Mucosal samples: in newly diagnosed patients having a colonoscopy for diagnostic purposes, an additional 6 mucosal biopsy samples; 2 from the terminal ileum when possible, 2 from the proximal colon and 2 from the distal colon will be taken (14-16 are collected at normal colonoscopy). An additional 2 biopsy samples will also be collected from the duodenum during upper endoscopy.