Mapping of disease-associated variants in admixed populations

High-throughput genotyping and sequencing will enable refined estimation of ancestry, thus enhancing disease loci identification in admixed populationsA major goal of human genetics is to identify genetic variation causally related to either Mendelian or complex diseases. More broadly, a fundamental goal of genetics is to describe the genetic architecture underlying any trait of interest. Most candidate gene studies, linkage studies, or genome-wide association studies to date have focused on European populations, for which large samples of ancestrally homogeneous individuals from relatively homogeneous environments have been established. For example, approximately 90% of genome-wide association studies have been performed using samples of individuals with European ancestry [1]. However, expanding human genetic studies to include diverse worldwide populations is needed to: (i) identify novel loci absent or not readily identifiable in European populations due to low allele frequencies and the resulting low statistical power; (ii) establish the extent to which findings from studies of European populations generalize or transfer to non-European populations; and (iii) study diseases or traits, such as podoconiosis and human African trypanosomiasis (sleeping sickness), present in non-European populations only [2-4].In this article, we highlight the special value of admixed populations in disease mapping studies. Admixed populations are not ancestrally homogeneous but rather are populations with ancestry from more than one parental population. Admixed populations that have successfully contributed to the mapping of susceptibility loci include African Americans, who have African and European ancestry, and Latino Americans, who have African, European, and Native American ancestry. These admixed populations afford opportunities for the study of health inequalities or group differences, which can occur when there are differences in traits such as disease susceptibility (for ex