Figure 2.

Graphical diagram of relationships between risk factor (X), mediator (M), outcome (Y), and genetic variant (${\mathit{G}}_{\mathit{j}}$). Causal relationships between variables are indicated by solid lines. Associations of the genetic variant are indicated by dashed lines. The direct effect ${\theta }_{\mathit{D}}={\theta }_2.$ The indirect effect ${\theta }_I={\theta }_1{\theta }_3.$ The total effect ${\theta }_{\mathit{T}}={\theta }_{\mathit{D}}+{\theta }_{\mathit{I}}={\theta }_2+{\theta }_1{\theta }_3.$