孕妇血浆中胎儿DNA在产前诊断中的应用

Detection of fetal DNA in maternal plasma for prenatal diagnosis

目的依据孕妇血浆中存在游离胎儿DNA的理论，寻找一种无创性产前基因诊断的新方法。方法提取42例孕14-40周的产妇血浆中游离胎儿DNA，采用引物延伸预扩增（primer extension preamplification，PEP）后行PCR，特异性扩增其Y染色体重复序列（DYZ3）基因。同时采用9个短串联重复序列（short tandem repeat，STR）多态性位点的多重扩增方法以检出血浆中胎儿DNA。结果DYZ3-PCR中，32例妊娠男性胎儿孕妇中有28例血浆中出现基因扩增带，检出率为87．5％，10例妊娠女性胎儿孕妇血浆有2例假阳性结果。性别总符合率为85．7％，STR-PCR中，检测出孕妇血浆中父源性胎儿DNA的存在。结论应用孕妇血浆中胎儿DNA作产前诊断敏感性和特异性较高，是一种无创性产前基因诊断方法，具有广泛的临床应用前景。

Objective To explore the application of fetal DNA in maternal plasma for non-invasive prenatal diagnosis. Methods The DNA template was extracted by QIAamp Blood DNA midi kit from 42 maternal （14-40 weeks） plasma. A Y-chromosome-specific repeat sequence DYZ3 gene was chosen to be amplified after primer extension preamplification （PEP） based-PCR. Multiplex PCR amplification at nine different polymorphic short tandem repeat loci was applied to detect the fetal DNA in maternal plasma. Results The fragment was identified in all maternal plasma bearing male fetus. The detection rate was 87. 5% （28 cases） among 32 with male fetus and 2 false positive results were found in 10 women with female fetus. The final accuracy of 85.7% was obtained in all cases. The paternal allele gene sequences were detected by STR-PCR. Conclusions Detecting fetal DNA in maternal plasma is a non-invasive prenatal gene diagnosis with high sensitivity and specificity and is very promising in clinical practice.