1. Department of Pediatric Stem Cell Transplantation, Leiden University Medical Centre, Leiden, the Netherlands;
2. Pediatric Hematology/Oncology, Fondazione Istituti di Ricovero e Cura a Catattere Scientifico (IRCCS) Policlinico San Matteo, University of Pavia, Pavia, Italy; and
3. Immunohematology and Stem Cell Research, Leiden University Medical Centre, Leiden, the Netherlands