New research has identified a genetic marker that may identify people at high risk for major depression, which scientists say could lead to earlier treatment.

Using blood samples from more than 1,100 Mexican Americans from 40 extended families, researchers at the Texas Biomedical Research Institute in San Antonio and Yale University found an association between a gene called RNF123, which plays a role in the growth of nerve cells, and the risk of major depression.  They used a new method that analyzed more than 11,000 different genetic variables.

“We were looking for the biological basis of this psychiatric disorder, and there is a lot less known about the biology behind psychiatric conditions than about other medical conditions,” said John Blangero, a co-author and director of Texas Biomedical’s AT&T Genomics Computing Center.

Higher levels of RNF123 in the blood are associated with lower risk of major depression, and the relationship between RNF123 and major depression is very strong, Blangero explained.

“It’s stronger than the genetic link between high-density lipoprotein [HDL] cholesterol and cardiovascular disease,” he said.

RNF123 can easily be measured in a person’s blood, which may make it possible to identify people at risk for this debilitating disorder.

“Once you find a gene, it opens up a whole new window for drug targeting,” said Blangero.  Major depression is a serious mental illness, and predicting risk can potentially lead to earlier treatment, he added.

While they don’t know exactly how RNF123 may lead to depression, the authors believe it could influence the structure of certain parts of the brain.

Scientists not involved in the study say this is a very promising new approach to zeroing in on how genetic factors manifest themselves in certain disorders.

“There have been a few markers shown to have some relationship to depression, but it’s been really hard to identify specific ones related to major depression,” said Adam Naj of the John P. Hussman Institute for Human Genomics at the University of Miami’s Miller School of Medicine.

Conventional methods of  evaluating genetic risk involve comparing the genetic makeup of people who have a certain medical condition to people who don’t, and then going back to try to figure out what effects they have on the body.  This type of analysis, Naj said, allows for more detailed identification of genetic factors.

“With this approach, we can try to figure out what the genetic variations may do to features closely related to the disorder,” he said.

Naj also said this method of analyzing heritable factors has been used in research on other conditions, such as cardiovascular disease and diabetes.