Department of Gastroenterology Peking Union Medical College Hospital Chinese Academy of Medical Sciences and Peking Union Medical College Beijing 100730 China;
Department of Pathology Peking Union Medical College Hospital Chinese Academy of Medical Sciences and Peking Union Medical College Beijing 100730 China;
Division of Gastroenterology University of Calgary Calgary Alberta Canada;
Department of Pathology and Laboratory Medicine University of Calgary Cummings School of Medicine and Calgary Laboratory Services Calgary Canada;
Department of Pathology University of Washington School of Medicine Seattle USA;