XRCC1 and nasopharyngeal carcinoma: However, to date, no major susceptibility gene such as BRCA1 for breast cancer, has been identified for NPC with significantly increased risk, although several genes including HLA haplotypes (12) and genes of T cell receptors (13), cytochrome P450 2E1 (14), TLR family (15,16), DNA repair enzymes XRCC1 and hOGG1 (17), have been reported to be associated with the risk of NPC.