1. Division of Gastroenterology, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea;
2. Institute of Gastroenterology Research, Yonsei University College of Medicine, Seoul, Korea;
3. Digestive Disease Center, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Korea;
4. Division of Gastroenterology, Department of Internal Medicine, Yongin Severance Hospital, Yonsei University College of Medicine, Gyeonggi-do, Korea;
5. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Ewha Womans University College of Medicine, Seoul, Korea;
6. Division of Infectious Diseases, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.