Joint testing of genotype and ancestry association in admixed families

Abstract

Current genome‐wide association studies (GWAS) often involve populations that have experienced recent genetic admixture. Genotype data generated from these studies can be used to test for association directly, as in a non‐admixed population. As an alternative, these data can be used to infer chromosomal ancestry, and thus allow for admixture mapping. We quantify the contribution of allele‐based and ancestry‐based association testing under a family‐design, and demonstrate that the two tests can provide non‐redundant information. We propose a joint testing procedure, which efficiently integrates the two sources information. The efficiencies of the allele, ancestry and combined tests are compared in the context of a GWAS. We discuss the impact of population history and provide guidelines for future design and analysis of GWAS in admixed populations. Genet. Epidemiol . 34:783‐791, 2010.