HLA-DQ2 and HLA-DQ8 are HLA (Human Leukocyte Antigen) Class II genes that play a crucial role in the development of coeliac disease (gluten-related autoimmunity). These genes are responsible for presenting gluten proteins to the immune system. In individuals who carry HLA-DQ2 or HLA-DQ8, ingestion of gluten can trigger an abnormal immune response that damages the lining of the small intestine, leading to coeliac disease.
Main functions and relevance
HLA (Human Leukocyte Antigen) proteins
These are proteins found on the surface of cells that are essential for presenting antigens (foreign substances) to immune cells, allowing the immune system to recognise and eliminate pathogens or other foreign materials.
HLA-DQ2 and HLA-DQ8
These are specific alleles of HLA Class II that are strongly associated with immune responses to gluten, particularly in coeliac disease.
Disease mechanism
In individuals who carry HLA-DQ2 or HLA-DQ8, consumption of gluten leads to exposure to gliadin, a component of gluten. These genes cause the immune system to mistakenly recognise gluten as harmful and mount an immune attack against the small intestinal mucosa, resulting in impaired nutrient absorption and the typical symptoms of coeliac disease.
Key clinical facts
- Approximately 95% of patients with coeliac disease carry HLA-DQ2
- Most of the remaining patients carry HLA-DQ8
- Absence of both HLA-DQ2 and HLA-DQ8 makes coeliac disease very unlikely
What is gluten?
Gluten is a protein found in cereals such as wheat, rye, and barley.
Role of HLA-DQ2 / DQ8 testing
This test is used to:
- Rule out coeliac disease when the result is negative
- Assess genetic susceptibility
- Support diagnosis when blood test results or clinical symptoms are unclear
Summary of the Importance of HLA-DQ2 and HLA-DQ8
- Presence of HLA-DQ2 or HLA-DQ8 indicates increased risk
- These genes are a necessary but not sufficient condition for developing coeliac disease
Diagnosis must be considered alongside:
- Antibody tests (tTG-IgA, EMA-IgA)
- Clinical features, and in some cases endoscopy with intestinal biopsy
Final summary
HLA-DQ2 and HLA-DQ8 are genetic factors that increase susceptibility to coeliac disease and serve as markers of gluten sensitivity, but they alone do not confirm the diagnosis.
