1. Department of Pediatrics; Aarhus University Hospital; Aarhus Denmark
2. Department of Pediatrics; Institution for Clinical Sciences; Queen Silvia Children's Hospital; Gothenburg Sweden
3. Department of Medical Biosciences and Genetics; Umeå University Hospital; Umeå Sweden
4. Department of Pediatrics; Hong Kong Pediatric Hematology & Oncology Study Group; Queen Mary Hospital; Hong Kong China
5. Children's Hospital; University of Helsinki and Helsinki University Hospital; Helsinki Finland
6. Department of Pediatrics; Landspitalinn; Reykjavik Iceland
7. Department of Pediatrics and Adolescent Medicine; Rigshospitalet; University of Copenhagen; Copenhagen Denmark
8. Department of Woman's and Children's Health; Uppsala University; Uppsala Sweden
9. Department of Pediatric Medicine; Oslo University Hospital; Oslo Norway