1Fondazione IRCCS Ca’ GrandaOspedale Maggiore Policlinico Angelo Bianchi Bonomi Hemophilia and Thrombosis Center Milan Italy2Dr. von Hauner Children's Hospital, Munich Medical Center of the University of Munich Munich Germany3Haemophilia Comprehensive Care CentreDepartment of Molecular Medicine and HaematologyFaculty of Health Sciences University of the Witwatersrand and National Health Laboratory Service Johannesburg South Africa4Division of Haematology/OncologyDepartment of PaediatricsChild Health Evaluative Sciences Research Institute, Hospital for Sick Children University of Toronto TorontoON Canada5Hemophilia and Thrombosis CenterDepartment of Hematology S. Bortolo Hospital AULSS 8 BericaVicenza Italy