that lie in between HCP and LCP, and are neither HCPs nor LCPs (Fig. 1A). A summarized methylation level was calculated for each gene based on the average signal intensity of all the probes within the gene’s regulatory region, from −1,300 bp to +500 bp (Average level analysis). We considered promoters with DNA methylation levels higher than 1.3-fold of the genome-wide median methylation level as hypermethylated promoters. This threshold is also similar to that used in the MeDIP-chip analysis of human fibroblast.54 Promoters with DNA methylation levels lower than 1.3-fold of the genome-wide median methylation level were considered as hypomethylated promoters.54
