What is Celiac Disease?
Celiac disease is an autoimmune disorder triggered by gluten ingestion in genetically susceptible individuals, causing immune-mediated damage to the small intestinal mucosa that leads to villous atrophy and malabsorption. 1, 2
Pathophysiology
The disease develops through a complex immune response involving both adaptive and innate mechanisms when gluten proteins are consumed 2. In genetically predisposed individuals—particularly those carrying HLA-DQ2 or HLA-DQ8 haplotypes—gluten exposure triggers an immunological reaction in the small intestinal epithelium that destroys the mucosal architecture 1, 3. The autoantigen involved is tissue transglutaminase-2 (TG2), which became a cornerstone of modern diagnostic testing 4.
Epidemiology
The global prevalence is approximately 1% (range 0.7-1.4%) of the general population 1, 2. The disease is strongly genetically dependent, with nearly all patients carrying HLA-DQ2 or HLA-DQ8 4, 1. First-degree relatives have a 7.5% risk of developing celiac disease 4.
Clinical Presentation
The clinical manifestations are highly variable and include:
Gastrointestinal Symptoms
- Diarrhea or constipation
- Malabsorption symptoms including failure-to-thrive in children 4
Extraintestinal Manifestations
Subclinical Cases
Many patients present with minimal or no symptoms, contributing to significant underdiagnosis 1, 2.
Associated Conditions
Celiac disease occurs at increased frequency (5-10%) in patients with:
- Type 1 diabetes
- Autoimmune thyroid disease
- Autoimmune liver disease
- Down syndrome
- Turner syndrome 4
Diagnosis
Diagnosis requires a combination of:
Positive serology: IgA anti-tissue transglutaminase 2 (TG2-IgA) and anti-endomysial antibodies 2, 3
- For IgA-deficient patients, use IgG deaminated gliadin peptide 1
Histological findings: Villous atrophy on duodenal biopsy 1, 2
Symptom resolution: Following initiation of a gluten-free diet 1
Critical diagnostic pitfall: Patients must be consuming gluten at the time of testing, as avoidance reduces sensitivity of both serology and biopsy 4. If already on a gluten-free diet, patients should consume three slices of wheat bread daily for 1-3 months before repeat testing 4.
Complications of Untreated Disease
- Osteoporosis
- Malnutrition and vitamin deficiencies
- Small bowel lymphoma (intestinal lymphoma)
- Infertility 1, 2, 3
Treatment
The only effective treatment is lifelong, strict adherence to a gluten-free diet 1, 2, 3, 5. Symptom improvement typically occurs within weeks of initiating therapy 1. However, adherence is challenging and socially isolating, requiring multidisciplinary support including dietitian involvement 5, 6.
Gluten-free oats may be included in adults 5, and should not be unnecessarily restricted in children 5.