1. McMaster University; Department of Medicine, Division of Gastroenterology; 1280 Main Street West Hamilton Ontario Canada L8S 4K1
2. St. James's University Hospital; Department of Academic Medicine; Beckett Street Leeds UK LS9 7TF
3. Gastroenterology Unit, Hospital Universitario de la Princesa, Instituto de Investigación Sanitaria Princesa (IP), and Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd); Madrid Spain
4. International Agency for Research on Cancer; 150 cours Albert-Thomas Lyon France 69372
5. Hospital de Sabadell & Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd); Servei de Malalties Digestives; Parc Taulí, s/n Sabadell Spain 08208
6. McGill University Health Centre; Faculty of Medicine; Royal Victoria Hospital 687 Pine Avenue West, Room R228 Montreal Quebec Canada H3A 1A1
7. University of Arkansas for Medical Sciences; Department of Epidemiology; 4301 West Markham, # 820 Little Rock AR USA
8. Universita del Piemonte Orientale; Paediatric Endoscopy Units; Via Solaroli 17 Novara Italy 28100
9. Università degli Studi di Bologna; Dipartimento di Scienze Mediche e Chirurgiche; Policlinico S.Orsola Via Massarenti 9, Via Borgo San Pietro 137 Bologna Italy I-40138