Twin cohort for the study of (pre)clinical Inflammatory Bowel Disease in the Netherlands
The TWIN-study

Inflammatory Bowel Diseases (IBD), i.e. Crohn’s Disease (CD) and Ulcerative Colitis (UC), are thought to arise in genetically susceptible individuals in the context of environmental triggers, with a potential dominant role for the interplay between the gut microbiota, and the mucosal immune system. However, the relative importance and the exact role of these factors in the pathogenesis of IBD is presently unknown. Interpretation of published research in this field is often hampered by reverse causation, and data generated in animal models cannot be directly extrapolated to the human condition. The disease is probably triggered years before the occurrence of symptoms, but currently patients are only identified when clinical disease is established. The preclinical phase of IBD might hold the key to understanding the pathogenesis of IBD and could provide a huge window of opportunity of halting or even preventing disease development. At this time, data on this phase of the disease are virtually non-existent. What we do know is that unaffected twin-siblings of an IBD affected individual are at increased risk of developing IBD. Therefore, studying IBD-discordant, IBD-concordant and non-IBD-concordant twins or multiples gives the unique opportunity to 1) define mechanisms that underlie (the early development of) IBD and 2) identify markers of (pre)clinical IBD.

Primary Objective: To gain insight in the disease mechanisms of IBD.

Secondary Objective(s): To identify biomarkers and study functional and mechanistic properties of the mucosal immune system, gut and oral microbiome, epithelium, mucus barrier, metabolome and nutritional factors in established and (pre)clinical IBD. Furthermore, we strive to identify symptoms and quality of life alterations associated with IBD.

Participants are invited for follow-up visits every 6 months during a period of 2 years. Afterwards the possible development of IBD will be assessed on a regular basis.

This is an observational cohort study, designed to explore factors possibly contributing to the pathogenesis of Inflammatory Bowel Disease.

From all participants the following data will be collected:

- Demographics

- Disease history

- Medication history

- Current medication use

- Risk factors

- Family history

- Quality of life

- Food frequency questionnaires



From all participants the following samples will be collected:

- Feces

- Pharyngeal swabs

- Urine

- Blood

- Rectal biopsies

- Colonic or ileal biopsies (in case of a colonoscopy for a clinical indication)