Genetic Mutation Linked to Impulsive Violence

(NewsCore) - The discovery of a genetic mutation that can contribute to impulsive and motiveless violence, especially among men under the influence of alcohol, was making headlines Thursday.

Research with violent criminals in Finnish prisons has revealed that they are three times more likely to carry an abnormal variant of the HTR2B gene than ordinary people, suggesting that it can make people more susceptible to bouts of sudden aggression.

The findings offer insights into the inherited factors behind a propensity to spontaneous violence, though the mutation is not a gene “for” such behavior and many other genetic and environmental triggers are involved, according to experts cited by The (London) Times.

The HTR2B mutation, known as Q20*, is found only in Finns, so it cannot explain impulsive violence in countries such as the US, Britain or Australia. About one in a hundred Finns carries the variant, and most of those are not aggressive or dangerous and have never been convicted of a crime.

This means that it would be impossible to screen even the Finnish population for the variant to identify people at high risk of violence before they have committed a crime.

The discovery, by David Goldman, of the US National Institute on Alcohol Abuse and Alcoholism, shows that genetic factors can help to make some people more prone to random attacks, especially when combined with drug or alcohol abuse.

Other genes may also be mutated that predispose people to violent reactions, the researchers said.

“It is highly unlikely that Finns are unique in possessing a severe genetic variation leading to impulsivity,” they wrote in the journal Nature.

The Q20* mutation did not by itself cause impulsive violence, but appears to raise the risk of it, in combination with environmental effects. The Finns were chosen because they are genetically distinct, which makes it easier to find mutations with significant effects.

“Interestingly, we found that the genetic variant alone was insufficient to cause people to act in such ways,” said Dr Goldman said. “Carriers of the HTR2B variant who had committed impulsive crimes were all male, and all had become violent only while drunk from alcohol, which itself leads to behavioral disinhibition.”

The mutation effectively stops the brain from making a type of serotonin, a key brain signaling chemical that may influence impulsivity.

Further evidence for the mutation’s effects emerged from a follow-up study in which the HTR2B gene was knocked out in mice. These animals showed more impulsive behavior than is typical.