Aetiology and pathogenesis of ulcerative colitis and Crohn's disease.

Ulcerative colitis and Crohn's disease continue to baffle us with regard to their aetiology and pathogenesis. Indeed, our understanding has increased little since the early days of ulcerative colitis when the major debate concerned the role of the intestinal flora and the host's response to it. It seems well established that the familial incidence is about 10-15% and recent studies from Sweden, in twins, have suggested that the genetic factor may operate