A final area of study to be discussed in the context of candidate gene studies is gene-environment interaction studies. Several gene-environment interaction studies of substance use disorders have been conducted in Caucasian samples, but only one such study has been conducted in a Native American population. This study investigated whether a relation between a functional polymorphism in the monoamine oxidase A gene (MAOA) and alcoholism and antisocial personality disorder was moderated by childhood sexual abuse in the Southwest American Indian population [36]. The MAOA gene has been previously implicated in antisocial personality disorder, and in one of the first gene-environment interaction studies conducted, the relation between MAOA and antisocial behavior was moderated by childhood maltreatment such that individuals possessing the ‘high-risk’ genotype and were abused in childhood were more likely to exhibit antisocial behavior later in life relative to the other groups [64]. A similar interaction was observed in females from the Southwest American Indian population in which women with the ‘high-risk’ genotype were more likely to develop co-morbid alcohol dependence and antisocial personality disorder but only if they were exposed to childhood sexual abuse. Though preliminary, this study highlights the potential impact of gene x environment interaction studies.
