Mental-health professionals and those who suffer from major depression are aware that the debilitating disease can run in families. But they know this primarily through observation and experience. Now, two separate, independent studies have identified a DNA region that could supply physical evidence of this inherited link. Researchers at Washington University School of Medicine in St. Louis and King's College London have independently identified DNA on chromosome 3 as a culprit in major depression. Both studies, published in the American Journal of Psychiatry, identified the region, which contains up to 90 genes.
"What's remarkable is that both groups found exactly the same region in two separate studies," senior investigator Pamela A. F. Madden, professor of psychiatry at Washington University, said in a statement. "We were working independently and not collaborating on any level, but as we looked for ways to replicate our findings, the group in London contacted us to say, 'We have the same linkage peak, and it's significant.'"
As is always the case in these kinds of studies, more and broader studies will be needed to confirm this genetic link. Neither research team has isolated any single gene or group of genes and linked them specifically to depression. However, the peak of the linkage they do report is located on a part of the chromosome known to house GRM7, which other scientists have suggested is linked to major depression.
"Our linkage findings highlight a broad area," said lead author Michele L. Pergadia in a news release. "I think we're just beginning to make our way through the maze of influences on depression. The U.K. samples came from families known to be affected by depression. Our samples came from heavy smokers, so one thing we might do as we move forward is try to better characterize these families, to learn more about their smoking and depression histories, in addition to all of their genetic information in this area."