[1] Newcastle Univ, Leukaemia Res Cytogenet Grp, No Inst Canc Res, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England
[2] Univ Oxford, CTSU, Oxford, England
[3] Univ Leeds, Dept Paediat Haematol, LIMM, Leeds, W Yorkshire, England
[4] Sheffield Childrens Hosp, Dept Pediat Hematol, Sheffield, S Yorkshire, England
[5] John Radcliffe Hosp, Childrens Hosp, Pediat Hem Onc Unit, Oxford OX3 9DU, England