RESUMO
<p><b>OBJECTIVE</b>To investigate the expression of placenta-derived RASSF1A gene in maternal plasma during first and second trimesters, and to explore its value for the prediction of pre-eclampsia.</p><p><b>METHODS</b>For 325 pregnant women of the first trimester, free DNA of plasma samples was extracted at 7-12, 13-18, and 19-24 gestational weeks, respectively. Methylation-sensitive restriction enzyme digestion followed by fluorescence quantitative PCR (MSRE+ PCR) was employed for analyzing the concentrations of hypermethylated RASSF1A gene. Blood pressure, proteinuria and clinical feature were monitored at the same time. Those who had subsequently developed pre-eclampsia were selected as the pre-eclamptic group, 30 normal pregnant women were selected as the control group. Hypermethylated RASSF1A gene in maternal plasma was retrospectively analyzed. The relationship between clinical classification, type of pre-eclampsia and concentrations of the gene were further analyzed.</p><p><b>RESULTS</b>Twenty-six out of the 325 pregnant women developed pre-eclampsia as their only complication. At 13-18 gestational weeks, the mean concentrations of fetus-specific RASSF1A sequences were 141.62 copies/mL in maternal plasma of pre-eclamptic pregnancies, which was significantly greater than that of the controls (98.90 copies/mL). Fetus-derived RASSF1A levels were 2.03 fold higher in pre-eclamptic subjects than controls at 19-24 gestational weeks. There was a significant difference in the level of hypermethylated RASSF1A gene between the mild and severe pre-clamptic subjects at 13-24 gestational weeks (P< 0.05). The concentrations of the sequences were significantly higher in early-onset severe pre-eclampsia than late-onset severe pre-eclampsia at 19-24 gestational weeks (P< 0.05).</p><p><b>CONCLUSION</b>Altered expression of hypermethylated RASSF1A gene may be detected in maternal plasma during second trimester, which has important significance for early prediction of pre-eclampsia.</p>