Gene Exists that Affects Chances of Depression but Has Small Impact

There is strong evidence that depression has a genetic foundation and researchers have found a particular variant, often referred to as the depression gene, which may increase the chances that a person will suffer. However, researchers from the University of Michigan say that although they have found more evidence of the gene’s existence, the effect is probably pretty small.

Genetic Variation Probably Accounts for 5-7% of Chances of Developing Depression

Dr. Srijan Sen, an assistant professor of psychiatry at the University of Michigan Medical School, and colleagues examined evidence from 54 studies conducted between 2001 and 2010 that specifically focused on the 5-HTTLPR region of a gene called SLC644. This gene is responsible for coding the serotonin transporter and 5-HTT is the major site of serotonin reuptake. A variant to the 5-HTTLPR s allele is associated with an increased risk of developing depression under stress.
Serotonin is a neurotransmitter that helps relay messages from one area of the brain to another. Brain cells most influenced by serotonin are those that control mood, appetite, sleep, memory and learning and other social behavior. Researchers believe that an imbalance in serotonin levels leads to depression.
Although many studies strongly support the existence of a “depression gene”, Dr. Sen says that having the genetic variant probably only accounts for about 5 to 7 percent of one’s likelihood of developing clinical depression. There are likely other genetic factors involved, he stresses.
However, a better understanding of this region of the serotonin transporter gene may be able to help predict those with a predisposition toward depression and perhaps better individualize treatment and provide support to those at risk.
"Over the last ten years, there are more and more people looking at how to promote positive emotions instead of just playing defense against the negative ones," says Sen. "For those with a genetic predisposition towards depression, it will become very important to learn how to promote positive emotions and resilience in these patients to ward off a possible episode of depression."
Medication development is another area that could benefit from this knowledge. Currently, there are many who do not respond positively to the most popular class of antidepressant medications, known as SSRIs, or selective serotonin reuptake inhibitors. Genetic research may help pharmaceutical makers develop a better drug to help those who suffer from depression due to this gene mutation.