‘Warrior gene’ link to violent crime

Up to one in 10 people who commit a violent crime possess two genes which make them more disposed to inclined to exhibit repeated vicious behaviour.

Scientists in Sweden think having MAOA and CDH13 genotypes in a person’s DNA could make them up to 13 times more likely to exhibit repeated violent behaviour. Karolinska Institute scientists studied the genetic make-up of almost 900 criminals in Finland. They found in developed countries, the majority of all violent crime is committed by a small group of “anti-social recidivistic offenders”.

“Our results, from two independent cohorts of Finnish prisoners, revealed that a monoamine oxidase A [MAOA] low-activity genotype as well as the CDH13 gene are associated with extremely violent behaviour, at least 10 committed homicides, attempted homicides or batteries,” the researchers wrote in the Molecular Psychiatry journal.

“No substantial signal was observed for either MAOA or CDH13 among non-violent offenders, indicating that findings were specific for violent offending, and not largely attributable to substance abuse or anti-social personality disorder.”

They concluded that at least 5% to 10% of all severe violent crime in Finland is attributable to the genes.

Lead researcher Jari Tiihonen said MAOA, which is sometimes known as the ‘warrior gene’, metabolises an important neurotransmitter called dopamine and that the presence of that genetic variant and substance abuse helps create a perfect storm.

“If this activity is decreased, it might lead to a larger dopamine burst in the brain when alcohol, cocaine, or amphetamine is used,” said Prof Tiihonen.

However, researchers stressed the genes cannot be used to screen potential criminals, as not everyone who has the genetic combination will commit a crime.