1. Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, Seoul, South Korea;
2. Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam-si, South Korea;
3. Department of Internal Medicine, Institute of Gastroenterology, Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea;
4. Department of Gastroenterology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea;
5. Department of Human Systems Medicine, Seoul National University College of Medicine, Seoul, South Korea.