Imputation was performed using the IMPUTE software package (v2)26 using two reference panels, P0 (HapMap2, rel 22, combined CEU+YRI+ASN panels) and P1 (610k+, including the combined HumanHap610k and 1M array). Post-imputation, SNPs were filtered at a MAF > 5% and IMPUTE info value of >0.8 resulting in a total of 2,029,988 SNPs available for testing.
