SELENON and medical procedure: Notably, all 4 of the variants associated with both SELENOP status and CRC risk in the SNP only analysis were from 2 selenoprotein genes; rs4659382, rs11247710, and rs2072749 in SELENON and the PACT borderline significant rs11111979 variant in TXNRD1. Selenoproteins SELENOP, SELENON, and TXNRD1 are antioxidant enzymes and their genetic variations plus regulation by SELENOP levels may be important factors in relation to colorectal carcinogenesis.