associations with genotyping batch were removed. Genetic ancestry was determined by principal component analysis performed using EIGENSTRAT [61]. Imputation was completed using the Michigan Imputation Server [45] and the Haplotype Reference Consortium [62] as the reference panel. Genotypes were then converted to hard calls, and filtered for SNP imputation quality (R2 < 0.3), individual missingness (>2%), SNP missingness (>2%), MAF (<1%) and HWE (p < 1 × 10−10). The resulting dataset contained 9,330,483 SNPs on 67,588 individuals of European ancestry.
