Hereditary continuous muscle fiber activity

General Information (adopted from Orphanet):

Synonyms, Signs: CONTINUOUS MUSCLE FIBER ACTIVITY, HEREDITARY, INCLUDED
MYOKYMIA WITH PERIODIC ATAXIA MYOKYMIA 1, INCLUDED
ATAXIA, EPISODIC, WITH MYOKYMIA
MYOKYMIA 1 WITH OR WITHOUT HYPOMAGNESEMIA, INCLUDED
PAROXYSMAL ATAXIA WITH NEUROMYOTONIA, HEREDITARY
EPISODIC ATAXIA WITH MYOKYMIA
ISAACS-MERTENS SYNDROME, INCLUDED
EA1
AEM
EAM
AEMK
Isaacs-Mertens syndrome
Number of Symptoms 28
OrphanetNr: 972
OMIM Id: 160120
ICD-10: G71.1
UMLs:
MeSH:
MedDRA:
Snomed:

Prevalence, inheritance and age of onset:

Prevalence: No data available.
Inheritance: Autosomal dominant inheritance
[Omim]
Age of onset: Juvenile onset
[Omim]

Disease classification (adopted from Orphanet):

Parent Diseases: Non-dystrophic myopathy
 -Rare genetic disease
 -Rare neurologic disease

Symptom Information: Sort by abundance 

1
(HPO:0002321) Vertigo 58 / 7739
2
(HPO:0100022) Abnormality of movement Very frequent [Orphanet] 129 / 7739
3
(HPO:0001347) Hyperreflexia 363 / 7739
4
(HPO:0001276) Hypertonia Very frequent [Orphanet] 317 / 7739
5
(HPO:0001337) Tremor 200 / 7739
6
(HPO:0002066) Gait ataxia Frequent [Orphanet] 327 / 7739
7
(HPO:0003487) Babinski sign 179 / 7739
8
(HPO:0002167) Neurological speech impairment Frequent [Orphanet] 308 / 7739
9
(HPO:0001250) Seizures Occasional [Orphanet] 1245 / 7739
10
(HPO:0001260) Dysarthria 329 / 7739
11
(HPO:0002315) Headache 175 / 7739
12
(HPO:0002131) Episodic ataxia 16 / 7739
13
(HPO:0001350) Slurred speech 16 / 7739
14
(HPO:0002064) Spastic gait 46 / 7739
15
(HPO:0000775) Abnormality of the diaphragm Occasional [Orphanet] 62 / 7739
16
(HPO:0003457) EMG abnormality Very frequent [Orphanet] 78 / 7739
17
(OMIM) Jerking movements of face and limbs 2 / 7739
18
(OMIM) Incoordination of the hands 2 / 7739
19
(OMIM) Myokymia, interictal 2 / 7739
20
(HPO:0030089) Abnormal muscle fiber protein expression Very frequent [Orphanet] 64 / 7739
21
(OMIM) Episodic vertigo 4 / 7739
22
(OMIM) Leg stiffness 2 / 7739
23
(OMIM) [DEL]Increased serum creatine kinase during episodes 3 / 7739
24
(OMIM) Calf muscle enlargement 2 / 7739
25
(OMIM) Muscle biopsy shows enlargement of type I muscle fibers, consistent with denervation 2 / 7739
26
(OMIM) Hand posture resembling carpopedal spasm, episodic 2 / 7739
27
(OMIM) Blurred vision, episodic 3 / 7739
28
(OMIM) EMG shows polyphasic continuous motor unit discharges 2 / 7739

Associated genes:

ClinVar (via SNiPA)

Gene symbol Variation Clinical significance Reference

Additional Information:

Description: (OMIM) Episodic ataxia is a neurologic condition characterized by spells of incoordination and imbalance, often associated with progressive ataxia (Jen et al., 2007).

- Genetic Heterogeneity of Episodic Ataxia

Episodic ataxia is a genetically heterogeneous ...

Clinical Description OMIM Van Dyke et al. (1975) described a kindred in which 11 persons in 3 consecutive generations had continuous muscle movement (myokymia) and periodic ataxia. Only 2 of the 11 affected were male and no male-to-male transmission was noted. ...
Molecular genetics OMIM Browne et al. (1994) demonstrated mutations in the KCNA1 gene in 4 families with AEMK (176260.0001-176260.0004). A different missense point mutation was present in heterozygous state in each. All affected individuals are heterozygous.

In 2 families ...