[Fetal sex determination with real time PCR of fetal DNA in maternal plasma]

Abstract

Introduction: Non-invasive methods using maternal plasma and serum for molecular genetic diagnosis become an important field of interest in prenatal genetic diagnosis. Free fetal DNA in maternal plasma and serum has been shown to be useful for fetal gender determination, and seems to offer a new possibility to perform non-invasive prenatal genetic diagnosis. A possible application is fetal sex determination for couples at risk of X-linked diseases. The aim of this study was to control the reliability and reproducibility of the real-time PCR amplification of the SRY region.

Materials and methods: Maternal serum before amniocentesis, and amnionic fluid samples were obtained from 56 pregnant women during the 11th to 22nd weeks of gestation. Real-time PCR analysis of the SRY region was performed in order to determine the fetal sex. Routine karyotyping of cultured amnionic cells was also performed on the samples. Six cases were excluded.

Results: In 26 of 50 pregnancies were found male fetuses by cytogenetic analysis. Real time PCR of maternal plasma has been positive for the SRY region in 27 cases. In 47 cases the cytogenetic gender and the real-time PCR result was correlating. In one case of 46,XY karyotype the PCR reaction for SRY region was negative, in two cases of SRY positivity the karyotype was 46,XX. In this study are presented the results of fetal sex determination in maternal plasma using real time PCR method.

Conclusions: The real time PCR detection of fetal DNA in maternal plasma seems to be an easy non-invasive method to determine the fetal sex at this gestational age. Our experience is promising in terms of the specificity and sensitivity of the method.