According to our results, the rs6269 minor allele G-tagged COMT rs6269-rs4633-rs4818-rs4680 haplotype G-C-G-G was associated with an increased PTSD risk (OR = 2.46 and P = 0.0144) when the rs1800497 genotype AA was present. The gene discussed is COMT; the disease is post-traumatic stress disorder.