应用引物延伸预扩增反应技术检测孕妇血浆中的胎儿DNA

目的：建立一种检测孕妇血浆中胎儿DNA的新方法。方法；对65例5－41孕周的孕妇血浆中胎儿DNA采用引物延伸预扩增（PEP）后行特异性位点聚合酶链反应（PCR）扩增，并用探针微孔板杂交法检测PCR产物。扩增的基因为Y染色体短臂SRY基因，扩增片段的大小分别为351bp和254bp。结果：46例妊娠男性胎儿的孕妇中41例血浆中出现SRY基因扩增带，检出率89．13％；19例妊娠女性胎儿的孕妇中3例（15．79％）为假阳性。本研究孕早、中、晚期的性别符合率分别为100％、90．91％、75％，总符合率86．15％。结论：利用PEP法能解决孕妇外周血中胎儿细胞数量太少达不到常规扩增条件所要求的最低模板量的问题，同时配合探针微孔板杂交法能使诊断结果更准确。

Detection of fetal DNA using primer extension preamplification followed by nested PCR

Objective:To establish the new technology for detection of fetal DNA in maternal plasma.Methods:A single copy human SRY gene of Y chromosome of fetal DNA sequence from 65 pregnant maternal plasma(5 41 weeks) was amplified by PEP based PCR and detected by special probe microplate hybridization.A 351bp and 254bp male specific fragment was obtained.Results:The fragment was identified in 41 of 46 male bearing pregnant women plasma.The diagnosis accordance rate was 89.13%.Only 4 of 19 female bearing pregnant women has positive results.Among the 65 pregnant women,the diagnosis accordance rate was 100% at early pregnant stage,90.91% at medium pregnant stage,75% at late pregnant stage.The final accuracy of 86.15%(56/65) was attained in all cases.Conclusion:The new technology called primer extention preamplification (PEP) can increase the amount of polymerase chain reaction (PCR) templates by amplifying fetal DNA of the whole genome,and then using special probe microplate hybridization to detect the PCR product.So PEP matching with microplate hybridization made successfully the diagnosis more accurate.