Admixture mapping as a tool in gene discovery

Abstract

Admixture mapping is a rapidly developing method to map susceptibility alleles in complex genetic disease associated with continental ancestry. Theoretically, when admixture between continental populations has occurred relatively recently, the chromosomal segments derived from the parental populations can be deduced from the differences in genotype allele frequencies. Progress in computational algorithms, in identification of ancestry informative single nucleotide polymorphisms, and in recent studies applying these tools suggests that this approach will complement other strategies for identifying the variation that underlies many complex diseases.

Figure 1

Power of admixture mapping as a function of admixture mapping information. The power was determined from simulations using 700 cases and 700 controls and SNP sets with admixture information corresponding to the key for the SNP set used [8^••]. The power curves shown were determined by using the AdmixMap program and deCODE genetic map for either case-only (CO) or case–control (CC) analyses. The appropriate α level for these analyses, based on extensive simulations, was a normalized score of 4.0. The results were obtained from a minimum of 50 separate simulations and analysis of each measurement. Similar results were obtained with AncestryMap and MALDsoft algorithms in more limited analyses (data not shown). Figure reproduced, with permission, from study by Tian et al. [8^••].