1. Division of Medical Genetics; Nemours/Alfred I. duPont Hospital for Children; Wilmington Delaware
2. Gait Laboratory; Nemours/Alfred I. duPont Hospital for Children; Wilmington Delaware
3. Department of Research; Nemours/Alfred I. duPont Hospital for Children; Wilmington Delaware
4. Institute for Clinical and Translational Research; Johns Hopkins School of Medicine; Baltimore Maryland
5. Departments of Human Genetics and Pediatrics; McGill University-Montreal Children's Hospital Research Institute; Montreal Quebec