Scientists have created the most comprehensive physical map yet of the human genes, an achievement that should speed up the search for disease-causing genes.
The map covers nearly 90 percent of the strandlike material called DNA that holds the estimated 100,000 human genes, researcher Daniel Cohen said.The map does not pinpoint the location of all the genes in the DNA it covers. Rather, it is basically a user's guide to a standard set of more than 10,000 overlapping DNA fragments. The set of fragments is stored in refrigerators in many laboratories.
The fragments include a total of about 2,000 markers, which are genetic signposts that are relatively easy to spot in the DNA of people.
The map can help scientists isolate unknown genes once their studies of DNA from people show that a gene in question lies between a given pair of markers. Scientists can pull the proper fragments from the refrigerator and begin the job of pinpointing the gene.
Such a map is called a physical map, because it reveals physical distances between two markers. Cohen - general manager of the Center for the Study of Human Polymorphisms in Paris and scientific director of Genethon in Evry, France - and his colleagues describe the map in Thursday's issue of the journal Nature.
"It will provide an enormous practical boost to gene-hunters," said Dr. Francis Collins, director of the National Center for Human Genome Research.
Cohen and co-authors called their result a "first-generation" map to emphasize that it contains mistakes and must still be refined. One task is to fill in the 10 percent of DNA not yet covered.
Among other problems, the map probably assigns some fragments to the wrong places among the markers, Cohen said.