母体循环中胎儿游离DNA的定量分析

Detection of fetal SRY gene in maternal plasma by real-time fluorescence quantitative PCR

目的依据孕妇血浆中存在游离胎儿DNA的理论,从孕妇外周血浆中分离出胎儿DNA并加以鉴定,预防X连锁遗传病患儿的出生。方法从孕早期、中期共78名孕妇外周血浆中分离胎儿DNA,用实时荧光定量聚合酶链反应(fluorescence quantitative polymerase chain reaction,FQ-PCR)的方法检测其中的Y性别决定区(sex-determining region Y,SRY)基因。结果孕早期怀男胎的孕妇28名,25名SRY基因阳性,其平均浓度为(58.82±25.22)拷贝/ml;孕中期怀男胎的孕妇20名,SRY基因均为阳性,平均为(152.08±62.61)拷贝/ml;怀女胎的孕妇均为阴性。结论用实时荧光定量PCR的方法最早在孕62天的孕妇外周血浆中就可以检测到胎儿SRY基因,随孕周的增加,母血中胎儿DNA的量也在逐渐增加。实时荧光定量PCR技术在进行无创伤性产前性别诊断中有重要的价值。

Objective： To isolate fetal DNA from maternal plasma and examine its fetal origin. Methods： Fetal DNA in maternal plasma was isolated from 40 cases in the first trimester and 38 in the mid - trimester of pregnancy, respectively. Real - time Fluorescence Quantitative Polymerase Chain - reaction （ FQ - PCR） was used to determine sex - determining region Y （SRY） gene on Y chromosome. Results ： 28 women in the first trimester and 20 women in the mid - trimester carried male fetuses, 25 and 20 cases of them were positive, respectively. The mean concentrations were （58. 82 ± 25.22） copies/ml and （152.08 ± 62. 61 ） copies/ml. The results of FQ - PCR were negative in the women who carried female fetuses. Conclusion ： The results show that fetal SRY gene can be found as early as 62 days of gestation in maternal plasma by the use of FQ - PCR. The number of fetal DNA increases with gestational age. The real - time FQ - PCR is of great value in the non - invasive prenatal diagnosis.