The study consisted of two stages. In stage 1, a meta-analysis was conducted on directly genotyped and imputed SNPs from 14 studies of individuals of European ancestry, with a total sample size of 20,288. Details of these studies are given in Table 1. This meta-analysis provided loci for further genotyping in up to 32,184 individuals of European origin (stage 2a) and in silico comparisons in 22,092 individuals of European origin (stage 2b).
