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Episodic Ataxia type 2 (EA2)
EA2 is an autosomal dominantly inherited disorder with episodes of markedly impaired upper-body ataxia lasting hours to days, with interictal eye movement abnormalities. About 50% of individuals with EA2 have migraine headaches. Attacks can be triggered by stress, exertion, caffeine, alcohol, and phenytoin. Attacks can be stopped or decreased in frequency and severity by administration of acetazolamide. Between attacks, individuals may initially be asymptomatic but eventually develop interictal findings that can include nystagmus and ataxia.
EA2 is caused by mutations of a calcium channel gene CACNA1A on 19p, which is highly expressed in the cerebellum.Mutations in this gene are also associated with familial hemiplegic migraine (FHM) and spinocerebellar ataxia type 6 (SCA6).
