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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。
Objective To select short tandem repeat (STR) loci which are closely linked with survival motor neuron (SMN) gene and rich in polymorphic information, and apply it to spinal muscular atrophy SMA) prenatal genetic diagnosis. Methods 11 STR loci closely linked to SMN gene were amplified by PCR, detected by polyacrylamide gel electrophoresis (PAGE) and analyzed by silver staining. STR loci were selected according to the size of polymorphic information content (PIC), and 6 SMA families (including parents, probands and fetuses) were analyzed by PCR-PAGE and gene scanning using the preferred STR loci. Results We selected 3 sites (D5S435, D5F149, D5S351) out of 11 STR loci, 8,19,18 polymorphic fragments were detected in 100 healthy individuals PIC values were 0.84, 0.91, 0.92, respectively. Prenatal diagnosis of six SMA pedigrees was performed using the above three loci, and four carriers and two healthy individuals were found in six fetuses. Conclusion The prenatal genetic diagnosis of SMA can be rapidly performed through the optimized 3 STR loci and the maternal blood contamination can be accurately excluded. Moreover, healthy individuals and gene carriers can be identified in the fetus, which further improves the prenatal genetic diagnosis system of SMA.