LD in African-Americans

making the case for the utility of admixed populations (with greater LD) in genotyping and association studies.

Dissecting Linkage Disequilibrium in African American Genomes: Roles of Markers and Individuals.

Xu S, Huang W, Wang H, He Y, Wang Y, Wang Y, Qian J, Xiong M, Jin L.

Mol Biol Evol. 2007 Jul 13; [Epub ahead of print]

Abstract: Substantial increases of linkage disequilibrium (LD) both in magnitude and in range have been observed in recently admixed populations such as African American (AfA). On the other hand, it has also been shown that LD in African Americans was very similar to that of African. In this study, we attempted to resolve these contradicting observations by conducting a systematic examination of the LD structure in African Americans by genotyping a sample of African American individuals at 24,341 SNPs spanning almost the entire chromosome 21, with an average density of 1.5 kb/SNP. The overall LD in African Americans is similar to that in African populations and much less than that in European populations. Even when the ancestry-informative markers (AIMs) were used, extended LD in AfA was found to be limited to certain magnitude range (0.2