Track Description:

Haplotype blocks derived from common SNPs on Chromosome 21 by Perlegen as described in "Common High-Resolution Haplotypes." Patil, N. et. al. Science 294:1719-1723 (2001) [Science]. The location of each haplotype block is represented by a blue horizontal line with tall vertical blue bars at the first and last SNPs of the block. Blocks are displayed as starting at the first SNP and ending at the last SNP of the block. This display is slightly different from the Perlegen web site where blocks are stretched until they abut each other. They define haplotype block boundaries as the midpoint between the last SNP of one block, and the first SNP of the next block. The shade of the blue indicates the minimum number of SNP's required to discriminate between haplotype patterns that account for at least 80% of genotyped chromosomes, darker colors indicate fewer SNPs are necessary. Individual SNPs are denoted by smaller black vertical bars. At multi-megabase resolution in dense mode clusters of tall blue bars may indicate hotspots for recombination. More information is available for the individual block selected at the "Outside Link" above and general information on the blocks is available at Perlegen's main haplotype map page http://www.perlegen.com/haplotype/