In conclusion, we provide a comprehensive genome-wide investigation of opioid-related traits, highlighting different molecular mechanisms that could underlie exposure and dependence. These findings draw attention to challenges associated with the use of unexposed controls in genetic association studies for OD and potentially for other SUDs (where exposure is not widespread, as is the case for alcohol, or more recently marijuana). This information should be used to guide the next generation of human genetic studies of opioid-related behaviors.
