HLA-DQA1 (Human Leukocyte Antigen DQ Alpha 1 Chain): HLA-DQA1 is a key component of the MHC class II molecule complex. It plays an essential role in the immune system by presenting peptide antigens to CD4+ T cells. This function is critical for triggering the adaptive immune response against pathogens. Variations in the HLA-DQA1 gene are linked to susceptibility to autoimmune diseases like type 1 diabetes and celiac disease, highlighting its importance in immune regulation and disease risk.