Considering that each of these polymorphisms appeared to have a weak effect on NPC risk, we next investigated the combined effects of three functional polymorphisms (MDM2 SNP309, p53 Arg72Pro and PTEN C-9G) and two associated polymorphisms (AKT1 SNP4 and SNP5) on NPC risk. The gene discussed is MDM2; the disease is nasopharyngeal carcinoma.