GV effect was then either modeled on the factor (Figure 1a; Figure 1g A1–A3), affecting via the factor all phenotypes defining the factor (in which case the GV effect is weighted by the factor loadings; the lower the factor loading, the smaller the GV effect on a phenotype), or specifically on the residual variance of one phenotype (Figure 1e; Figure 1g E1–E3). Note that a sum score only summarizes both phenotypic and genetic information exhaustively if the GV affects the factor; if the GV affects one phenotype specifically, the sum score operationalisation is not sufficient from a genetic perspective.
