The Analysis of Ethnic Mixtures

Population of ethnic mixtures can be useful in genetic studies. Admixture mapping, or mapping by admixture linkage disequilibrium (MALD), is specially developed for admixed populations and can supplement traditional genome-wide association analyses in the search for genetic variants underlying complex traits. Admixture mapping tests the association between a trait and locus-specific ancestries. The locus-specific ancestries are in linkage disequilibrium (LD), which is generated by an admixture process between genetically distinct ancestral populations. Because of the highly correlated-locus specific ancestries, admixture mapping performs many fewer independent tests across the genome than current genome-wide association analysis. Therefore, admixture mapping can be more powerful because it reduces the penalty due to multiple tests. In this chapter, we introduce the theory behind admixture mapping and explain how to conduct the analysis in practice.