1. Gastroenterology Unit, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy;
2. Centre for Esophageal Diseases, Guy's and St. Thomas Hospital, London, UK;
3. GSSI, Gran Sasso Science Institute, L'Aquila, Italy;
4. Division of Gastroenterology, University Washington University School of Medicine, St. Louis, Missouri, USA;
5. Division of Gastroenterology, Department of Surgery, Oncology and Gastroenterology, University of Padua, Padua, Italy;
6. Division of Gastroenterology, Department of Internal Medicine (DIMI), University of Genoa, Genoa, Italy;
7. Gastroenterology and Endoscopy Unit, Department of Pathophysiology and Transplantation, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy;
8. Guy's and St Thomas' Esophagogastric Centre, London, UK.