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Coeliac Disease

Definition

  • Autoimmune disorder affecting the small intestine causing immune response to gluten

 

Risk factors

  • Family history
  • Specific HLA alleles
    • HLA-DQ2 (95% of European coeliac’s have this)
    • HLA-DQ8 (more common in middle east)
    • Both have very low penetrance – so having these alleles doesn’t mean you will get coeliac disease
  • Other autoimmune disorders – eg autoimmune thyroid disease
  • IgA deficiency
  • Infection eg rotavirus or adenovirus causing initial reaction

 

Differential diagnosis

  • Food allergy
  • Crohn’s disease
  • Ulcerative colitis
  • IBS
  • Colorectal cancer
  • Peptic duodenitis
  • Chronic pancreatitis
  • Giardiasis
  • Immunodeficiency
  • Post-gastroenteritis

 

Epidemiology

  • Prevalence of about 1%
  • Less common in people from sub-saharan Africa and SE Asia
  • Affects more men than women (like most autoimmune disease)
  • Most common age of diagnosis in US is 40
    • Initial peak in infancy on first exposure
    • Another peak in middle age (40-50s)
    • Can occur at any age

 

Aetiology

  • Specific HLA alleles
    • HLA-DQ2 (95% of European coeliac’s have this)
    • HLA-DQ8 (more common in middle east)
    • Both have very low penetrance – so having these alleles doesn’t mean you will get coeliac disease
  • Infection eg rotavirus or adenovirus causing initial reaction
  • Is caused by a reaction to prolamins - gliadin
    • These are storage proteins containing proline and glutamine
  • Autoimmune reaction truncates villi
    • Leads to malabsorption

 

Clinical features

  • Abdominal pain, colicky crampy
  • Diarrhoea – pale. Voluminous
  • Bloating (with abdominal distension)
  • Mouth ulcers
  • Lactose intolerance
  • Malabsorption
    • Weight loss
    • Fatigue
    • Anaemia (iron deficiency and/or megaloblastic from folate/B12 deficiency) and associated symptoms
    • Calcium and vitamin D malabsorption
      • Osteopenia
      • Osteoporosis
    • Vitamin K malabsorption
      • Clotting abnormalities (insufficient clotting)
  • Growth stunting and puberty delay (in children)
  • Recurrent miscarriage/unexplained infertility

 

Pathophysiology

  • Reaction to peptides in gliadin, and other prolamins
  • Peptides gain access to lamina propria – exact mechanism unknown
    • Faulty tight junctions
    • Sampling and presentation by dendritic cells
  • Stimulation of T helper cells
    • Th1: cell death and tissue remodelling
    • Th2: antibody production to gliadin and anti-tTG

 

Investigations

  • FBC (anaemia) and blood film
  • Iron studies
  • Tissue transglutaminase (tTG) antibodies (IgA-tTG, but can also test for IgG-tTG)
  • Folic acid and B12 deficiency
  • Thyroid function

 

Management

  • Follow gluten-free diet
  • No pharmacological intervention proven effective yet

 

Prognosis

  • Lasting resolution with gluten free diet in 90% of cases
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