We use an additive genetic model to characterize gene expression traits: (1)Yg=∑kwk,gXk+ϵ where Yg is the expression trait of gene g, wk,g is the effect size of marker k for gene g, Xk is the number of reference alleles of marker k, and ϵ is the contribution of other factors that determine the expression trait assumed to be independent of the genetic component. We note that the summation in model (1) is the genetically determined component of gene expression (i.e., GReX).
