Using Differential Threshold Effects of Individual and Combined Periconceptional Methyl Donor Status on Maternal Genomic LINE-1 and Imprinted H19 DNA Methylation to Predict Birth Weight Variance in the Taiwan Pregnancy-Newborn Epigenetics (TPNE) Cohort Study

Abstract

Few studies have comprehensively examined the effect of methyl donor status on maternal DNA methylation and birth outcomes. This study examined associations between periconceptional methyl donor status and genome-wide and specific imprinted gene methylation and fetal growth indices in the Taiwan Pregnancy-Newborn Epigenetics cohort. Plasma folate, choline (free form), and betaine concentrations of the participants enrolled at 7-10 weeks of gestation were analyzed. DNA methylation at regulatory sequences of the imprinted H19 gene and genomic long interspersed nuclear element 1 (LINE-1) were measured in maternal lymphocytes using bisulfite/high-resolution melt polymerase chain reaction. Associations with birth weight (BW) were estimated through multiple regressions from 112 mother-newborn pairs. A nonlinear "L-shaped" relation and an inverse association between maternal plasma folate in T1 (mean ± SE: 17.6±5.1 nmol/L) and lymphocytic LINE-1 methylation (β:-0.49, P=0.027) were characterized. After adjusting for LINE-1 methylation, individual maternal folate concentrations were positively associated with BW variance (β=0.24, P=0.035), and the association was more pronounced in mothers with choline in T1 (mean ± SE: 5.4±0.6 μmol/L; β: 0.40, P=0.039). Choline status of the mothers in T2 (mean ± SE: 7.2±0.6 μmol/L) was inversely associated with LINE-1 methylation (β: -0.43, P=0.035), and a positive association was evident between T1 choline and H19 methylation (β: 0.48, P=0.011). After adjusting for epigenetic modification, maternal choline status predicted a positive association with BW (β: 0.56, P=0.005), but the effect was limited to mothers with high betaine concentrations in T3 (mean ± SE: 36.4±8.8 μmol/L), depending on folate status. Our data highlight the differential threshold effects of periconceptional folate, choline, and betaine status on genomic LINE-1 and H19 DNA methylation and how their interplay has a long-term effect on BW variance.