1. Department of Pediatric Oncology; Astrid Lindgren Children's Hospital; Stockholm Sweden
2. Childhood Cancer Research Unit; Department of Women's and Children's Health; Karolinska Institute; Stockholm Sweden
3. Department of Pediatric Oncology; Uppsala University Hospital; Uppsala Sweden
4. Department of Medical Biosciences; Umeå University; Umeå Sweden
5. Department of Pediatrics and Adolescent Medicine; University Hospital Rigshospitalet; Copenhagen Denmark
6. Department of Pediatrics; Drammen Hospital; Drammen Norway
7. Department of Pediatrics; Turku University Hospital and Turku University; Turku Finland
8. Children's Hospital; Landspitali University Hospital; Reykjavik Iceland