de Vries M, Nedeljkovic I, van der Plaat DA, et al. - Since there is no clarity regarding the role of epigenetics in people with COPD who never smoked, therefore, researchers investigated differential DNA methylation related to lung function in never smokers. This study included four independent cohorts, LifeLines COPD&C (N = 903), LifeLines DEEP (N = 166), Rotterdam Study (RS)-III (N = 150) and RS-BIOS (Biobank-based Integrative Omics Studies) (N = 206). In blood samples obtained from never smokers in these cohorts, experts determined epigenome-wide DNA methylation levels of 396,243 CpG (cytosine-phosphate-guanine)-sites (Illumina 450 K). To recognize differentially methylated CpG-sites with FEV₁ (forced expiratory volume in 1 s)/FVC (forced vital capacity), they meta-analyzed the cohort-specific methylation outcomes. In the BIOS, Expression Quantitative Trait Methylation analysis was carried out. In this study, 35 CpG-sites that were unique for never smokers were discovered. Findings revealed the link of DNA methylation with FEV₁/FVC in individuals that never smoked and hence DNA methylation is not only associated with smoking.