OBJECTIVETo investigate the CAG trinucleotide repeat expansion and clinical characteristics of a Chinese Uygur family with spinocerebellar ataxia type 12 (SCA12) in Xinjiang Uygur Autonomous Region.

METHODSIn the Uygur SCA12 family, 6 patients and 54 "healthy" members were analyzed by polymerase chain reaction, agarose gel electrophoresis, recombinant DNA technology by T-Vector cloning and restriction enzyme digestion, and direct sequencing. The diagnosis of SCA12 was confirmed. The CAG trinucleotide expansion was also analyzed.

RESULTSSix members in the family were diagnosed as SCA12 patients and 13 were presymptomatic. Five of them were successfully detected by sequencing. The CAG repeat numbers of 4 patients were 47, 51, 52 and 53, respectively, and 48 in the presymptomatic patient. We also observed that in the CAG repeat region there was replacement of single nucleotide C, A or G.

CONCLUSIONForty-seven CAG repeats of SCA12 has been reported as the shortest known causative expanded alleles. The present study is the first report of the characteristics of SCA12 gene mutation in Chinese. It will provide basis for the accurate classification, disease etiology, treatment and prenatal diagnosis of this disease.