TO READ: Approaching a Genetic Understanding of Depression
Scientists continue to chip away - and sometimes blast away - at the mystery of depression. And they're making progress. In a major step forward, a consortium of psychiatric researchers announced last month the identification of a region on chromosome 15 that has "a very good chance" of ultimately explaining why some people develop depression.

You probably know that both genetic and environmental factors are believed to be responsible for depression. A better understanding of specifically which genes (there are thought to be several) in our DNA place us at risk for depression would constitute a major research breakthrough: If scientists can locate the key genes, they can determine how they affect the brain and, as a result, can develop more effective therapies for the illness.

Two studies reported in the February American Journal of Psychiatry were conducted by groups at six universities, led by Stanford professor Douglas Levinson, M.D. First these researchers studied 650 families in which two or more members had experienced multiple bouts of severe depression that began in childhood or early adult life. They scanned the entire genome and found areas of "linkage" between depression and DNA markers in several areas. Then they homed in on the most suspicious region, which lies on chromosome 15.

What they found, after studying more than 88 DNA markers in that area, was what Levinson called "one of the strongest genetic linkage findings for depression so far."

The consortium is now studying more than 2,000 people to identify specific genes in the regions, including on chromosome 15, that look most likely to carry variations that increase depression risk.