Genetic and non-genetic influences during pregnancy on infant global and site specific DNA methylation: role for folate gene variants and vitamin B12

• Published in: PloS one 2012, Vol.7 (3), p.e33290
• Main Authors: McKay, Jill A, Groom, Alexandra, Potter, Catherine, Coneyworth, Lisa J, Ford, Dianne, Mathers, John C, Relton, Caroline L
• Format: Article
• Language: English
• Subjects: Adult; Age; Biology; Biomarkers; Carbon; Cation Transport Proteins - genetics; Colorectal cancer; Correlation; CpG Islands - genetics; Cyanocobalamin; Deoxyribonucleic acid; Disease; DNA; DNA Methylation; Enzymes; Epidemiology; Epigenetics; Erythrocytes; Female; Ferredoxin-NADP Reductase - genetics; Ferredoxin-NADP Reductase - metabolism; Folic acid; Folic Acid - blood; Folic Acid - metabolism; Gene expression; Gene Frequency; Genes; Genetic diversity; Genetic factors; Genetic variance; Genomes; Genotype; Gestation; Gestational Age; Homocysteine; Humans; Infant; Infant, Newborn; Infants; Influence; Insulin-Like Growth Factor Binding Protein 3 - genetics; Insulin-like growth factor II; Insulin-Like Growth Factor II - genetics; Insulin-like growth factor-binding protein 3; Insulin-like growth factors; Integrated approach; Linear Models; Male; Maternal Age; Medicine; Metabolism; Methylenetetrahydrofolate reductase; Methylenetetrahydrofolate Reductase (NADPH2) - genetics; Methylenetetrahydrofolate Reductase (NADPH2) - metabolism; Molecular biology; Multivariate Analysis; Nutrition research; Polymerase Chain Reaction; Polymorphism, Genetic; Pregnancy; Smoking; Stochasticity; Studies; Vitamin B; Vitamin B 12 - blood; Vitamin B 12 - metabolism; Vitamin B12; Vitamin deficiency; Young Adult
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0033290

Inter-individual variation in patterns of DNA methylation at birth can be explained by the influence of environmental, genetic and stochastic factors. This study investigates the genetic and non-genetic determinants of variation in DNA methylation in human infants. Given its central role in provision of methyl groups for DNA methylation, this study focuses on aspects of folate metabolism. Global (LUMA) and gene specific (IGF2, ZNT5, IGFBP3) DNA methylation were quantified in 430 infants by Pyrosequencing®. Seven polymorphisms in 6 genes (MTHFR, MTRR, FOLH1, CβS, RFC1, SHMT) involved in folate absorption and metabolism were analysed in DNA from both infants and mothers. Red blood cell folate and serum vitamin B(12) concentrations were measured as indices of vitamin status. Relationships between DNA methylation patterns and several covariates viz. sex, gestation length, maternal and infant red cell folate, maternal and infant serum vitamin B(12), maternal age, smoking and genotype were tested. Length of gestation correlated positively with IGF2 methylation (rho = 0.11, p = 0.032) and inversely with ZNT5 methylation (rho = -0.13, p = 0.017). Methylation of the IGFBP3 locus correlated inversely with infant vitamin B(12) concentration (rho = -0.16, p = 0.007), whilst global DNA methylation correlated inversely with maternal vitamin B(12) concentrations (rho = 0.18, p = 0.044). Analysis of common genetic variants in folate pathway genes highlighted several associations including infant MTRR 66G>A genotype with DNA methylation (χ(2) = 8.82, p = 0.003) and maternal MTHFR 677C>T genotype with IGF2 methylation (χ(2) = 2.77, p = 0.006). These data support the hypothesis that both environmental and genetic factors involved in one-carbon metabolism influence DNA methylation in infants. Specifically, the findings highlight the importance of vitamin B(12) status, infant MTRR genotype and maternal MTHFR genotype, all of which may influence the supply of methyl groups for DNA methylation. In addition, gestational length appears to be an important determinant of infant DNA methylation patterns.