Spinocerebellar ataxia type 13

Spinocerebellar ataxia type 13, abbreviated SCA13, is a rare autosomal dominant disorder of the cerebellum. As with other spinocerebellar ataxias, it is marked by slurred speech, involuntary eye movements and unsteadiness of gait, stance and the limbs. Patients also tend to have epilepsy, an inability to run and exaggerated reflexes. The cerebellar dysfunction is permanent and progressive. The cause is mutation of KCNC3, a gene that encodes the voltage-gated potassium channel KV3.3. Two mutations are known, and unlike many other forms of the disease they are point mutations that leave channels with no current or altered kinetics rather than polyglutamine expansions.