KCNC3 and spinocerebellar ataxia type 13: Notably, a tremor phenotype has been described in patients with mutations in KCNA1 (Kv1.1; EA; OMIM 160120)8 and missense dominant negative mutations in KCNC3 (Kv3.3) are associated with hyperexcitability, cerebellar neurodegeneration and subsequent movement defects including spinocerebellar ataxia (SCA13; OMIM 605259)9.