TNF and Parkinson disease: Using this variant in Mendelian randomization models, no effects of TNF-TNFR1 inhibition on PD risk (OR 0.99 per 10% reduction in circulating CRP; 95% CI 0.91–1.08) or age at onset (0.13 years of increase; 95% CI −0.66 to 0.92) were predicted (figure 2).