HLA-DQB1 (Human Leukocyte Antigen DQ Beta 1): HLA-DQB1 is a gene that encodes part of the MHC class II molecule, essential for presenting foreign peptide antigens to CD4+ T helper cells. It plays a key role in initiating immune responses and maintaining self-tolerance. Variations in HLA-DQB1 have been linked to autoimmune diseases such as type 1 diabetes and celiac disease.