1. Down Syndrome Program, Division of Medical Genetics and Metabolism, Department of Pediatrics Massachusetts General Hospital Boston Massachusetts USA
2. Department of Neurology, Division of Hospital Medicine, Division of Stroke and Cerebrovascular Diseases Brigham and Women's Hospital Boston Massachusetts USA
3. Harvard Medical School Boston Massachusetts USA
4. Department of Clinical Genetics Aarhus University Hospital Aarhus Denmark
5. Department of Clinical Medicine Aarhus University Aarhus Denmark
6. Department of Pediatrics Harvard Medical School Boston Massachusetts USA