From the Department of Psychiatry and the Department of Genetics, Washington University School of Medicine, St. Louis; the Center for Tobacco Research and Intervention, School of Medicine and Public Health, University of Wisconsin, Madison; the Department of Epidemiology, Michigan State University, East Lansing; the Department of Human Genetics, Eccles Institute of Human Genetics, and the Department of Psychiatry, University of Utah School of Medicine, Salt Lake City; the Institute of Genetic Medicine, Johns Hopkins University, Baltimore; the Department of Biostatistics, University of Washington, Seattle; and the Division of Health, Social, and Economic Research, Research Triangle Institute, Research Triangle Park, N.C.