Prenatal diagnosis of fetal sex by molecular analysis of maternal plasma after 8 weeks of gestation

ABSTRACT

Prenatal diagnosis of fetal sex is usually performed by invasive methods such as sampling through amniocentesis or chorionic villus sampling. One potential non-invasive approach involves analysis of cell-free fetal DNA in maternal plasma or serum. The objective of our study was to investigate the feasibility of using fetal DNA in maternal plasma for prenatal diagnosis of fetal sex. In this experimental study, a nested polymerase chain reaction [PCR] techniques was developed for fetal SRY gene identification using cell-free fetal DNA in maternal plasma. Peripheral blood samples were obtained from 32 pregnant women at the gestational period from 8 to 13 weeks and cell-free DNA was extracted by the phenol/chloroform method from plasma. The nested PCR was carried out to amplify the fragment of SRY gene by two sets of PCR primer pairs. Analysis was then performed on the PCR product. Specifically, the presence of Y-chromosome sequences in maternal blood plasma indicated that the fetus is male, whereas lack of signal will indicate that the fetus is female. Among the 32 pregnant women, SRY sequences were detected in 14 plasma samples after nested PCR amplification, while the 18 women bearing female fetuses had the negative results. The sensitivity of this technique was 87.5%. The phenol/chloroform extraction of fetal DNA in maternal plasma is an effective and simple method, and the nested PCR amplification of SRY sequence is a convenient and low-cost approach for the non-invasive early prenatal diagnosis of fetal sex