Case-control pairings. All 488 PROGENI cases that were recently included in a genomewide association study  were matched to a control by minimizing the distance between each case-control pair in four dimensional space (age, gender, and two ethnicity components). Figure 1 shows the pairs in two dimensional space (just the ethnicity components). Those with pairings with 4-dimensional distances greater than three standard deviations from the mean were not included in the analyses (color coded in orange). Based on those samples where religion and country of origin was known to be homogeneous for all four grandparents (~15% of samples), we have inferred that those samples in region A represent Northwestern European ancestry, region B represents Southern European and the Middle Eastern ancestry, and region C represents Ashkenazi Jewish ancestry. The significance of the ethnicity component plotted on the Y axis did not follow a clear recognizable pattern.