1. Department of Haematology, Barts and The London School of Medicine and Dentistry, London, United Kingdom;
2. Department of Haematology, St George's Healthcare, National Health Service (NHS) Trust, London, United Kingdom;
3. Division of Haematology/Oncology, University of Toronto, The Hospital for Sick Children, Toronto, ON;
4. Department of Clinical Haematology, Manchester Royal Infirmary, Manchester, United Kingdom;
5. Department of Pediatrics, New York Hospital, New York, NY;
6. St George Clinical School, University of New South Wales, Sydney, Australia;
7. Department of Pathology and Laboratory, Hospital of the University of Pennsylvania, Philadelphia;
8. Puget Sound Blood Center and The University of Washington, Seattle;
9. Service de Médecine Interne, Assistance-Publique Hôpitaux de Paris, Paris, France;
10. Royal Manchester Children's Hospital, Manchester, United Kingdom;
11. Hull York Medical School, University of York, York, United Kingdom;
12. Thrombosis & Haemostasis, King's College, London, and Departments of Haematology, Pathology, and Rheumatology, Guy's & St Thomas' National Health Service (NHS) Foundation Trust, London, United Kingdom;
13. University Children's Hospital, Basel, Switzerland;
14. Obstetric Anaesthesia, St James' University Hospital, Leeds, United Kingdom;
15. The Scripps Research Institute, La Jolla, CA;
16. Department of Cell Therapy and Hematology, San Bortolo Hospital, Vicenza, Italy;
17. Department of Haematology, Hospital Universitario La Fe, Valencia, Spain;
18. Comprehensive Bleeding Disorders Center, Peoria, IL;
19. ITP Support Association, Bedford, United Kingdom;
20. Platelet Disorder Support Association, Rockville, MD; and
21. Department of Hematology, Massachusetts General Hospital and Harvard Medical School, Boston