中文摘要：

目的建立遗传性脊髓小脑性共济失调（SCA）亚型中核苷酸重复序列稳定、准确、直观的检测技术方法和平台。方法运用荧光聚合酶链反应、8％变性聚丙烯酰胺凝胶电泳、毛细管凝胶电泳、重组DNA结合直接测序等技术对50例诊断为SCA3／MJD患者的CAG三核苷酸病理重复次数进行检测．并对运用毛细管凝胶电泳和重组DNA两种方法得到的不同的CAG病理重复次数进行对比分析。结果50例8％变性聚丙烯酰胺凝胶电泳检测为SCA3／MJD的患者，毛细管凝胶电泳检测方法得到的CAG三核苷酸病理重复次数范围为63～74次，平均（69．56±2．12）次；重组DNA结合直接测序得到的CAG三核苷酸病理重复次数范围为67—80次，平均（73．72±3．29）次。毛细管凝胶电泳计算所得到的CAG三核苷酸病理重复次数有减少的趋势，和应用重组DNA技术得到的结果相比差异有统计学意义（r=-9．610，P=0．000）。结论变性聚丙烯酰胺凝胶电泳、毛细管凝胶电泳可以对核苷酸重复序列进行初步筛选，最终重复核苷酸序列的确定仍需要直接测序；重组DNA结合直接测序技术是检测SCA各亚型核苷酸重复次数和分析核苷酸多态性的一种稳定、准确和直观的技术方法。

英文摘要：

Objective To determine a stable, exact and direct detection method for expanded nucleotide repeat sequences of the causative gene in patients with hereditary spinocerebellar ataxias （SCAs）. Methods Quantitative fluorescent-polymerase chain reaction, 8% denaturing polyacrylamide gel electrophoresis （PAGE）, capillary electrophoresis （CE） and recombinant DNA technology by direct sequencing technique were employed to detect the CAG-repeat numbers of abnormal allele in 50 patients diagnosed as having SCA3/MJD. And then, the differences of CAG repeat numbers detected by CE and recombinant DNA technology were statistically analyzed. Results Of the 50 patients with SCA3/MJD detected by 8% denaturing PAGE, the expanded CAG repeat numbers measured by CE and recombinant DNA technology ranged from 63 to 74 （69.56±2.12） and from 67 to 80 （73.72±3.29）, respectively. Significantly decreasedtendency was showed in the mean CAG repeat numbers of 69.56±2.12 using CE as compared with that in those of 73.72±3.29 using recombinant DNA technology, （t=-9.61, P=0. 000）. Conclusion Denaturing PAGE and CE can be used as preliminary screening for nucleotide repeat numbers, while the exact numbers depend on the recombinant DNA and direct sequencing technologies. Recombinant DNA technology combined with direct sequencing is a predominant, stable, exact and direct method to detect the repeat numbers of SCAs and analyze the polymorphism of nucleotide sequence.