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Distal muscle weakness

MedGen UID:
140883
Concept ID:
C0427065
Finding
Synonyms: Distal limb muscle weakness; Distal limb weakness; Distal muscle weakness of the limbs; Distal muscular weakness; Muscle weakness, distal; Muscle weakness, distal limbs, due to neuronopathy
SNOMED CT: Distal muscle weakness (249942005)
 
HPO: HP:0002460

Definition

Reduced strength of the musculature of the distal extremities. [from HPO]

Conditions with this feature

Dejerine-Sottas disease
MedGen UID:
3710
Concept ID:
C0011195
Disease or Syndrome
Dejerine-Sottas neuropathy is a demyelinating peripheral neuropathy with onset in infancy. It can show autosomal dominant or recessive inheritance. Affected individuals have delayed motor development due to severe distal motor and sensory impairment, resulting in difficulties in gait. Some patients have generalized hypotonia in infancy. Other features may include pes cavus, scoliosis, and sensory ataxia. Nerve conduction velocities are severely decreased (sometimes less than 10 m/s), and sural nerve biopsy shows severe loss of myelinated fibers (summary by Baets et al., 2011).
Roussy-Lévy syndrome
MedGen UID:
64430
Concept ID:
C0205713
Disease or Syndrome
Roussy-Levy syndrome is an autosomal dominant disorder characterized by early onset of prominent ataxia followed by late onset of mild motor involvement. Symptoms progress very slowly, and affected individuals may remain ambulatory throughout life (Auer-Grumbach et al., 1998; Plante-Bordeneuve et al., 1999).
Welander distal myopathy
MedGen UID:
67441
Concept ID:
C0221054
Disease or Syndrome
Welander distal myopathy (WDM) is an autosomal dominant disorder characterized by adult onset of distal muscle weakness predominantly affecting the distal long extensors of the hands, with slow progression to involve all small hand muscles and the lower legs. Skeletal muscle biopsy shows myopathic changes and prominent rimmed vacuoles. Rare homozygous patients showed earlier onset, faster progression, and proximal muscle involvement. This disorder is common in Sweden and Finland (summary by Hackman et al., 2013).
Inclusion body myositis
MedGen UID:
68659
Concept ID:
C0238190
Disease or Syndrome
Sporadic inclusion body myositis (IBM) is the most common age-related muscle disease in the elderly that results in severe disability. Although traditionally considered an inflammatory myopathy, it is now considered to be more consistent with a myodegenerative disease (Sugarman et al., 2002; Askanas and Engel, 2006).
Charcot-Marie-Tooth disease, type IA
MedGen UID:
75727
Concept ID:
C0270911
Disease or Syndrome
For a general phenotypic description and a discussion of genetic heterogeneity of Charcot-Marie-Tooth disease type 1, see CMT1B (118200). CMT1A is the most common form of CMT. The average age of onset of clinical symptoms is 12.2 +/- 7.3 years. Slow nerve conduction velocity (NCV) less than 38 m/s is highly diagnostic and is a 100% penetrant phenotype independent of age (Lupski et al., 1991, 1992).
Charcot-Marie-Tooth disease type 1B
MedGen UID:
124377
Concept ID:
C0270912
Disease or Syndrome
Charcot-Marie-Tooth disease is a sensorineural peripheral polyneuropathy. Affecting approximately 1 in 2,500 individuals, Charcot-Marie-Tooth disease is the most common inherited disorder of the peripheral nervous system (Skre, 1974). Autosomal dominant, autosomal recessive, and X-linked forms have been recognized. Classification On the basis of electrophysiologic properties and histopathology, CMT has been divided into primary peripheral demyelinating (type 1, or HMSNI) and primary peripheral axonal (type 2, or HMSNII) neuropathies. The demyelinating neuropathies classified as CMT type 1 are characterized by severely reduced motor NCVs (less than 38 m/s) and segmental demyelination and remyelination with onion bulb formations on nerve biopsy. The axonal neuropathies classified as CMT type 2 are characterized by normal or mildly reduced NCVs and chronic axonal degeneration and regeneration on nerve biopsy (see CMT2A1; 118210). Distal hereditary motor neuropathy (dHMN) (see 158590), or spinal CMT, is characterized by exclusive motor involvement and sparing of sensory nerves (Pareyson, 1999). McAlpine (1989) proposed that the forms of CMT with very slow nerve conduction be given the gene symbol CMT1A (118220) and CMT1B, CMT1A being the gene on chromosome 17 and CMT1B being the gene on chromosome 1. CMT2 was the proposed symbol for the autosomal locus responsible for the moderately slow nerve conduction form of the disease (axonal). For a phenotypic description and discussion of genetic heterogeneity of the various subtypes of CMT, see CMTX1 (302800), CMT2A1 (118210), CMT3 (DSS; 145900), CMT4A (214400), and CMTDIB (606482). Genetic Heterogeneity of Autosomal Dominant Demyelinating CMT1 Autosomal dominant demyelinating CMT1 is a genetically heterogeneous disorder and can be caused by mutations in different genes; see CMT1A (118220), CMT1C (601098), CMT1D (607678), CMT1E (607734), CMT1F (607734), CMT1G (618279), CMT1H (619764), CMT1I (619742), and CMT1J (620111). See also 608236 for a related phenotype characterized by isolated slowed nerve conduction velocities (NCVs).
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).
Oculopharyngeal muscular dystrophy
MedGen UID:
75730
Concept ID:
C0270952
Disease or Syndrome
Oculopharyngeal muscular dystrophy (OPMD) is characterized by ptosis and dysphagia due to selective involvement of the muscles of the eyelids and pharynx, respectively. For the vast majority of individuals with typical OPMD, the mean age of onset of ptosis is usually 48 years and of dysphagia 50 years; in 5%-10% of individuals with severe OPMD, onset of ptosis and dysphagia occur before age 45 years and is associated with lower limb girdle weakness starting around age 60 years. Swallowing difficulties, which determine prognosis, increase the risk for potentially life-threatening aspiration pneumonia and poor nutrition. Other manifestations as the disease progresses can include limitation of upward gaze, tongue atrophy and weakness, chewing difficulties, wet voice, facial muscle weakness, axial muscle weakness, and proximal limb girdle weakness predominantly in lower limbs. Some individuals with severe involvement will eventually need a wheelchair. Neuropsychological tests have shown altered scores in executive functions in some.
Hereditary motor and sensory neuropathy with optic atrophy
MedGen UID:
140747
Concept ID:
C0393807
Disease or Syndrome
MFN2 hereditary motor and sensory neuropathy (MFN2-HMSN) is a classic axonal peripheral sensorimotor neuropathy, inherited in either an autosomal dominant (AD) manner (~90%) or an autosomal recessive (AR) manner (~10%). MFN2-HMSN is characterized by more severe involvement of the lower extremities than the upper extremities, distal upper-extremity involvement as the neuropathy progresses, more prominent motor deficits than sensory deficits, and normal (>42 m/s) or only slightly decreased nerve conduction velocities (NCVs). Postural tremor is common. Median onset is age 12 years in the AD form and age eight years in the AR form. The prevalence of optic atrophy is approximately 7% in the AD form and approximately 20% in the AR form.
Charcot-Marie-Tooth disease X-linked dominant 1
MedGen UID:
98290
Concept ID:
C0393808
Disease or Syndrome
GJB1 disorders are typically characterized by peripheral motor and sensory neuropathy with or without fixed CNS abnormalities and/or acute, self-limited episodes of transient neurologic dysfunction (especially weakness and dysarthria). Peripheral neuropathy typically manifests in affected males between ages five and 25 years. Although both men and women are affected, manifestations tend to be less severe in women, some of whom may remain asymptomatic. Less commonly, initial manifestations in some affected individuals are stroke-like episodes (acute fulminant episodes of reversible CNS dysfunction).
Myopathy, centronuclear, 2
MedGen UID:
98049
Concept ID:
C0410204
Disease or Syndrome
Any centronuclear myopathy in which the cause of the disease is a mutation in the BIN1 gene.
Spinocerebellar ataxia type 1
MedGen UID:
155703
Concept ID:
C0752120
Disease or Syndrome
Spinocerebellar ataxia type 1 (SCA1) is characterized by progressive cerebellar ataxia, dysarthria, and eventual deterioration of bulbar functions. Early in the disease, affected individuals may have gait disturbance, slurred speech, difficulty with balance, brisk deep tendon reflexes, hypermetric saccades, nystagmus, and mild dysphagia. Later signs include slowing of saccadic velocity, development of up-gaze palsy, dysmetria, dysdiadochokinesia, and hypotonia. In advanced stages, muscle atrophy, decreased deep tendon reflexes, loss of proprioception, cognitive impairment (e.g., frontal executive dysfunction, impaired verbal memory), chorea, dystonia, and bulbar dysfunction are seen. Onset is typically in the third or fourth decade, although childhood onset and late-adult onset have been reported. Those with onset after age 60 years may manifest a pure cerebellar phenotype. Interval from onset to death varies from ten to 30 years; individuals with juvenile onset show more rapid progression and more severe disease. Anticipation is observed. An axonal sensory neuropathy detected by electrophysiologic testing is common; brain imaging typically shows cerebellar and brain stem atrophy.
Danon disease
MedGen UID:
209235
Concept ID:
C0878677
Disease or Syndrome
Danon disease is a multisystem condition with predominant involvement of the heart, skeletal muscles, and retina, with overlying cognitive dysfunction. Males are typically more severely affected than females. Males usually present with childhood onset concentric hypertrophic cardiomyopathy that is progressive and often requires heart transplantation. Rarely, hypertrophic cardiomyopathy can evolve to resemble dilated cardiomyopathy. Most affected males also have cardiac conduction abnormalities. Skeletal muscle weakness may lead to delayed acquisition of motor milestones. Learning disability and intellectual disability, most often in the mild range, are common. Additionally, affected males can develop retinopathy with subsequent visual impairment. The clinical features in females are broader and more variable. Females are more likely to have dilated cardiomyopathy, with a smaller proportion requiring heart transplantation compared to affected males. Cardiac conduction abnormalities, skeletal muscle weakness, mild cognitive impairment, and pigmentary retinopathy are variably seen in affected females.
Charcot-Marie-Tooth disease type 2D
MedGen UID:
316946
Concept ID:
C1832274
Disease or Syndrome
The phenotypic spectrum of GARS1-associated axonal neuropathy ranges from GARS1 infantile-onset SMA (GARS1-iSMA) to GARS1 adolescent- or early adult-onset hereditary motor/sensory neuropathy (GARS1-HMSN). GARS1-iSMA. Age of onset ranges from the neonatal period to the toddler years. Initial manifestations are typically respiratory distress, poor feeding, and muscle weakness (distal greater than proximal). Weakness is slowly progressive, ultimately requiring mechanical ventilation and feeding via gastrostomy tube. GARS1-HMSN. Age of onset is most commonly during the second decade (range eight to 36 years). Initial manifestations are typically muscle weakness in the hands sometimes with sensory deficits. Lower limb involvement (seen in ~50% of individuals) ranges from weakness and atrophy of the extensor digitorum brevis and weakness of toe dorsiflexors to classic peroneal muscular atrophy with foot drop and a high steppage gait.
Charcot-Marie-Tooth disease type 4D
MedGen UID:
371304
Concept ID:
C1832334
Disease or Syndrome
Charcot-Marie-Tooth disease type 4D (CMT4D) is an autosomal recessive disorder of the peripheral nervous system characterized by early-onset distal muscle weakness and atrophy, foot deformities, and sensory loss affecting all modalities. Affected individuals develop deafness by the third decade of life (summary by Okamoto et al., 2014). For a phenotypic description and a discussion of genetic heterogeneity of autosomal recessive Charcot-Marie-Tooth disease, see CMT4A (214400).
Desmin-related myofibrillar myopathy
MedGen UID:
330449
Concept ID:
C1832370
Disease or Syndrome
Myofibrillar myopathy (MFM) is a noncommittal term that refers to a group of morphologically homogeneous, but genetically heterogeneous chronic neuromuscular disorders. The morphologic changes in skeletal muscle in MFM result from disintegration of the sarcomeric Z disc and the myofibrils, followed by abnormal ectopic accumulation of multiple proteins involved in the structure of the Z disc, including desmin, alpha-B-crystallin (CRYAB; 123590), dystrophin (300377), and myotilin (TTID; 604103). Genetic Heterogeneity of Myofibrillar Myopathy Other forms of MFM include MFM2 (608810), caused by mutation in the CRYAB gene (123590); MFM3 (609200), caused by mutation in the MYOT gene (604103); MFM4 (609452), caused by mutation in the ZASP gene (LDB3; 605906); MFM5 (609524), caused by mutation in the FLNC gene (102565); MFM6 (612954), caused by mutation in the BAG3 gene (603883); MFM7 (617114), caused by mutation in the KY gene (605739); MFM8 (617258), caused by mutation in the PYROXD1 gene (617220); MFM9 (603689), caused by mutation in the TTN gene (188840); MFM10 (619040), caused by mutation in the SVIL UNC45B gene (611220); MFM11 (619178), caused by mutation in the UNC45B gene (611220); and MFM12 (619424), caused by mutation in the MYL2 gene (160781). 'Desmin-related myopathy' is another term referring to MFM in which there are intrasarcoplasmic aggregates of desmin, usually in addition to other sarcomeric proteins. Rigid spine syndrome (602771), caused by mutation in the SEPN1 gene (606210), is another desmin-related myopathy. Goebel (1995) provided a review of desmin-related myopathy.
Charcot-Marie-Tooth disease type 4B1
MedGen UID:
321947
Concept ID:
C1832399
Disease or Syndrome
Charcot-Marie-Tooth disease, type 4B1 (CMT4B1) is a severe early-onset demyelinating CMT peripheral sensorimotor polyneuropathy. It was initially described in an Italian family and around 10 additional families have been described so far. Onset occurs during early childhood with distal and proximal muscular weakness starting in the lower extremities, sensory loss and cranial nerve involvement. Foot deformities are frequent and diaphragmatic and facial involvement has been reported. CMT4B1 is caused by mutations in the gene encoding myotubularin-related protein 2 (MTMR2; 11q22), involved in polyphosphoinositide signaling. Transmitted in an autosomal recessive manner.
Charcot-Marie-Tooth disease type 2B
MedGen UID:
371512
Concept ID:
C1833219
Disease or Syndrome
A severe form of axonal Charcot-Marie-Tooth disease, a peripheral sensorimotor neuropathy. Onset in the second or third decade has manifestations of ulceration and infection of the feet. Symmetric and distal weakness develops mostly in the legs together with a severe symmetric distal sensory loss. Tendon reflexes are only reduced at ankles and foot deformities including pes cavus or planus and hammer toes, appear in childhood.
Neuropathy, congenital, with arthrogryposis multiplex
MedGen UID:
320286
Concept ID:
C1834206
Disease or Syndrome
Bethlem myopathy
MedGen UID:
331805
Concept ID:
C1834674
Disease or Syndrome
Bethlem myopathy-1 (BTHLM1) is a congenital muscular dystrophy characterized by distal joint laxity and a combination of distal and proximal joint contractures. Weakness usually begins in mid-childhood or adolescence, but progression is slow and ambulation is retained into adulthood (summary by Butterfield et al., 2013). Genetic Heterogeneity of Bethlem Myopathy See Bethlem myopathy-1B (BTHLM1B; 620725), caused by mutation in the COL6A2 gene (120240) on chromosome 21q22; Bethlem myopathy-1C (620726), caused by mutation the COL6A3 gene (120250) on chromosome 2q37; and Bethlem myopathy-2 (BTHLM2; 616471), caused by mutation in the COL12A1 gene (120320) on chromosome 6q13-q14.
Neuronopathy, distal hereditary motor, type 2A
MedGen UID:
322471
Concept ID:
C1834692
Disease or Syndrome
Distal hereditary motor neuropathy, type II is a progressive disorder that affects nerve cells in the spinal cord. It results in muscle weakness and affects movement, primarily in the legs.\n\nSome individuals with distal hereditary motor neuropathy, type II have weakening of the muscles in the hands and forearms. This weakening is less pronounced than in the lower limbs and does not usually result in paralysis.\n\nOnset of distal hereditary motor neuropathy, type II ranges from the teenage years through mid-adulthood. The initial symptoms of the disorder are cramps or weakness in the muscles of the big toe and later, the entire foot. Over a period of approximately 5 to 10 years, affected individuals experience a gradual loss of muscle tissue (atrophy) in the lower legs. They begin to have trouble walking and running, and eventually may have complete paralysis of the lower legs. The thigh muscles may also be affected, although generally this occurs later and is less severe.
Neuronopathy, distal hereditary motor, type 7A
MedGen UID:
322474
Concept ID:
C1834703
Disease or Syndrome
Autosomal dominant distal hereditary motor neuronopathy-7 (HMND7) is a neurologic disorder characterized by onset in the second decade of progressive distal muscle wasting and weakness affecting the upper and lower limbs and resulting in walking difficulties and hand grip. There is significant muscle atrophy of the hands and lower limbs. The disorder is associated with vocal cord paresis due to involvement of the tenth cranial nerve (summary by Barwick et al., 2012). For a general phenotypic description and a discussion of genetic heterogeneity of autosomal dominant distal HMN, see HMND1 (182960).
Alpha-N-acetylgalactosaminidase deficiency type 2
MedGen UID:
324539
Concept ID:
C1836522
Disease or Syndrome
Alpha-N-acetylgalactosaminidase (NAGA) deficiency is a very rare lysosomal storage disorder with atypical features. It is clinically heterogeneous with 3 main phenotypes: type I is an infantile-onset neuroaxonal dystrophy (609241); type II, also known as Kanzaki disease, is an adult-onset disorder characterized by angiokeratoma corporis diffusum and mild intellectual impairment; and type III is an intermediate disorder (see 609241) with mild to moderate neurologic manifestations (Desnick and Schindler, 2001).
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.
Posterior column ataxia-retinitis pigmentosa syndrome
MedGen UID:
324636
Concept ID:
C1836916
Disease or Syndrome
Posterior column ataxia with retinitis pigmentosa 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).
Macular degeneration, age-related, 3
MedGen UID:
373276
Concept ID:
C1837187
Disease or Syndrome
Age-related macular degeneration-3 (ARMD3) is characterized by numerous small round yellow lesions visible at the temporal edge of the macula. Larger, less distinct yellow areas near the center of the macula are also observed, which represent areas of pigment epithelial detachment (Stone et al., 2004). For a phenotypic description and a discussion of genetic heterogeneity of age-related macular degeneration, see 603075.
Myofibrillar myopathy 2
MedGen UID:
324735
Concept ID:
C1837317
Disease or Syndrome
Alpha-B crystallin-related myofibrillar myopathy is an autosomal dominant muscular disorder characterized by adult onset of progressive muscle weakness affecting both the proximal and distal muscles and associated with respiratory insufficiency, cardiomyopathy, and cataracts. There is phenotypic variability both within and between families (Fardeau et al., 1978; Selcen and Engel, 2003). A homozygous founder mutation in the CRYAB gene has been identified in Canadian aboriginal infants of Cree origin who have a severe fatal infantile hypertonic form of myofibrillar myopathy; see 613869. For a phenotypic description and a discussion of genetic heterogeneity of myofibrillar myopathy, see MFM1 (601419).
Autosomal recessive limb-girdle muscular dystrophy type 2J
MedGen UID:
324741
Concept ID:
C1837342
Disease or Syndrome
A form of limb-girdle muscular dystrophy that usually has a childhood onset (but can range from the first to third decade of life) of severe progressive proximal weakness, eventually involving the distal muscles. Some patients may remain ambulatory but most are wheelchair dependant 20 years after onset. Caused by homozygous mutation in the titin gene (TTN).
Charcot-Marie-Tooth disease axonal type 2L
MedGen UID:
324826
Concept ID:
C1837552
Disease or Syndrome
A form of axonal Charcot-Marie-Tooth disease, a peripheral sensorimotor neuropathy. In the single family reported to date, CMT2L onset is between 15 and 33 years. Patients present with a symmetric distal weakness of legs and occasionally of the hands, absent or reduced tendon reflexes, distal legs sensory loss and frequently a pes cavus. Progression is slow.
Amyotrophic lateral sclerosis type 8
MedGen UID:
325237
Concept ID:
C1837728
Disease or Syndrome
A neurodegenerative disease with characteristics of progressive muscular paralysis reflecting degeneration of motor neurons in the primary motor cortex, corticospinal tracts, brainstem and spinal cord. Caused by heterozygous mutation in the VAPB gene on chromosome 20q13.
Neuronopathy, distal hereditary motor, autosomal dominant 8
MedGen UID:
373984
Concept ID:
C1838492
Disease or Syndrome
The autosomal dominant TRPV4 disorders (previously considered to be clinically distinct phenotypes before their molecular basis was discovered) are now grouped into neuromuscular disorders and skeletal dysplasias; however, the overlap within each group is considerable. Affected individuals typically have either neuromuscular or skeletal manifestations alone, and in only rare instances an overlap syndrome has been reported. The three autosomal dominant neuromuscular disorders (mildest to most severe) are: Charcot-Marie-Tooth disease type 2C. Scapuloperoneal spinal muscular atrophy. Congenital distal spinal muscular atrophy. The autosomal dominant neuromuscular disorders are characterized by a congenital-onset, static, or later-onset progressive peripheral neuropathy with variable combinations of laryngeal dysfunction (i.e., vocal fold paresis), respiratory dysfunction, and joint contractures. The six autosomal dominant skeletal dysplasias (mildest to most severe) are: Familial digital arthropathy-brachydactyly. Autosomal dominant brachyolmia. Spondylometaphyseal dysplasia, Kozlowski type. Spondyloepiphyseal dysplasia, Maroteaux type. Parastremmatic dysplasia. Metatropic dysplasia. The skeletal dysplasia is characterized by brachydactyly (in all 6); the five that are more severe have short stature that varies from mild to severe with progressive spinal deformity and involvement of the long bones and pelvis. In the mildest of the autosomal dominant TRPV4 disorders life span is normal; in the most severe it is shortened. Bilateral progressive sensorineural hearing loss (SNHL) can occur with both autosomal dominant neuromuscular disorders and skeletal dysplasias.
Charcot-Marie-Tooth disease X-linked recessive 5
MedGen UID:
374254
Concept ID:
C1839566
Disease or Syndrome
X-linked Charcot-Marie-Tooth neuropathy type 5 (CMTX5), part of the spectrum of PRPS1-related disorders, is characterized by peripheral neuropathy, early-onset (prelingual) bilateral profound sensorineural hearing loss, and optic neuropathy. The onset of peripheral neuropathy is between ages five and 12 years. The lower extremities are affected earlier and more severely than upper extremities. Initial manifestations often include foot drop or gait disturbance. Onset of visual impairment is between ages seven and 20 years. Intellect and life span are normal. Carrier females do not have findings of CMTX5.
Autosomal dominant limb-girdle muscular dystrophy type 1F
MedGen UID:
333983
Concept ID:
C1842062
Disease or Syndrome
Autosomal dominant limb-girdle muscular dystrophy-2 (LGMDD2) is a myopathy characterized by proximal muscle weakness primarily affecting the lower limbs, but also affecting the upper limbs in most patients. Affected individuals also have distal muscle weakness of the hands and lower leg muscles. There is variability in presentation and progression. Some patients present in early childhood with mildly delayed walking and difficulty running and jumping, whereas others present as adults with mainly pelvic-girdle weakness. Patients with early onset tend to have a more severe disorder, and may develop contractures, loss of independent ambulation, and respiratory insufficiency. Muscle biopsy shows dystrophic changes with abnormal nuclei, rimmed vacuoles, and filamentous inclusions (summary by Melia et al., 2013). For a phenotypic description and a discussion of genetic heterogeneity of autosomal dominant limb-girdle muscular dystrophy, see LGMDD1 (603511).
Charcot-Marie-Tooth disease dominant intermediate C
MedGen UID:
334023
Concept ID:
C1842237
Disease or Syndrome
A rare hereditary motor and sensory neuropathy characterized by intermediate motor median nerve conduction velocities (usually between 25 and 60 m/s). It presents with moderately severe, slowly progressive usual clinical features of Charcot-Marie-Tooth disease (muscle weakness and atrophy of the distal extremities, distal sensory loss, reduced or absent deep tendon reflexes, feet deformities, extensor digitorum brevis atrophy). Findings in nerve biopsies include age-dependent axonal degeneration, reduced number of large myelinated fibers, segmental remyelination, and no onion bulbs.
Charcot-Marie-Tooth disease axonal type 2K
MedGen UID:
375064
Concept ID:
C1842983
Disease or Syndrome
A severe early-onset form of axonal Charcot-Marie-Tooth peripheral sensorimotor polyneuropathy. Onset occurs in the neonatal period or early infancy with a clinical picture including hypotonia, scoliosis, a hoarse voice, vocal cord paralysis and respiratory insufficiency. However, nerve conduction velocities and pathological findings from sural nerve biopsies are indicative of a predominantly axonal neuropathy with some demyelinating features. Caused by mutations in the GDAP1 gene (8q13.3), encoding a protein required for mitochondrial fission.
Charcot-Marie-Tooth disease dominant intermediate D
MedGen UID:
334318
Concept ID:
C1843075
Disease or Syndrome
A rare hereditary motor and sensory neuropathy with characteristics of intermediate motor median nerve conduction velocities (usually between 25 and 45 m/s) and signs of both axonal degeneration and demyelination without onion bulbs in nerve biopsies. It presents with usual Charcot-Marie-Tooth disease clinical features of variable severity (progressive muscle weakness and atrophy of the distal extremities, distal sensory loss, reduced or absent deep tendon reflexes, and feet deformities). Other findings in some of the families include debilitating neuropathic pain and mild postural/kinetic upper limb tremor.
Charcot-Marie-Tooth disease type 2J
MedGen UID:
375107
Concept ID:
C1843153
Disease or Syndrome
For a phenotypic description and a discussion of genetic heterogeneity of axonal CMT, see CMT2A1 (118210).
Charcot-Marie-Tooth disease type 1F
MedGen UID:
334337
Concept ID:
C1843164
Disease or Syndrome
A form of Charcot-Marie-Tooth disease type 1, with a variable clinical presentation that can range from severe impairment with onset in childhood to mild impairment appearing during adulthood. The disease has characteristics of progressive peripheral motor and sensory neuropathy with distal paresis in the lower limbs that varies from mild weakness to complete paralysis of the distal muscle groups, absent tendon reflexes and reduced nerve conduction. Caused by mutations in the NEFL gene (8p21.2).
Charcot-Marie-Tooth disease axonal type 2H
MedGen UID:
334344
Concept ID:
C1843173
Disease or Syndrome
An axonal peripheral sensorimotor polyneuropathy associated with pyramidal involvement. So far, it has been described in 13 members of a large Tunisian family. Onset occurred during the first decade of life with progressive distal atrophy involving both the upper and lower limbs, associated with a mild pyramidal syndrome (brisk patellar and upper limb reflexes, absent ankle reflexes and unattainable plantar reflexes). Transmitted in an autosomal recessive manner and the disease-causing locus has been mapped to 8q13-21.1.
Charcot-Marie-Tooth disease, axonal, with vocal cord paresis, autosomal recessive
MedGen UID:
375113
Concept ID:
C1843183
Disease or Syndrome
Charcot-Marie-Tooth disease type 2E
MedGen UID:
375127
Concept ID:
C1843225
Disease or Syndrome
A form of axonal Charcot-Marie-Tooth disease a peripheral sensorimotor neuropathy. Onset is in the first to sixth decade with a gait anomaly and a leg weakness that reaches the arms secondarily. Tendon reflexes are reduced or absent and after years all patients have a pes cavus. Other signs may be present including hearing loss and postural tremor.
Charcot-Marie-Tooth disease type 1D
MedGen UID:
334709
Concept ID:
C1843247
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).
Neuronopathy, distal hereditary motor, type 7B
MedGen UID:
375157
Concept ID:
C1843315
Disease or Syndrome
The spectrum of DCTN1-related neurodegeneration includes Perry syndrome, distal hereditary motor neuronopathy type 7B (dHMN7B), frontotemporal dementia (FTD), motor neuron disease / amyotrophic lateral sclerosis (ALS), and progressive supranuclear palsy. Some individuals present with overlapping phenotypes (e.g., FTD-ALS, Perry syndrome-dHMN7B). Perry syndrome (the most common of the phenotypes associated with DCTN1) is characterized by parkinsonism, neuropsychiatric symptoms, hypoventilation, and weight loss. The mean age of onset in those with Perry syndrome is 49 years (range: 35-70 years), and the mean disease duration is five years (range: 2-14 years). In most affected persons, the reported cause/circumstance of death relates to sudden death/hypoventilation or suicide.
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+").
Charcot-Marie-Tooth disease X-linked recessive 3
MedGen UID:
375530
Concept ID:
C1844865
Disease or Syndrome
A rare genetic peripheral sensorimotor neuropathy with an X-linked recessive inheritance pattern and the childhood to adolescent-onset of progressive, distal muscle weakness and atrophy (beginning in the lower extremities and then affecting the upper extremities), as well as distal, pan sensory loss in the upper and lower extremities, pes cavus, and absent or reduced distal tendon reflexes. Pain and paraesthesia are frequently the initial sensory symptoms. Spastic paraparesis (manifested by clasp-knife sign, hyperactive deep-tendon reflexes, and Babinski sign) has also been reported.
Charcot-Marie-Tooth disease X-linked recessive 2
MedGen UID:
336803
Concept ID:
C1844873
Disease or Syndrome
A rare genetic peripheral sensorimotor neuropathy with an X-linked recessive inheritance pattern and the infantile to childhood-onset of progressive, distal muscle weakness and atrophy (more prominent in the lower extremities than in the upper extremities), pes cavus, and absent tendon reflexes. Sensory impairment and intellectual disability has been reported in some individuals.
Glycogen storage disease IXd
MedGen UID:
335112
Concept ID:
C1845151
Disease or Syndrome
Phosphorylase kinase (PhK) deficiency causing glycogen storage disease type IX (GSD IX) results from deficiency of the enzyme phosphorylase b kinase, which has a major regulatory role in the breakdown of glycogen. The two types of PhK deficiency are liver PhK deficiency (characterized by early childhood onset of hepatomegaly and growth restriction, and often, but not always, fasting ketosis and hypoglycemia) and muscle PhK deficiency, which is considerably rarer (characterized by any of the following: exercise intolerance, myalgia, muscle cramps, myoglobinuria, and progressive muscle weakness). While symptoms and biochemical abnormalities of liver PhK deficiency were thought to improve with age, it is becoming evident that affected individuals need to be monitored for long-term complications such as liver fibrosis and cirrhosis.
X-linked distal spinal muscular atrophy type 3
MedGen UID:
335168
Concept ID:
C1845359
Disease or Syndrome
A rare distal hereditary motor neuropathy with characteristics of slowly progressive atrophy and weakness of distal muscles of hands and feet with normal deep tendon reflexes or absent ankle reflexes and minimal or no sensory loss, sometimes mild proximal weakness in the legs and feet and hand deformities in males.
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.
Charcot-Marie-Tooth disease axonal type 2F
MedGen UID:
335784
Concept ID:
C1847823
Disease or Syndrome
A form of axonal Charcot-Marie-Tooth disease, a peripheral sensorimotor neuropathy with symmetric weakness primarily occurring in the lower limbs and reaching the arms only after 5 to 10 years, occasional and predominantly distal sensory loss and reduced tendon reflexes. Presents with gait anomaly between the first and sixth decade and early onset is generally associated to a more severe phenotype that may include foot drop.
Charcot-Marie-Tooth disease dominant intermediate B
MedGen UID:
338346
Concept ID:
C1847902
Disease or Syndrome
Charcot-Marie-Tooth disease is a clinically and genetically heterogeneous disorder of the peripheral nervous system, characterized by progressive weakness and atrophy, initially of the peroneal muscles and later of the distal muscles of the arms. Classification CMT neuropathy is subdivided into CMT1 (see 118200) and CMT2 (see 118210) types on the basis of electrophysiologic and neuropathologic criteria. CMT1, or hereditary motor and sensory neuropathy type I (HMSN I), is a demyelinating neuropathy, whereas CMT2, or HMSN II, is an axonal neuropathy. Most patients with CMT are classified as having CMT1 or CMT2 by use of a cut-off value of 38 m/s for the motor median nerve conduction velocity (NCV). However, in some families with CMT, patients have motor median NCVs ranging from 25 to 45 m/s. Families of this type were reported by Salisachs (1974) and Davis et al. (1978). Davis et al. (1978) proposed that this form be designated 'intermediate' CMT. Claeys et al. (2009) stated that some CMT families may have an even broader range of NCV than 25 to 45 m/s, with the lowest levels around 25 and the highest levels within the normal range (50+ m/s). They also suggested that the term 'intermediate' should not be used to describe a single NCV value, but rather the CMT subtype at the level of the family (e.g., in families with a range or combinations of NCV values). Berciano et al. (2017) provided a detailed review of the different forms of intermediate CMT, noting that diagnoses may be controversial because of variable classification issues. The authors presented an algorithm for the interpretation of electrophysiologic studies in CMT, and suggested that nerve conduction studies should be conducted on the upper arm (axilla to elbow). They noted that distal axonal degeneration can result in secondary myelination defects, which may cause significantly decreased motor NCV and CMAP values that may be misinterpreted. Genetic Heterogeneity of Autosomal Dominant Intermediate CMT In addition to CMTDIB, which is caused by mutation in the DNM2 gene, other forms of dominant intermediate CMT include CMTDIA (620378), mapped to chromosome 10q24-q25; CMTDIC (608323), caused by mutation in the YARS gene (603623) on chromosome 1p35; CMTDID (607791), caused by mutation in the MPZ gene (159440) on chromosome 1q22; CMTDIE with focal segmental glomerulosclerosis (CMTDIE; 614455), caused by mutation in the INF2 gene (610982) on chromosome 14q32; CMTDIF (615185), caused by mutation in the GNB4 gene (610863) on chromosome 3q26; and CMTDIG (617882), caused by mutation in the NEFL gene (162280) on chromosome 8p21.
Trichomegaly-retina pigmentary degeneration-dwarfism syndrome
MedGen UID:
338532
Concept ID:
C1848745
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).
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.
Radiculoneuropathy, fatal neonatal
MedGen UID:
376592
Concept ID:
C1849471
Disease or Syndrome
Giant axonal neuropathy 1
MedGen UID:
376775
Concept ID:
C1850386
Disease or Syndrome
GAN-related neurodegeneration comprises a phenotypic continuum ranging from severe (sometimes called classic giant axonal neuropathy) to milder pure early-onset peripheral motor and sensory neuropathies. The classic giant axonal neuropathy phenotype typically manifests as an infantile-onset neurodegenerative disorder, starting as a severe peripheral motor and sensory neuropathy and evolving into central nervous system impairment (intellectual disability, seizures, cerebellar signs, and pyramidal tract signs). Most affected individuals become wheelchair dependent in the second decade of life and eventually bedridden with severe polyneuropathy, ataxia, and dementia. Death usually occurs in the third decade. At the milder end of the spectrum are predominantly motor and sensory neuropathies (with little to no CNS involvement) that overlap with the axonal form of Charcot-Marie-Tooth neuropathies.
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.
Myosclerosis
MedGen UID:
338098
Concept ID:
C1850671
Disease or Syndrome
Collagen VI-related dystrophies (COL6-RDs) represent a continuum of overlapping clinical phenotypes with Bethlem muscular dystrophy at the milder end, Ullrich congenital muscular dystrophy (UCMD) at the more severe end, and a phenotype in between UCMD and Bethlem muscular dystrophy, referred to as intermediate COL6-RD. Bethlem muscular dystrophy is characterized by a combination of proximal muscle weakness and joint contractures. Hypotonia and delayed motor milestones occur in early childhood; mild hypotonia and weakness may be present congenitally. By adulthood, there is evidence of proximal weakness and contractures of the elbows, Achilles tendons, and long finger flexors. The progression of weakness is slow, and more than two thirds of affected individuals older than age 50 years remain independently ambulatory indoors, while relying on supportive means for mobility outdoors. Respiratory involvement is not a consistent feature. UCMD is characterized by congenital weakness, hypotonia, proximal joint contractures, and striking hyperlaxity of distal joints. Decreased fetal movements are frequently reported. Some affected children acquire the ability to walk independently; however, progression of the disease results in a loss of ambulation by age ten to eleven years. Early and severe respiratory insufficiency occurs in all individuals, resulting in the need for nocturnal noninvasive ventilation (NIV) in the form of bilevel positive airway pressure (BiPAP) by age 11 years. Intermediate COL6-RD is characterized by independent ambulation past age 11 years and respiratory insufficiency that is later in onset than in UCMD and results in the need for NIV in the form of BiPAP by the late teens to early 20s. In contrast to individuals with Bethlem muscular dystrophy, those with intermediate COL6-RD typically do not achieve the ability to run, jump, or climb stairs without use of a railing.
Hereditary myopathy with lactic acidosis due to ISCU deficiency
MedGen UID:
342573
Concept ID:
C1850718
Disease or Syndrome
Hereditary myopathy with lactic acidosis (HML) is an autosomal recessive muscular disorder characterized by childhood onset of exercise intolerance with muscle tenderness, cramping, dyspnea, and palpitations. Biochemical features include lactic acidosis and, rarely, rhabdomyolysis. It is a chronic disorder with remission and exacerbation of the muscle phenotype (summary by Sanaker et al., 2010).
Spinocerebellar ataxia, autosomal recessive, with axonal neuropathy 2
MedGen UID:
340052
Concept ID:
C1853761
Disease or Syndrome
Ataxia with oculomotor apraxia type 2 (AOA2) is characterized by onset of ataxia between age three and 30 years after initial normal development, axonal sensorimotor neuropathy, oculomotor apraxia, cerebellar atrophy, and elevated serum concentration of alpha-fetoprotein (AFP).
GNE myopathy
MedGen UID:
381298
Concept ID:
C1853926
Disease or Syndrome
GNE myopathy is a slowly progressive muscle disease that typically presents between age 20 and 40 years with bilateral foot drop caused by anterior tibialis weakness. Lower-extremity muscle involvement progresses from the anterior to the posterior compartment of the lower leg, followed by hamstrings, then hip girdle muscles, with relative sparing of the quadriceps. A wheelchair may be needed about ten to 20 years after the onset of manifestations. The upper extremities, which may be affected within five to ten years of disease onset, do not necessarily follow a distal-to-proximal progression. In advanced stages, neck and core muscles can become affected.
Autosomal recessive distal spinal muscular atrophy 2
MedGen UID:
344189
Concept ID:
C1854023
Disease or Syndrome
Autosomal recessive distal hereditary motor neuronopathy-2 (HMNR2) is a neuromuscular disorder characterized by onset of distal muscle weakness and wasting affecting the lower and upper limbs in the first decade; there is no sensory involvement (summary by Li et al., 2015). For a general phenotypic description and a discussion of genetic heterogeneity of autosomal recessive HMN, see HMNR1 (604320).
Adult-onset proximal spinal muscular atrophy, autosomal dominant
MedGen UID:
340120
Concept ID:
C1854058
Disease or Syndrome
Spinal muscular atrophy is characterized by degeneration of the anterior horn cells in the spinal cord, leading to symmetric muscle weakness and wasting. See also autosomal recessive adult-onset proximal spinal muscular atrophy (SMA4; 271150), caused by defect in the SMN1 gene (600354), and autosomal dominant childhood-onset proximal SMA (158600).
Myopathy, proximal, and ophthalmoplegia
MedGen UID:
381340
Concept ID:
C1854106
Disease or Syndrome
Congenital myopathy-6 with ophthalmoplegia (CMYP6) is a relatively mild muscle disorder characterized by childhood onset of symptoms. The disorder is either slowly progressive or nonprogressive, and affected individuals retain ambulation, although there is variable severity. CMYP6 can show both autosomal dominant and autosomal recessive inheritance; the phenotype is similar in both forms (summary by Lossos et al., 2005 and Tajsharghi et al., 2014). For a discussion of genetic heterogeneity of congenital myopathy, see CMYP1A (117000).
Charcot-Marie-Tooth disease type 2B2
MedGen UID:
381352
Concept ID:
C1854150
Disease or Syndrome
Charcot-Marie-Tooth disease type 2B2 (CMT2B2) is an autosomal recessive sensorineural axonal peripheral neuropathy manifest as distal muscle weakness and atrophy and distal sensory impairment. The disorder predominantly affects the lower limbs, resulting in gait impairment, although upper limb and hand involvement also occurs. The age at onset and severity is variable: most have onset in the third decade, although earlier onset has been reported. The disorder is slowly progressive, and some patients may lose independent ambulation later in life. More variable features may include ataxia, dysarthria, cerebellar atrophy, and eye movement abnormalities (summary by Leal et al., 2018). For a phenotypic description and a discussion of genetic heterogeneity of axonal CMT type 2, see CMT2A1 (118210).
Charcot-Marie-Tooth disease type 2B1
MedGen UID:
343064
Concept ID:
C1854154
Disease or Syndrome
Charcot-Marie-Tooth disease constitutes a clinically and genetically heterogeneous group of hereditary motor and sensory neuropathies. On the basis of electrophysiologic criteria, CMT is divided into 2 major types: type 1, the demyelinating form, characterized by a motor median nerve conduction velocity less than 38 m/s (see CMT1B; 118200); and type 2, the axonal form, with a normal or slightly reduced nerve conduction velocity. For a phenotypic description and a discussion of genetic heterogeneity of axonal CMT type 2, see CMT2A1 (118210).
Charcot-Marie-Tooth disease type 4G
MedGen UID:
343122
Concept ID:
C1854449
Disease or Syndrome
HMSNR is an autosomal recessive progressive complex peripheral neuropathy characterized by onset in the first decade of distal lower limb weakness and muscle atrophy resulting in walking difficulties. Distal impairment of the upper limbs usually occurs later, as does proximal lower limb weakness. There is distal sensory impairment, with pes cavus and areflexia. Laboratory studies suggest that it is a myelinopathy resulting in reduced nerve conduction velocities in the demyelinating range as well as a length-dependent axonopathy (summary by Sevilla et al., 2013). For a discussion of genetic heterogeneity of autosomal recessive hereditary motor and sensory neuropathy, also known as Charcot-Marie-Tooth disease, see CMT4A (214400).
Charcot-Marie-Tooth disease type 4B2
MedGen UID:
346869
Concept ID:
C1858278
Disease or Syndrome
Autosomal recessive Charcot-Marie-Tooth disease type 4B is a demyelinating hereditary motor and sensory neuropathy characterized by abnormal folding of myelin sheaths. CMT4B1 (601382) is a clinically similar disorder caused by mutation in the MTMR2 gene (603557) on 11q22. For a phenotypic description and a discussion of genetic heterogeneity of autosomal recessive demyelinating CMT, see CMT4A (214400).
Autosomal recessive distal spinal muscular atrophy 1
MedGen UID:
388083
Concept ID:
C1858517
Disease or Syndrome
Autosomal recessive distal hereditary motor neuronopathy-1 (HMNR1) is characterized by distal and proximal muscle weakness and diaphragmatic palsy that leads to respiratory distress. Without intervention, most infants with the severe form of the disease die before 2 years of age. Affected individuals present in infancy with inspiratory stridor, weak cry, recurrent bronchopneumonia, and swallowing difficulties. The disorder is caused by distal and progressive motor neuronopathy resulting in muscle weakness (summary by Perego et al., 2020). Genetic Heterogeneity of Autosomal Recessive Distal Hereditary Motor Neuronopathy See also HMNR2 (605726), caused by mutation in the SIGMAR1 gene (601978); HMNR3 (607088) (encompassing Harding HMN types III and IV), which maps to chromosome 11q13; HMNR4 (611067), caused by mutation in the PLEKHG5 gene (611101); HMNR5 (614881), caused by mutation in the DNAJB2 gene (604139); HMNR6 (620011), caused by mutation in the REEP1 gene (609139); HMNR7 (619216), caused by mutation in the VWA1 gene (611901); HMNR8 (618912), caused by mutation in the SORD gene (182500); HMNR9 (620402), caused by mutation in the COQ7 gene (601683); and HMRN10 (620542), caused by mutation in the VRK1 gene (602168).
Charcot-Marie-Tooth disease type 4A
MedGen UID:
347821
Concept ID:
C1859198
Disease or Syndrome
GDAP1-related hereditary motor and sensory neuropathy (GDAP1-HMSN) is a peripheral neuropathy (also known as a subtype of Charcot-Marie-Tooth disease) that typically affects the lower extremities earlier and more severely than the upper extremities. As the neuropathy progresses, the distal upper extremities also become severely affected. Proximal muscles can also become weak. Age at onset ranges from infancy to early childhood. In most cases, disease progression causes disabilities within the first or second decade of life. At the end of the second decade, most individuals are wheelchair bound. Disease progression varies considerably even within the same family. The neuropathy can be either of the demyelinating type with reduced nerve conduction velocities or the axonal type with normal nerve conduction velocities. Vocal cord paresis is common. Intelligence is normal. Life expectancy is usually normal, but on occasion may be reduced because of secondary complications.
Amyotrophic lateral sclerosis with polyglucosan bodies
MedGen UID:
347953
Concept ID:
C1859805
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.
Charcot-Marie-Tooth disease type 2A1
MedGen UID:
350076
Concept ID:
C1861678
Disease or Syndrome
MFN2 hereditary motor and sensory neuropathy (MFN2-HMSN) is a classic axonal peripheral sensorimotor neuropathy, inherited in either an autosomal dominant (AD) manner (~90%) or an autosomal recessive (AR) manner (~10%). MFN2-HMSN is characterized by more severe involvement of the lower extremities than the upper extremities, distal upper-extremity involvement as the neuropathy progresses, more prominent motor deficits than sensory deficits, and normal (>42 m/s) or only slightly decreased nerve conduction velocities (NCVs). Postural tremor is common. Median onset is age 12 years in the AD form and age eight years in the AR form. The prevalence of optic atrophy is approximately 7% in the AD form and approximately 20% in the AR form.
Giant axonal neuropathy 2
MedGen UID:
400593
Concept ID:
C1864695
Disease or Syndrome
Giant axonal neuropathy-2 is an autosomal dominant peripheral axonal neuropathy characterized by onset of distal sensory impairment and lower extremity muscle weakness and atrophy after the second decade. Foot deformities may be present in childhood. More severely affected individuals may develop cardiomyopathy. Sural nerve biopsy shows giant axonal swelling with neurofilament accumulation (summary by Klein et al., 2014).
Finnish upper limb-onset distal myopathy
MedGen UID:
400595
Concept ID:
C1864706
Disease or Syndrome
Distal myopathy-3 (MPD3) is an autosomal dominant skeletal muscle disorder characterized by adult onset of slowly progressive distal muscular weakness and atrophy affecting the upper and lower limbs, leading to difficulties using the hands and walking difficulties. Proximal muscle involvement may occur later in the disease, but patients typically remain ambulatory. Muscle biopsy shows myopathic changes with rimmed vacuoles (Hackman et al., 2021).
Amyotrophic lateral sclerosis type 4
MedGen UID:
355983
Concept ID:
C1865409
Disease or Syndrome
Juvenile amyotrophic lateral sclerosis-4 (ALS4) is an autosomal dominant disorder characterized by distal muscle weakness and atrophy, normal sensation, and pyramidal signs, with onset of symptoms before the age of 25 years, a slow rate of progression, and a normal life span (summary by Chen et al., 2004). For a phenotypic description and a discussion of genetic heterogeneity of amyotrophic lateral sclerosis, see ALS1 (105400).
Amyotrophic lateral sclerosis type 5
MedGen UID:
356388
Concept ID:
C1865864
Disease or Syndrome
Autosomal recessive juvenile amyotrophic lateral sclerosis-5 (ALS5) is a neurodegenerative disorder characterized by onset of upper and lower motor neuron signs before age 25. Affected individuals have progressive spasticity of limb and facial muscles associated with distal amyotrophy. The disorder is slowly progressive, with cases of prolonged survival of more than 3 decades (summary by Orlacchio et al., 2010). For a phenotypic description and a discussion of genetic heterogeneity of amyotrophic lateral sclerosis (ALS), see ALS1 (105400).
Vacuolar Neuromyopathy
MedGen UID:
355637
Concept ID:
C1866139
Disease or Syndrome
Autosomal dominant myopathy with rimmed ubiquitin-positive autophagic vacuolation (MRUPAV) is characterized by adult onset of slowly progressive skeletal muscle weakness variably affecting the distal or proximal lower limbs. Some patients may also have upper limb involvement or neck muscle weakness, but respiratory and bulbar involvement only rarely occurs. EMG studies show a myopathic process, and myotonia may also be observed. Skeletal muscle biopsy shows myopathic features, rimmed vacuoles, and abnormal subsarcolemmal protein aggregation with activation of the autophagy pathway (Ruggieri et al., 2020).
Charcot-Marie-Tooth disease type 4C
MedGen UID:
356581
Concept ID:
C1866636
Disease or Syndrome
SH3TC2-related hereditary motor and sensory neuropathy (SH3TC2-HMSN) is a demyelinating neuropathy characterized by severe spine deformities (scoliosis or kyphoscoliosis) and foot deformities (pes cavus, pes planus, or pes valgus) that typically present in the first decade of life or early adolescence. Other findings can include cranial nerve involvement (most commonly tongue involvement, facial weakness/paralysis, hearing impairment, dysarthria) and respiratory problems.
Neuronopathy, distal hereditary motor, autosomal dominant 1
MedGen UID:
356618
Concept ID:
C1866784
Disease or Syndrome
Distal hereditary motor neuronopathy (dHMN or HMN) is a heterogeneous group of neuromuscular disorders caused by anterior horn cell degeneration and characterized by progressive distal motor weakness and muscular atrophy of the peripheral nervous system without sensory impairment. Distal HMN is also referred to as spinal Charcot-Marie-Tooth disease (spinal CMT). Distal HMN is often referred to as a 'neuronopathy' instead of a 'neuropathy' based on the hypothesis that the primary pathologic process resides in the neuron cell body and not in the axons (Irobi et al., 2006). Historically, Harding (1993) proposed a clinical classification of distal HMN into 7 phenotypic subtypes according to age at onset, mode of inheritance, and presence of additional features; see NOMENCLATURE. Genetic Heterogeneity of Autosomal Dominant Distal Hereditary Motor Neuronopathy Genetically distinct forms of autosomal dominant distal hereditary motor neuropathy include HMND1; HMND2 (158590), caused by mutation in the HSPB8 gene (608014); HMND3 (608634), caused by mutation in the HSPB1 gene (602195); HMND4 (613376), caused by mutation in the HSPB3 gene (604624); HMND5 (600794), caused by mutation in the GARS gene (600287); HMND6 (615575), caused by mutation in the FBXO38 gene (608533); HMND7 (158580), caused by mutation in the SLC5A7 gene (608761); HMND8 (600175), caused by mutation in the TRPV4 gene (605427); HMND9 (617721), caused by mutation in the WARS gene (191050); HMND10 (620080), caused by mutation in the EMILIN1 gene (130660); HMND11 (620528), caused by mutation in the SPTAN1 gene (182810); HMND12 (614751), caused by mutation in the REEP1 gene (609139); HMND13 (619112), caused by mutation in the BSCL2 gene (606158); and HMND14 (607641), caused by mutation in the DCTN1 gene (601143). See also X-linked HMN (HMNX; 300489), caused by mutation in the ATP7A gene (300011) on chromosome Xq21. Additional disorders with overlapping features include autosomal dominant ALS4 (602433), caused by mutation in the SETX gene (608465); and CMS7A (616040), caused by mutation in the SYT2 gene (600104).
Charcot-Marie-Tooth disease type 4J
MedGen UID:
370808
Concept ID:
C1970011
Disease or Syndrome
Charcot-Marie-Tooth disease type 4J is an autosomal recessive progressive neurologic disorder with a highly variable phenotype and onset ranging from early childhood to adulthood. Most patients have both proximal and distal asymmetric muscle weakness of the upper and lower limbs. There is significant motor dysfunction, followed by variably progressive sensory loss, which may be mild. Nerve conduction studies and nerve biopsies indicate demyelination as well as axonal loss (summary by Nicholson et al., 2011). For a phenotypic description and a discussion of genetic heterogeneity of autosomal recessive demyelinating Charcot-Marie-Tooth disease, see CMT4A (214400).
Neuronopathy, distal hereditary motor, autosomal recessive 4
MedGen UID:
369682
Concept ID:
C1970211
Disease or Syndrome
A rare genetic neuromuscular disease characterized by proximal muscle weakness with an early involvement of foot and hand muscles following normal motor development in early childhood, a rapidly progressive disease course leading to generalized areflexic tetraplegia with contractures, severe scoliosis, hyperlordosis, and progressive respiratory insufficiency leading to assisted ventilation. Cranial nerve functions are normal and tongue wasting and fasciculations are absent. Milder phenotype with a moderate generalized weakness and slower disease progress was reported. There is evidence the disease is caused by homozygous mutation in the gene encoding pleckstrin homology domain-containing protein, family G member 5 (PLEKHG5) on chromosome 1p36.
Hereditary spastic paraplegia 38
MedGen UID:
436764
Concept ID:
C2676732
Disease or Syndrome
A complex hereditary spastic paraplegia with characteristics of mild to severe lower limbs spasticity, hyperreflexia, extensor plantar responses, pes cavus and significant wasting and weakness of the small hand muscles. Impaired vibration sensation, temporal lobe epilepsy and cognitive dysfunction were also reported.
Syndromic X-linked intellectual disability 94
MedGen UID:
437111
Concept ID:
C2678051
Disease or Syndrome
A syndromic X-linked intellectual disability characterized by moderate intellectual disability with variable occurrence of asthenic body habitus, dysmorphic features, autistic features, macrocephaly, seizures, myoclonic jerks, and hyporeflexia that has material basis in mutation in the GRIA3 gene on chromosome Xq25.
Amyotrophic lateral sclerosis type 9
MedGen UID:
395629
Concept ID:
C2678468
Disease or Syndrome
A neurodegenerative disease with characteristics of progressive muscular paralysis reflecting degeneration of motor neurons in the primary motor cortex, corticospinal tracts, brainstem and spinal cord. Caused by heterozygous mutation in the angiogenin gene (ANG) on chromosome 14q11.
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.
Charcot-Marie-Tooth disease axonal type 2N
MedGen UID:
413754
Concept ID:
C2750090
Disease or Syndrome
A mild form of axonal Charcot-Marie-Tooth disease, a peripheral sensorimotor neuropathy, with characteristics of distal legs sensory loss and weakness that can be asymmetric. Tendon reflexes are reduced in the knees and absent in ankles. Progression is slow.
Myofibrillar myopathy 6
MedGen UID:
414119
Concept ID:
C2751831
Disease or Syndrome
Myofibrillar myopathy-6 is an autosomal dominant severe neuromuscular disorder characterized by onset in the first decade of rapidly progressive generalized and proximal muscle weakness, respiratory insufficiency, cardiomyopathy, and skeletal deformities related to muscle weakness. Muscle biopsy shows fiber-type grouping, disruption of the Z lines, and filamentous inclusions, and sural nerve biopsy shows a neuropathy, often with giant axonal neurons. Most patients are severely affected by the second decade and need cardiac transplant, ventilation, and/or a wheelchair (summary by Jaffer et al., 2012). For a phenotypic description and a discussion of genetic heterogeneity of myofibrillar myopathy (MFM), see MFM1 (601419).
Hereditary spastic paraplegia 17
MedGen UID:
419034
Concept ID:
C2931276
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.
Neuropathy, hereditary sensory and autonomic, type 1C
MedGen UID:
462246
Concept ID:
C3150896
Disease or Syndrome
Hereditary sensory and autonomic neuropathy type IC (HSAN1C) is an autosomal dominant neurologic disorder characterized by sensory neuropathy with variable autonomic and motor involvement. Most patients have adult onset of slowly progressive distal sensory impairment manifest as numbness, tingling, or pain, as well as distal muscle atrophy. Complications include ulceration and osteomyelitis. Some patients may have a more severe phenotype with onset in childhood. Electrophysiologic studies show a predominantly axonal neuropathy with some demyelinating features. Some patients may have evidence of central nervous system involvement, including macular telangiectasia type 2 and/or pyramidal signs. Affected individuals have increased levels of plasma 1-deoxysphingolipids (1-deoxySLs), which are thought to be neurotoxic. (summary by Rotthier et al., 2010, Gantner et al., 2019, and Triplett et al., 2019). Oral supplementation with serine decreases 1-deoxySL and may offer some clinical benefits (Fridman et al., 2019). For a discussion of genetic heterogeneity of HSAN, see HSAN1A (162400).
Progressive demyelinating neuropathy with bilateral striatal necrosis
MedGen UID:
462323
Concept ID:
C3150973
Disease or Syndrome
Thiamine metabolism dysfunction syndrome-4 is an autosomal recessive metabolic disorder characterized by childhood onset of episodic encephalopathy, often associated with a febrile illness, and causing transient neurologic dysfunction. Most patients recover fully, but some may have mild residual weakness. Affected individuals also develop a slowly progressive axonal polyneuropathy beginning in childhood. Brain imaging during the acute episodes shows lesions consistent with bilateral striatal degeneration or necrosis (summary by Spiegel et al., 2009). For a discussion of genetic heterogeneity of disorders due to thiamine metabolism dysfunction, see THMD1 (249270).
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.
Charcot-Marie-Tooth disease axonal type 2O
MedGen UID:
481850
Concept ID:
C3280220
Disease or Syndrome
A rare genetic subtype of autosomal dominant Charcot-Marie-Tooth disease type 2 with characteristics of early childhood-onset of slowly progressive, predominantly distal, lower limb muscle weakness and atrophy, delayed motor development, variable sensory loss and pes cavus in the presence of normal or near-normal nerve conduction velocities. Additional variable features may include proximal muscle weakness, abnormal gait, arthrogryposis, scoliosis, cognitive impairment, and spasticity. Caused by heterozygous mutation in the DYNC1H1 gene on chromosome 14q32.
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.
Peripheral neuropathy-myopathy-hoarseness-hearing loss syndrome
MedGen UID:
482186
Concept ID:
C3280556
Disease or Syndrome
Peripheral neuropathy-myopathy-hoarseness-hearing loss syndrome is a rare, syndromic genetic deafness characterized by a combination of muscle weakness, chronic neuropathic and myopathic features, hoarseness and sensorineural hearing loss. A wide range of disease onset and severity has been reported even within the same family.
Charcot-Marie-Tooth disease axonal type 2P
MedGen UID:
482427
Concept ID:
C3280797
Disease or Syndrome
A rare genetic axonal hereditary motor and sensory neuropathy disorder with characteristics of adulthood-onset of slowly progressive, occasionally asymmetrical, distal muscle weakness and atrophy (predominantly in the lower limbs), pan-modal sensory loss, muscle cramping in extremities and/or trunk, pes cavus and absent or reduced deep tendon reflexes. Gait anomalies and variable autonomic disturbances, such as erectile dysfunction and urinary urgency, may be associated. The disease can be caused by homozygous or heterozygous mutation in the LRSAM1 gene on chromosome 9q33.
Charcot-Marie-Tooth disease type 1E
MedGen UID:
501212
Concept ID:
C3495591
Disease or Syndrome
A rare subtype of CMT1 characterized by a variable clinical presentation. Onset within the first two years of life with a delay in walking is not uncommon; however, onset may occur later. CMT1E is caused by point mutations in the <i>PMP22</i> (17p12) gene. The disease severity depends on the particular <i>PMP22</i> mutation, with some cases being very mild and even resembling hereditary neuropathy with liability to pressure palsies, while others having an earlier onset with a more severe phenotype (reminiscent of Dejerine-Sottas syndrome) than that seen in CMT1A, caused by gene duplication. These severe cases may also report deafness and much slower motor nerve conduction velocities compared to CMT1A patients.
Charcot-Marie-Tooth disease type 4F
MedGen UID:
761704
Concept ID:
C3540453
Disease or Syndrome
Charcot-Marie-Tooth disease type 4F is an autosomal recessive demyelinating neuropathy characterized by distal sensory impairment and distal muscle weakness and atrophy affecting the lower more than the upper limbs. Nerve conduction velocities are decreased and sural nerve biopsy shows loss of myelinated fibers. The age at onset is variable and can range from childhood to adult years. When the onset is in infancy, the phenotype is characterized as Dejerine-Sottas syndrome (DSS; 145900). For a phenotypic description and a discussion of genetic heterogeneity of autosomal recessive demyelinating Charcot-Marie-Tooth disease, see CMT4A (214400).
Amyotrophic lateral sclerosis type 21
MedGen UID:
813851
Concept ID:
C3807521
Disease or Syndrome
Amyotrophic lateral sclerosis-21 (ALS21) is an autosomal dominant neurodegenerative disorder affecting upper and lower motor neurons, resulting in muscle weakness and respiratory failure. Some patients may develop myopathic features or dementia (summary by Johnson et al., 2014). For a discussion of genetic heterogeneity of amyotrophic lateral sclerosis, see ALS1 (105400).
Charcot-Marie-Tooth disease recessive intermediate C
MedGen UID:
815639
Concept ID:
C3809309
Disease or Syndrome
CMTRIC is an autosomal recessive peripheral neuropathy characterized by distal sensory impairment predominantly affecting the lower limbs and resulting in walking difficulties due to muscle weakness and atrophy. The upper limbs may also be affected. Electrophysiologic studies and sural nerve biopsy show mixed features of demyelinating and axonal neuropathy. The age at onset and the severity of the disease are variable (summary by Azzedine et al., 2013). For a discussion of genetic heterogeneity of autosomal recessive intermediate CMT, see CMTRIA (608340).
Charcot-Marie-Tooth disease type 2I
MedGen UID:
854756
Concept ID:
C3888087
Disease or Syndrome
A form of axonal Charcot-Marie-Tooth disease a peripheral sensorimotor neuropathy. A late onset with severe sensory loss associated with distal weakness mainly of the legs and absent or reduced deep tendon reflexes.
Myopathy, distal, infantile-onset
MedGen UID:
860162
Concept ID:
C4011725
Disease or Syndrome
Congenital myasthenic syndrome 7
MedGen UID:
863475
Concept ID:
C4015038
Disease or Syndrome
Presynaptic congenital myasthenic syndrome-7A with distal motor neuropathy (CMS7A) is an autosomal dominant neuromuscular disorder characterized by onset of foot deformities, delayed motor development, and slowly progressive distal muscle weakness resulting in gait difficulties in early childhood. Other features may include hyporeflexia, muscle atrophy, and upper limb involvement. Electrophysiologic studies show low compound muscle action potentials (CMAPs), consistent with a distal hereditary motor neuropathy (dHMN), as well as a decremental response to repetitive stimulation, indicating presynaptic defects at the neuromuscular junction (NMJ), consistent with myasthenic syndrome (summary by Fionda et al., 2021). The complex phenotype of patients with dominant SYT2 mutations likely results from impairment of 2 fundamental functions of SYT2: (1) disturbance of calcium-dependent synchronous presynaptic neurotransmitter release, resulting in a myasthenic disorder, and (2) disruption of exocytosis and endocytosis, causing a degenerative process affecting peripheral motor nerve terminals and resulting in a motor neuropathy (Maselli et al., 2021). For a discussion of genetic heterogeneity of CMS, see CMS1A (601462). For a discussion of genetic heterogeneity of dHMN, see 182960.
Polyglucosan body myopathy type 2
MedGen UID:
863889
Concept ID:
C4015452
Disease or Syndrome
Polyglucosan body myopathy-2 is an autosomal recessive disorder characterized by proximal muscle weakness of the lower limbs resulting in gait disturbances. Some patients also have involvement of the upper limbs and/or distal muscle weakness. The age at onset is highly variable, and the disorder is slowly progressive. Muscle biopsy shows accumulation of polyglucosan, which contains abnormally long and poorly branched glucosyl chains and is variably resistant to digestion by alpha-amylase (summary by Malfatti et al., 2014). For a discussion of genetic heterogeneity of PGBM, see PGBM1 (615895).
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.
Charcot-Marie-Tooth disease axonal type 2U
MedGen UID:
906504
Concept ID:
C4084821
Disease or Syndrome
Charcot-Marie-Tooth disease type 2U (CMT2U) is an autosomal dominant neurologic disorder characterized by late-adult onset of distal sensory impairment resulting in distal muscle weakness and atrophy affecting the upper and lower limbs. The disorder is slowly progressive (summary by Gonzalez et al., 2013). For a phenotypic description and a discussion of genetic heterogeneity of axonal CMT, see CMT2A1 (118210).
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 1
MedGen UID:
897191
Concept ID:
C4225153
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+").
Congenital myasthenic syndrome 19
MedGen UID:
897962
Concept ID:
C4225235
Disease or Syndrome
Congenital myasthenic syndrome-19 (CMS19) is an autosomal recessive disorder resulting from a defect in the neuromuscular junction, causing generalized muscle weakness, exercise intolerance, and respiratory insufficiency. Patients present with hypotonia, feeding difficulties, and respiratory problems soon after birth, but the severity of the weakness and disease course is variable (summary by Logan et al., 2015). For a discussion of genetic heterogeneity of CMS, see CMS1A (601462).
Charcot-Marie-Tooth disease dominant intermediate E
MedGen UID:
928336
Concept ID:
C4302667
Disease or Syndrome
Autosomal dominant intermediate Charcot-Marie-Tooth disease E with focal segmental glomerulonephritis is characterized by the neurologic features of CMT, including distal muscle weakness and atrophy and distal sensory loss, and the features of FSGS, including proteinuria, progression to end-stage renal disease, and a characteristic histologic pattern on renal biopsy (summary by Boyer et al., 2011). Isolated focal segmental glomerulosclerosis-5 (FSGS5; 613237) is also caused by heterozygous mutation in the INF2 gene. For a discussion of genetic heterogeneity of CMTDI, see 606482.
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 4
MedGen UID:
934700
Concept ID:
C4310733
Disease or Syndrome
Autosomal recessive progressive external ophthalmoplegia with mitochondrial DNA deletions-4 (PEOB4) is characterized by adult onset of eye muscle weakness and proximal limb muscle weakness associated with deletions of mtDNA on skeletal muscle biopsy, which results from defective mtDNA replication in post-mitotic muscle tissue. Additional features are more variable (summary by Ronchi et al., 2012). For a discussion of genetic heterogeneity of autosomal recessive PEO, see PEOB1 (258450).
Autosomal recessive limb-girdle muscular dystrophy type 2Y
MedGen UID:
1385152
Concept ID:
C4511482
Disease or Syndrome
Autosomal recessive myopathy with rigid spine and distal joint contractures (MRRSDC) is characterized by onset of slowly progressive muscle weakness in the first or second decades of life. There is initial involvement of the proximal lower limbs, followed by distal upper and lower limb muscle weakness and atrophy. Other features include joint contractures, rigid spine, and restricted pulmonary function; some patients may have mild cardiac involvement (summary by Kayman-Kurekci et al., 2014).
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, autosomal recessive 26
MedGen UID:
1617917
Concept ID:
C4539948
Disease or Syndrome
Myopathy, centronuclear, 6, with fiber-type disproportion
MedGen UID:
1627492
Concept ID:
C4540345
Disease or Syndrome
Centronuclear myopathy-6 with fiber-type disproportion (CNM6) is an autosomal recessive, slowly progressive congenital myopathy with onset in infancy or early childhood. Patients may be hypotonic at birth, but all show delayed motor development and walking difficulties due to muscle weakness mainly affecting the proximal lower and upper limbs. Other features include scapular winging, scoliosis, and mildly decreased respiratory vital capacity. The phenotype and muscle biopsy abnormalities are variable, although centralized nuclei and fiber-type disproportion appear to be a common finding on muscle biopsy (summary by Vasli et al., 2017). For a discussion of genetic heterogeneity of centronuclear myopathy, see CNM1 (160150).
Miyoshi muscular dystrophy 1
MedGen UID:
1640757
Concept ID:
C4551973
Disease or Syndrome
Dysferlinopathy includes a spectrum of muscle disease characterized by two major phenotypes: Miyoshi muscular dystrophy (MMD) and limb-girdle muscular dystrophy type 2B (LGMD2B); and two minor phenotypes: asymptomatic hyperCKemia and distal myopathy with anterior tibial onset (DMAT). MMD (median age of onset 19 years) is characterized by muscle weakness and atrophy, most marked in the distal parts of the legs, especially the gastrocnemius and soleus muscles. Over a period of years, the weakness and atrophy spread to the thighs and gluteal muscles. The forearms may become mildly atrophic with decrease in grip strength; the small muscles of the hands are spared. LGMD2B is characterized by early weakness and atrophy of the pelvic and shoulder girdle muscles in adolescence or young adulthood, with slow progression. Other phenotypes in this spectrum are scapuloperoneal syndrome and congenital muscular dystrophy. Asymptomatic hyperCKemia is characterized by marked elevation of serum CK concentration only. DMAT is characterized by early and predominant distal muscle weakness, particularly of the muscles of the anterior compartment of the legs.
Mitochondrial DNA depletion syndrome 1
MedGen UID:
1631838
Concept ID:
C4551995
Disease or Syndrome
Mitochondrial neurogastrointestinal encephalopathy (MNGIE) disease is characterized by progressive gastrointestinal dysmotility (manifesting as early satiety, nausea, dysphagia, gastroesophageal reflux, postprandial emesis, episodic abdominal pain and/or distention, and diarrhea); cachexia; ptosis/ophthalmoplegia or ophthalmoparesis; leukoencephalopathy; and demyelinating peripheral neuropathy (manifesting as paresthesias (tingling, numbness, and pain) and symmetric and distal weakness more prominently affecting the lower extremities). The order in which manifestations appear is unpredictable. Onset is usually between the first and fifth decades; in about 60% of individuals, symptoms begin before age 20 years.
MYH7-related skeletal myopathy
MedGen UID:
1647391
Concept ID:
C4552004
Disease or Syndrome
Laing distal myopathy is characterized by early-onset weakness (usually before age 5 years) that initially involves the dorsiflexors of the ankles and great toes and then the finger extensors, especially those of the third and fourth fingers. Weakness of the neck flexors is seen in most affected individuals and mild facial weakness is often present. After distal weakness has been present for more than ten years, mild proximal weakness may be observed. Life expectancy is normal.
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.
Jaberi-Elahi syndrome
MedGen UID:
1647359
Concept ID:
C4693848
Disease or Syndrome
JABELS is an autosomal recessive neurodevelopmental disorder characterized by developmental delay and intellectual disability with additional variable features. Patients have onset of symptoms in infancy, but the severity is highly variable. Some patients have social interaction and learn to walk but have an ataxic gait and abnormal movements, such as tremor or dystonia, whereas others do not achieve any motor control and are unable to speak. Additional features may include retinal anomalies, visual impairment, microcephaly, abnormal foot or hand posturing, and kyphoscoliosis; some patients have dysmorphic facial features or seizures. Brain imaging typically shows cerebellar atrophy and hypoplasia of the corpus callosum (summary by et al., 2016 and Bertoli-Avella et al., 2018).
Charcot-Marie-Tooth disease type 4E
MedGen UID:
1648303
Concept ID:
C4721436
Disease or Syndrome
Congenital hypomyelinating neuropathy (CHN) is characterized clinically by onset of hypotonia at birth, areflexia, distal muscle weakness, and very slow nerve conduction velocities (often less than 10 m/s). Warner et al. (1997, 1998) noted that pathologic findings on sural nerve biopsies show hypomyelination of most or all fibers. Based on these findings, CHN is considered to be a result of congenital impairment in myelin formation. There has been some controversy and difficulty in differentiating congenital hypomyelination from Dejerine-Sottas syndrome (DSS; 145900) because there is considerable overlap in clinical presentation. Based on pathologic findings of sural nerve biopsies (the absence of active myelin breakdown and the paucity of the onion bulbs in CHN and the presence of demyelination/remyelination and an abundance of well-organized onion bulbs in DSS; see Balestrini et al., 1991), CHN is considered to result from a congenital impairment in myelin formation, whereas DSS is thought to be due to aberrant demyelination and subsequent remyelination of the peripheral nerve. There is also variation in the prognosis of patients diagnosed with CHN. In patients with CHN, Harati and Butler (1985) showed correlation of morbidity and mortality with the presence/absence of onion bulbs: patients with few onion bulbs died in early infancy, usually because of difficulty in swallowing and respiration after birth. Patients with atypical onion bulbs survived but were affected with severe motor and sensory impairment. These differences in outcome may represent genetic heterogeneity such that mutations in essential early myelin gene(s) cause a severe phenotype, whereas mutations in other, possibly later acting gene(s), such as MPZ, lead to a less severe outcome. Genetic Heterogeneity of Congenital Hypomyelinating Neuropathy See also CHN2 (618184), caused by mutation in the MPZ gene (159440) on chromosome 1q23; and CHN3 (618186), caused by mutation in the CNTNAP1 gene (602346) on chromosome 17q21.
Charcot-Marie-Tooth disease type 2A2
MedGen UID:
1648317
Concept ID:
C4721887
Disease or Syndrome
MFN2 hereditary motor and sensory neuropathy (MFN2-HMSN) is a classic axonal peripheral sensorimotor neuropathy, inherited in either an autosomal dominant (AD) manner (~90%) or an autosomal recessive (AR) manner (~10%). MFN2-HMSN is characterized by more severe involvement of the lower extremities than the upper extremities, distal upper-extremity involvement as the neuropathy progresses, more prominent motor deficits than sensory deficits, and normal (>42 m/s) or only slightly decreased nerve conduction velocities (NCVs). Postural tremor is common. Median onset is age 12 years in the AD form and age eight years in the AR form. The prevalence of optic atrophy is approximately 7% in the AD form and approximately 20% in the AR form.
Charcot-Marie-Tooth disease type 5
MedGen UID:
1648461
Concept ID:
C4721916
Disease or Syndrome
Hereditary motor and sensory neuropathies (HMSN) are a heterogeneous group of peripheral nervous system disorders affecting motor and sensory function. HMSN I, also known as Charcot-Marie-Tooth (CMT) disease, or peroneal muscular atrophy, type 1, is a demyelinating neuropathy (see CMT1B; 118200) and HMSN II, also known as CMT type 2, is an axonal neuropathy (see CMT2A1; 118210). See also HMSN III (145900) and HMSN IV (266500). For an autosomal recessive disorder with similarities to HMSN V, see 607731.
Charcot-marie-tooth disease, axonal, type 2DD
MedGen UID:
1648475
Concept ID:
C4747974
Disease or Syndrome
Charcot-Marie-Tooth disease type 2DD is an autosomal dominant peripheral sensorimotor neuropathy mainly affecting the lower limbs. Affected individuals have gait impairment due to distal muscle weakness and atrophy. Some patients may also have involvement of the distal upper limbs, resulting in atrophy of the intrinsic hand muscles. The age at onset and severity of the disorder is highly variable, even within families, and those with earlier onset in late childhood or the teenage years tend to have a more severe disease course. Patients remain ambulatory even late in the disease, although some may require orthotic devices (summary by Lassuthova et al., 2018). For a phenotypic description and a discussion of genetic heterogeneity of axonal CMT type 2, see CMT2A (118210).
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).
Charcot-Marie-Tooth disease, demyelinating, type 1G
MedGen UID:
1648290
Concept ID:
C4748940
Disease or Syndrome
Charcot-Marie-Tooth disease type 1G is an autosomal dominant progressive peripheral sensorimotor neuropathy characterized by distal muscle weakness and atrophy with onset in the first or second decade. Affected individuals have difficulty walking, distal sensory impairment with decreased or absent reflexes, and often have foot deformities. Median motor nerve conduction velocities (NCV) are decreased (less than 38 m/s) and sural nerve biopsy shows myelin defects and onion bulb formation (summary by Hong et al., 2016 and Motley et al., 2016). For a phenotypic description and a discussion of genetic heterogeneity of autosomal dominant Charcot-Marie-Tooth disease type 1, see CMT1B (118200).
Neuronopathy, distal hereditary motor, autosomal recessive 5
MedGen UID:
1667915
Concept ID:
C4749918
Disease or Syndrome
HMNR5 is an autosomal recessive neurologic disorder characterized by young adult onset of slowly progressive distal muscle weakness and atrophy resulting in gait impairment and loss of reflexes due to impaired function of motor nerves. Sensation and cognition are not impaired (summary by Blumen et al., 2012). For a discussion of genetic heterogeneity of autosomal recessive HMN, see HMNR1 (604320).
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).
Charcot-Marie-Tooth disease, axonal, type 2EE
MedGen UID:
1677426
Concept ID:
C5193076
Disease or Syndrome
Charcot-Marie-Tooth disease type 2EE (CMT2EE) is an autosomal recessive sensorimotor peripheral axonal neuropathy with onset in the first or second decades of life. The disorder primarily affects the lower limbs and is slowly progressive, sometimes resulting in loss of ambulation, with later onset of upper limb involvement. There is significant distal muscle weakness and atrophy, usually with foot or hand deformities. Skeletal muscle biopsy shows findings of disturbed mitochondrial maintenance. Cognition is unaffected, and chronic liver disease is absent (summary by Baumann et al., 2019). For a phenotypic description and a discussion of genetic heterogeneity of axonal CMT type 2, see CMT2A (118210).
Spastic ataxia 9, autosomal recessive
MedGen UID:
1680026
Concept ID:
C5193100
Disease or Syndrome
Myopathy, distal, 6, adult-onset, autosomal dominant
MedGen UID:
1684760
Concept ID:
C5203349
Disease or Syndrome
Autosomal dominant adult-onset distal myopathy-6 (MPD6) is a muscle disorder characterized by slowly progressive distal muscle weakness, primarily affecting the lower limbs and resulting in gait difficulties. Some patients develop involvement of proximal and upper limb muscles (summary by Savarese et al., 2019)
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).
Myopathy, congenital, with tremor
MedGen UID:
1684886
Concept ID:
C5231401
Disease or Syndrome
Congenital myopathy-16 (CMYP16) is an autosomal dominant muscle disorder characterized by onset of hypotonia and tremor in infancy. Patients have mildly delayed walking, unsteady gait, proximal muscle weakness, and a high-frequency tremor of the limbs. Some may develop secondary mild contractures or spinal deformities. Cognition is normal and the disease course tends to stabilize after adolescence (summary by Stavusis et al., 2019). For a discussion of genetic heterogeneity of congenital myopathy, see CMYP1A (117000).
Oculopharyngeal myopathy with leukoencephalopathy 1
MedGen UID:
1684701
Concept ID:
C5231436
Disease or Syndrome
Myopathy, congenital, with structured cores and z-line abnormalities
MedGen UID:
1684705
Concept ID:
C5231445
Disease or Syndrome
Congenital myopathy-8 (CMYP8) is an autosomal dominant disorder of the skeletal muscle characterized by hypotonia and delayed motor development apparent from infancy or childhood, resulting in difficulties walking or loss of ambulation within the first few decades. Affected individuals show respiratory insufficiency, high-arched palate, and scoliosis; external ophthalmoplegia may also be present. Skeletal muscle biopsy shows cores and myofibrillar disorganization (Lornage et al., 2019). For a discussion of genetic heterogeneity of congenital myopathy, see CMYP1A (117000).
Neuropathy, hereditary sensory and autonomic, type 1A
MedGen UID:
1716450
Concept ID:
C5235211
Disease or Syndrome
SPTLC1-related hereditary sensory neuropathy (HSN) is an axonal form of hereditary motor and sensory neuropathy distinguished by prominent early sensory loss and later positive sensory phenomena including dysesthesia and characteristic "lightning" or "shooting" pains. Loss of sensation can lead to painless injuries, which, if unrecognized, result in slow wound healing and subsequent osteomyelitis requiring distal amputations. Motor involvement is present in all advanced cases and can be severe. After age 20 years, the distal wasting and weakness may involve proximal muscles, possibly leading to wheelchair dependency by the seventh or eighth decade. Sensorineural hearing loss is variable.
Wieacker-Wolff syndrome, female-restricted
MedGen UID:
1715791
Concept ID:
C5393303
Disease or Syndrome
Female-restricted Wieacker-Wolff syndrome (WRWFFR) is an X-linked dominant syndromic form of neurogenic arthrogryposis multiplex congenita (AMC) with central and peripheral nervous system involvement. Affected individuals have decreased fetal movements causing the development of contractures in utero and resulting in AMC and diffuse contractures involving the large and small joints apparent at birth. There is global developmental delay with difficulty walking or inability to walk, hypotonia that often evolves to spasticity, and variably impaired intellectual development with poor or absent speech and language. Dysmorphic facial features, including hypotonic facies, ptosis, microretrognathia, and small mouth, are seen in most patients. Seizures are uncommon; some patients have evidence of a peripheral motor neuropathy with distal muscle weakness. The level of X inactivation in lymphocytes and fibroblasts is often skewed, but may not predict the severity of the phenotype. Most cases occur sporadically; rare X-linked dominant inheritance has been reported in families (summary by Frints et al., 2019).
Mitochondrial DNA depletion syndrome 18
MedGen UID:
1713890
Concept ID:
C5394140
Disease or Syndrome
Mitochondrial DNA depletion syndrome-18 (MTDPS18) is an autosomal recessive neuromuscular disorder characterized by early-onset progressive weakness and atrophy of the distal limb muscles, resulting in loss of ambulation as well as atrophy of the intrinsic hand muscles with clawed hands. Affected individuals may also develop scoliosis and have hypo- or hyperreflexia and decreased pulmonary vital capacity. Examination of skeletal muscle shows neurogenic atrophy and combined mitochondrial oxidative phosphorylation deficiency associated with mtDNA depletion. The clinical phenotype is reminiscent of spinal muscular atrophy (see SMA, 253300) and the metabolic profile is reminiscent of 2-aminoadipic 2-oxoadipic aciduria (AMOXAD; 204750), which is caused by mutation in the DHTKD1 gene (614984) (summary by Boczonadi et al., 2018). For a discussion of genetic heterogeneity of autosomal recessive mtDNA depletion syndromes, see MTDPS1 (603041).
Oculopharyngodistal myopathy 2
MedGen UID:
1718769
Concept ID:
C5394548
Disease or Syndrome
Oculopharyngodistal myopathy-2 (OPDM2) is an autosomal dominant muscle disorder characterized by onset of distal muscle weakness, mainly of the lower limbs, and/or ophthalmoplegia in the second or third decades of life. The disorder is slowly progressive, and patients develop facial weakness, bulbar weakness, and difficulty walking or climbing stairs. Some patients may have upper limb involvement and subclinical respiratory insufficiency. Laboratory studies show increased serum creatine kinase; skeletal muscle biopsy shows myopathic changes with abnormal cytoplasmic and intranuclear inclusions (summary by Deng et al., 2020). For a discussion of genetic heterogeneity of OPDM, see OPDM1 (164310).
Neuronopathy, distal hereditary motor, type 5A
MedGen UID:
1723540
Concept ID:
C5399969
Disease or Syndrome
The phenotypic spectrum of GARS1-associated axonal neuropathy ranges from GARS1 infantile-onset SMA (GARS1-iSMA) to GARS1 adolescent- or early adult-onset hereditary motor/sensory neuropathy (GARS1-HMSN). GARS1-iSMA. Age of onset ranges from the neonatal period to the toddler years. Initial manifestations are typically respiratory distress, poor feeding, and muscle weakness (distal greater than proximal). Weakness is slowly progressive, ultimately requiring mechanical ventilation and feeding via gastrostomy tube. GARS1-HMSN. Age of onset is most commonly during the second decade (range eight to 36 years). Initial manifestations are typically muscle weakness in the hands sometimes with sensory deficits. Lower limb involvement (seen in ~50% of individuals) ranges from weakness and atrophy of the extensor digitorum brevis and weakness of toe dorsiflexors to classic peroneal muscular atrophy with foot drop and a high steppage gait.
Spinal muscular atrophy, infantile, James type
MedGen UID:
1764556
Concept ID:
C5436669
Disease or Syndrome
The phenotypic spectrum of GARS1-associated axonal neuropathy ranges from GARS1 infantile-onset SMA (GARS1-iSMA) to GARS1 adolescent- or early adult-onset hereditary motor/sensory neuropathy (GARS1-HMSN). GARS1-iSMA. Age of onset ranges from the neonatal period to the toddler years. Initial manifestations are typically respiratory distress, poor feeding, and muscle weakness (distal greater than proximal). Weakness is slowly progressive, ultimately requiring mechanical ventilation and feeding via gastrostomy tube. GARS1-HMSN. Age of onset is most commonly during the second decade (range eight to 36 years). Initial manifestations are typically muscle weakness in the hands sometimes with sensory deficits. Lower limb involvement (seen in ~50% of individuals) ranges from weakness and atrophy of the extensor digitorum brevis and weakness of toe dorsiflexors to classic peroneal muscular atrophy with foot drop and a high steppage gait.
Charcot-Marie-Tooth Disease, axonal, type 2GG
MedGen UID:
1794143
Concept ID:
C5561933
Disease or Syndrome
Charcot-Marie-Tooth disease type 2GG (CMT2GG) is an autosomal dominant axonal peripheral neuropathy characterized by slowly progressive distal muscle weakness and atrophy primarily affecting the lower limbs and causing difficulty walking. The onset is usually in adulthood, although rare patients may have mild symptoms from childhood. Some individuals may also have involvement of the hands. Although most patients have hypo- or areflexia at the ankles, distal sensory impairment is not always present, indicating a spectrum of disease encompassing both distal hereditary neuropathy and axonal CMT. Electrophysiologic studies are consistent with a axonal process (summary by Mendoza-Ferreira et al., 2020). For a discussion of genetic heterogeneity of axonal CMT, see CMT2A1 (118210).
Charcot-Marie-Tooth disease, axonal, Type 2HH
MedGen UID:
1794213
Concept ID:
C5562003
Disease or Syndrome
Axonal Charcot-Marie-Tooth disease type 2HH (CMT2HH) is an autosomal dominant peripheral neuropathy characterized predominantly by onset of vocal cord weakness resulting in stridor in infancy or early childhood. The vocal cord paresis remains throughout life and may be severe enough to require tracheostomy. Additional features of the disorder usually include pes cavus and scoliosis. Some patients have mild distal muscle weakness and atrophy primarily affecting the lower limbs, although the upper limbs may also be involved, and distal sensory impairment, often with hyporeflexia (Sullivan et al., 2020). For a discussion of genetic heterogeneity of axonal CMT, see CMT2A1 (118210).
Autosomal dominant Charcot-Marie-Tooth disease type 2W
MedGen UID:
1798909
Concept ID:
C5567486
Disease or Syndrome
Charcot-Marie-Tooth disease type 2W is an autosomal dominant neurologic disorder characterized by a peripheral neuropathy mainly affecting the lower limbs and resulting in gait difficulties and distal sensory impairment, although most patients also have upper limb involvement. The age at onset is highly variable, ranging from childhood to late adulthood (summary by Safka Brozkova et al., 2015). For a phenotypic description and a discussion of genetic heterogeneity of axonal CMT, see CMT2A1 (118210).
Hereditary spastic paraplegia 9A
MedGen UID:
1800401
Concept ID:
C5568978
Disease or Syndrome
Autosomal dominant spastic paraplegia-9A is a neurologic disorder characterized by onset of slowly progressive spasticity mainly affecting the lower limbs. The age at onset usually ranges from adolescence to adulthood, and patients have gait difficulties, motor neuropathy, and dysarthria. Additional variable features include cerebellar signs, cataract, pes cavus, and urinary urgency (summary by Coutelier et al., 2015). For a general phenotypic description and a discussion of genetic heterogeneity of autosomal dominant spastic paraplegia, see SPG3A (182600).
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).
Acute infantile liver failure-cerebellar ataxia-peripheral sensory motor neuropathy syndrome
MedGen UID:
1800507
Concept ID:
C5569084
Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-21 is a neurologic disorder characterized by onset of cerebellar ataxia associated with cerebellar atrophy in early childhood. Affected individuals also have recurrent episodes of liver failure in the first decade, resulting in chronic liver fibrosis, as well as later onset of a peripheral neuropathy. Mild learning disabilities may also occur (summary by Schmidt et al., 2015). The phenotype is highly variable: all patients appear to have episodic and severe liver dysfunction in early childhood that tends to resolve with age. Affected individuals also show mild developmental or language delay and/or later onset of variable neurologic features, such as motor dysfunction (summary by Lenz et al., 2018).
Carey-Fineman-Ziter syndrome 1
MedGen UID:
1804638
Concept ID:
C5676876
Disease or Syndrome
Carey-Fineman-Ziter syndrome-1 (CFZS1) is a multisystem congenital disorder characterized by hypotonia, Moebius sequence (bilateral congenital facial palsy with impairment of ocular abduction), Pierre Robin complex (micrognathia, glossoptosis, and high-arched or cleft palate), delayed motor milestones, and failure to thrive. More variable features include dysmorphic facial features, brain abnormalities, and intellectual disability. It has been postulated that many clinical features in CFZS1 may be secondary effects of muscle weakness during development or brainstem anomalies (summary by Pasetti et al., 2016). Di Gioia et al. (2017) determined that CFZS1 represents a slowly progressive congenital myopathy resulting from a defect in myoblast fusion. Genetic Heterogeneity of Carey-Fineman-Ziter Syndrome Carey-Fineman-Ziter syndrome-2 (CFZS2) is caused by mutation in the MYMX gene (619912) on chromosome 6p21.
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).
Oculopharyngodistal myopathy 4
MedGen UID:
1809981
Concept ID:
C5676941
Disease or Syndrome
Oculopharyngodistal myopathy-4 (OPDM4) is an autosomal dominant neuromuscular disorder characterized by progressive ptosis, ophthalmoparesis, facial and masseter weakness, and muscle weakness of the distal limbs. Initial symptoms of the disorder, ptosis and limited eye movements, most commonly appear in the second or third decades. There is slow progression with development of dysarthria, dysphagia, and distal limb weakness and atrophy associated with absent deep tendon reflexes; sensation is normal. Serum creatine kinase is often increased, and skeletal muscle biopsy typically shows chronic myopathic changes with rimmed vacuoles and filamentous intranuclear inclusions (summary by Yu et al., 2022). For a discussion of genetic heterogeneity of OPDM, see OPDM1 (164310).
Spinal muscular atrophy, distal, autosomal recessive, 6
MedGen UID:
1823974
Concept ID:
C5774201
Disease or Syndrome
Autosomal recessive distal hereditary motor neuronopathy-6 (HMNR6) is a neuromuscular disorder characterized by onset of distal muscle weakness in early infancy. Affected individuals often present at birth with distal joint contractures or foot deformities and show delayed motor development, often with inability to walk or frequent falls. Hypo- or hyperreflexia may be observed; limb muscle atrophy may also be present. Patients often show respiratory distress or diaphragmatic palsy. Electrophysiologic studies are consistent with a peripheral motor neuropathy without sensory involvement (Maroofian et al., 2019). For a discussion of genetic heterogeneity of autosomal recessive distal HMN, see HMNR1 (604320).
Charcot-Marie-Tooth disease, demyelinating, type 1J
MedGen UID:
1824022
Concept ID:
C5774249
Disease or Syndrome
Charcot-Marie-Tooth disease type 1J (CMT1J) is an autosomal dominant sensorimotor peripheral neuropathy characterized by distal muscle weakness and atrophy, as well as distal sensory impairment, predominantly affecting the lower limbs and resulting in gait abnormalities. The age at onset is highly variable, ranging from early childhood to mid-adulthood, and the disorder is progressive, although the severity is also variable. Additional features may include foot deformities, upper limb or hand involvement, and decreased or absent deep tendon reflexes. Electrophysiologic studies tend to show nerve conduction velocities in the demyelinating range, although some patients may have results in the intermediate range, likely reflecting secondary axonal degeneration (summary by Ronkko et al., 2020). For a discussion of genetic heterogeneity of autosomal dominant Charcot-Marie-Tooth disease type 1, see CMT1B (118200).
Rhabdomyolysis, susceptibility to, 1
MedGen UID:
1824080
Concept ID:
C5774307
Finding
Susceptibility to rhabdomyolysis-1 (RHABDO1) is an autosomal recessive disorder characterized by recurrent episodes of rhabdomyolysis beginning in the teenage years. Some of the episodes may be triggered by exercise or heat; others occur spontaneously. Severe cases may result in acute renal failure or compartment syndrome. Affected individuals tend to have myalgia or muscle weakness in childhood and between episodes. Laboratory studies show increased serum creatine kinase and nonspecific myopathic features on skeletal muscle biopsy (Cabrera-Serrano et al., 2022).

Professional guidelines

PubMed

Lehmann HC, Burke D, Kuwabara S
J Neurol Neurosurg Psychiatry 2019 Sep;90(9):981-987. Epub 2019 Apr 16 doi: 10.1136/jnnp-2019-320314. PMID: 30992333
Montagnese F, Barca E, Musumeci O, Mondello S, Migliorato A, Ciranni A, Rodolico C, De Filippi P, Danesino C, Toscano A
J Neurol 2015;262(4):968-78. Epub 2015 Feb 12 doi: 10.1007/s00415-015-7664-0. PMID: 25673129
Auer-Grumbach M, De Jonghe P, Wagner K, Verhoeven K, Hartung HP, Timmerman V
Neurology 2000 Nov 28;55(10):1552-7. doi: 10.1212/wnl.55.10.1552. PMID: 11094113

Recent clinical studies

Etiology

Zambon AA, Pini V, Bosco L, Falzone YM, Munot P, Muntoni F, Previtali SC
Brain 2023 Mar 1;146(3):806-822. doi: 10.1093/brain/awac452. PMID: 36445400Free PMC Article
Broers MC, Bunschoten C, Drenthen J, Beck TAO, Brusse E, Lingsma HF, Allen JA, Lewis RA, van Doorn PA, Jacobs BC
Eur J Neurol 2021 Jun;28(6):2065-2073. Epub 2021 Apr 9 doi: 10.1111/ene.14796. PMID: 33657260Free PMC Article
Volodarsky M, Kerkhof J, Stuart A, Levy M, Brady LI, Tarnopolsky M, Lin H, Ainsworth P, Sadikovic B
J Med Genet 2021 Apr;58(4):284-288. Epub 2020 May 6 doi: 10.1136/jmedgenet-2019-106641. PMID: 32376792
van den Dorpel JJA, Poelman E, Harlaar L, van Kooten HA, van der Giessen LJ, van Doorn PA, van der Ploeg AT, van den Hout JMP, van der Beek NAME
Orphanet J Rare Dis 2020 Sep 14;15(1):247. doi: 10.1186/s13023-020-01482-w. PMID: 32928284Free PMC Article
Mathis S, Goizet C, Tazir M, Magdelaine C, Lia AS, Magy L, Vallat JM
J Med Genet 2015 Oct;52(10):681-90. Epub 2015 Aug 5 doi: 10.1136/jmedgenet-2015-103272. PMID: 26246519

Diagnosis

Zambon AA, Pini V, Bosco L, Falzone YM, Munot P, Muntoni F, Previtali SC
Brain 2023 Mar 1;146(3):806-822. doi: 10.1093/brain/awac452. PMID: 36445400Free PMC Article
Volodarsky M, Kerkhof J, Stuart A, Levy M, Brady LI, Tarnopolsky M, Lin H, Ainsworth P, Sadikovic B
J Med Genet 2021 Apr;58(4):284-288. Epub 2020 May 6 doi: 10.1136/jmedgenet-2019-106641. PMID: 32376792
Lehmann HC, Burke D, Kuwabara S
J Neurol Neurosurg Psychiatry 2019 Sep;90(9):981-987. Epub 2019 Apr 16 doi: 10.1136/jnnp-2019-320314. PMID: 30992333
Jani-Acsadi A, Ounpuu S, Pierz K, Acsadi G
Pediatr Clin North Am 2015 Jun;62(3):767-86. Epub 2015 Apr 15 doi: 10.1016/j.pcl.2015.03.012. PMID: 26022174
Vallat JM, Mathis S, Funalot B
Curr Opin Neurol 2013 Oct;26(5):473-80. doi: 10.1097/WCO.0b013e328364c04b. PMID: 23945280

Therapy

Õunpuu S, Garibay E, Acsadi G, Brimacombe M, Pierz K
Gait Posture 2021 Mar;85:198-204. Epub 2021 Feb 12 doi: 10.1016/j.gaitpost.2021.02.005. PMID: 33610823
van den Dorpel JJA, Poelman E, Harlaar L, van Kooten HA, van der Giessen LJ, van Doorn PA, van der Ploeg AT, van den Hout JMP, van der Beek NAME
Orphanet J Rare Dis 2020 Sep 14;15(1):247. doi: 10.1186/s13023-020-01482-w. PMID: 32928284Free PMC Article
Pogoryelova O, González Coraspe JA, Nikolenko N, Lochmüller H, Roos A
Orphanet J Rare Dis 2018 May 2;13(1):70. doi: 10.1186/s13023-018-0802-x. PMID: 29720219Free PMC Article
Malekirad AA, Faghih M, Mirabdollahi M, Kiani M, Fathi A, Abdollahi M
Arh Hig Rada Toksikol 2013;64(1):1-8. doi: 10.2478/10004-1254-64-2013-2296. PMID: 23705196
Jasim S, Shaibani A
Int J Neurosci 2013 Jul;123(7):516-20. Epub 2013 Feb 19 doi: 10.3109/00207454.2013.765871. PMID: 23311755

Prognosis

Cantó-Santos J, Valls-Roca L, Tobías E, García-García FJ, Guitart-Mampel M, Esteve-Codina A, Martín-Mur B, Casado M, Artuch R, Solsona-Vilarrasa E, Fernandez-Checa JC, García-Ruiz C, Rentero C, Enrich C, Moreno-Lozano PJ, Milisenda JC, Cardellach F, Grau-Junyent JM, Garrabou G
J Cachexia Sarcopenia Muscle 2023 Apr;14(2):964-977. Epub 2023 Mar 1 doi: 10.1002/jcsm.13178. PMID: 36860172Free PMC Article
Morais J, Oliveira AA, Pires O, Burmester I, Regadas MJ, Gouveia P
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Bussmann J, Storkebaum E
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Prieto-González S, Grau JM
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Auer-Grumbach M
Orphanet J Rare Dis 2008 Mar 18;3:7. doi: 10.1186/1750-1172-3-7. PMID: 18348718Free PMC Article

Clinical prediction guides

Alonso-Pérez J, González-Quereda L, Bruno C, Panicucci C, Alavi A, Nafissi S, Nilipour Y, Zanoteli E, Isihi LMA, Melegh B, Hadzsiev K, Muelas N, Vílchez JJ, Dourado ME, Kadem N, Kutluk G, Umair M, Younus M, Pegorano E, Bello L, Crawford TO, Suárez-Calvet X, Töpf A, Guglieri M, Marini-Bettolo C, Gallano P, Straub V, Díaz-Manera J
Brain 2022 Apr 18;145(2):596-606. doi: 10.1093/brain/awab301. PMID: 34515763Free PMC Article
Mateus T, Martins F, Nunes A, Herdeiro MT, Rebelo S
Int J Environ Res Public Health 2021 Feb 12;18(4) doi: 10.3390/ijerph18041794. PMID: 33673200Free PMC Article
Deschauer M, Hengel H, Rupprich K, Kreiß M, Schlotter-Weigel B, Grimmel M, Admard J, Schneider I, Alhaddad B, Gazou A, Sturm M, Vorgerd M, Balousha G, Balousha O, Falna M, Kirschke JS, Kornblum C, Jordan B, Kraya T, Strom TM, Weis J, Schöls L, Schara U, Zierz S, Riess O, Meitinger T, Haack TB
Brain 2021 Mar 3;144(2):574-583. doi: 10.1093/brain/awaa418. PMID: 33459760
Parman Y, Battaloğlu E
Handb Clin Neurol 2013;115:847-61. doi: 10.1016/B978-0-444-52902-2.00048-5. PMID: 23931818
Auer-Grumbach M
Orphanet J Rare Dis 2008 Mar 18;3:7. doi: 10.1186/1750-1172-3-7. PMID: 18348718Free PMC Article

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