HLA-DQ2

HLA-DQ2 is a serotype group within the HLA-DQ (DQ) system, a part of the human leukocyte antigen (HLA) system. The HLA system is a gene complex that encodes for proteins on the surface of cells that are responsible for regulation of the immune system in humans. HLA-DQ2 is associated with several autoimmune diseases, most notably celiac disease.

Structure and Function

HLA-DQ2 is a heterodimeric protein complex that is encoded by two genes, DQA1 and DQB1, which are located on chromosome 6. The DQ2 molecule is composed of an α-chain (DQA1*05) and a β-chain (DQB1*02). The α-chain is encoded by the DQA1 gene and the β-chain is encoded by the DQB1 gene. The DQ2 molecule is expressed on the surface of antigen presenting cells, where it plays a crucial role in the immune response by presenting peptides to CD4+ T cells.

Association with Diseases

HLA-DQ2 is associated with several autoimmune diseases. The most well-known association is with celiac disease, an autoimmune disorder triggered by the ingestion of gluten. Approximately 90-95% of celiac disease patients carry HLA-DQ2. Other diseases associated with HLA-DQ2 include type 1 diabetes, rheumatoid arthritis, and multiple sclerosis.

Testing and Diagnosis

Testing for HLA-DQ2 is often used in the diagnosis of celiac disease. If a patient tests positive for HLA-DQ2, it does not confirm a diagnosis of celiac disease, but it does indicate a genetic susceptibility. Conversely, a negative test result can effectively rule out celiac disease.

Treatment and Management

There is currently no cure for diseases associated with HLA-DQ2. Management of these diseases typically involves managing symptoms and avoiding triggers. For example, in the case of celiac disease, a strict gluten-free diet is the only effective treatment.