DNA分析法快速诊断21三体综合征

目的　建立适合于快速诊断 2 1三体的 DNA分析方法。方法　用 PCR法扩增 2 1号染色体上 2个串联重复序列 D2 1S1435和 D2 1S2 0 5 5基因座 ,聚丙烯酰胺凝胶电泳 ,银染分型。根据谱带的条数和浓度判断是否为2 1三体 ,根据谱带的位置 ,与父母的基因型比对 ,判断三体的亲代来源。结果　应用此法检出所有核型分析确诊的游离型 2 1三体 ,能准确地判断出三体的亲代来源。结论　该法无须细胞培养 ,适于含一定 DNA的各种有核细胞样本 ,检测过程简便、快速 ,较传统方法省时、省力 ,适于大范围的 2 1三体综合征筛查

A Method for Rapid and Early Diagnosis of Trisomy 21 Using Molecular Techniques

Objective Using molecular techniques, we typed 2 short tandem repeat (STR) loci on 21 chromosome to establish the method for rapid and accurate diagnosis of trisomy 21. Methods Genomic DNA samples from 50 individuals diagnosed previously by karyotype as trisomy 21 and 40 children with severe mental retardation (IQ<50) suspected of trisomy 21 were analyzed for 2 short tandem repeat loci on 21 chromosome, D21S1435 and D21S2055. Typing was carried out after polymerase chain reaction (PCR) and silver staining. The trisome was identified by the number of alleles: 3 alleles bands whose density is same, two alleles bands with one obvious higher density compared to the other and one allele band whose density is three times than the normal control. Results All of the complete trisomy 21 were detected by this method; the parental source was easily determined. Conclusion This method for diagnosing trisomy 21 is rapid and accurate.