KCNC3 and spinocerebellar ataxia type 13: Interestingly, spinocerebellar ataxia type 13 (SCA13) caused by mutations in KCNC3/KV3.3, also exists in distinct forms which have been associated with a phenotypic spectrum that includes both non-progressive congenital-onset ataxia and (slowly) progressive infancy to adult-onset cerebellar ataxia.