Gangfuß A, Czech A, Hentschel A, Münchberg U, Horvath R, Töpf A, O'Heir E, Lochmüller H, Stehling F, Kiewert C, Sickmann A, Kuechler A, Kaiser FJ, Kölbel H, Christiansen J, Schara-Schmidt U, Roos A
J Pathol 2022 Jan;256(1):93-107. Epub 2021 Nov 18 doi: 10.1002/path.5812. PMID: 34599609
Cook CB, Armstrong L, Boerkoel CF, Clarke LA, du Souich C, Demos MK, Gibson WT, Gill H, Lopez E, Patel MS, Selby K, Abu-Sharar Z; CAUSES Study, Elliott AM, Friedman JM
Cold Spring Harb Mol Case Stud 2021 Dec;7(6) Epub 2021 Dec 9 doi: 10.1101/mcs.a006125. PMID: 34697084Free PMC Article
Rohanizadegan M, Siddharath A, Retterer K, Hung C, Bodamer O
Cold Spring Harb Mol Case Stud 2020 Apr;6(2) Epub 2020 Apr 1 doi: 10.1101/mcs.a004846. PMID: 31969346Free PMC Article

Prognosis

Ramadesikan S, Hickey S, De Los Reyes E, Patel AD, Franklin SJ, Brennan P, Crist E, Lee K, White P, McBride KL, Koboldt DC, Wilson RK
Cold Spring Harb Mol Case Stud 2022 Feb;8(2) Epub 2022 Mar 24 doi: 10.1101/mcs.a006165. PMID: 35091508Free PMC Article
Rohanizadegan M, Siddharath A, Retterer K, Hung C, Bodamer O
Cold Spring Harb Mol Case Stud 2020 Apr;6(2) Epub 2020 Apr 1 doi: 10.1101/mcs.a004846. PMID: 31969346Free PMC Article

Clinical prediction guides

Ramadesikan S, Hickey S, De Los Reyes E, Patel AD, Franklin SJ, Brennan P, Crist E, Lee K, White P, McBride KL, Koboldt DC, Wilson RK
Cold Spring Harb Mol Case Stud 2022 Feb;8(2) Epub 2022 Mar 24 doi: 10.1101/mcs.a006165. PMID: 35091508Free PMC Article
Perez Y, Shorer Z, Liani-Leibson K, Chabosseau P, Kadir R, Volodarsky M, Halperin D, Barber-Zucker S, Shalev H, Schreiber R, Gradstein L, Gurevich E, Zarivach R, Rutter GA, Landau D, Birk OS
Brain 2017 Apr 1;140(4):928-939. doi: 10.1093/brain/awx013. PMID: 28334855Free PMC Article

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    Clinical resources

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