1. Department of Medical Psychology and Medical Sociology, Medical Faculty, Ruhr-University of Bochum, Bochum, Germany.
2. Human Genetics, Ruhr-University of Bochum, Bochum, Germany.
3. Medical Department, Knappschaftskrankenhaus Ruhr-University of Bochum, Bochum, Germany.
4. Division of Gastroenterology and Hepatology, BG Kliniken Bergmannsheil, Ruhr-University of Bochum, Bochum, Germany.