In all the analyses, we accounted for unknown technical confounders (such as batch effects) and biological confounders (such as inter-individual differences in cell-type-composition) by correcting the expression data for up to 25 expression principal components (PCs) that were not associated with genetics (Methods). This correction adjusted for the majority of cell-type-composition effects in a subset of samples (BIOS cohort, N up to 3,831; Supplementary Note, Supplementary Figure 3). Nevertheless, we acknowledge that our dataset may include residual cell-type-composition effects.
