PTPRD and alcohol abuse: As noted above, we initially identified and others have confirmed PTPRD as a target for antiaddiction therapeutic development based on modest but repeated genetic associations between variants at the PTPRD locus and human individual differences in 1) vulnerability to develop a substance use disorder (polysubstance use (7–9), opioid use disorder (10) and alcohol use disorder (11)); 2) ability to quit smoking (12, 13); 3) ability to quit use of opioids (14); and 4) ability to reduce alcohol use (when aided by naltrexone) (15).