Unscrambling Genetic Codes: A Progress Report

After years of sleuthing, scientists are zeroing in on the gene that causes Huntington's disease, an inherited brain disorder that leads to involuntary jerking movements, memory loss, and death. In fact, rival researchers report two promising discoveries in the November issue of Nature Genetics. A team led by James F. Gusella of Massachusetts General Hospital is betting on a gene on chromosome 4 that "codes" for a protein crucial to the inner structure of cells. Michael R. Hayden and colleagues at the University of British Columbia have linked the disease in one patient to a rearrangement of the normal sequence of a nearby gene. Proving either theory would be a major step forward.

Meanwhile, other scientists are moving briskly to identify the functions of all 50,000 to 100,000 human genes. In the Oct. 29 Nature, French geneticists said they have constructed a relatively detailed map of human DNA. It provides chromosome signposts that make it easier to find specific genes. The new map, researchers say, means the Human Genome Project, as the gene-discovery effort is called, is ahead of schedule. Some now predict that all human genes will be decoded by 1999.