Epidémiologie et génétique des maladies inflammatoires cryptogénétiques

Abstract

Inflammatory bowel diseases (IBD) have been reported throughout the world, but their frequency is highest in Northern Europe and the USA. The mean incidence of ulcerative colitis is 6/10(5) inhabitants, and that of Crohn's disease is 4/10(5) inhabitants. Inflammatory bowel diseases occur in young adults, especially Crohn's disease which reachs a peak of incidence between 20 and 30 years. Among possible factors influencing their incidence, only tobacco smoking has been shown to facilitate the acute episodes and relapses of Crohn's disease and to diminish those of ulcerative colitis. The frequency of familial inflammatory bowel diseases, which mainly affects first degree relatives, varies from 6 to 36 %. A genetic component is present and probably more important for Crohn's disease than for ulcerative colitis, although no genetic marker has yet been identified