Our results were also in line with previous findings that A allele of COMT rs4680 p.V158M were modestly higher in PD patients with depression than those without depression ([OR] = 1.87, 95% CI = 1.15–3.05, P = 0.01), although the difference did not reach the significance level after Bonferroni correction. The gene discussed is COMT; the disease is major depressive disorder.