[1] UCL, Sch Med, Dept Haematol, London WC1E 6HX, England
[2] UCL Hosp, Dept Haematol, London, England
[3] Radcliffe Infirm, Clin Trial Serv Unit, Oxford OX2 6HE, England
[4] Univ Birmingham, Clin Trials Unit, Birmingham, W Midlands, England
[5] St Marys Hosp, Imperial Coll, Sch Med, Dept Haematol, London, England
[6] Cardiff Univ, Dept Haematol, Cardiff CF4 4XN, S Glam, Wales
[7] Guys Hosp, Guys Kings & St Thomas Sch Med, Div Med & Mol Genet, London SE1 9RT, England