Genotyping was performed using the Illumina Infinium HumanHap550 v3, Human610-Quad v1 or Human660W-Quad v1 Infinium Beadchip and common SNPs across all platforms were identified for each sample. SNPs were excluded if they showed < 95% genotyping success rate per SNP, minor allele frequency (MAF) < 0.01 or Hardy–Weinberg equilibrium (HWE) p-value < 1E − 7. Quality control was carried out using PLINK v1.07 for each cohort separately prior to imputation and was determined by comparing the subjects reported gender with the genotypic gender determined using PLINK's check sex algorithm.
