The serotonergic system has been implicated in the neurobiology of aggression and antisocial behavior (Ficks and Waldman, 2014; van Goozen et al., 2007), and thus genes implicated in the metabolism and availability of serotonin have emerged as plausible candidates for association. Two polymorphisms in serotonergic system genes, the monoamine oxidase-A promoter variable number of tandem repeats (MAOA-uVNTR in the MAOA gene) and serotonin transporter-linked polymorphic region (5-HTTLPR in the SLC6A4 gene), are among the most commonly studied candidates for behavioral outcomes (Gunter et al., 2010). A meta-analysis found significant association between the MAOA-uVNTR low activity allele and aggressive or antisocial behavior (OR = 1.08) as well as association between the 5-HTTLPR short allele and aggressive or antisocial behavior, OR = 1.41 (Ficks and Waldman, 2014).
