COMT and Parkinson disease: However, after Bonferroni correction with conservative P value for significance, all the studied genotype or allele frequency of COMT rs6267, COMT rs6269, COMT rs4633, COMT rs48418, COMT rs4680, SNCA9A rs6746030, and OPRM1rs1799971 did not significantly differ between PD patients with and without depression.