Different genotyping platforms were used across the cohorts (Table 1)14. Imputation was conducted using either MACH65 or BIMBAM66 to generate approximately 2.5 million autosomal SNP genotype dosages for meta-analysis. The imputation methods perform similarly, although MACH generally produces higher accuracy rates than the imputation process used in BIMBAM (fastPHASE)67. Differing imputation methods across cohorts is not a source of bias for meta-analysis since all comparisons using the imputed data are within-cohort comparisons.
