[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 150 samples in the first trimester and mid-trimester of pregnancy, respectively. Real-time fluorescence quantitative polymerase chain reaction PCR (FQ-PCR) was used to determine sex-determining region Y (SRY) gene on Y chromosome. RESULTS: Eighty-two women in the first trimester and 90 women in the mid-trimester carried male fetuses,70 and 90 samples of them were positive, respectively. The mean concentrations were (58.82+/-20.90) 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 at a time as early as 42 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.