1. Department of Epidemiology; Johns Hopkins Bloomberg School of Public Health; Baltimore; Maryland
2. Departments of Epidemiology, Psychiatry, and Mental Health; Johns Hopkins Medical Institutions; Baltimore; Maryland
3. Lurie Center for Autism; Massachusetts General Hospital for Children; Lexington; Massachusetts
4. Department of Public Health Sciences and the M.I.N.D. Institute; MS1C; University of California, Davis; Davis; California