1 Department of Gastroenterology, Princess Alexandra Hospital, Hamstel Rd, Harlow, UK.
2 Department of Pathology, University College London, London, UK.
3 Institute of Clinical Medicine, University of Tartu, Tartu, Estonia.
4 Department of Gastroenterology, Whipps Cross University Hospital-Barts Health Trust, Queen Mary University of London, Whipps Cross Road, London, E11 1NR, UK. cinzia.papadia@nhs.net.