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30 Jul, 2014 17:27

DNA test may predict suicide risk - study

DNA test may predict suicide risk - study

A new genetic discovery by researchers may lead to the creation of a blood test that could use DNA to determine a person’s risk of suicide.

A team of Johns Hopkins University doctors have published their research in The American Journal of Psychiatry regarding a series of experiments conducted on brains and blood that showed a mutation in the gene SKA2 that involved how the brain responds to stress could foreshadow one’s risk of attempting suicide.

Dr. Zachary Kaminsky, lead author and assistant professor of psychiatry and behavioral sciences at Johns Hopkins, and his fellow researchers had previously identified a chemical alteration that can show women at risk for postpartum depression. Like postpartum depression, suicide is linked with a hormonal cause. In suicide’s case, it is the stress hormone cortisol.

“We get stressed out and flooded with cortisol,” Kaminsky told The Daily Beast. “We have to wake up, fight or flight, run away, or just catch a cab to work. Cortisol is going to go up, but it should go back down again. We think SKA2 is important in that. If you have less, which is what we’re finding, then you’re going to have less of an ability to turn that off.”

The SKA2-gene mutation was first noticed by Kaminsky’s team during a set of genome scans of postmortem brain samples from both healthy individuals and people with mental illness. The brains of those who died by suicide had less SKA2. Researchers also found evidence of chemical changes, or epigenetic modifications, in the way DNA functioned in the body.

Epigenetics deals with control of genes and their expression; in the case of suicide, it deals with suppression. While the gene stays the same, chemicals known as methyl groups can manipulate genetic functions, acting like on-off switches for genes affected by factors like stress or nutrition. Those who committed suicide were found to have higher quantities of methylation.

The research team then used blood samples from living test patients, finding high levels of methylation, or “bad instructions,” in those who said they had thoughts of suicide or had attempted to kill themselves.

This information allowed researchers to analyze previous samples, finding that they could predict those at risk of suicide with 80 percent to 90 percent accuracy based on levels of risk.

Kaminsky said he’s cautiously optimistic despite the limitations of a fairly low sample size of about 550.

“If we can identify who is at risk, we may be able to intervene in effective ways,” Kaminsky said. “Notably, we could identify individuals in military populations who are more vulnerable to stress. We know they’re going to be experiencing stress when they go off to combat.”

He said the research team will not test hundreds of samples from soldiers both pre- and post-deployment in a collaboration with the US Army STARRS project, a major mental health study with the military

Suicide is the 10th leading cause of death in the US, according to the Centers for Disease Control and Prevention. Active service members have a suicide rate 50 percent higher than the national rate.