中文摘要：

目的 优选出与运动神经元生存（survival motor neuron，SMN）基因紧密连锁且多态信息含量丰富的短串联重复序列（STR）位点，并将其应用于脊髓性肌萎缩症（spinal muscular atrophy，SMA）产前基因诊断中。方法 用PCR扩增与SMN基因紧密连锁的11个STR位点，聚丙烯酰胺凝胶电泳（PAGE）检测，银染法显色分析结果。通过多态信息含量（PIC）大小优选STR位点，并利用优选出的STR位点分别采用PCR-PAGE及基因扫描技术对6个SMA家系（包括父母、先证者和胎儿）进行连锁分析。结果我们从11个STR位点中优选出了3个位点（D5S435、D5F149、D5S351），这3个位点在100名健康人中分别检测出8、19、18种多态性片段，其PIC值分别为0．84、0．91、0．92。应用上述3个位点对6个SMA家系进行产前诊断连锁分析，在6名胎儿中发现4名携带者和2名健康者。结论 通过优选出的3个STR位点可快速进行SMA产前基因诊断，准确地排除母血污染，而且可在胎儿中甄别出健康个体与基因携带者，进一步完善了SMA产前基因诊断体系。

英文摘要：

Objective To optimize the short tandem repeats （STR） which link closely to survival motor neuron （SMN） and have redundant polymorphism information contents, and to use these STR in the prenatal diagnosis of spinal muscular atrophy （SMA）. Methods Eleven STR loci （ D5S435, D5FI53, D5F151, D5S637, D5S1413, D5S125, D5S464, D5S1556, D5F149, D5S351, MAP1B-5＇） were amplified by PCR. Then the PCR products were detected by polyacrylamide gel electrophoresis （PAGE） and analyzed by silver staining. STR loci were evaluated and optimized by their PIC values. PCR-PAGE and gene scan were combined to make genetic link analysis for SMA families based on the optimized STR. Results Three STR loci （D5S435, D5F149 and D5S351 ） were selected with 8, 19 and 18 polymorphic fragments detected respectively in 100 normal individuals. Their PIC values were 0. 84, 0. 91 and 0. 92 respectively. Four carriers and 2 normal individuals were detected from 6 SMA families with linkage analysis by using the 3 STR. Conclusion This genetic diagnosis system based on the 3 STR loci can provide rapid prenatal diagnosis for SMA families, can eliminate maternal blood contamination, and also can discriminate carriers from normal individuals in the fetuses, which makes the prenatal diagnosis system of SMA perfect.