THE "VIOLENT" GENE

Dr Daniel Weinberger, of the US National Institute of Mental Health, and his team conducted a study which suggests that people who are genetically predisposed to violence have a different brain structure to others. The gene called Monoamine Oxidase or more commonly referred to as MAOA has been found to increase aggressiveness in human behavioral patterns.

According to Australian neurogeneticist Professor Peter Schofield, the most profound demonstration of the link was a study more than 10 years ago of a rare family in the Netherlands that had a catastrophic mutation in that gene. "All the males in that family with that mutation were arsonists and rapists," Professor Schofield, who heads the Prince of Wales Medical Research Institute in Sydney, said. In addition, he says animal studies have shown that mice without an MAOA gene have aggressive tendencies.

The data provided identified neural mechanisms associated with one specific gene epidemiologically associated with risk for violent and impulsive behavior. The gene, which is carried on the X chromosome, produces an enzyme that mops up stress hormones in the brain which leads to violent and unpredicted actions. 

Furthermore, Dr Weinberger and team have tried to find out more about how this complex interaction of genes and environment works. Dr Weinberger and team studied the genes and brains of 142 healthy men and women, who had no history of violence. 

The researchers showed the study participants pictures of angry and fearful faces and monitored the structure and function of their brains using magnetic resonance imaging. They found those with the low-expressing version of MAOA were more impulsive. Parts of their brain associated with emotion differed in size and activity to those with the high-expressing version. The study also found that activity of those parts of the brain in males with low-expression MAOA differed more greatly than their female counterparts. 

Dr Weinberger and team say their work sheds light on the neural mechanisms involved in genetic predisposition to violence and it could help in finding ways to combat violence using biological approaches. But they emphasise the genetic contribution to violence is small.

Reference: http://www.micro.siu.edu/micr302/MAO.html, : http://www.pnas.org/content/early/2009/01/23/0808376106.abstract, and http://www.abc.net.au/news/newsitems/200603/s1597238.htm

Tutor: Pat Ward

By: Naaman Narayan