Researchers at Washington University School of Medicine in St. Louis and King's College London have independently identified a DNA region on chromosome 3 that appears to be related to depression. Major depression affects approximately 20 percent of people at some point during their lives, and family studies have long suggested that depression risk is influenced by genetics. The new studies identify a DNA region containing up to 90 genes. Both studies were published online on May 15, 2011, in the American Journal of Psychiatry. "What's remarkable is that both groups found exactly the same region in two separate studies," says senior investigator Dr. Pamela A. F. Madden, professor of psychiatry at Washington University. "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.'" Dr. Madden and the other researchers believe it is likely that many genes are involved in depression. While the new findings won't benefit patients immediately, the discovery is an important step toward understanding what may be happening at the genetic and molecular levels, she says. The group at King's College London followed more than 800 families in the United Kingdom affected by recurrent depression. The Washington University group gathered data from 91 families in Australia and another 25 families in Finland. At least two siblings in each family had a history of depression, but the Australian and Finnish participants were studied originally because they were heavy smokers. "Major depression is more common in smokers, with lifetime reports as high as 60 percent in smokers seeking treatment," says lead author Dr. Michele L. Pergadia, research assistant professor of psychiatry at Washington University.
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