Subjects for the study were recruited from three sources. The Yale-Penn discovery sample includes 6,188 AAs and 6,835 EAs participants who were ascertained for genetic studies of dependence on opioids, cocaine or alcohol between 2000 and 2017 by advertisement and through treatment settings at Yale University School of Medicine, University of Pennsylvania, University of Connecticut Health Center, the Medical University of South Carolina, University of Pennsylvania, and McLean Hospital in Belmont, Massachusetts [26, 27]. Psychiatric interviews were conducted using the Semi-Structured Assessment for Drug Dependence and Alcoholism (SSADDA) [28, 29].
