1. University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
2. Hannover Medical School, Hannover, Germany
3. Justus-Liebig-University Giessen, Giessen, Germany
4. Pediatric Hematology and Oncology, University Hospital Muenster, Muenster, Germany
5. University of Giessen, Giessen, Germany
6. Depart. Pathology, Kiel, Germany
7. University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany
8. University Children's Hospital, Zuerich, Switzerland
9. Charles University and University Hospital Motol, Prague, Czech Republic
10. St. Anna Children's Hospital, Vienna, Austria
11. University Hospital Giessen, Giessen, Germany
12. University Hospital Münster, Münster, Germany