SCA36

SCA36, or spinocerebellar ataxia type 36, is a rare hereditary neurodegenerative disorder classified among the spinocerebellar ataxias. It presents with progressive problems of balance and coordination, including gait ataxia and limb ataxia, often accompanied by speech disturbance (dysarthria) and nystagmus. The onset is typically in adulthood, but age at onset can range from adolescence to late adulthood, and progression is gradual.

Genetics: SCA36 is caused by expansion of a hexanucleotide repeat, GGCCTG, in the NOP56 gene. It is inherited in an autosomal dominant pattern. The disease is part of the group of repeat expansion disorders; larger repeats tend to correlate with earlier onset and more severe disease, reflecting anticipation in some families.

Diagnosis: Suspected based on clinical features and family history; confirmation requires genetic testing showing the pathogenic hexanucleotide repeat expansion in NOP56. Brain MRI commonly shows cerebellar atrophy, sometimes with pontine or brainstem involvement.

Management: There is no disease-modifying therapy. Management is supportive and multidisciplinary, including physical therapy, balance training, occupational therapy, and speech therapy for dysarthria, with assistive devices as needed. Regular monitoring for progression and complications is recommended. Genetic counseling is advised for affected individuals and their families.

Prognosis: The disease course is variable, generally progressive over years. Life expectancy may be affected by gait impairment, aspiration risk, and falls, but many individuals maintain functional independence for extended periods.