A University of California, Los Angeles, research team may have uncovered data that could lead to new diagnostic tests for post-traumatic stress disorder. Armen Goenjian, a professor at UCLA's David Geffen School of Medicine, headed up a team that analyzed DNA from 200 adults across multiple generations of 12 extended Armenian families who reported suffering from PTSD after an earthquake struck the northern part of the country in 1988. The results of their study were published in the April issue of the Journal of Affective Disorders.
In their paper, Goenjian and his colleagues show that individuals with specific variants of two genes — TPH1 and TPH2 — are more likely to develop PTSD after experiencing a traumatic event. Both genes encode rate-determining enzymes for the biosynthesis of serotonin, a neurohormone involved in the regulation of mood and sleep.
Before these findings can be translated into the clinic to treat the growing population of war veterans returning from Iraq and Afghanistan with PTSD, Goenjian and his team need to replicate their findings and identify other genes that may contribute to the disorder. Then they can start looking for affordable ways to locate these and other genes that might indicate whether an individual is at risk for developing PTSD, or confirm the diagnosis of the disorder.
"In this study, these two genes combined explain about 8 percent of the variance of PTSD symptoms, so we would like to identify more genes, which we plan on doing," Goenjian says. "We think that this is an early step, and that, along with similar findings, they will lead us [to] define PTSD based on neurobiology rather than clinical observations and find treatments that target these genes."
While Goenjian says that next--generation sequencing platforms would be a boon to diagnostic tool development for PTSD, there is currently a dearth of samples necessary for adequate studies. "Our samples would be ideal for that because we have multiple affected [people] in families so we could narrow the search to chromosomal regions shared amongst the affected," he adds.
Goenjian plans to identify additional candidate genes that code for other neurohormones involved in the disorder, and may eventually test prototype diagnostic tests for these genes in US military veterans. But for now, he adds, the researchers are still trying to identify genes using a single ethnic population, which is less heterogeneous than the US veteran population and hence has fewer confounding factors.