[1] Hannover Med Sch, Dept Pediat Hematol Oncol, D-3000 Hannover, Germany
[2] Univ Jena, Dept Pediat Hematol & Oncol, Jena, Germany
[3] Univ Childrens Hosp Hamburg Eppendorf, Dept Pediat Hematol & Oncol, Hamburg, Germany
[4] Carl Gustav Carus Univ, Dept Pediat Hematol & Oncol, Dresden, Germany
[5] Hannover Med Sch, Dept Pediat Neurol, D-3000 Hannover, Germany