Defining the Brain Phenotype of Children With Williams Syndrome

Background: \- Little is known about how the brain changes during childhood and adolescence, how genes affect this process, or how the brains of people with 7q11.23 genetic variation change during this period. Researchers are interested in using magnetic resonance imaging to study how the brain changes in healthy children and children with 7q11.23 genetic variation, including Williams syndrome and 7q11.23 duplication syndrome. Objectives: \- To study developmental changes in the brains of healthy children and children who have been diagnosed with Williams syndrome,7q11.23 duplication syndrome, or other 7q11.23 genetic variation. Eligibility: * Healthy children and adolescents between 5 and 17 years of age. * Children and adolescents between 5 and 17 years of age who have been diagnosed with Williams syndrome, 7q11.23 duplication syndrome, or have other 7q11.23 genetic variation. Design: * Participants will have a brief physical examination and tests of memory, attention, concentration, and thinking. Parents will be asked about their child s personality, behavior characteristics, and social interaction and communication skills. * Both participants and their parents may be asked to complete additional questionnaires or take various tests as required for the study. * Participants will have approximately 10 hours of magnetic resonance imaging (MRI) scanning, usually over 4 to 5 days, within a one month period. Some of these tests will require the participants to do specific tasks while inside the MRI scanner. * Participants will be asked to return to the National Institutes of Health clinical center to repeat these procedures every 2 years thereafter until age 18.