Characteristics of differentially methylated regions. Characteristics of (A) tissue-specific differentially methylated regions (tDMRs) and (B) age-dependent differentially methylated regions (aDMRs). The characteristics of Polycomb complex binding targets and histone markers were based on the previous report on embryonic stem cells whereas the information on CG islands (CGI) was available from Illumina. *P < 0.05, **P < 0.005, ***P < 0.0005. 'Percentage of loci' refers to the percentage of loci in the microarray that contains the specified features.