The completion of the human genome sequence in 2003, though momentous, was only the first step toward grasping the core mechanisms of human biology and disease. This ultimate biomedical goal also requires a comprehensive catalog of the genetic diversity in the human genome sequence across human populations. A flurry of high-profile scientific papers published this week heralds the success of pulling together such a catalog. The manuscripts describe both the content and uses of HapMap, a catalog that maps human genetic variation and relates it both to disease and to human evolutionary history. HapMap gives scientists worldwide a first good look at the “order in variety” that is the human genome.
All these studies are grounded in data presented in a significant paper published in the Oct. 27 issue of the journal Nature by an international consortium of more than 200 researchers from Canada, China, Japan, Nigeria, the United Kingdom, and the United States. In this paper, the authors describe the patterns of genetic variation in hundreds of human DNA samples collected from four sites around the world.

Perhaps the most striking finding in this mountain of data is the overwhelming evidence for previous work that suggested that human genetic variants located physically close to each other in the genome are collectively inherited as groups, or “haplotypes.” The implications – and potential value – of the genome’s haplotype structure for medicine has only begun to be realized.