319 AA pedigrees (848 persons, counting ungenotyped progenitors) and 302 EA pedigrees (707 persons, also counting ungenotyped progenitors) were recruited from 4 sites: Yale University School of Medicine (Yale; APT Foundation; New Haven, CT), University of Connecticut Health Center (UConn; Farmington, CT), McLean Hospital (Harvard Medical School; Belmont, MA), and Medical University of South Carolina (MUSC; Charleston, SC). These families were recruited on the basis of containing at least one affected sibling pair for cocaine or opioid dependence; additional relatives were recruited where possible (Gelernter et al., 2005; Gelernter et al., 2006). Probands with a clinical diagnosis of a major psychotic illness (schizophrenia or schizoaffective disorder) were excluded. Most subjects had comorbidity with other substances such as tobacco, opiates, or alcohol (Table 1). Nicotine dependence was the most common comorbid substance dependence. Additional unrelated self-identified AA (n=738; male 58% and female 41%) and EA (n=404; male 57% and female 43%) subjects were recruited at Yale, UConn, MUSC and UPenn (University of Pennsylvania School of Medicine). Only significant haplotypes derived from family-based analysis were selected for replication in unrelated subjects.
