KCNC3 and spinocerebellar ataxia type 13: Kv3.3 pathogenic variants, which cause spinocerebellar ataxia 13 (SCA13), have similar voltage sensor mutations (R420H and R423H) and other regions, including the N-terminus, the S1, S5 and S6 segments, and the C-terminus (Zhang and Kaczmarek, 2016).