scientists and even practitioners of traditional medicine have long believed that understanding the genetic makeup of a person could help tailor a healthier diet. The same principle can now be extended to a database of small variations in a person's genetic makeup called HapMap, to devise more effective cures and treatments.
HapMap is a map of haplotypes. A haplotype is a set of closely linked markers on a single chromosome that tend to be inherited as a group. The International HapMap Consortium recently released the HapMap (Nature, Vol 437, No 7063, October 27, 2005). The database will be freely available on the Internet. A follow-up of the Human Genome Project, the HapMap Project was initiated in 2002.
The database has information on small bits of dna called single nucleotide polymorphisms (snps), which number about 3 billion. The scientists studied over 3 million snp s in two phases. The HapMap suggests a small percentage of snps (260,000 to 470,000) can be used as a shortcut to understand the role of genetic material in diseases such as Alzheimer's, asthma, cancer, diabetes and heart disease.
"Such information can help doctors prescribe the right drug in the right dose for each patient, as well as recommend prevention strategies that take into account individuals' varying responses to environmental factors such as diet,' writes Elizabeth G Phimister in the New England Journal of Medicine . Recently, Josephine Hoh and colleagues at Yale University used the HapMap to study macular degeneration, a leading cause of blindness in the us.
Researchers say HapMap is not meant to minimise the role of environmental factors in disease development. "In fact, studying genetic factors may greatly increase the likelihood of our understanding the environmental contribution to illness,' says Thomas Hudson, leader of the HapMap group at McGill University, Canada. As the genes have modified over time, the HapMap also gives clues to how evolution has modified dna and shaped variation in natural populations.