June 7, 2009

‘Warrior gene’ linked to gang membership

Boys who carry a variation of the gene Monoamine oxidase A, are more likely to join gangs and be among the most violent members, U.S. researchers said.

Criminologist Kevin M. Beaver at Florida State University said the findings apply only to males -- not girls with the same variant of the so-called warrior gene.

While gangs typically have been regarded as a sociological phenomenon, our investigation shows that variants of a specific MAOA gene, known as a 'low-activity 3-repeat allele,' play a significant role, Beaver said in a statement. Previous research has linked low-activity MAOA variants to a wide range of antisocial, even violent, behavior, but our study confirms that these variants can predict gang membership.

The MAOA gene affects levels of neurotransmitters such as dopamine and serotonin that are related to mood and behavior, and those variants that are related to violence are hereditary, Beaver said.

The MAOA gene is located on the X-chromosome and as a result, males, who have one X-chromosome and one Y-chromosome, possess only one copy of this gene, while females, who have two X-chromosomes, carry two.

If a male has an allele -- variant -- for the MAOA gene that is linked to violence, there isn't another copy to counteract it, Beaver said. Females have two copies, so even if they have one risk allele, they have another that could compensate for it.

The findings are scheduled to be published in the journal Comprehensive Psychiatry.