The long-term impact of folic acid in pregnancy on offspring DNA methylation: follow-up of the Aberdeen Folic Acid Supplementation Trial (AFAST)

Abstract

BackgroundIt has been proposed that maternal folic-acid supplement use may alter the DNA-methylation patterns of the offspring during the in-utero period, which could influence development and later-life health outcomes. Evidence from human studies suggests a role for prenatal folate levels in influencing DNA methylation in early life, but this has not been extended to consider persistent effects into adulthood.MethodsTo better elucidate the long-term impact of maternal folic acid in pregnancy on DNA methylation in offspring, we carried out an epigenome-wide association study (EWAS) nested within the Aberdeen Folic Acid Supplementation Trial (AFAST—a trial of two different doses: 0.2 and 5 mg, folic acid vs placebo). Offspring of the AFAST participants were recruited at a mean age of 47 years and saliva samples were profiled on the Illumina Infinium Human Methylation450 array. Both single-site and differentially methylated region analyses were performed.ResultsWe found an association at cg09112514 (p = 4.03×10–9), a CpG located in the 5’ untranslated region of PDGFRA, in the main analysis comparing the intervention arms [low- (0.2 mg) and high-dose (5 mg) folic acid combined (N = 43)] vs placebo (N = 43). Furthermore, a dose–response reduction in methylation at this site was identified in relation to the intervention. In the regional approach, we identified 46 regions of the genome that were differentially methylated in response to the intervention (Sidak p-value <0.05), including HLA-DPB2, HLA-DPB1, PAX8 and VTRNA2–1. Whereas cg09112514 did not replicate in an independent EWAS of maternal plasma folate, there was suggested replication of differential methylation in PAX8.ConclusionsThe results of this study suggest that maternal folic-acid supplement use is associated with changes in the DNA methylation of the offspring that persist for many years after exposure in utero. These methylation changes are located in genes implicated in embryonic development, immune response and cellular proliferation. Further work to investigate whether these epigenetic changes translate into detectable phenotypic differences is required.

LINE‐1 methylation in cleft lip tissues: Influence of infant MTHFR c.677C>T genotype

“…Our observation of inverse association in TT cases could be suggested as an outcome of impaired folate metabolism during development of TT embryos, eventually leading to altered DNA methylation at the lip prominences, and ultimately impairing their correct fusion. This observation of differential methylation at the lip prominences with functional variant in MTHFR gene is in line to previous supporting evidence linking folate metabolism and epigenetic modifications in the pathogenesis of nsCL/P (Richmond et al, ) and supports the hypothesis that both genetic and environmental factors can influence DNA methylation level in lip tissues (McKay et al, ; Sun, ).…”

Epigenomic profiling of newborns with isolated orofacial clefts reveals widespread DNA methylation changes and implicates metastable epiallele regions in disease risk

“…For example, Gonseth et al [29] observed an inverse correlation between periconceptional folate supplementation and methylation in newborns in that mostly hypomethylation events were observed with increasing maternal folate intake. This trend, though counterintuitive, is consistent with observations made on methylation sites in newborn DNA that associate with maternal plasma folate levels during pregnancy [30] and within offspring DMRs associated with lowand high-dose maternal folate supplementation [31].…”

Heritable methylation marks associated with breast and prostate cancer risk

“…36 This locus has also been described as a metastable epiallele as the imprinting of this region can be modulated by periconceptional environment and persist through adulthood. [37][38][39] Van Dijk et al have reported that hypomethylation in the VTRNA2-1 region in newborns was associated with a 2.1fold increased risk of childhood obesity compared with monoallelic methylation (95% CI 1.3-3.4, P = 0.002). 40 Some transgenerationally heritable DNA methylation marks have been associated with nearby genetic variation 14,41 but allele-specific methylation at VTRNA2-1 has not yet been linked to any underlying genetic variation.…”

“…Imprinted regions are often associated with tissue growth and a loss of imprinting (LOI) can be linked to tumorigenesis as shown for the H19/IGF2 region . This locus has also been described as a metastable epiallele as the imprinting of this region can be modulated by periconceptional environment and persist through adulthood . Van Dijk et al have reported that hypomethylation in the VTRNA2‐1 region in newborns was associated with a 2.1‐fold increased risk of childhood obesity compared with monoallelic methylation (95% CI 1.3‐3.4, P = 0.002) …”