FIG 9.

PCA plot for the first two principal components for four populations from the NIEHS data. The left plot has no ascertainment bias. In the right plot, ascertainment was performed using all the 24 individuals from the Asian populations. All SNPs that were polymorphic in the four populations were used. Out of the 8,231 SNPs, 2,751 were ascertained in the left plot. We resampled 2,751 random SNPs without replacement from the 8,231 SNPs and performed PCA on them. None of the 1,000 resamples gave a higher distance between the European Americans than the distance between the African Americans and the Africans.