Several heterozygous mutations in the KCNA1 gene, which encodes the Kv1.1 subunit, have been identified in episodic ataxia type 1 (EA1), a familial disorder characterized by paroxysmal cerebellar incoordination and interictal myokymia, and occasionally with other features such as epilepsy4, 5, 6, 7, 8. The gene discussed is KCNA1; the disease is episodic ataxia type 1.