Application of an African Ancestry Index as a genomic control approach in a Brazilian population.

Ten ancestry informative markers were investigated in 101 coronary artery disease patients and 102 healthy controls from a Southern Brazilian population, in order to determine if stratification occurs in this population. The degree of African admixture detected in this population was estimated to be as high as 6%, but no differences between cases and controls were observed. Using an African Ancestry Index (AAI) that estimates admixture at the individual level it was possible to remove from the samples those individuals with evidence of African admixture. Therefore we have shown that it is possible to control for population stratification by choosing individuals, without the loss of statistical power that occurs with the use of other methods of genomic control.