 Rare mutations in the gene are associated with Brunner syndrome.A study based on the Dunedin cohort concluded that maltreated children with a low-activity polymorphism in the promoter region of the MAO-A gene were more likely to develop antisocial conduct disorders than maltreated children with the high-activity variant.Out of the 442 total males in the study (maltreated or not), 37% had the low activity variant.