Abstract:
Admixture mapping (also known as “mapping by admixture linkage disequilibrium,” or MALD) provides a wayof localizing genes that cause disease, in admixed ethnic groups such as African Americans, with∼100 times fewermarkers than are required for whole-genome haplotype scans. However, it has not been possible to perform powerfulscans with admixture mapping because the method requires a dense map of validated markers known to have largefrequency differences between Europeans and Africans. To create such a map, we screened through databasescontaining∼450,000 single-nucleotide polymorphisms (SNPs) for which frequencies had been estimated in Africanand European population samples. We experimentally confirmed the frequencies of the most promising SNPs in amultiethnic panel of unrelated samples and identified 3,011 as a MALD map (1.2 cM average spacing). We estimatethat this map is∼70% informative in differentiating African versus European origins of chromosomal segments.This map provides a practical and powerful tool, which is freely available without restriction, for screening fordisease genes in African American patient cohorts. The map is especially appropriate for those diseases that differin incidence between the parental African and European populations.
