varies markedly across the genome, with overlapping agnostic/focused regions having substantially greater numbers of individuals in the analysis. Most of these reports fail to specify the sample size on a per-SNP basis, making it impossible to confidently calculate z′. (3) Starting from the 22 quantitative traits, we found reference studies that explicitly reported the allele associated with direction of effect for 18. Furthermore, to be confident that the direction of effect was consistent between PAGE and previous reports, we restricted analysis to asymmetric SNPs (A/C, A/G, C/T and G/T). These criteria yielded 589 previously reported genome-wide significant variants, distributed across the 18 traits (Supplementary Table 7). Only 110 of these variants were traditionally genome-wide significant (P < 5 × 10−8) and therefore overlap with the SNP × PC heterogeneity analysis. We compared the PAGE z′ (both pooled and stratified) to the GWAS Catalog z′ in a linear regression.
