UGT1A9 and colorectal carcinoma: 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).