Spinocerebellar ataxia type 22

Spinocerebellar ataxia type 22 (SCA22) is a rare, slowly progressive autosomal dominant cerebellar ataxia. It was originally described in a large Chinese family and has since been recognized as allelic with spinocerebellar ataxia type 19 (SCA19), with both conditions now often referred to as SCA19/SCA22. The disease is caused by mutations in the KCND3 gene, which encodes a voltage-gated potassium channel subunit (Kv4.3) important for neuronal signaling. The primary body system affected is the central nervous system, particularly the cerebellum, leading to progressive gait and limb ataxia. Key clinical features include slowly progressive cerebellar ataxia with gait unsteadiness, dysarthria (slurred speech), and impaired coordination. Some patients may also develop cognitive impairment, nystagmus, and mild peripheral neuropathy. Cerebellar atrophy is typically observed on brain imaging. The severity and rate of progression can vary considerably, even within the same family. Onset is generally in adulthood, though age of onset can range from childhood to late adulthood. There is currently no cure or disease-modifying treatment for SCA22. Management is supportive and symptomatic, including physical therapy and occupational therapy to maintain mobility and function, speech therapy for dysarthria, and assistive devices as needed. Genetic counseling is recommended for affected families given the autosomal dominant inheritance pattern.

Common questions about Spinocerebellar ataxia type 22