Several studies now indicate that inefficient activity of genes regulating mesocortical dopamine confer heightened risk of poor outcomes in animals and humans exposed to ELS. For example, polymorphisms in genes in the dopamine receptor family (e.g. DRD4), increase the risk of attention problems (Schmidt et al., 2001) and disordered patterns of relationship functioning in children (Lakatos et al., 2002; Lakatos et al., 2000). Similar to the studies involving serotonin, however, gene by ELS interactions have been noted. For example, the 7-repeat DRD4 polymorphism is associated with disorganized attachment behavior only when infants are reared by mothers who suffer from unresolved trauma and loss (Van Ijzendoorn and Bakermans-Kranenburg, 2006). Given evidence that the DRD4 polymorphism impacts mesocortical dopamine activity, further research is called for to examine whether DRD4 interacts with ELS to impact development of attention-and emotion-regulatory systems. In fact, given the rapidly evolving nature of the field of molecular behavioral genetics, consideration of the moderating effects of genes beyond SERT and DRD4 are warranted.
