Washington: A new study has revealed the reason why some people are more susceptible to stress and stress-related psychiatric disorders.
Researchers at the Duke University found that the tiny addition of a chemical mark atop a gene that has been well known for its involvement in clinical depression and posttraumatic stress disorder could affect the way a person's brain responds to threats.
The study focused on the serotonin transporter, a molecule that regulates the amount of serotonin signaling between brain cells and has been a major target for treatment of depression and mood disorders. In the 1990s, scientists discovered that differences in the DNA sequence of the serotonin transporter gene seemed to give some individuals exaggerated responses to stress, including the development of depression.
Sitting on top of the serotonin transporter's DNA, are chemical marks called methyl groups that help regulate where and when a gene was active, or expressed. DNA methylation was one form of epigenetic modification being studied by scientists trying to understand how the same genetic code could produce so many different cells and tissues as well as differences between individuals as closely related as twins.
Ahmad Hariri, a professor of psychology and neuroscience, said that in looking for methylation differences, they decided to start with the serotonin transporter because we know a lot about it biologically, pharmacologically, behaviorally, and it's one of the best characterized genes in neuroscience.
He further added that if they were going to make claims about the importance of epigenetics in the human brain, they wanted to start with a gene that they have a fairly good understanding of.
The study is published in Nature Neuroscience.