Each study in the discovery sample was genotyped using commercially available platforms. Before imputation, genetic homogeneity was assessed in each sample using multi-dimensional scaling (MDS) analysis (Extended Data Fig. 2). Ancestry outliers were excluded through visual inspection of the first two components. Quality control filtering was applied to remove genotyped SNPs with low minor allele frequency (< 0.01), poor genotype call rate (< 95%), and deviations from Hardy–Weinberg equilibrium (P < 1 × 10−6) before imputation. The imputation protocols used MaCH34 for haplotype phasing and minimac35 for imputation and are freely available online (http://enigma.ini.usc.edu/protocols/genetics-protocols/). Full details of quality control procedures and any deviations from the imputation protocol are given in Supplementary Table 3.
