Figure 1

Single nucleotide polymorphisms (SNPs), tag SNPs and microsatellites as genomic markers. (a) An autosome with evenly spaced microsatellites about 1 million base pairs (bp) apart. (b) A segment of DNA between microsatellite markers. SNPs within the segment are indicated by letters. Tag SNPs (C, H and K) travel with other indicated SNPs as blocks (haplotypes) and can serve as a surrogate for these haplotypes and, more importantly, for disease-causing genes in close proximity. (c) DNA segment with alternative alleles and genomic markers of the same genes as in (b). Note that in (b, c) the microsatellite markers are not as close to the genes as the noted SNPs are. Reprinted with permission from [24].