Participants were from the Study of Addiction: Genes and Environment (SAGE) [25]. All SAGE participants provided written informed consent for genetic studies and agreed to share their DNA and phenotypic information for research purposes. All samples were de-identified and only subjects who consented to health research were included. The institutional review boards at all data collection sites granted approval for use of the data (Washington University in St. Louis, Henry Ford Health Sciences Center, Indiana University, The State University of New York Downstate Medical Center, University of Connecticut Health Center, University of California San Diego).
