[1] German Canc Res Ctr, Div Mol Genet, D-6900 Heidelberg, Germany
[2] Univ Heidelberg Hosp, Dept Pediat Oncol Hematol & Immunol, Heidelberg, Germany
[3] Univ Med Ctr Hamburg Eppendorf, Dept Pediat Hematol & Oncol, Hamburg, Germany
[4] Nurnberg Childrens Hosp, Cnopfsche Kinderklin, Nurnberg, Germany
[5] German Canc Res Ctr, Clin Cooperat Unit Pediat Oncol, D-6900 Heidelberg, Germany
[6] Univ Heidelberg, Dept Neuropathol, D-6900 Heidelberg, Germany
[7] German Canc Res Ctr, Clin Cooperat Unit Neuropathol, D-6900 Heidelberg, Germany
[8] Hosp Sick Children, Brain Tumor Res Ctr, Toronto, ON M5G 1X8, Canada