An international team has tracked a million DNA variations in volunteers around the world, as part of an effort to map the diversity of human genes. Experts say the growing catalogue, called the HapMap, will help to pinpoint genetic causes of disease and develop more effective treatments.
"It's a major leap for genetic research," says Tom Hudson of McGill University in Montreal, who led the Canadian contribution to the HapMap.
Any two people have DNA sequences that are typically 99.9% similar. The few tiny differences between their genetic codes account for they way they vary in traits from eye colour to susceptibility to disease. Many of these differences consist of changes in single bases of the genetic code, also called single nucleotide polymorphisms or SNPs. The human genome is about 3 billion bases long, and there are roughly 10 million sites where SNPs (pronounced 'snips') are thought to occur commonly.
Researchers hope that by cataloguing SNPs and the frequency with which they occur in different populations they will boost efforts to target drugs at different genetic types. Because there are so many SNPs, the HapMap project aims to sort them in ways that will make such analyses easier.