[1] Birmingham Childrens Hosp NHS Trust, Dept Haematol, Birmingham, W Midlands, England
[2] Queen Elizabeth Hosp, Dept Haematol, Birmingham, W Midlands, England
[3] Royal Hosp Sick Children, Dept Haematol, Glasgow G3 8SJ, Lanark, Scotland
[4] Glasgow Royal Infirm, Haemophilia & Thrombosis Ctr, Glasgow G4 0SF, Lanark, Scotland
[5] Walsgrave Gen Hosp, Dept Clin Haematol, Coventry, W Midlands, England