HLADQB1

HLA-DQB1 is a gene in the human leukocyte antigen (HLA) system that encodes the beta chain of the HLA-DQ class II heterodimer. The HLA-DQ molecule is expressed on the surface of professional antigen-presenting cells and plays a key role in adaptive immunity by presenting extracellular peptide antigens to CD4+ T helper cells. The DQB1 gene is located on chromosome 6p21.3 within the major histocompatibility complex (MHC) class II region and is highly polymorphic, with numerous alleles designated by the DQB1 nomenclature (for example DQB102:01, DQB103:02).

In the HLA-DQ heterodimer, the beta chain encoded by DQB1 pairs with an alpha chain encoded by HLA-DQA1 to form a peptide-binding groove. The peptide repertoire that can be presented to T cells depends on the combination of DQA1 and DQB1 alleles, making these genes central to individual differences in immune responses and disease susceptibility.

Polymorphisms in DQB1 have been associated with various autoimmune and inflammatory diseases. For instance, certain DQA1/DQB1 haplotypes forming DQ2.5 or DQ8 are strongly linked with celiac disease, while HLA-DQB106:02 is a well-established risk factor for narcolepsy. Other alleles can confer protection or modulate risk for different conditions.

Clinically, HLA-DQB1 typing is used in research and medical contexts for disease risk assessment and, together with other HLA loci, in transplantation donor-recipient matching. See also HLA-DQA1 and broader HLA class II genetics.