In this study, we show that externalizing and addiction risk share a substantial proportion of their genetic influences in common, but that each construct retains meaningful unique genetic variance. These results can be carried forward into future studies, in which we can leverage the genetic correlations among these phenotypes to boost power to detect associations for SUDs, the gene-identification efforts of which have lagged behind other psychiatric traits. This will also facilitate a more fine-grained exploration of the genetic influences unique to each externalizing addiction risk phenotype, thereby allowing exploration of both broad and specific dimensions of genetic risk.
