Free fetal DNA in maternal plasma in anembryonic pregnancies: confirmation that the origin is the trophoblast

TLDR

The study aimed to test whether free fetal DNA in maternal plasma mainly originates from the placenta by measuring ffDNA levels in anembryonic pregnancies. Maternal plasma and chorionic tissue from 15 normal and 9 anembryonic pregnancies were analyzed for Y‑chromosome DYS14 using real‑time PCR and quantitative fluorescence PCR. All plasma samples correctly identified fetal sex, and in anembryonic pregnancies male Y‑chromosome signals were detected in plasma when chorionic tissue was male, with median ffDNA concentrations similar to controls, indicating trophoblasts are the main source of ffDNA. © 2007 John Wiley & Sons, Ltd.

Abstract

Abstract Objective To test the hypothesis that free fetal DNA (ffDNA) circulating in maternal plasma originates mainly from the placenta we studied ffDNA levels in anembryonic pregnancies. Methods Maternal blood samples were collected from 15 normal first‐trimester pregnancies in which fetal sex was subsequently determined and nine patients with a diagnosis of anembryonic gestation (AG). The Y chromosome DYS14 gene was quantified by real‐time quantitative PCR (RT‐PCR) for the determination of fetal sex in both plasma and chorionic tissue samples. Fetal sex in chorionic tissue samples was also determined using quantitative fluorescence PCR (QF‐PCR). Results The correct sex result was obtained from maternal plasma in all. Four AG pregnancies were female (DYS14 negative) results. In five of the AG cases, the chorionic tissue was found to be male (by both QF‐PCR and RT‐PCR which agreed) and positive male signal was found in maternal plasma by RT‐PCR. There was no statistical difference between median free fetal DNA concentration in plasma between the AG male cases (148.3 GE/mL) and controls (145.8 GE/mL). Conclusion Since ffDNA levels are normal in pregnancies without a fetus, the data support the hypothesis that the trophoblastic cells are the major source ffDNA in maternal plasma. Copyright © 2007 John Wiley & Sons, Ltd.