Global DNA methylation is influenced by smoking behaviour

The level of epigenetic DNA methylation is an important factor in the pathogenesis of various human diseases. As smoking may influence DNA methylation, we investigated the effect of smoking habits on global DNA methylation in 298 genomic DNA samples (73 fathers, 69 mothers and 156 offspring). We did not find a direct effect of smoking on global DNA methylation. However, there was an association of the offspring's DNA methylation with paternal DNA methylation that was strongest if both had never smoked (R2corr = 0.41, Beta = 0.68, p = 0.02) and completely vanished if the offspring smoked or had ever smoked. These findings suggest an association between smoking behaviour and global DNA methylation, which may be of importance for a wide range of diseases.