HLA-DQ9

HLA-DQ9 is a human leukocyte antigen serotype within the HLA-DQ (DQ) serotype group. The serotype is determined by the antibody recognition of β9 subset of DQ β-chains. The β-chain of DQ is encoded by the HLA-DQB1 gene. DQ9 is a split antigen of the DQ3 broad antigen, and it is the second most common DQ antigen in the Japanese population.

Structure and Function

HLA-DQ9 is a cell surface receptor protein found on antigen presenting cells. It is involved in the immune system's response to foreign substances. The protein is a heterodimer consisting of an α and β chain, which are encoded by separate genes, HLA-DQA1 and HLA-DQB1 respectively. The combination of these two chains forms a binding site for peptides, which are then presented to T cells to initiate an immune response.

Disease Association

HLA-DQ9 has been associated with several autoimmune diseases, including type 1 diabetes, rheumatoid arthritis, and celiac disease. The mechanism of this association is not fully understood, but it is believed to involve the presentation of self-peptides to T cells, leading to an autoimmune response.

Distribution

HLA-DQ9 is most commonly found in East Asian populations, particularly in Japan. It is less common in other populations, such as those of European or African descent.

See Also

• HLA-DQ
• HLA-DQA1
• HLA-DQB1
• Human leukocyte antigen