1 Department of Medicine III, University Hospital, Ludwig-Maximilians-University Munich, 81377 Munich, Germany. Electronic address: rolf.issels@med.uni-muenchen.de.
2 Department of Medicine III, University Hospital, Ludwig-Maximilians-University Munich, 81377 Munich, Germany.
3 Clinic of Paediatric Oncology, Haematology and Immunology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
4 Department of Medical Information Sciences, Biometry, and Epidemiology, Ludwig-Maximilians-University Munich, Munich, Germany.