Eleven groups contributed data for analysis; nine contributed individual-level data and two groups could only share single-nucleotide polymorphism (SNP)-level summary statistics. These two groups implemented the quality control (QC) and GWAS analyses outlined below before sharing summary statistics. Individual-level genotypes are necessary for genome-wide complex trait analysis (GCTA) and polygenic risk scoring (PRS), and hence these two data sets are not included in the polygenic analyses. For all data sets, the first analytical step was ancestry assignment. As described below, this yielded 19 ancestry-assigned data sets for analysis across the 11 contributing studies. Next, QC procedures and imputation were performed and then single SNP (GWA and meta-analyses) and polygenic analyses (GCTA, PRS, and linkage disequilibrium (LD) score regression (LDSC)) were completed.
