1. Department of Haematology; VU University Medical Center; Amsterdam the Netherlands
2. Department of Laboratory Medicine, Haematology; Ghent University Hospital; Ghent Belgium
3. Department of Paediatric Oncology/Haematology; VU University Medical Center; Amsterdam the Netherlands
4. Princess Máxima Center for Paediatric Oncology; Utrecht the Netherlands
5. Department of Immunology; Erasmus MC; University Medical Center Rotterdam; Rotterdam the Netherlands
6. Dutch Childhood Oncology Group; The Hague the Netherlands
7. Department of Paediatric Haematology-Oncology and Stem Cell Transplantation; Ghent University Hospital; Ghent Belgium
8. Cancer Research Institute Ghent; Ghent Belgium
9. Department of Paediatric Oncology/Haematology; Beatrix Children's Hospital; University Medical Center Groningen; University of Groningen; Groningen the Netherlands
10. Department of Paediatric Oncology/Haematology; Erasmus MC; University Medical Center Rotterdam; Rotterdam the Netherlands
11. Department of Clinical Biology, Microbiology and Immunology; Ghent University; Ghent Belgium