Department of Paediatrics, Medical University of Vienna, Vienna, Austria. Electronic address: christoph.male@meduniwien.ac.at. Bayer AG, Wuppertal, Germany. Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA. Nationwide Children's Hospital, The Ohio State University, Columbus, OH, USA. Kazan State Medical University, Russia. Riley Hospital for Children at IU Health, Indianapolis, IN, USA. M3C-Necker Enfants malades, Université Paris Descartes, Sorbonne Paris Cité, Paris, France. The Noah's Ark Children's Hospital for Wales, Cardiff, UK. Department of Hematology and Oncology, University Medical Center Groningen, Beatrix Children's Hospital, Groningen, Netherlands. Department of Hematology and Oncology, Cook Children's Medical Center, Fort Worth, TX, USA. McMaster Children's Hospital, Hamilton, ON, Canada. Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, The Israeli National Hemophilia Center and Thrombosis Unit, and The Amalia Biron Thrombosis Research Institute, Sheba Medical Center, Tel Hashomer, Israel. Charité University Medicine, Department of Paediatric Haematology and Oncology, Berlin, Germany. Haemostasis and Thrombosis Unit, Department of Haematology, University Hospital Vall d'Hebron, Barcelona, Spain. Paediatric and Congenital Cardiology Department, M3C Regional Reference Centre, Montpellier University Hospital, PhyMedExp, INSERM, CNRS, Montpellier, France. Royal Hospital for Children, Glasgow, UK. Thrombotic and Haemorrhagic Diseases Unit, Department of Medicine (DIMED), Padua University Hospital, Padua, Italy. Ann & Robert H Lurie Children's Hospital of Chicago, Feinberg School of Medicine, Northwestern University, IL, USA. Baylor College of Medicine and Texas Children's Hospital, Houston, TX, USA. Ural Federal University and Ural State Medical University, Yekaterinburg, Russia. Department of Medicine I, Division of Haematology and Haemostaseology, University Hospital "Carl Gustav Carus" Dresden, and King's Thrombosis Service, Department of Haematology, King's College London, UK. Department of Haematology, The Newcastle upon Tyne Hospitals NHS Foundation Trust Newcastle Upon Tyne, UK. Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, A Bianchi Bonomi Haemophilia and Thrombosis Centre, Milan, Italy. University Hospital Città della Salute e della Scienza, Turin, Italy. Department of Paediatric Haematology, Emma Children's Hospital, University Medical Centres, Location Academic Medical Centre, Amsterdam, Netherlands. Department of Paediatric Haematology and Stem Cell Transplantation, Central Hospital of Southern Pest, National Institute of Haematology and Infectious Diseases, Budapest, Hungary. Nemours Children's Specialty Care, Jacksonville, FL, USA. Department of Paediatrics, University of Alberta, Edmonton, AB, Canada. Children's Hospital Los Angeles, University of Southern California Keck School of Medicine, Los Angeles, USA. Bayer, Whippany, NJ, USA. Department of Medicine, McMaster University, Hamilton, ON, Canada. Department of Clinical Epidemiology and Medical Technology Assessment, Maastricht University Medical Centre, Maastricht, Netherlands. Department of Clinical Haematology, Royal Children's Hospital, Haematology Research Murdoch Children's Research Institute, Department of Paediatrics, University of Melbourne, VIC, Australia.