Presynaptic congenital myasthenic syndromes

General Information (adopted from Orphanet):

Synonyms, Signs: FIMG2, FORMERLY
MYASTHENIA, FAMILIAL INFANTILE
MYASTHENIA GRAVIS, FAMILIAL INFANTILE, 2, FORMERLY
CMS1A2
MYASTHENIC SYNDROME, PRESYNAPTIC, CONGENITAL, ASSOCIATED WITH EPISODIC APNEA
CMS-EA
FIM
CMS Ia2
CONGENITAL MYASTHENIC SYNDROME TYPE Ia2
Number of Symptoms 31
OrphanetNr: 98914
OMIM Id: 254210
ICD-10: G70.2
UMLs:
MeSH:
MedDRA:
Snomed:

Prevalence, inheritance and age of onset:

Prevalence: No data available.
Inheritance: Autosomal recessive inheritance
[Omim]
Age of onset: Congenital onset
[Omim]

Disease classification (adopted from Orphanet):

Parent Diseases: Congenital myasthenic syndromes
 -Rare eye disease
 -Rare genetic disease
 -Rare neurologic disease

Symptom Information: Sort by abundance 

1
 (HPO:0000508) Ptosis 459 / 7739
2
 (HPO:0000597) Ophthalmoparesis 71 / 7739
3
 (HPO:0000486) Strabismus 576 / 7739
4
 (HPO:0003473) Fatigable weakness 39 / 7739
5
 (HPO:0003397) Generalized hypotonia due to defect at the neuromuscular junction 2 / 7739
6
 (HPO:0003402) Decreased miniature endplate potentials 3 / 7739
7
 (HPO:0002015) Dysphagia 301 / 7739
8
 (HPO:0002804) Arthrogryposis multiplex congenita 93 / 7739
9
 (HPO:0002033) Poor suck 37 / 7739
10
 (HPO:0002098) Respiratory distress 75 / 7739
11
 (HPO:0002882) Sudden episodic apnea 3 / 7739
12
 (HPO:0001612) Weak cry 17 / 7739
13
 (HPO:0002872) Apneic episodes precipitated by illness, fatigue, stress 3 / 7739
14
 (HPO:0002747) Respiratory insufficiency due to muscle weakness 48 / 7739
15
 (HPO:0002715) Abnormality of the immune system 46 / 7739
16
 (HPO:0003403) EMG: decremental response of compound muscle action potential to repetitive nerve stimulation 7 / 7739
17
 (HPO:0003554) Type 2 muscle fiber atrophy 14 / 7739
18
 (HPO:0001283) Bulbar palsy 31 / 7739
19
 (HPO:0003577) Congenital onset 133 / 7739
20
 (OMIM) Electron microscopy shows decreased size of synaptic vesicles 1 / 7739
21
 (HPO:0000007) Autosomal recessive inheritance 2538 / 7739
22
 (OMIM) Absence of acetylcholine receptor (AChR) autoantibodies 8 / 7739
23
 (OMIM) Quantal content declines with activity 1 / 7739
24
 (OMIM) Arthrogryposis multiplex in severe cases 4 / 7739
25
 (OMIM) Poor feeding due to muscle weakness 5 / 7739
26
 (OMIM) Mild-moderate fatigable weakness of limb muscles 2 / 7739
27
 (OMIM) Sudden episodic apnea, severe, may cause death 2 / 7739
28
 (OMIM) EMG shows decremental response of compound muscle action potential (CMAP) to repetitive nerve stimulation 2 / 7739
29
 (OMIM) Slow recovery (10-15 minutes) 2 / 7739
30
 (OMIM) Muscle biopsy shows type 2 fiber atrophy 6 / 7739
31
 (OMIM) Defect in resynthesis and packaging of acetylcholine 1 / 7739

Associated genes:

ClinVar (via SNiPA)

Gene symbol Variation Clinical significance Reference

Additional Information:

Description: (OMIM) Congenital myasthenic syndromes are genetic disorders of the neuromuscular junction and can be classified by the site of the transmission defect: presynaptic, synaptic, and postsynaptic. CMS-EA is an autosomal recessive form of presynaptic CMS. For a discussion of ...
Clinical Description OMIM Walsh and Hoyt (1959) and Rothbart (1937) each reported a family in which 4 affected brothers had a familial form of childhood congenital myasthenia. Greer and Schotland (1960) reported myasthenia gravis in the newborn. Kott and Bornstein (1969) ...
Molecular genetics OMIM In 5 patients with CMS-EA, Ohno et al. (2001) identified compound heterozygosity for different mutations in the CHAT gene (118490.0001-118490.0010).

In a consanguineous Turkish family in which 2 sibs had CMS-EA, Kraner et al. (2003) identified ...