Genetic Mutation May Lead to Violent and Reckless Behavior

Dec. 22, 2010— -- In a discovery that could help scientists further understand impulsivity in humans, researchers announced that they found a genetic variant that may contribute to spontaneous violent behavior.

In a new study released in the journal Nature, a multinational research team examined the genes of 96 violent criminal offenders in Finland with behavioral disorders and compared it with DNA from a control group of 96 people in the country who had no such psychiatric diagnoses.

Scientists found that the criminal offenders were three times more likely to have a genetic mutation, known as the HTR2B Q20* mutation than the control group.

The offenders had been diagnosed with antisocial personality disorder, borderline personality disorder or intermittent explosive disorder, all conditions with symptoms of impulsive aggression.

The mutation was found to affect the brain's levels of serotonin, a neurotransmitter that affects mood, appetite, sleep and impulsive behavior.

"Impulsivity is a normal dimension of behavior, but it also plays a role in many psychiatric disorders, including alcoholism and suicidalism," said Dr. David Goldman, chief of the Laboratory of Neurogenetics at the National Institute on Alcohol Abuse and Alcoholism, in Bethesda, Md., and senior author of the study. "These disorders are often difficult to disentangle at the causal level, but by studying traits, we can find genes that contribute to important aspects of them."

Researchers specifically conducted the study in Finland because of its unique population and medical genetics. Goldman said modern Finns descend from a relatively small number of original settlers, which increased the chance of finding specific genes that influence impulsive behavior.

"Finns have the same degree of genetic diversity as people from other cultures, but their genetic disease diversity is reduced," said Goldman. "Genetic heterogeneity tends to be reduced in Finland because of its unique population, which was founded by two major waves of migration."