APOB and metabolic syndrome: Of the 29 proteins for which we found IVs, 3 showed Bonferroni significant causal effects on MetS (Fig. 4), namely apolipoprotein E3 (APOE3) (Wald-Ratio = − 0.12, Wald-p = 3.63e−13), apolipoprotein B (APOB) (Wald-Ratio = − 0.09, Wald-p = 2.54e−04) and proto-oncogene tyrosine-protein kinase receptor (RET) (Wald-Ratio = 0.10, Wald-p = 5.40e−04).