1. Department of Internal Medicine, Seoul National University College of Medicine, Seoul 03080, Korea.
2. Institute of Allergy and Clinical Immunology, Seoul National University Medical Research Center, Seoul 03080, Korea.
3. Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam 13620, Korea.
4. Biomedical Research Institute, Seoul National University Bundang Hospital, Seongnam 13620, Korea.
5. Department of Internal Medicine, Kangdong Sacred Heart Hospital, Seoul 05355, Korea.
6. Department of Internal Medicine, Korea University Medical Center Anam Hospital, Seoul 02841, Korea.
7. Department of Internal Medicine, The Armed Forces Capital Hospital, Seongnam 13574, Korea.