Genetic linkage studies implicate chromosome 15.
Stanford University researchers located a specific region on one chromosome they believe contributes to predisposition to severe depression. “This finding has a very good chance of leading to a discovery of a gene that could yield important information about why some people develop depression,” says Dr. Levinson.
If problematic genetic variations could be identified, it would open the door to a whole new world of investigation, and eventually, treatment possibilities.
The research was led by Douglas Levinson, M.D., professor of psychiatry and behavioral sciences at the Stanford University School of Medicine. The team’s results are reported in two papers that will be published in the February issue of the American Journal of Psychiatry.
Dr. Levinson’s group, comprising researchers from six universities, studied 650 families in which at least two members suffered from repeated bouts of severe depression that began in childhood or early adult life. The first of the studies was a genome-wide scan that looked for evidence of genetic linkage, within families, between depression and DNA markers on the various chromosomes. The second study was a more detailed look at the most suspicious of these regions, located on chromosome 15.
Dr. Levinson says the team studied six DNA markers in this region in the first study and an additional 88 in the second. “We found highly significant evidence for linkage to depression in this particular part of chromosome 15,” notes Dr. Levinson.
“We don’t think depression is entirely genetic, by any means, but there are important genetic factors,” cautions Dr. Levinson. “If we can succeed in finding one or more genes in which there are specific DNA sequence variations that affect one’s risk of depression, then we would be able to understand what type of gene is it, what it does in the brain, and by what mechanism it could make one more or less predisposed to depression.”