The Genetic Environmental Microbial (GEM) Project - identifying environmental and microbial risk factors for Crohn’s disease

Study code

Lead researcher
Dr Miles Parkes

Study type
Participant re-contact

Institution or company
University of Cambridge

Researcher type

Speciality area
Genomics and Rare Diseases, Gastroenterology

Recruitment Site


The goal of the GEM study is to identify environmental and microbial risk factors for Crohn’s disease by prospectively recruiting and sampling from a large cohort of individuals who are at high risk of developing Crohn’s disease by virtue of having an affected first degree relative. This reduces the confounding effect that gut inflammation has on the gut microbiota – which has always fundamentally undermined attempts to define microbial triggers for IBD.

The IBD BioResource provides a very efficient way of recruiting unaffected first degree relatives: we can email our patients with Crohn’s disease who are IBD BioResource volunteers and ask them to forward an information sheet and invitation to their relatives. Any that are willing can then contact our research group directly. Overall we anticipate that the process will be much more efficient than trying to recruit to this study through the clinic. 

For unaffected siblings and offspring of CD patients who are recruited, information on environmental exposures will be collected prospectively, and biological samples collected in a prospective manner. These Subjects will be followed for up to 6 years after the completion of study enrolment. When a “sufficient” number of Subjects have developed disease, a nested case-control sampling of this cohort will allow for a focused examination of the changes in microbial flora, intestinal permeability, and immune response to bacterial antigen (Ag) and immune regulation, in relation to expressed IBD susceptibility genes.

Only in this way can we determine which pathogenic events may have contributed to disease prior to disease development. 

The GEM study is being run in multiple centres globally. See here for further details. 

Publications from the study can be found here