1. Department of Pediatric Oncology/Hematology; Erasmus MC, Sophia Children's Hospital; Rotterdam 3015 GJ The Netherlands
2. UCL Institute of Child Health; London WC1N 1EH UK
3. Biometrics Department; Netherlands Cancer Institute, Antonie van Leeuwenhoek Ziekenhuis; Amsterdam The Netherlands
4. Department of Histopathology; School of Medicine; Cardiff University; Heath Park Cardiff CF14 4XN UK
5. Great Ormond Street Hospital; London WC1N 1EH UK
6. NHS Northern Genetics Service; Newcastle upon Tyne UK