GSTM1, 2, 4 (encode glutathione S-transferase Mu 1, 2, 4), UGDH (encodes UDP-glucose 6-dehydrogenase), UGP2 (encodes the enzyme UDP glucose pyrophosphorylase 2), UGT1A9, and UGT2B17 (encode uridine diphosphate glucuronosyl transferase 1A9 and 2B17) are silenced in all clinical stages of CRC (Table 2). Here, GSTM1 is linked to colorectal carcinoma.