Scientists discover genetic marker that predicts suicide risk

Scientists have discovered a genetic mutation linked to the human stress response that may be able to determine a person’s likelihood of committing suicide. They say they hope their discovery could lead to a simple blood test that would predict a person’s suicide risk.

A group of researchers from Johns Hopkins compared the brain tissue of people who had committed suicide to that of people without mental health problems, and found a key difference in a gene called SKA2.

SKA2 is found in the prefrontal cortex, a portion of the brain that regulates negative thoughts and impulsive behavior. The scientists discovered that in the brains of people who had killed themselves, levels of SKA2 were lower than in brains of people without mental health problems. Because SKA2 shuts down the stress response, the mutation effectively prompted the body to continue to release cortisol and other stress hormones in the people who were suicidal.

Previous studies have associated problems with cortisol release with suicide risk.

“We think that SKA2 acts like a chaperone for the stress hormone receptor,” said Zachary Kaminsky, a psychiatry and behavioral sciences professor at Johns Hopkins Medicine in Baltimore, Maryland, and one of the authors of the research, which was published Wednesday in the Journal of American Psychiatry. “It’s like a brake pad for the stress response.”

Kaminsky said he and his team were surprised to discover the new molecular marker, so they sought to replicate the results — and continued to find the SKA2 mutation in the brains of two other cohorts of people who had committed suicide. “This doesn’t happen usually,” he said. “But [the genetic marker] was still there, no matter who we looked at, so we thought, what will happen if we look in the blood?”

The scientists then examined blood samples from three different groups of people who had been asked about whether they had thought about or attempted suicide, including one group of more than 300 people. They found the same genetic marker — and were able to use it to predict with 80 percent accuracy whether a person had thought about committing suicide.

And among people who had actually attempted suicide, the marker was even stronger; they could use it to predict suicide attempts with 90 percent accuracy.

“We’re really identifying a new player in terms of genes to behavior,” Kaminsky said.

He stressed that a great deal more of research needs to be done to figure out what causes this particular expression of the SKA2 gene — he and his group don’t know whether people who committed suicide started out with that marker, or whether the SKA2 gene changed in response to something, such as elevated cortisol levels. “We really have a chicken or the egg problem” that needs to be examined further, he said.

Suicide is the 10th leading cause of death in the U.S., with more than 30,000 self-inflicted deaths occurring annually and more than 713,000 people visiting the emergency room for self-inflicted injuries each year, according to the Centers for Disease Control.

Suicide has been a particularly dire problem among military veterans, and Kaminsky’s group has suggested that perhaps a blood test that can predict a genetic predisposition to suicide could be used in military populations. They also suggested it could be used to identify people at risk for suicide attempts in psychiatric emergency rooms or other health care settings to determine how aggressive a response a patient needs.

“With a test like ours, we may be able to stem suicide rates by identifying those people and intervening early enough to head off a catastrophe,” Kaminsky said.