We also obtained access to the individual-level genotype and phenotype data of the ARIC cohort, a population-based study of Americans28, and the QIMR cohort, a twin study of Australians29. The ARIC samples were genotyped by Affymetrix 6.0 SNP array, and the QIMR samples were genotyped by Illumina 610K or 370K array. After quality control filtering of SNPs, 593,521 and 274,604 genotyped SNPs were retained in the ARIC (excluding SNPs with missingness of >2%, MAF of <0.01 or Hardy-Weinberg equilibrium (HWE) P value of <1 × 10–3) and QIMR cohorts (excluding SNPs with missingness of >5%, MAF of <0.01 and HWE P value of <1 × 10–6), respectively. After sample quality control analysis, 8,682 and 11,742 individuals of European ancestry in the ARIC and QIMR cohorts, respectively, were included for further analysis. The quality control protocol has been detailed previously for the ARIC cohort18,30 and for the QIMR cohort14,29. We then estimated pairwise genetic relationships between individuals14 and removed one of each pair of individuals with an estimated relatedness of >0.025. After these quality control steps, 6,654 and 3,924 unrelated individuals
