Mapping human haplotypes

Abstract

Scientists at Genaissance Pharmaceuticals estimate that there are roughly 14 versions of each human gene. In their analysis, they studied 3899 single nucleotide polymorphisms (SNPs) that were derived from 313 genes present in 82 unrelated Africans, Americans, Asians or Latinos. It is very hard to predict disease susceptibility by analyzing how single SNPs vary between individuals. By looking at the combinations of several SNPs, however, a more defined picture or haplotype emerges. If the SNPs were independent, there would be millions of possible combinations, instead the researchers defined 4304 different haplotypes of linked SNPs. These results will help in understanding patterns of human genomic evolution and lead the way towards individualized medicine and healthcare. For example, patients can be classified into drug-response groups on the basis of associated SNPs. One such clinical trial to determine how genetic polymorphisms are related to the efficacy of a drug used to treat asthma has already been initiated by Genaissance Pharmaceuticals. In addition, the NIH recently announced a concerted effort to map human haplotypes. The project is envisaged to last for two years, and, according to Francis Collins, the director of the National Human Genome Research Institute, is expected to involve the Wellcome Trust and the British government. [Stephens, J. C. et al. (2001) Science 293, 489–493] AP and SG