An extension of the candidate gene approach tests whether the importance of a particular candidate gene varies across environmental conditions.34–36 Some of these studies have tested whether these specific gene-environment interaction (GxE) effects differ in EAs and AAs. For example, studies have found that the protective effects of ADH1B variants against different alcohol phenotypes are reduced in risky environments, such as involvement with peers that drink37 or exposure to childhood adversity,38 in EAs but not AAs. Other GxE research has been conducted within available AA populations, for example one study found that genetic variants related to the stress-response are protective against the effect of childhood trauma on suicidal behavior in substance dependent respondents. 39 However, systematic study of particular genes and environments that interact in hypothesized directions among AAs has not been a widespread area of study. Additionally, the small sample sizes of AAs in these analyses have limited the ability to detect significant interactions, if they exist. Closer collaborations between scientists who work in genetics and scientists who study cultural and environmental influences that impact substance use in AAs could lead to more hypothesis-driven research in this area.
