For the variance explained analyses within the independent Airwave cohort, we use three trait-specific GRSs (SBP, DBP, PP). Each GRS includes all variants, but weights are trait-specific, using the beta coefficients from the analysis of each of the three different BP traits, e.g. the SBP-GRS is weighted by the beta coefficients from the SBP-GWAS. To calculate the percent of variance for each BP trait explained by its corresponding trait-specific GRS, not accounted for by known factors, we generate the residuals from the regression model of each trait against covariates of age, age2, sex and body mass index. We then fit a second linear model for the trait residuals with all the variants in the GRS plus the top 10 PCs.
