The individuals in the study were enrolled in a bupropion double-blind placebo-controlled pharmacogenetic smoking cessation trial conducted by the University of Pennsylvania Transdisciplinary Tobacco Use Research Center. All appropriate IRB approvals were obtained by participating institutions as part of the Pharmacogenetics of Nicotine Addiction and Treatment Consortium. Smokers were recruited from April 1999 to October 2001 at Georgetown University (Washington, DC, USA) and SUNY Buffalo (New York, USA). Details of the eligibility criteria and flow of participants through the enrollment, treatment, and follow-up phases of the trial can be found elsewhere (20). Briefly, trial participants included 600 smokers who were >18 years of age, and reported smoking more than 10 cigarettes a day for the prior 12 months. Exclusion criteria included pregnancy, a history of DSMIV axis I psychiatric disorder, seizure disorder, and current use of antidepressants or other psychotropic medications. All participants in the trial provided informed consent for both genotyping and treatment; however, at the time of this genotyping analysis, samples remained for 534 subjects. Analyses were limited to individuals of European ancestry with both phenotype and genotype
