To test the hypothesis that the P403A variant altered Kv1.1 function and caused epilepsy and ataxia in the affected patient, we transfected HEK 293 cells with equal amount of WT (5 μg) or P403A (5 μg) cDNAs alone or in 1:1 ratio (5 μg + 5 μg). The gene discussed is KCNA1; the disease is cerebellar ataxia.