HHEX and type 2 diabetes mellitus: Of note, 10 of these CpG sites mapped to KCNQ1 and 6 sites mapped to TCF7L2. A simultaneous change in mRNA expression was seen for four of the T2D candidate genes (HHEX, IGF2BP2, JAZF1 and TCF7L2) where mRNA expression decreased while DNA methylation increased in response to exercise (q<0.05, Table 5).