1. Division of Pediatric Hematology-Oncology, First Department of Pediatrics, School of Medicine, National and Kapodistrian University of Athens, 11527 Athens, Greece
2. Department of Pathophysiology, School of Medicine, National and Kapodistrian University of Athens, 11527 Athens, Greece
3. First Department of Pathology, School of Medicine, National and Kapodistrian University of Athens, 11527 Athens, Greece
4. Department of Internal Medicine, University of Connecticut, Farmington, CT 06030, USA