1 Royal Free Unit for Endoscopy and Centre for Gastroenterology, The Royal Free Hospital and University College London Institute for Liver and Digestive Health, London, United Kingdom.
2 Royal Free Unit for Endoscopy and Centre for Gastroenterology, The Royal Free Hospital and University College London Institute for Liver and Digestive Health, London, United Kingdom; Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
3 Department of Medicine, Division of Gastroenterology, Jichi Medical University, Shimotsuke, Japan.