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Crohn's Disease Notes

Medicine Notes > Gastrointestinal (GI) System Notes

This is an extract of our Crohn's Disease document, which we sell as part of our Gastrointestinal (GI) System Notes collection written by the top tier of Bristol University students.

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Lecture 24 Crohn's Disease






What is Crohn's disease?
o Chronic inflammatory disease, effects anywhere from mouth-anus (UC is only colon) o Characterised by patchy inflammation with ulceration (unlike UC, which is confluent) o Symptoms determined by site of disease and severity of inflammation & the complications of inflammation Symptoms o Pain: Constant or in waves (inflammatory stricture of bowel) o Diarrhoea: Loose/severe, may be bloody o Weight loss: Due to disease, poor absorption & loss of appetite o Fatigue: Partly anaemia, but hard to treat Who gets it?
o Getting more common o Bimodal=young adults & middle aged o 1 in 500 o Can run in families; Developed nations o More common in smokers (opposite of UC) Site of disease o Enterocolitis (small & large bowel) 50%
o Enteritis (small bowel) 29%
o Colitis (large bowel) 19%
o Other sites (e.g. cutaneous) 2%
What causes Crohn's disease?
o BACTERIA (abnormal)
? Bacterial flora change (is it because of CD or does it cause CD?)
? In general, reduced diversity of Firmicutes & Bacterioides
? Increased mucosa-associated E. coli in Crohn's disease

* Adherent Invasive E. Coli (AIEC)- able to penetrate gut wall, difficult to kill once there and sit in macs causing inflammation
? Abnormalities

* Loss of some Firmicutes & Bacterioides

* Role of (AIEC)

* BUT- Crohn's disease not transmittable, & what about familial risk?
o Mucus (defective)
? Too much mucin (opposite of UC)
? Mutation of MUC 19 gene in CD o Bowel wall (leaky)
? Abnormal permeability

* In CD patients and relatives

* Tight junction defects

* May be secondary to inflammation BUT o MYO9B gene mutation associated with UC o Gene in CD disputed
? Abnormal defence

* Defective mucus layer and epithelial barrier MAY permit invasion of gut wall by bacteria


Recognition (abnormal); Inflammation (dysregulated); Enhanced recruitment of inflammatory cells
? Macrophages

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