Comprehensive evaluation of smoking exposures and their interactions on DNA methylation

Data from up to 15,014 adults were meta-analyzed across 5 cohorts with DNA methylation measured in blood using Illumina’s EPIC array for current smoking (2,560 exposed), quit <1 year (500 exposed), in utero (286 exposed), and environmental tobacco smoke (ETS) exposure (676 exposed). Using false discovery rate (FDR<0.05), 65,857 CpGs were differentially methylated in relation to current smoking, 4,025 with recent quitting, 594 with in utero exposure, and 6 with ETS. Most current smoking CpGs attenuated within a year of quitting. There was also evidence that 4-71 smoking related CpGs may be modified by sex or dietary intake (i.e., fibre, folate, and vitamin C).