Episodic ataxia type 1 (EA1) is an autosomal dominant and sporadic neurological disorder characterized by frequent, short-lasting attacks of uncoordinated movements and involuntary, repetitive muscle contraction (myokymia); genetic analyses indicate that EA1 is associated with mutations in the KCNA1 gene on chromosome 12p that encodes the human Kv1.1 α subunit18, 19, 20, 21, 22. Here, KCNA1 is linked to hereditary continuous muscle fiber activity.