妊娠早期孕妇外周血中胎儿游离DNA的定量分析

Quantitative analysis of fetal cell-free DNA in maternal plasma at early pregnant stage

目的对早孕期孕妇外周血中胎儿游离DNA行定量分析,以确定正常浓度范围,为实施无创性产前诊断提供科学依据。方法从孕早期50名孕妇外周血血浆中提取胎儿DNA,用实时荧光定量聚合酶链反应(fluorescence quantitative poly-merase chain reaction,FQ-PCR)技术检测其中的Y性别决定区(sex-determining region Y,SRY)基因。结果早孕期孕男胎的孕妇38名,32名SRY基因阳性,平均浓度为(149.25±1.96×59.17)拷贝数/ml,中位数为149.1拷贝数/ml。孕女胎的孕妇12名均为阴性。结论用实时荧光定量PCR的方法从早孕7、8、9w孕妇外周血浆中检测胎儿SRY基因,特异度100%,灵敏度84.21%。提示母体血浆中游离的胎儿DNA的定量分析在无创性产前诊断中有重要价值。

Objective ： A mean concentration was shown by quantitative analysis of fetal cell- free DNA in maternal plasma. Methods： Fetal DNA in maternal plasma was isolated from 50 samples （range, 7 - 9weeks） . Fetal DNA in maternal plasma was measured using real - time fluorescence quantitative polymerase chain reaction （FQ- PCR） for the SRY gene on the Y chromosome. Results：38 women at early pregnant stage （ range, 7 - 9weeks） carried male fetuses, 32 samples of them were positive. The mean concentrations in women carrying male fetuses were（ 149.25 ± 1.96 × 59.17） copies/ml. The median fetal DNA levels were 149.1 copies/ml. The results of FQ- PCR were negative in the 12 women who carried female fetuses. Conclusions The results show that fetal SRY gene can be found at early pregnant stage in maternal plasma by the use of FQ - PCR. The specificity, of the system reaches 100% and the sensitivity 84.21%. Quantitative analysis of fetal cell - free DNA in maternal plasma is of great value in the non - invasive prenatal diagnosis .