DNA methylation is an epigenetic event whose pattern is altered frequently in a wide variety of human diseases. Smoking affects DNA methylation possibly leading to abnormal expression of a broad spectrum of genes which in turn may result to the various side effects and diseases associated with smoking. The long term effects of smoking have been widely studied but the mechanism(s) by which those effects may be reversible by smoking cessation are not clearly understood. Here, we conducted an epigenome-wide association study in peripheral-blood DNA in 464 individuals who were current, former and never-smokers. We identified 15 distinct loci (10 of which were novel) where DNA methylation was reduced in smokers and was reversed (but did not reach non-smoking levels) upon smoking cessation within 12 weeks. Although the functional impact of this reversal of DNA methylation is still not understood, this study illustrates the potential of epigenomics to provide insights into mechanisms of environmental and lifestyle exposures, and to suggest new avenues for clinical intervention
Overall design
Bisulfite converted DNA from the 464 samples were hybridized to the Illumina Infinium HumanMethylation450 BeadChip
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