Fig. 1.

Diagram of the instrumental variables assumptions for Mendelian randomisation. The three assumptions are: (1) the genetic variant must be robustly associated with the exposure; (2) the genetic variant should not be associated with confounders of the exposure-outcome association; and (3) the genetic variant must influence the outcome through the exposure only and not through any direct or alternative pathways. The dashed lines represent pathways that violate the assumptions. CAD coronary artery disease