An international collaborative effort, initiated in 2002, to identify and catalogue the common genetic variations among human populations. The information is made freely available to researchers to enable them to identify genes that contribute to human diseases and affect responses to drugs. The project is based on the premise that much of the human genome consists of segments that are inherited more or less intact as haplotypes. A key phase in the project is to identify the 10 million or so single nucleotide polymorphisms (SNPs) that are scattered throughout the human genome and select those that can be used to tag each haplotype uniquely. It is estimated that 300 000–600 000 SNPs can effectively tag all human haplotypes. Hence a researcher need determine only these tag SNPs to identify the collection of haplotypes in the genome of an individual, rather than all 10 million SNPs, which makes it a lot easier to characterize a person's genotype. This then provides a means of comparing the genotypes of individuals with different traits and of identifying the differences in genetic makeup that could contribute to, for example, the occurrence of high blood pressure or diabetes in certain persons. The HapMap consortium is currently sampling four human populations with African, Asian, and European ancestry, to assess how haplotype frequencies vary according to ethnic origin and determine the most common haplotypes in each population.
Subjects: Biological Sciences.