Quantification and application of the placental epigenetic signature of the RASSF1A gene in maternal plasma.

OBJECTIVES

The aims of the detection of hypermethylated RASSF1A gene in maternal plasma from all three trimesters of pregnancy were to show its feature of cell-free fetal DNA and to make up deficients of genetic markers. This study also aimed at investigating of its application value in pre-eclampsia compared with third trimester.

METHODS

Eighty pregnant women (7-41 gestational weeks) including normal pregnant women (60 cases) and pre-eclamptic pregnant women (20 cases) were selected as study groups and 20 normal non-pregnant women were selected as control group. Free DNA of plasma samples was extracted, and RASSF1A levels before and after double-methylation-sensitive restriction enzyme digestion of HinP1I and HhaI were determined to measure total and fetal cell-free DNA, respectively. beta-Actin gene was detected as a control to confirm complete enzyme digestion.

RESULTS

The median concentrations of hypermethylated RASSF1A gene were 46 copies/mL in first trimester, 96 copies/mL in second trimester, 527 copies/mL in third trimester and 1947 copies/mL in pre-eclampsia. There was positive correlation between fetal-derived hypermethylated RASSF1A levels and the severity of pre-eclampsia.

CONCLUSION

Hypermethylated RASSF1A gene may be considered as an epigenetic marker to detect the fetal DNA in maternal plasma and expands the clinical application of non-invasive prenatal diagnosis.