MONDAY, July 1, 2002 (HealthDayNews) -- Genes play a role in who will suffer depression and who will be spared, and researchers have also found these "depression genes" are different for men and women.
Now, Pittsburgh researchers have identified a specific chromosome region that affects the risk of depression in women but not men.
"The results of this study suggest that sex-specific genes for recurrent major depression may actually be the rule rather than the exception," says George S. Zubenko, the study's author and a professor at the University of Pittsburgh School of Medicine and at Carnegie Mellon University in Pittsburgh.
The finding appears in today's Molecular Psychiatry.
More than 18 million U.S. adults, or about 9.5 percent of the population, suffer a depressive disorder in a given year, according to the National Institute of Mental Health.
Zubenko and his team compared genetic markers from 100 men and women with RE-MDD, a severe form of depression that runs in families, with 100 men and women with no history of depression. They wanted to see which chromosomal regions were associated with the depression.
In a previous study, they had found that 19 chromosomal regions were associated with RE-MDD and 16 were significantly associated with depression in either men or women, but not both. Now, they have confirmed that one region, located on chromosome 2, affects the risk of severe depression among women but not men.
"Our study is the first systematic study of chromosome regions," Zubenko says. "We anticipated some genes contributed differently to the onset of depression in men and women, and in a previous study suggest it is the rule rather than the exception. This study took a closer look at chromosome 2. We know the region of the chromosome, but not the exact gene."
Research continues, however, he says, and "we've got a great candidate."
The goal is to pinpoint the exact gene. "This kind of stepwise study will eventually lead us to the gene of interest," he says.
Once such genetic information is acquired, Zubenko says, it will be possible to engineer drugs or develop other treatments that will have an impact on the molecular level. "It might be possible to develop a treatment that acts on the gene or gene product or a protein produced by the gene," he says.
That application is in the future, Zubenko admits, but there is also a more immediate application of the discovery. Drug companies could "piggyback" studies that test new antidepressants on patients with different genotypes to see how they respond to the medicine.
The new study sheds some much-needed light on the condition of depression, says Julio Licinio, a professor of psychiatry and medicine/endocrinology at the UCLA School of Medicine in Los Angeles. He co-wrote an editorial accompanying the study.
"Depression has always been found to be more common in women than men, some two-and-a-half times more common," Licinio says. "But it has never been understood completely why."
"In this study, the important finding is they segregated [subjects] by sex and looked at genetic markers," Licinio says. "They found one [marker] predisposed women but not men."
Licinio adds it's important to realize that not everyone with the gene will become depressed. "The gene could interact with other genes or the environment [before depression sets in]," he says. Just like not everyone with the so-called breast cancer genes gets breast cancer, he adds, not everyone with the gene the Pittsburgh team evaluated will become depressed.
The genetic information may help those dealing with depression decide to seek professional help, he adds. "Many people think of depression as something you can just pull yourself up by the bootstraps [and recover]," he says.
Not so, he adds: "Depression is a biological disease."
What To Do
For information on women and depression, see the American Psychological Association or the National Institute of Mental Health.
