Ulcerative colitis and Crohn’s disease are the principal forms of inflammatory bowel disease. Collaborators: Ian Arnott, Kevin J Barrett, R Mark Beattie, Stuart Bloom, Keith Bodger, Richard R Brady, Matthew J Brookes, Steven R Brown, Jeffrey R Butterworth, Christopher R Calvert, Rachel Campbell, Tom Creed, Nicholas M Croft, Fraser Cummings, R Justin Davies, David Devadason, Anjan Dhar, Chris Dipper, Julie Duncan, Malcolm Dunlop, Dharmaraj Durai, Martyn D Evans, Omar Faiz, Nicola S Fearnhead, Alexander C Ford, Aileen Fraser, Vikki Garrick, Daniel R Gaya, James Goodhand, Nigel Hall, Richard Hansen, Marcus Harbord, A Barney Hawthorne, Bu’Hussain Hayee, Sarah Hearnshaw, Paul Henderson, Philip Hendy, Tariq Iqbal, Paul D Johnston, Nicholas A Kennedy, Christopher A Lamb, Jimmy K Limdi, James O Lindsay, Alan J Lobo, Miranda Lomer, Richard E Lovegrove, John C Mansfield, Simon Mclaughlin, Christopher G Mountford, Rafeeq Muhammed, Nurulamin M Noor, Simon Panter, Gareth C Parkes, Miles Parkes, Thomas D Pinkney, Chris Probert, Tim Raine, Richard K Russell, Matthew D Rutter, Mark A Samaan, Jeremy D Sanderson, Christian P Selinger, Ashit Shah, Steve J Short, Baljit Singh, Philip J Smith, Melissa Smith, R Alexander Speight, Catherine Stansfield, Helen Steed, Stuart A Taylor, Helen Terry, Tony C Tham, Nick P Thompson, Gareth J Walker, Catherine L Wall, Janindra Warusavitarne, Gethin L Williams, R Graeme Wilson, David C Wilson, and Lisa C Younge