Supplementary Figure 1: Principal component analysis based on a selected set of polymorphic SNPs.

Transparent colored areas represent reference samples of different Hapmap3 populations (African, Asian, European, South-East Asian) as an indicator of ethnic ancestry. Black dots represent samples in the A) cases or B) controls. Dashed lines represent the thresholds used to classify a sample as being of European ancestry (PC1 >= 0.01 and PC2 >= 0.04)