[1] Kwandong Univ, Coll Med, Dept Internal Med, Div Gastroenterol,Myongji Hosp, Goyang 412270, South Korea
[2] Yonsei Univ, Dept Internal Med, Grad Sch, Coll Med, Seoul 120752, South Korea
[3] Yonsei Univ, Severance Biomed Sci Inst, Brain Korea Project Med Sci 21, Dept Internal Med,Coll Med,Div Gastroenterol, Seoul 120752, South Korea