KCND3 and Parkinson disease: Loss-of-function mutations in the human KCND3 gene, which encodes the KV4.3 channel, have been associated with spinocerebellar ataxia type 19 and 22 (SCA19/22), a clinically heterogeneous group of neurodegenerative disorders characterized by variable degrees of cerebellar ataxia, parkinsonism, cognitive dysfunction, epilepsy, and extrapyramidal signs (MIM#607346) [6,7,8,9,10].