The hope is that as disease researchers and epidemiologists compare the genetics of patients with ailments such as asthma or schizophrenia to those of healthy people, the map will guide them to the differences in genes or combinations of genes that put a person at risk. Not only can such information be critical in forewarning at-risk individuals, it can also provide invaluable clues to drug developers searching for the biological mechanisms that cause the diseases.
The most immediate impact of the HapMap, though, is likely to be the prediction of how a patient will respond to a drug (see “Startups Seek Genomics’ Killer App” ). Adverse drug reactions cause more than 100,000 deaths each year in the United States alone. And, says David Goldstein, a geneticist at the University College of London, identifying the genetic factors underlying different responses to drugs could lead to quick and easy tests to screen patients. “There is absolutely no doubt that the haplotype map will help,” he says. “Even if that’s all the HapMap does, it will be a critical contribution to medicine.”