1. Department of Pediatric Hematology and Oncology; University Hospital Essen; Essen Germany
2. Eye Oncogenetics Research Group; University Hospital Essen; Essen Germany
3. Institute for Medical Informatics; Biometry and Epidemiology; University Hospital Essen; Essen Germany
4. German Childhood Cancer Registry; Institute of Medical Biostatistics; Epidemiology and Informatics; University Medical Centre of the Johannes Gutenberg University Mainz; Mainz Germany
5. Department of Ophthalmology; University Hospital Essen; Essen Germany
6. Department of Radiotherapy; University Hospital Essen; Essen Germany
7. Institute of Human Genetics; University Hospital Essen; Essen Germany