1. Department of Gastroenterology, The Fourth People's Hospital of Shaanxi, Xi'an, Shanxi 710032, P.R. China
2. Hunan Children's Research Institute, Hunan Children's Hospital, University of South China, Changsha, Hunan 410007, P.R. China
3. Center of Hepatobiliary Pancreatic Disease, Beijing Tsinghua Changgung Hospital, Beijing 102218, P.R. China