ID1 and cancer: Several differentially methylated loci identified in this study appear within genes that may be potential novel targets in the setting of cancer, such as FRK, BCL2A1, GABRA5, DIO3, P2RX7, CCL3 and ID. Overall, there appears to be a clustering of methylation in CpG sites across genes with similar functions within anal SCC and these epigenetic differences may have potential utility as biomarkers of HPV-associated carcinogenesis (Table S1) [68]–[93].