Consortium unveils first human genetic variation map

An international team of scientists has published a map of human genetic variation, an achievement they say will speed the search for genes involved in conditions such as diabetes and heart disease. The 'HapMap' project, launched in 2002 by the International HapMap consortium, is looking at DNA samples from 270 people from around the world, to help uncover the genetic differences linked to common diseases. The scientists published their results in the journal Nature, and also presented details of their research at the annual meeting of the American Society of Human Genetics, held in Salt Lake City.

The HapMap scientists looked at genetic markers (called single nucleotide polymorphisms, or SNPs) that have been inherited together in a block over many generations, indicating that they are physically close to each other. To identify these 'haplotype blocks', the researchers studied people originating from China, Nigeria, Japan and the US. Between them, these populations are thought to represent the majority of human genetic variation.

Now they are catalogued, it is hoped that the haplotype blocks will provide 'shortcuts' for researchers trying to identify genes involved in common diseases. Instead of having to study all of the estimated ten million SNPS, scientists will only have to look at SNPs in key positions within each block. Team member Peter Donnelly, of the University of Oxford, says that by using such an approach to look for genes involved in diseases such as stroke and heart disease, 'we might be able to get away with only comparing 5-10 per cent of the 10 million SNPs, suddenly making searches affordable'.

The data from the HapMap project is freely available to researchers via genetic databases, and has already been used to identify some disease genes - a team at Yale University has linked a gene called HF1 to age-related macular degeneration, a leading cause of blindness in the US. Team leader Josephine Hoh told the Scientist magazine that she was glad to have the HapMap data, adding it saved a lot of energy and time. Francis Collins, director of the US National Human Genome Research Institute, predicts there will be 'an outpouring of discovery in the next two to three years'.