For blood count traits, EA GWASs sample sizes were 106-108K individuals. Optimal PRSs had SNPs selected according to EA GWAS, but optimal weights differed between traits (HCHS/SOL, meta-analysis, or no weights). Interestingly, the number of SNPs used in the optimal PRSs for blood count traits is much lower than the number of SNPs used in the optimal PRSs for anthropometric traits, while achieving similar variance explained percentages. This may reflect different genetic architecture: less SNPs with stronger effects for blood count compared to anthropometric traits, and potentially different effect sizes between population groups.
