[1] Univ Birmingham, CRCTU, Birmingham, W Midlands, England
[2] Univ Nottingham, Childrens Brain Tumour Res Ctr, Nottingham NG7 2RD, England
[3] Cent Manchester Univ Hosp NHS Fdn Trust, Manchester, Lancs, England
[4] Guys & St Thomas NHS Fdn Trust, Dept Neurol, London, England
[5] Rigshosp, Dept Paediat Oncol, DK-2100 Copenhagen, Denmark