XRCC1 and xeroderma pigmentosum group D: Other mutations that can affect colon cancer pharmacology therapy may include bilirubin uridine diphosphate glucuronosyl transferase (UGT1A1), excision repair 1, endonuclease non-catalytic subunit (ERCC1), X-ray Repair Cross Complementing 1 (XRCC1), X-ray Repair Cross Complementing 3 (XRCC3), xeroderma pigmentosum group D (XPD), Glutathione S-Transferase Theta 1 (GSTT1), Glutathione S-Transferase Pi 1 (GSTP1), Glutathione S-Transferase Mu 1 (GSTM1), and the Thymidylate synthase enhancer region (TSER) [85,86].