Abnormal Fecal Microbiota in Healthy Subjects at High Risk for Crohn's Disease
Condition: Crohn's Disease; Genetic Predisposition
MeSH terms: Crohn Disease; Genetic Predisposition to Disease
Study type: Observational [Patient Registry]

Summary: 
      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.
    

Detailed description: 
      Crohn's disease is a chronic inflammatory bowel disease associating flares and remission
      periods. Its etiology is unknown and there are no specific therapy. CD affects young patients
      and has a major impact on quality of life. There are few population-based studies and there
      are about 2.5 million affected patients in Europe and North America. From data from EPIMAD
      Registry the number of affected patients in France should be 200 000. The Crohn's disease
      pathogenesis is bad known; It coul be the results of the activation of the gastro-intestinal
      immune system toward gut microbiota in genetically susceptible hosts. In CD patients there is
      an important ecologic modification of the flora with an excess of Bacteroidetes and
      Proteobacteria and a decrease of anti inflammatory bacteria (Firmicutes). In ileum of CD
      patients a specific E Coli (adherent and invasive E Colo) is found in two thirds of cases.The
      presence of this AIEC seems to be associated to the variant NOD2 (results from our team in
      multiplex families).

      In a family with at least 1 patient with CD, the healthy first degree relatives present a
      high risk (* 10) to also develop a 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.
    

Intervention name(s): biomarkers
Intervention type(s): Other
Intervention description(s): fecal microbiota analysis antibodies in serum and saliva DNA polymorphisms
Other intervention name(s): Dysbiosis
Observational model: Family-Based
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Transversal multicentric French study on the microbiota in patients with Crohn's disease
        (n=60) and their first degree healthy relatives (n=120) and controls (n=60).
      
Biospecimen description: 
      Blood, saliva, stools
    
Keywords: Crohn's Disease; Healthy relatives; Dysbiosis; Biomarkers