Scientists have identified two gene variants that put people at higher risk of developing post-traumatic stress disorder (PTSD).
Researchers from the University of California, Los Angeles found that heredity influences a person's risk of developing PTSD.
"Many people suffer with post-traumatic stress disorder after surviving a life-threatening ordeal like war, rape or a natural disaster," said lead author Dr Armen Goenjian, a researcher at the Semel Institute for Neuroscience and Human Behavior at UCLA.
"But not everyone who experiences trauma suffers from PTSD. We investigated whether PTSD has genetic underpinnings that make some people more vulnerable to the syndrome than others," Goenjian said.
In 1988, Goenjian, an Armenian American, went to Spitak, Armenia, after a 6.8 magnitude earthquake devastated the country.
With support from the Armenian Relief Society, Goenjian and his colleagues helped establish a pair of psychiatric clinics that treated earthquake survivors for 21 years.
A dozen multigenerational families in northern Armenia agreed to allow their blood samples to be sent to UCLA, where Goenjian and his colleagues combed the DNA of 200 individuals for genetic clues to psychiatric vulnerability, 'medicalxpress.Com' reported.
In 2012, his team discovered that PTSD was more common in survivors who carried two gene variants associated with depression.
In the current study, Goenjian and first author Julia Bailey, an adjunct assistant professor of epidemiology at the UCLA Fielding School of Public Health, focused on two genes called COMT and TPH-2 that play important roles in brain function.
COMT is an enzyme that degrades dopamine, a neurotransmitter that controls the brain's reward and pleasure centers, and helps regulate mood, thinking, attention and behaviour.
TPH-2 controls the production of serotonin, a brain hormone that regulates mood, sleep and alertness - all of which are disrupted in PTSD.
"We found a significant association between variants of COMT and TPH-2 with PTSD symptoms, suggesting that these genes contribute to the onset and persistence of the disorder," said Goenjian.
"Our results indicate that people who carry these genetic variants may be at higher risk of developing PTSD," Goenjian said.
