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A public–private research consortium has contracted two companies, Motorola and Celera, to develop a tool to find genes involved in heritable diseases.

The tool is a statistical map of inheritance patterns of single-nucleotide polymorphisms (SNPs), the sequence variants scattered throughout the genome that account for most genetic differences between individuals. The information will help researchers find areas of the genome associated with hereditary diseases.

The SNP Consortium — a collaboration of university sequencing centres, ten pharmaceutical companies and the Wellcome Trust, a British medical research charity — has so far compiled a public list of almost 2 million SNPs.

Because they vary from person to person, SNPs are effective markers for tracking genetic regions through family histories. But because chromosomes exchange DNA with each generation, researchers need to know the probability of nearby SNPs staying together.

In the collaboration, announced on 28 August, the sequencing firm Celera, of Rockville, Maryland, and the life sciences unit of Motorola, in Deerfield, Illinois, will chart inheritance patterns of 2,000 SNPs in 650 people from 50 families. Although Celera claims to have identified more than 3 million SNPs, only public data will be used in this project. Financial details have not been disclosed.

The map is due to be completed by the end of this year. A plan announced in July to produce a much more detailed map of up to 1.5 million SNPs is expected to take several years (see Nature 412, 105; 2001).

The small number of SNPs being mapped in the Celera–Motorola project will be useful only for studies within families. Studies of the population at large, in which genetic recombination has been much more extensive, will require larger numbers of SNPs.

Current linkage maps use another genetic variant, microsatellites, which have been very effective, says David Altshuler, a geneticist at Harvard Medical School and leader of a team that published 1.4 million SNPs earlier this year.

He expects people to jump on the SNP bandwagon as technology for detecting them improves. “No one is pouring a lot of money into making microsatellite genotyping cheaper and easier,” he says. “But a lot of companies are making SNP genotyping cheaper and easier.”