Extended Data Fig. 3

(a) the causal effect of a microbial trait on a disease, whereby any invalidation of the exclusion restriction criteria implies a pleiotropic association between the genetic variant and the disease independent of the microbial trait, (b) the genetic variant seemingly associated with the microbial trait is predominantly associated with the disease, which in turn effects the microbial trait (i.e., reverse causation) and (c) the genetic variant is associated with an external variable that is independently associated with the microbial trait and outcome.