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

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.