Objective: To study the normal range of (CTA/CTG)n repeats of ATXN8OS gene in Chinese Hans, and the frequency of ATXN8OS (CTA/CTG)n repeat expansion in spinocerebellar ataxia(SCA) patients in Mainland China.
Methods: The (CTA/CTG)n repeats of ATXN8OS gene were detected using fluorescence-PCR, 8% denaturing polyacrylamide gel and capillary electrophoresis technique in 132 SCA patients in whom CAG expansion at the SCA1, SCA2, SCA3, SCA6, SCA7, SCA12, SCA17 and dentatorubral-pallidoluysian atrophy(DRPLA) loci has been excluded, and 261 healthy controls.
Results: There were no obvious abnormal changes of the (CTA/CTG)n repeats of ATXN8OS gene in the 132 SCA patients. Thirty-five SCA patients were homozygotes (26.5%), and the range of CTA/CTG repeat number was 17 to 47 (24.20+/-4.57), among which 18 repeats appeared most frequently. In 261 normal controls, 70 were homozygotes (26.8%), and the range of the CTA/CTG repeat number was from 12 to 43 (24.04+/-4.53), among which 18 repeats was the most frequent.
Conclusion: SCA8 is a rare subtype of SCA in Mainland China. The low prevalence of SCA8 seems to be correlated with the low frequency of large (CTA/CTG)n copy number alleles in Chinese population.