[1] Charles Univ Prague, Fac Med Pilsen, Biomed Ctr, Plzen, Czech Republic
[2] German Canc Res Ctr, Div Canc Epidmiol, Heidelberg, Germany
[3] Hopp Childrens Canc Ctr KiTZ, Heidelberg, Germany
[4] German Canc Consortium DKTK, Div Pediat Neurooncol, German Canc Res Ctr DKFZ, Heidelberg, Germany
[5] Inst Canc Res, Div Genet & Epidemiol, London, England
[6] Royal Marsden Hosp NHS Fdn Trust, Haematooncol Unit, Sutton, Surrey, England