Fig. 3

Mendelian randomization (MR) analysis results for T1DM and its impact on Parkinson’s disease (PD) risk. (A) A scatter plot illustrating the potential effects of single nucleotide polymorphisms (SNPs) on T1DM and PD risk using IVW, MR-Egger, and weighted median methods. The slope of the fitted lines represents the estimated MR effect per method, while the 95% CI for the effect size on T1DM is shown as vertical lines, and the 95% CI for PD risk is shown as horizontal lines. (B) A funnel plot for T1DM shows the estimation using the inverse of the standard error of the causal estimate with each SNP as a tool. The vertical line depicts the estimated causal effect obtained using IVW and MR-Egger methods. (C) A forest plot demonstrating the impact of each SNP in the MR analysis. (D) A forest plot presenting the results of the leave-one-out sensitivity analysis, where each SNP in the instrument was iteratively removed to check the stability of the result