1 Gastroenterology Department, University College London Hospitals NHS Foundation Trust, 235 Euston Rd, London, NW1 2BU, UK.
2 Gastroenterology Department, University College London Hospitals NHS Foundation Trust, 235 Euston Rd, London, NW1 2BU, UK; University College London, Gower St, Bloomsbury, London WC1E 6BT, UK. Electronic address: flaskaratos@gmail.com.
3 Histopathology Department, University College London NHS Foundation Trust, 235 Euston Rd, London, NW1 2BU, UK.