Fig. 2: Structural causal model of age-dependent genetic effects.
The observed phenotype P* at time point t (0 = baseline, 1 = follow-up) was modelled as a function of time-invariant (baseline) genetics (G0), time-varying (longitudinal) genetics (GE) and the environment (E). All arrows labelled with Greek letters represent the structural coefficients of the underlying data-generating process, where α is the (main) baseline genetic effect, β the (main) environmental effect and γ the gene-by-environment effect. εt is the measurement error in the phenotype.
