CXCL9 and Parkinson disease: The findings of the IVW method demonstrated that PD was suggestively correlated with an decreased level of monokine induced by interferon gamma (MIG; OR: 0.91, 95%CI: 0.84–0.98, P = 0.014), beta nerve growth factor (bNGF; OR: 0.92, 95%CI: 0.85–0.99, P = 0.019), interleukin-17 (IL-17; OR: 0.94, 95%CI: 0.89–0.99, P = 0.028), IL-2 (OR: 0.92, 95%CI: 0.86–0.99, P = 0.036), and interferon gamma (IFNg; OR: 0.95, 95%CI: 0.90–1.00, P = 0.044).