KCNA1 and hereditary continuous muscle fiber activity: The first K+ channel gene directly linked to a human disease was KCNA1. Linkage studies and mutation analysis identified 4 different KCNA1 dominant missense mutations across 4 families that caused the neurological disease episodic ataxia type 1 (EA1), which is characterized by periodic stress-induced incoordination and myokymia (i.e., muscle rippling) [31].