HLA-DQA2 is a major histocompatibility complex class II alpha chain that functions in antigen presentation to CD4+ T cells. As part of the HLA-DQ molecule, HLA-DQA2 binds peptides derived from exogenous antigens processed through the endocytic pathway and displays them on antigen-presenting cell surfaces 1. Unlike the canonical HLA-DQA1/DQB1 pair, HLA-DQA2 expression is restricted to specific cell types, particularly Langerhans cells in human epidermis, where it forms functional heterodimers with HLA-DQβ2 chains that localize to early endosomes and cell surfaces 2. HLA-DQA2 can also form mixed heterodimers with HLA-DQβ1 chains, potentially expanding antigen presentation complexity 2. Clinically, HLA-DQA2 has emerged as a disease-associated target in multiple conditions. High pre-infection HLA-DQA2 expression was associated with prevention of sustained SARS-CoV-2 infection in nasopharyngeal tissue 3. HLA-DQA2 has been identified as a shared genetic target between Parkinson's disease and inflammatory bowel disease through gut-brain axis mechanisms 4. Additionally, HLA-DQA2 was identified in glomerulonephritis pathology, particularly in membranous nephropathy 5, and proteome-wide Mendelian randomization studies identified HLA-DQA2 as a direct causal target for primary sclerosing cholangitis risk 6, suggesting therapeutic potential in autoimmune cholestatic liver disease.