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GENATLAS PHENOTYPE

last update : 03-06-2010

Symbol	EA2
Location	19p13.2
Name	episodic ataxia, type 2
Other name(s)	episodic (paroxysmal) vestibular cerebellar ataxia 2 cerebellopathy, hereditary paroxysmal
Corresponding gene	CACNA1A
Other symbol(s)	APCA
Main clinical features	beginning in the first or second decade, with long lasting dysarthria, vertigo, migraines and interictal nystagmus, atrophy of the cerebellar vermis, acetazolamide responsive, without myokymia may be associated to primary generalized epilepsy, allelic to SCA6 or to ataxic spells induced by fevers or high environmental temperature
Genetic determination	autosomal dominant
Function/system disorder	neurology
Type	disease

Gene product

Name	calcium voltage gated channel (CACNA1A)

Mechanism(s)

Gene mutation	Chromosome rearrangement	Effect	Comments
unknown		abnormal protein/loss of function	point mutation or a moderate expansion of the CAG repeat
missense			deficiency in protein misfolding and trafficking associated with the C287Y and G293R mutants may contribute to the slowly progressive cerebellar ataxia

Remark(s)

mutation in the intracellular domain between s4 and s5 of repeat 3 can cause atypical nystagmus/cerebellar phenotypes, including isolated nystagmus

Genotype/Phenotype correlations

mutations in the pore-forming subunit of the P/Q-type calcium channels associated to episodic ataxia in childhood and late-onset dystonia