HLA-DPA1 (Major Histocompatibility Complex, Class II, DP Alpha 1): The HLA-DPA1 gene is part of the human leukocyte antigen (HLA) system, which plays a vital role in the immune system. This gene is specifically involved in presenting peptides derived from extracellular proteins to T cells. Its importance lies in regulating immune responses and its association with various autoimmune diseases. The allele diversity in the HLA-DPA1 gene is crucial for the adaptive immune response, making it a key focus in transplant medicine, autoimmune disease research, and studies on vaccine responses.