[1] Univ Calif San Francisco, San Francisco, CA 94143 USA
[2] Inst Canc Res, Leukaemia Res Fund Ctr, London SW3 6JB, England
[3] St Marys Hosp, Immunogenet Lab, Manchester, Lancs, England
[4] Royal Manchester Childrens Hosp, Acad Unit Pediat Oncol, Manchester, Lancs, England
[5] Christie Hosp NHS Trust, Manchester M20 4BX, Lancs, England
[6] Univ Edinburgh, Sch Med, Dept Publ Hlth Sci, Edinburgh, Midlothian, Scotland