Inability to detect cell free fetal DNA in the urine of normal pregnant women nor in those affected by preeclampsia associated HELLP syndrome.

Abstract

Recent reports have indicated that cell-free fetal DNA can be detected in the urine of pregnant women. We attempted to reproduce those data. Urine samples were collected from 18 normal pregnant women (11 with a male fetus). Urinary DNA was examined by Y-chromosome-specific nested polymerase chain reaction (PCR) or real-time PCR. Samples were also examined from two pregnancies complicated by HELLP (hemolysis, elevated liver enzymes, and low platelets) syndrome, which had very high levels of cell-free fetal DNA in the maternal plasma. To validate our data, a quantitative comparison of different DNA extraction procedures used in the previous reports was performed. In no instance were we able to detect any fetal DNA in maternal urine, although copious quantities of cell-free fetal DNA were present in the maternal plasma of those pregnancies affected by HELLP syndrome. Our quantitative analysis of the various extraction procedures used indicated that the commercial column elution method we used was comparable, if not superior, to the noncommercial methods used in previous reports. Our data strongly suggest that cell-free fetal DNA is not readily detectable in maternal urine, even under conditions known to increase kidney permeability.