1. Department of Internal Medicine and Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea.
2. Digestive Disease Center, CHA Bundang Medical Center, CHA University, Seongnam, Korea.
3. Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea.
4. Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea.