1. Pediatric Oncology Unit, Department of Women’s and Children’s Health, Uppsala University, Uppsala, Sweden;
2. Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden;
3. Experimental and Clinical Oncology Unit, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden;
4. Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark;
5. Hematology Center, Karolinska University Hospital, Stockholm, Sweden;
6. Department of Haematology, Rigshospitalet, Copenhagen, Denmark;
7. Department of Haematology, Aarhus University Hospital, Aarhus C, Denmark;
8. Department of Paediatrics and Adolescent Medicine, Rigshospitalet, Copenhagen, Denmark