Spinocerebellar Ataxia Type 8

Spinocerebellar ataxia type 8 (SCA8) is a subtype of type I autosomal dominant cerebellar ataxia (ADCA type I; see this term) characterized by cerebellar ataxia and cognitive dysfunction in almost three quarters of patients and pyramidal and sensory signs in approximately a third of patients.

Epidemiology

Prevalence is unknown. However, SCA8 accounts for approximately 3% of ADCA cases.

Clinical description

Other features include dysexecutive disorders and commonly psychiatric disorders.

Etiology

SCA8 is caused by a trinucleotide repeat on 13q21 that produces a polyglutamine expansion in the ataxin 8 gene (ATXN8). SCA8 is thought to result from RNA-mediated neurotoxicity.

Prognosis

Prognosis is relatively good. Disease usually progresses slowly over decades. Life expectancy is not significantly reduced.