1. Department of Gastroenterology and Hepatology, University Clinic of Essen, University of Duisburg-Essen, 45122 Essen, Germany
2. Department of Gastroenterology and Hepatology, Elisabeth Hospital, 58638 Iserlohn, Germany
3. Institute of Pharmacogenetics, University Clinic of Essen, University of Duisburg-Essen, 45122 Essen, Germany
4. Institute of Pathology, University Clinic of Essen, University of Duisburg-Essen, 45122 Essen, Germany
5. Department of Gastroenterology and Hepatology, Helios Clinic, 42549 Velbert, Germany
6. Department of Gastroenterology and Hepatology, Max Grundig Clinic, 77815 Bühl, Germany