We first evaluated association statistics for variants previously associated with HGB, HCT, or WBC count in AA and Hispanic/Latino populations (summarized in S11 Table). We assembled a list of 24 AA and 13 Hispanic/Latino previously identified autosomal signals from prior published GWAS or exome-based studies [1, 19, 20, 24–30]. Our lists excluded variants reported in multi-ethnic cohorts or meta-analysis including individuals of non-AA or non- Hispanic/Latino ancestry to guard against the scenario that the reported signals were driven predominantly by individuals of European or Asian ancestry. Among the previously reported 24 AA and 13 Hispanic/Latino variants, all but five (four SNPs and a 3.8 kb deletion variant esv2676630) passed variant quality-control filters in TOPMed freeze 5b and were subsequently well-imputed in our target AA and Hispanic/Latino data sets with a stringent post-imputation R2 filter of >0.8 (detailed in S12 Table). Among the 31 known HGB, HCT, or WBC count associations testable with TOPMed freeze 5b, our imputed/discovery cohorts confirmed 84% of these previously reported findings with a consistent direction of effect, using a stringent genome-wide significant threshold of p<5x10-8. Using
