Prenatal exposure to per- and polyfluoroalkyl substances and DNA methylation in the placenta: A prospective cohort study

Epidemiological studies regarding the relationship between per- and polyfluoroalkyl substances (PFAS) and DNA methylation were limited. We investigated the associations of maternal PFAS concentrations with placental DNA methylation and examined the mediating role of methylation changes between PFAS and infant development. We measured the concentrations of 11 PFAS in maternal plasma during early pregnancy and infant development at six months of age. We analyzed genome-wide DNA methylation in 16 placental samples using reduced representation bisulfite sequencing. Additionally, we measured DNA methylation levels using bisulfite amplicon sequencing in 345 mother-infant pairs for five candidate genes, including carbohydrate sulfotransferase 7 (CHST7), fibroblast growth factor 13 (FGF13), insulin receptor substrate 4 (IRS4), paired like homeobox 2Ap (PHOX2A), and plexin domain containing 1 (PLXDC1). We found that placental DNA methylation profiles related to PFOA mainly enriched in angiogenesis and neuronal signaling pathways. PFOA was associated with hypomethylation of IRS4 and PLXDC1, and PFNA was associated with PLXDC1 hypomethylation. There were positive associations of CHST7 methylation with PFTrDA and IRS4 methylation with PFDoA and PFTrDA. PLXDC1 hypomethylation mediated the association between PFOA and suspected developmental delay in infants. Future studies with larger sample sizes are warranted to confirm these findings.