1. Institute of Immunology, Ulm University Medical Center, Ulm, Germany;
2. ALL-BFM Study Group, Christian-Albrechts University Kiel, Kiel, Germany;
3. Department of Pediatrics I, University Medical Center Schleswig-Holstein, Kiel, Germany;
4. Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom;
5. Kiel Pediatric Tumor Registry, Department of Pediatric Pathology, University Medical Center Schleswig-Holstein, Kiel, Germany; and
6. Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, Ulm, Germany