FIGURE 3.

Scatter plots showing the effects of GDF-15 on three neurodegenerative diseases. No evident outlier SNPs were present in the Mendelian randomization analyses of GDF-15 on the risk of Alzheimer’s disease (A), Parkinson’s disease (B), and amyotrophic lateral sclerosis (C). As delineated by fitted lines, overall causal estimates were given by the IVW method (red solid line), weighted median (blue dotted line), and MR–Egger slope (green dashed lines). Individual SNP (black point) with its effect on the risk of neurodegenerative diseases (vertical line) against its effect on circulating levels of GDF-15 (horizontal line) was depicted in the background. AD, Alzheimer’s disease; ALS, amyotrophic lateral sclerosis; CI, confidence interval; GDF-15, growth differentiation factor 15; IVW, inverse-variance weighted model; PD, Parkinson’s disease; SNP, single-nucleotide polymorphism.