In all 28 discovery samples, genetic variants were imputed using the reference panel of the HRC or the 1000G Phase 1 version 3 reference panel. The regression analyses were adjusted for age at measurement, sex, and the first ten principal components. To harmonize the imputation, data preparation, and genome-wide association (GWA) analyses, a specific analysis protocol (Supplementary Note 1) was followed in the 18 BroadABC discovery samples. Further details on the genotyping (platform and quality control criteria), imputation, and GWA analyses for each cohort are provided in Supplementary Table 2.
