Overall, 17 of the 20 published GxE reports we located in the molecular genetics literature found at least one significant GxE, whereas 15 reported one or more non-significant GxE (Table 4). The substantial heterogeneity among samples, ascertainment strategies, environmental factors and drinking outcomes and the inconsistent patterns of results leave many questions about the neurobiological and behavioral consequences of GxE unanswered. Of studies that identified GxE, there were consistent findings regarding which genotype is associated with alcohol-related outcomes in response to environmental factors for CRHR1, ANKK1, and alcohol metabolizing genes, but conflicting findings for 5-HTTLPR and MAOA. While it is reasonable that GxE varies with development or stressor severity, there are too few studies on the same genes (aside from 5-HTTLPR) to assess whether sample characteristics and methodological factors are systematically related to GxE findings. When considering results in light of these wide-ranging inconsistencies, findings generally do not constitute replication and may overstate the true GxE effect size.
