KCNC3 encodes Kv3.3, a voltage-gated potassium channel critical for neuronal excitability. The channel exhibits rapid activation and inactivation kinetics 12, enabling fast-firing neurons to repolarize quickly. In cerebellar Purkinje cells, KCNC3 regulates action potential frequency, shape, and duration, thereby controlling calcium homeostasis and neuronal survival 3. The channel also organizes cortical actin cytoskeleton structures in neuronal growth cones through interactions with HAX1 and the Arp2/3 complex 4. KCNC3 is required for normal motor function 25. Mutations in KCNC3 cause spinocerebellar ataxia type 13 (SCA13), a neurodegenerative disorder presenting with variable onset and severity 6. Disease-causing mutations alter channel function through distinct mechanisms: some eliminate channel activity with dominant-negative effects (e.g., R420H) 7, others shift activation voltage curves, affecting neuronal firing patterns 8. The R420H mutation exhibits aberrant intracellular trafficking, with reduced surface expression and Golgi retention 9. SCA13 manifests as early-onset developmental delay or late-onset cerebellar ataxia, often accompanied by epilepsy, cognitive impairment, and progressive myoclonus 1011. Estimated KCNC3-related SCA13 prevalence in the Netherlands is 0.6-1.3% 8.