After 10 difficult years of work, researchers announced in 1993 that they had located the gene causing Huntington's disease. Since then, the pace at which other disease-causing genes have been found has greatly accelerated, so that genes are typically located in no more than two years. Now a new tool that can reduce the time needed for a critical step involved in gene identification, from perhaps as much as 10 months to a day, should allow gene discoveries to be made much faster still.

The tool is a map showing the approximate positions of thousands of genes-of still largely unidentified function-along the genome, the complete set of our 3 billion chemical "base pairs" of DNA. The map, which is being developed by an international consortium of 104 scientists, including researchers at the Whitehead/MIT Center for Genome Research (CGR), was made possible by a concerted previous effort that identified the chemical makeup of more than 450,000 short sections of DNA that lead to the manufacture of protein fragments. Researchers recognize that since genes direct protein production, the short sections-known as complementary DNAs, or cDNAs-are portions of genes and thus of potentially great value. But no widespread group of scientists has previously determined just what genes these DNA sections belong to.