EPISODIC ATAXIA MYOKYMIA SYNDROME IS ASSOCIATED WITH POINT MUTATIONS IN THE HUMAN POTASSIUM CHANNEL GENE, KCNA1

Episodic ataxia (EA) is a rare, familial disorder producing attacks of generalized ataxia, with normal or near-normal neurological function between attacks. One type of EA is characterized by brief episodes of ataxia with myokymia (rippling of muscles) evident between attacks. Li nkage studies in four such families suggested localization of an EA/my okymia gene near the voltage gated K+ channel gene, KCNA1 (Kv1.1), on chromosome 12p. Mutation analysis of the KCNA1 coding region in these families identified four different missense point mutations present in the heterozygous state, indicating that EA/myokymia can result from m utations in this gene.