Identification of tag single-nucleotide polymorphisms in regions with varying linkage disequilibrium

Abstract

We compared seven different tagging single-nucleotide polymorphism (SNP) programs in 10 regions with varied amounts of linkage disequilibrium (LD) and physical distance. We used the Collaborative Studies on the Genetics of Alcoholism dataset, part of the Genetic Analysis Workshop 14. We show that in regions with moderate to strong LD these programs are relatively consistent, despite different parameters and methods. In addition, we compared the selected SNPs in a multipoint linkage analysis for one region with strong LD. As the number of selected SNPs increased, the LOD score, mean information content, and type I error also increased.

Figure 1

Selected SNPs and linkage disequilibrium plots. Figure 1 depicts the LD (D') and the tag SNPs selected by each program. Red regions depict D' = 1.0 with strong confidence. Light blue regions are D' = 1.0 but decreased confidence. White regions are D' < 1 and state D' within the box. An X denotes that SNP was selected by the program. The gray shading in the HAPLOVIEW row represents the Gabriel blocks. The dark lines represent breaks between blocks for both HAPLOVIEW and HaploBlock Finder. For some chromosomes no blocks were identified and this is indicated by hatch marks across the SNPs.