While differences within continental populations, and population substructure, must also be considered (Bauchet, et al., 2007; Price, et al., 2008; Seldin, et al., 2006; Tian, et al., 2008), the larger difference in allele frequencies between continental populations potentially creates the greatest confounding problem in interpreting such association studies. At this point a large number of WGA studies have been conducted in populations of primarily or exclusively European ancestry. Thus, the issue of confounding by population stratification will become particularly evident as more genetic associations are conduced among multiethnic, and therefore substantially admixed populations, in order to evaluate ethnic disparities in disease risk. Addressing these differences in population structure is particularly relevant for extending genetic associations to underserved minority groups that include substantial admixture between continents.
