Results from this paper suggest that the degree of genetic overlap between externalizing and SUDs warrants exploration of genetic effects that jointly and uniquely influence these phenotypes. This is particularly important as gene identification efforts for SUDs have lagged behind consumption- and initiation-related traits and other forms of psychopathology, largely due to issues of power.47 Simultaneous analysis of SUDs and genetically correlated traits, such as the externalizing phenotypes included in the current study, can boost power to detect associations for SUDs.18 The use of genomic SEM, in particular, also allows for the study of residual phenotypes (e.g., variance specific to cannabis use disorder unique from what it shares with other externalizing traits), which provides insights into genetic architecture that is specific to a given trait.48–50 Pursuing these dual goals will allow us to overcome barriers to gene identification in SUDs while still investigating any potential disorder-specific effects.
