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