Using EA GWAS to select SNPs and choose weights for PRSs in non-EA populations may seem like a reasonable approach: Hispanics/Latinos are admixed with European ancestry, and previous studies have shown that many genetic EA genetic associations generalize to Hispanics/Latinos (Qi et al., 2017; Graff et al., 2017). Furthermore, EA GWASs are typically very large, with tens or hundreds of thousands of individuals, therefore having large statistical power to detect the most strongly associated variants from genomic association regions and obtain precise estimates of effects sizes. In fact, Dudbridge (2013) studied power and prediction accuracy of PRSs and suggested that hundreds of thousands of individuals may be needed to estimate SNP effects. While such numbers are available in EA GWASs, they are not currently available in GWASs of diverse populations such as Hispanics/Latinos. For example, in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), there are fewer than 13,000 individuals who consented for genetic studies. Of these, about 7,000 individuals participated in a GWAS of diabetes (Qi et al., 2017) which is the largest published GWAS to date in Hispanics/Latinos.
