A gene variant may be responsible for problem behaviors in adults with developmental disabilities, new research shows.

In a study of more than 100 men, researchers found that a common variant of the gene that encodes monoamine oxidize A, or MAOA, was present in 43 percent of participants with developmental disabilities and behavior problems. Among the remaining study participants — a control group and a group with developmental disabilities but no behavior problems — just 20 percent had the gene variant.

The MAOA gene regulates serotonin levels in the body, which impact appetite and mood. The same gene also affects a hormone which helps determine a person’s fight-or-flight response.

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“Problem behaviors in these populations account for billions of dollars in intervention costs each year, but nearly all of these interventions occur after the fact,” said Craig Kennedy, a co-author of the study and a professor of special education at Vanderbilt University. “This research suggests one way we might predict which individuals are at risk of being aggressive and destructive and provide treatment before problems occur.”

Problem behavior is an issue for 15 to 20 percent of adults with developmental disabilities.

In previous research, the same gene variant was linked to autism and the severity of it as well as communication difficulty. However, the gene variant has no association to problem behavior in those with fragile X syndrome, suggesting that further genetic and other factors contribute to behavior issues among those with developmental disabilities.

The study is published in the July issue of the American Journal on Intellectual and Developmental Disabilities.