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Understanding HLA-DQ2 in Celiac Disease

Mar 23, 2025

HLA DQ2 Antigen - An Overview

Introduction to Celiac Disease (CD)

  • Celiac disease is an autoimmune disorder triggered by gluten ingestion.
  • CD is often linked with genetic predispositions, particularly HLA-DQ2 and HLA-DQ8 haplotypes.
  • Common symptoms include intestinal disorders, malabsorption, diarrhea, fatigue, anemia, and various extra-intestinal symptoms.

Role of HLA-DQ2 in CD

  • Over 98% of CD patients carry DQ2 or DQ8 HLA class II alleles.
  • HLA-DQ2/DQ8 predispose individuals to CD by influencing immune response to gluten.
  • HLA-DQ2 homozygosity increases risk of developing CD.

Genetic Aspects

  • HLA-DQ molecules are heterodimers composed of alpha and beta chains.
  • Gene dose effect: Homozygous individuals for HLA-DQ2 are more susceptible to CD.
  • HLA-DQ2 expression influences the immune response strength to gluten.

Immune Mechanisms

  • The enzyme tissue transglutaminase (tTG) modifies gliadin, enhancing its binding to HLA-DQ2/DQ8.
  • This binding triggers adaptive immune responses, leading to inflammation and autoantibody production.
  • Autoantibodies like anti-tTG and anti-gliadin are markers for CD.

Diagnostic and Screening Tests

  • HLA-DQ2/DQ8 genetic tests are useful for CD screening.
  • Antibody tests (TTG IgA, antiendomysial, antigliadin) help in diagnosis.
  • Intestinal biopsy confirms diagnosis through histopathological changes.

Treatment and Management

  • Gluten-free diet is the primary treatment.
  • Monitoring involves checking antibody levels and nutritional deficiencies.
  • In resistant cases, corticosteroids may be considered.

Associated Conditions

  • Celiac disease is linked with other autoimmune diseases, including type 1 diabetes and thyroid disorders.
  • Dermatitis herpetiformis is a skin manifestation associated with CD.

Environmental and Genetic Influences

  • Environmental factors like infections and stress may trigger CD in susceptible individuals.
  • Non-HLA genes also contribute to CD susceptibility, though their roles are not fully defined.

Summary

  • HLA-DQ2 is a critical factor in CD, influencing genetic predisposition and immune response.
  • Diagnosis combines genetic testing, serology, and biopsy.
  • Treatment focuses on a gluten-free diet and managing nutritional deficiencies.