Gene Of The Week

Cystic fibrosis, cleft palate, muscular dystrophy, Alzheimer's disease, Huntington's chorea. The list of disorders that have been traced to a specific gene or gene region seems to grow on a weekly basis. The latest in this gene- of-the-week series: the discovery of a region on the X chromosome that is linked to manic depression, a mental disorder that affects as many as 2 million Americans. The finding, published in Nature by an American and Israeli research team, was based on studies of five families in Jerusalem. It marks the second time in three weeks that a genetic site has been linked to this disorder. The earlier work, based on studies of Amish families, found a manic depression marker on chromosome 11. The discoveries of two separate genetic defects that can lead to the same disease "aren't necessarily contradictory but complement each other," says Dr. Miron Baron, who headed the team. "Together they support the belief that manic depression is a group of disorders with common symptoms rather than a single entity."