DNA-Methylation Quantitative-Trait Loci Are Predominantly cis-Acting and Enriched in Sites at Which DNAm Is Highly Heritable
(A) The genomic distribution of Bonferroni-significant (p = 6.52 × 10−14) mQTLs in whole blood; the position on the x axis indicates the location of Illumina EPIC array probes, and the position on the y axis indicates the location of genetic variants. The color of the point corresponds to the difference in DNA methylation per allele compared to the reference allele; the largest effects are plotted in dark red. A clear positive diagonal can be observed, demonstrating that the majority of mQTLs are associated with genotype in cis.
(B) A bar plot of the percentage of DNA-methylation sites associated with common genetic variation and grouped by previous reported estimates of heritability (percent variation in DNAm is explained by additive genetic factors taken from van Dongen et al.13). Each bar plot demonstrates the percentage of DNA-methylation sites with Bonferroni significant genetic effects in cis only (blue), trans only (green), and both cis and trans (red) and with no significant genetic effects (white).