1. Kennedy Krieger Institute, Baltimore (Kalb, Holingue, Van Eck); Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore (Kalb, Holingue, Thrul); Genetic Epidemiology Research Branch, National Institute of Mental Health, Bethesda, Maryland (Stapp); Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore (Van Eck).