Abnormal Fecal Microbiota in Healthy Subjects at High Risk for Crohn's Disease (MAGIC)

Transversal multicentric French study on the microbiota in patients with Crohn's disease and their first degree healthy relatives The primary objective is the comparison of microbiota between patients with CD, healthy controls non genetically linked and first degree healthy relatives of patients with CD. The primary objective is the comparison of microbiota between patients with CD, healthy controls non genetically linked and first degree healthy relatives of patients with CD. The first endpoint is the Lachnospiraceae rates in each group. The secondary objectives are: 1. The search for an association between bacterial dysbiosis and different genetic backgrounds in patients with CD, their first degree healthy relatives and controls. 2. The quantification of potential invasive bacteria with invasive properties (E. coli including adherent-invasive E. coli, Shigella, Salmonella, Yersinia, Campylobacter), and fecal fungal flora (Candida albicans, in particular) and their association with genetic and serological profiles in patients with CD, their healthy relatives and control subjects. 3. A study of environmental risk factors using a questionnaire to be submitted to CD patients, their healthy relatives and control subjects. Observational n= 240.