Gene maps: the sites fill.

Gene maps: The sites fill

Understanding where specific genes lie on the strings of DNA that make up the chromosomes can help researchers understand the body's workings and malfunctionings. Scientists increasingly are filling in the details of such gene maps. Estimates put the number of genes in humans and mice at 50,000 to 100,000. Gene mappers have mapped some 1,400 human genes to their respective chromosomes and pinpointed more specific sites for a number of these. "We're discovering a [human] gene every three days at leat," says Frank H. Ruddle of Yale University in New Haven, Conn. The mouse map now contains 1,150 genes, 400 of which exist in humans as well and thus allow genetic studies in mice to answer specific questions about human disorcers, notes Thomas M. Roderick of the Jackson Laboratory in Bar Harbor, Maine.

Researchers hope a coordinated international effort, called the human genome project, will map the location of all human genes over the next decade. "If we were to do this all in the next 10 years, we [would] hav e essentially 5,000 genes a year or so to map on average," Ruddle says. "So we've got to increase the rate at which genes are being discovered."