1. From the Department of Pediatric Hematology and Oncology, University Children's Hospital, Muenster; Department of Pediatric Hematology and Oncology, University Children's Hospital, Frankfurt; Department of Pediatric Hematology and Oncology, Hannover Medical School, Hannover, Germany; St Anna Kinderspital and Children's Cancer Research Institute, Vienna, Austria; 2nd Medical Faculty, Charles University, Prague, Czech Republic