Genetic and clinical analyses of spinocerebellar ataxia type 8 in mainland China.

BACKGROUND

Spinocerebellar ataxia type 8 (SCA8) is a rare autosomal dominant neurodegenerative disease caused by CTA/CTG repeat expansion in the ATXN8/ATXN8OS gene.

METHODS

To analyze the frequency and clinical characteristics of SCA8 patients in mainland China, we combined polymerase chain reaction (PCR) and triplet repeat-primed PCR (TRP-PCR) to detect the CTA/CTG expansion. We studied a cohort of 362 ataxia patients in which the other known causative genes had been previously excluded, from among 1294 index patients. Positive samples were validated by southern blotting.

RESULTS

The CTA/CTG expansion was observed in six probands, accounting for approximately 0.46% (6/1294) in all patients, and 1.66% (6/362) in patients without definite molecular diagnosis. Clinically, aside from the typical SCA8 phenotype, some patients carrying the CTA/CTG expansion exhibited the cerebellar form of multisystem atrophy (MSA-C) and ataxia with paroxysmal kinesigenic dyskinesia (PKD).

CONCLUSION

For the first time, we described the PKD phenotype in association with CTA/CTG expansion, suggesting that CTA/CTG expansion might play a role in the pathogenesis of paroxysmal dyskinesia symptoms.