脊髓小脑性共济失调12型维吾尔族一家系的基因突变及临床特点

Gene mutation and clinical characteristics of a Chinese Uygur family with spinocerebellar ataxia type 12

目的 研究新疆地区维吾尔族脊髓小脑性共济失调12亚型（spinocerebellar ataxia type 12,SCA12）致病基因的CAG三核苷酸病理重复次数范围及临床特点.方法 依据Harding标准,收集一个维吾尔族家系,应用聚合酶链反应、琼脂糖凝胶电泳、T载体分子克隆技术并结合酶切鉴定、直接测序等技术对其中6例患者、54例家系＂健康＂个体进行分子遗传学诊断,基因诊断为SCA12型,同时对致病基因CAG三核苷酸病理重复次数进行突变分析.结果 发现该家系SCA12型患者6例,症状前患者13例.5例经基因重组检测发现：患者异常等位基因CAG重复数目分别是47次、51次、52次、53次;症状前患者是48次;其中在连续CAG重复中间有单个碱基C、A、G的互相替换.结论 SCA12型的47次CAG病理重复次数为国内外报道的最小CAG病理重复次数;国内首次对维吾尔族SCA12型的基因突变特点进行分析,从而对于该类疾病的准确分类、病因探讨、治疗、产前诊断等具有重要的意义.

Objective To 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. Methods In 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. Results Six members in the family were diagnosed as SCA12 patients and 13 were presymptomatic. Five of them were successfully detected by sequencing. The CAGrepeat 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.Conclusion Forty-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.