Distribution of methylation sites in the gene body. (a,b) Distribution of CCGG and CCWGG methylation sites 2 kb upstream and downstream of the transcription start site (TSS) region, respectively; (c,d) distribution of CCGG and CCWGG methylation sites in the gene-coding region, respectively; (e,f) distribution of CCGG and CCWGG methylation sites 2 kb upstream and downstream of the transcription termination site (TTS) region, respectively. Note: (a,b,e,f), the transverse axis represents the location of the methylation region at the TSS (or TTS) of genes, where a negative value indicates the number of bases upstream and a positive value indicates the number of bases downstream. (c,d), the transverse axis represents the degree of methylation, expressed as 0–1.