1 Department of Pediatrics, University Medical Center Ulm, Ulm, Germany.
2 Department of Pediatrics, Academic Hospital of RWTH Medical School Aachen, Germany, HELIOS Klinikum, Krefeld, Germany.
3 Institute for Clinical Transfusion Medicine and Immunogenetics Ulm, German Red Cross Blood Transfusion Service Baden Württemberg-Hessen and Institute of Transfusion Medicine, University of Ulm, Ulm, Germany.