先天愚型的快速基因诊断

RAPID GENETIC DIAGNOSIS OF DOWN’S SYNDROME

目的 探索一种简便、快速的先天愚型基因诊断方法。方法 选择先天愚型关键区域(Downsyndromecriticalregion ,DSCR)内部及附近的 4个短串联重复序列 (shorttandemrepeats ,STR)D2 1S1432、D2 1S1437、D2 1S12 70、D2 1S144 6 ,采用PCR -SSLP方法结合定量分析。 结果 先天愚型患者在某一STR位点的检测结果分 3种情况。①表现为该位点 3个不同等位基因的杂合子 ,PCR产物电泳结果显示 3条带 ,DNA定量结果接近 1:1:1;②表现为该位点 2个不同等位基因的杂合子 ,PCR电泳结果显示 2条带 ,DNA定量结果接近 2 :1;③表现为该位点某一等位基因的纯合子 ,PCR产物电泳结果显示 1条深带。结论 利用上述 4个STR多态位点 ,采用PCR -SSLP结合定量分析技术 ,可对先天愚型中的 2 1三体和部分三体作出快速而准确的基因诊断。

Objective To explore a simple and convenient genetic analysis of Down's syndrome.Methods PCR-SSLP Method and quantitative analysis were applied to D21S1432、D21S1437、D21S1270、D21S1446 inside and near the Down's syndrome critical region(DSCR).Results The determination results of the STR sites present three types.In Type One,a heterogote of 3 different allelic genes was discovered.The electrophoretic results of PCR products showed 3 bands and the quantitative result was approximately 1:1:1.In Type Two,a heterozygote of 2 different allelic genes was found.The electrophoretic results showed 2 bands and the quantitative result was approximately 2:1.In Type Three,a homozygote of one allelic gene was detected.The electrophoretic result showed 1 hyperchromatic band.Conclusion A Rapid and accurate genetic diagnosis of trisomy 21 and some other trisomies in the cases of Down's syndrome can be made by using the 4 STR polymorphous sites mentioned above and the PCR-SSLP method combined with a quantitative analysis.