Gene-environment interactions represent a new challenge in psychiatric genetics84 and further studies of these complex interactions on clinical phenotypes are required to increase our understanding of the underlying etiological mechanisms. Such interactions are likely to occur when the effect of exposure to an environmental risk factor on a phenotype depends on the genotype. This study suggests a hypothetical model, in which emotional trauma and SLC6A4 promoter variants interact to influence the AAO in BD. Further investigations in larger samples are required to test this hypothesis in order to help guide preventive strategies among subjects at risk of developing a BD (for example offspring of parents with BD and exposed to trauma).
