Figure 2

Genome-wide imputation based on the Affx 500 K plus 164 K custom array data of 200 Caucasian Americans and 200 African Americans from the CATIE cohort. The left panel shows Caucasian outperformed the African Americans. Also, pooled reference (HapMap YRI+CEU) greatly improved imputation comparing to using YRI reference alone. The middle and right panels shows African American's imputation accuracy was also boosted by pooled reference, although still trailing behind Caucasian counterparts.