International consortium completes map of human genetic variation 26/10/05. By the Wellcome Trust Sanger Institute The International HapMap Consortium has published a comprehensive catalogue of human genetic variation, a landmark achievement that is already accelerating the search for genes involved in common diseases, such as asthma, diabetes, cancer and heart disease.

In the report, published in the journal Nature on 27 October 2005, more than 200 researchers from Canada, China, Japan, Nigeria, the UK and the USA describe the initial results from their three-year public-private effort to chart the patterns of genetic variation that are common in the world's population.

Their findings show that the search for clinically relevant genes can be simplified by using the map of variation developed by the HapMap Project .

Much of our genetic variation is caused by single-nucleotide differences in our DNA code: these are called single nucleotide polymorphisms, or SNPs. As a result, each of us has a unique genetic code that typically differs in about three million nucleotides from every other person.

The HapMap project has shown patterns of association between SNPs studied in different populations from around the world. These can be used to simplify studies to understand how genetic variation contributes to health and disease.

"Humans are genetically 99.9 per cent identical: it is the tiny percentage that is different that holds the key to why some of us are more susceptible to common diseases such as diabetes and hypertension or respond differently to treatment with certain drugs," said Dr Panos Deloukas at the Wellcome Trust Sanger Institute.

"This report describes a remarkable step in our journey to understand human biology and disease," explained Professor Peter Donnelly, University of Oxford. "The human genome sequence provided us with the list of many of the parts to make a human. The HapMap provides us with indicators - like Post-It notes - which we can focus on in looking for genes involved in common disease."

Medical genetics will benefit enormously from the increased power that the HapMap provides. By using HapMap data to compare the SNP patterns of people affected by a disease with those of unaffected people, researchers can survey the whole genome and identify genetic contributions to common diseases more efficiently than has been possible without this genome-wide map of variation: the HapMap Project has simplified the search for gene variants as much as 20-fold.

The publicly available SNP datasets were used by medical researchers even before the first draft of the map was completed. For example, in March 2005, studies published in the journal Science used HapMap data to uncover a genetic variation that substantially increases the risk of age-related macular degeneration, the leading cause of severe vision loss in the elderly.

Further reading

Altshuler et al. A haplotype map of the human genome. Nature 2005 437;1299-320. Abstract .

Links

International HapMap Project