Figure 1.
Causal diagram demonstrating mediation and “mediator-outcome confounding.” Here, the variable set “U” represents a set of unmeasured or unknown variables that may show confounding effects in the mediation analysis. Mediation analysis can detect mediation of the effect of the eSNP on the trans-gene by the cis-gene, assuming mediator-outcome confounding is absent or adjusted for in the analysis. Mediation will not be detected if the effect of the eSNP on the trans-gene is through some alternative pathway that does not involve the cis-gene.
