1. Third Department of Pediatrics, National and Kapodistrian University of Athens, “ATTIKON” University Hospital, Athens, Greece;
2. Department of Pediatric Hematology-Oncology, Athens, Greece, “Aghia Sofia” Children's Hospital;
3. Oncology Department, “P&A Kyriakou” Children’s Hospital, Athens, Greece;
4. Hematology-Oncology Unit, First Department of Pediatrics, National and Kapodistrian University of Athens, “Aghia Sofia” Children's Hospital, Athens, Greece;
5. Stem Cell Transplant Unit, Aghia Sofia Children’s Hospital, Athens, Greece;
6. Cytology Laboratory, “Attikon” University Hospital, Athens, Greece;
7. The Stavros Niarchos Foundation-Collaborative Center for Clinical Epidemiology and Outcomes Research (CLEO), First and Second Departments of Pediatrics, National and Kapodistrian University of Athens, Athens, Greece