2 Questions
A 30-year-old woman has been experiencing chronic abdominal pain, bloating, and alternating bouts of diarrhea and constipation. After undergoing several tests, she was diagnosed with both Coeliac Disease (CD) and Irritable Bowel Syndrome (IBS).
A) Explain the pathophysiology of Coeliac Disease (CD). Include details on the genetic predisposition, the role of gluten, and the immune response involved (5 marks). Guide: Your answer should mention specific genes associated with CD, the impact of gluten on the small intestine, and the nature of the immune response that leads to intestinal damage.
Coeliac Disease is an immune mediated inflammatory disease on the small intestine caused by a sensitivity to gluten a protein found in wheat, barley and rye. The distribution of the disease is parallel to the distribution on human leukocyte antigen (HLA) genotypes that predispose to coeliac disease. Individuals with increased risk of coeliac disease are those with type 1 diabetes, autoimmune diseases and down and turner syndrome. It is normally prevalent on those with northern European descent. Coeliac induces a T-cell response in the cell specific to predisposed individuals leading to CD4+ T cells releasing pro-inflammatory cytokines which activate T-helpers which activate CD8 lymphocytes that are cytotoxic and attack the enterocytes on the intestinal villi causing damage leading to atrophy.
B) Describe the diagnostic criteria and procedures used to differentiate between Coeliac Disease (CD) and Irritable Bowel Syndrome (IBS) (5 marks). Guide: Your answer should cover the key diagnostic tests for CD (such as serology and biopsy) and the diagnostic approach for IBS (including the Rome IV criteria and exclusion of other conditions).
coeliac: Serological Tests Genetic Testing:
HLA-DQ2 and HLA-DQ8: Genetic predisposition is identified by testing for these alleles. While their presence supports the diagnosis, their absence makes CD highly unlikely. Duodenal Biopsy:
Histological Examination: A biopsy of the small intestine, typically taken during an upper gastrointestinal endoscopy, is considered the gold standard for diagnosing CD. IBS:
- Diagnosed based on the Rome IV criteria, which focus on symptom patterns, and by excluding other conditions through a combination of clinical evaluation, basic laboratory tests, and possibly imaging studies.
Explain the pathophysiology of Coeliac Disease, including genetic predisposition, the role of gluten, and the immune response involved.
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