Objectives: DNA methylation is one of the best characterized epigenetic mechanisms that play a regulatory role in genome programming and imprinting during embryogenesis. In this present study, we investigated the association between DNA methylation in the human placenta and the maternal folate and homocysteine concentrations on the Methylenetetrahydrofolatereductase (MTHFR) genetic polymorphism during pregnancy.
Methods: We investigated 107 pregnant women who visited Ewha Woman's University Hospital for prenatal care during their 24-28 weeks-period of gestation. During the second trimester, we measured the serum homocysteine and folate concentrations. The MTHFR 677 genetic polymorphism was determine by performing PCR-RFLP assay. The expression of DNA methylation in the human placentas was estimated by using immunohistochemistry method.
Results: Serum folate was negatively correlated with the serum homocysteine concentration for all the MTHFR genotypes. We found positive correlation between the folate concentrations and the DNA methylation in the human placenta (p<0.05). An increasing concentration of homocysteine was associated with reduced DNA methylation in the human placenta. The coefficient value was -2.03 (-3.77, -0.29) on the regression model (p<0.05).
Conclusion: These findings suggest that the maternal folate and homocysteine levels along with the MTHFR 677 genetic polymorphism during pregnancy affect the DNA methylation in the human placenta.