5hmC promoter profiles and their association with active genes in normal colon. (a) hmeDIP-seq profile for all genes around the TSS in normal colon tissue (n = 5). (b) Quantification of 5hmC enrichments in genomic features. (c) Two distinct promoter profiles were identified. Left panel: high 5hmC within a promoter window (-1 kb to +0.5 kb) with a ‘narrow’ promoter profile. Right panel: high 5hmC within gene bodies (from the TSS to the TTS) with a ‘broad’ promoter profile. Below are examples of each type of profile. (d) 5hmC and CpG content in the promoter. High, intermediate and low CpG content (HCP, ICP and LCP, respectively). Inset numbers represent the number of promoters for each category (LCP numbers not shown). (e) 5hmC content at promoter CpG islands. The levels represent an average of the population for each promoter type, thus individual loci may not necessarily display the full profile. Additional file 2 shows further examples. (f) Expression levels (log2 microarray intensity) of genes associated with 5hmC promoter profiles (P values were obtained by a Wilcox test).