The first- and second-generation versions of HapMap resulted from the analysis of DNA collected from 270 volunteers from four geographically diverse populations: Yoruba in Ibadan, Nigeria; Japanese in Tokyo; Han Chinese in Beijing; and Utah residents with ancestry from northern and western Europe.
The third-generation HapMap, reported in the Sept. 2 issue of the journal Nature, is the largest survey of human genetic variation performed thus far. It has data on 1,184 people, including the initial HapMap samples. Additional human samples were collected from the original populations and from seven new populations: individuals of African ancestry from the Southwestern United States; Chinese individuals from metropolitan Denver; Gujarati Indians from Houston; Luhya people from Webuye, Kenya; Maasai people from Kinyawa, Kenya; individuals of Mexican ancestry from Los Angeles; and individuals from Tuscany, Italy. No medical or personal identifying information was obtained from the HapMap donors. However, the samples are identified by the population from which they were collected.
Researchers analyzed approximately 1.6 million SNPs in about 500 samples from the four original populations and more than 650 samples from the seven new populations. In addition, the consortium sequenced 10 regions totaling about 1 million base pairs in 692 samples from this set in 10 of the 11 populations. More than 800 copy-number variants, where people have different numbers of copies of genomic regions, were also added to the resource.
As expected, the increased number of samples allows detection of variants that are much rarer than could be found by the earlier HapMaps. Because of human population history, lower-frequency variation is shared less among populations. For instance, 77 percent of the detected SNPs were new, rev
|Contact: Geoff Spencer|
NIH/National Human Genome Research Institute