Moreover, increased risk of colorectal cancer was revealed for pairs Gln/His-Arg/Arg (51Gln/His APEX-689Ser/Arg ERCC4), Val/Val-Asp/Glu (64Ile/Val APEX-148Asp/Glu APEX), Val/Val-Gly/Ala (64Ile/Val APEX-23Gly/Ala XPA), and Asp/Glu-Gly/Ala (148Asp/Glu APEX-23Gly/Ala XPA); while at the same time, risk was decreased for pairs Ile/Val-Asp/Asp (64Ile/Val APEX-148Asp/Glu APEX), Ile/Val-Gly/Gly, and Ile/Val-Ala/Ala (64Ile/Val APEX-23Gly/Ala XPA) as well as Asp/Asp-Gly/Ala and Asp/Glu-Gly/Gly (148Asp/Glu APEX-23Gly/Ala XPA). The gene discussed is APEX1; the disease is colorectal cancer.