Panel B presents the difference in the same genetic correlations, and the asterisks indicate a significant association with ALCP-specific after correcting for multiple testing. Overall, genetic correlations with other traits were attenuated for ALCP-specific compared to ALCP-total. For substance use, ALCP-total was genetically correlated with all other forms of substance use (rg = −0.22–0.82). Once we remove the shared variance due to EXT, ALCP-specific was only associated with drinks per week (rg = 0.69) and age of smoking initiation (rg = 0.14). ALCP-total was genetically correlated with most of the impulsivity and personality phenotypes (rg = −0.48–0.56). Only neuroticism (rg = 0.33), lack of perseverance (rg = 0.37), and positive urgency (rg = 0.32) were correlated with ALCP-specific. Finally, ALCP-total was genetically correlated with various psychiatric traits (rg = −31–0.49). ALCP-specific remained associated with most of these traits, notably bipolar disorder (rg = 0.18), major depressive disorder (rg = 0.23), post-traumatic stress disorder (rg = 0.26), and schizophrenia (rg = 0.17). Overall, a substantial portion of the observed genetic correlations between problematic alcohol use and other phenotypes is due to genetic variants that operate via externalizing liability.
