[1] UCL Canc Inst, Haematol, London, England
[2] Royal Free Hosp, Haemophilia Ctr, London, England
[3] Royal Free Hosp, Thrombosis Unit, London, England
[4] St Jude Childrens Res Hosp, Hematol, Memphis, TN USA
[5] St Jude Childrens Res Hosp, Surg, Memphis, TN USA