1. Department of Pediatric Hematology and Oncology, Istituto di Ricovero e Cura a Carattere Scientifico Ospedale Pediatrico Bambino Gesù, Rome, Italy;
2. Department of Pediatric Science, University of Pavia, Pavia, Italy; and
3. Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Centre, Faculty of Medicine, University of Freiburg, Freiburg, Germany