Philip W. Davidson is Professor of Pediatrics and Psychiatry and Director of the Strong Center for Developmental Disabilities, University of Rochester School of Medicine and Dentistry, United States of America Vee P. Prasher is Associate Professor – Neurodevelopmental Psychiatry within Birmingham Specialist Community Health NHS Trust (services for People with Learning Disabilities), United Kingdom Matthew P. Janicki is Research Associate Professor, Department of Disability and Human Development, University of Illinois at Chicago, United States of America Foreword written by Allen C. Crocker MD, Associate Professor of Pediatrics, Harvard Medical School, United States of America