We operationalized early adverse environment as having a mother with a history of recurrent MDD. Because the offspring of mothers with MDD have higher rates of psychopathology than do children of nondepressed mothers (Hammen, 2009), this operationalization may include an increased likelihood of inheriting depressive and anxiety disorders through a variety of pathways. Nevertheless, within the high early adverse environment group, AG girls reported significantly higher symptom levels of depression, physical anxiety, social anxiety and separation anxiety than did GG girls. Our results suggest that assessing the allelic variations of the OXTR rs2254298 polymorphism provides additional explanatory power over simply examining and comparing the girls' level of early adversity. Indeed, Costa et al. (2009) posit that OXTR rs2254298 polymorphism is in a linkage disequilibrium block that could bring important allelic variants and, consequently, may be relevant for increasing our understanding of MDD.
