1. Down Syndrome Program, Division of Medical Genetics and Metabolism, Department of Pediatrics Massachusetts General Hospital Boston Massachusetts USA
2. The Mongan Institute Survey Research Unit, MGH Boston Massachusetts USA
3. Heller School for Social Policy and Management Brandeis University Waltham Massachusetts USA
4. Department of Neurology Massachusetts General Hospital Boston Massachusetts USA
5. Psychology Assessment Center Massachusetts General Hospital Boston Massachusetts USA
6. Department of Psychiatry Harvard Medical School Boston Massachusetts USA
7. Department of Pediatrics Harvard Medical School Boston Massachusetts USA