Fig. 2. Age-associated changes in DNA methylation are enriched in CpG island shelves and sea, and depleted in CpG islands.

a Distribution to CpG islands, shores, shelves, and sea of sites that are not differentially methylated between age groups (top), and those that are (bottom). b Odds ratio for a differentially methylated site being distributed to each of the genomic locations. c Most differentially methylated sites in CpG islands are relatively hypermethylated in the older group. The percentage of sites that are relatively hypermethylated with age in a genomic region decreases with increasing distance from a CpG island. d Genes for which expression correlates most strongly with age, i.e., Top-AGE genes, are enriched in aDMRs, both hypomethylated and hypermethylated. Such enrichment is not observed in genes with expression that do not correlate with age, i.e., Top non-AGE genes. *p < 0.05