Fig. 4
MR regressions on Parkinson’s disease risk genetic architecture and CSF α-Syn and Aβ42 levels. a Association between META-PD risk and CSF α-Syn levels (four variants). Robust regression MR-Egger method effect = -1.40 and p = 0.06, which is not consistent with causality. b Association between Parkinson’s disase risk and CSF Aβ42 levels (twelve variants). Robust regression with MR-Egger method effect = 0.43 and p = 1.44 × 10−05, which is consistent with causality. Each dot corresponds to one genetic variant, with a 95% confidence interval (CI) of its genetic association with the exposure (α-Syn and Aβ42 levels) and the outcome (Parkinson’s disease risk). Regression lines correspond to the robust MR-Egger method regression; numerical results are given for all tested methods in Additional file 2: Table S8. c CSF Aβ42 regression using multiple MR methods. Each dot is one of the twelve variants included in this test; the effect of CSF Aβ42 levels on the x-axis and Parkinson’s disease risk on the y-axis. Each line represents the regression of one MR-method of CSF Aβ42 levels on Parkinson’s disease risk with one MR method. Additional details on the data sources and analysis methods to generate these figures are provided in Additional file 2: Table S8. d The forest plot illustrates the leave-one-out sensitivity analysis between CSF Aβ42 and META-PD risk. MR analysis without rs769449 decreased the I2 statistic (I2 = 0.0%) and increased the p-value to non-significant levels, suggesting that the association is mainly driven by this variant