KCNA1 and hereditary continuous muscle fiber activity: Episodic ataxia type 1 (EA1) is an autosomal dominant ion channel disorder mainly caused by missense variants in the KCNA1 gene on chromosome 12 (1) encoding the α-subunit of the voltage-gated potassium channel KV1.1 (Figure 1), which are expressed in the peripheral and the central nervous system including cerebellum and mostly present as heterotetramers with KV1.2 and KV1.4 subunits (2).