After adjusting for covariates, it was observed that those with the MAOA (rs6323) risk G-allele were significantly related to the risks of oral cavity and pharynx cancers (AOR = 1.98, 95% CI = 1.23–3.20) and OPMD (AOR = 2.89, 95% CI = 1.27–6.58), compared to the healthy control group (MAOA (rs6323) T-allele). The gene discussed is MAOA; the disease is pharynx cancer.