Figure 1. Schematic Representation of Bi-directional MR Analysis. (A) illustrates three assumptions of MR analysis as follows: 1) Instrumental variables must be associated with exposure, 2) instrumental variables must not be associated with confounders, and 3) instrumental variables must influence outcome only through exposure. (B) illustrates bi-directional MR analysis. In stage 1 analysis, influence of genetically predicted sarcopenia-related traits (body lean mass, left handgrip strength and right handgrip strength) on risk of CAD was estimated. In stage 2 analysis, influence of genetically predicted CAD on risk of sarcopenia-related traits (body lean mass, left handgrip strength and right handgrip strength) was estimated. TSMR: two-sample mendelian randomization; CAD: coronary artery disease.