Dominant-negative mutation p.Arg324Thr in KCNA1 impairs Kv1.1 channel function in episodic ataxia.

BackgroundEpisodic ataxia type 1 is a rare autosomal dominant neurological disorder caused by mutations in the KCNA1 gene that encodes the subunit of voltage-gated potassium channel Kv1.1. The functional consequences of identified mutations on channel function do not fully correlate with the clinical phenotype of patients. MethodsA clinical and genetic study was performed in a family with 5 patients with episodic ataxia type 1, with concurrent epilepsy in 1 of them. Protein expression, modeling, and electrophysiological analyses were performed to study Kv1.1 function. ResultsWhole-genome linkage and candidate gene analyses revealed the novel heterozygous mutation p.Arg324Thr in the KCNA1 gene. The encoded mutant Kv1.1 channel displays reduced currents and altered activation and inactivation. ConclusionsTaken together, we provide genetic and functional evidence that mutation p.Arg324Thr in the KCNA1 gene is pathogenic and results in episodic ataxia type 1 through a dominant-negative effect. (c) 2016 International Parkinson and Movement Disorder Society