Prenatal fetal sex diagnosis by detecting amelogenin gene in maternal plasma

Objectives To provide a new, reliable noninvasive method for fetal sex determination. Methods Fetal sex was detected in 32 early pregnant women by identifying the amelogenin gene in maternal plasma using nested PCR analysis. First, the 122/128 bp of X-Y homologous region containing 6 bp deletions in the intron 3 of amelogenin gene in X chromosome was amplified, and then the nested PCR was carried out, whose 3′ end of the upstream primer is just located in the deletion region. The fetus was male or female, depending on whether it had the 89-bp nested PCR product or not. Results The 89 bp of nested PCR product was detected in 19 plasma samples obtained from pregnant women, deducing they bear the male fetus and the remaining pregnant women bear female. When compared with the birth outcome, two samples were pseudo-positive. The coincidence was 93.8%. This method had high sensitivity that even trace amount of target fetal DNA (10 pg) could be detected. Conclusions This conventional nested PCR analysis of amelogenin gene promises to be a reliable method for noninvasive fetal sex determination at early pregnancy using maternal plasma DNA. Copyright © 2005 John Wiley & Sons, Ltd.