HLA-DQA1 (Major Histocompatibility Complex, Class II, DQ Alpha 1) is a Protein Coding gene. Diseases associated with HLA-DQA1 include Celiac Disease and Adult-Onset Myasthenia Gravis. Among its related pathways are ICos-ICosL Pathway in T-Helper Cell and CTLA4 Signaling. GO annotations related to this gene include peptide antigen binding and MHC class II receptor activity. An important paralog of this gene is HLA-DQA2.HLA-DQA1 belongs to the HLA class II alpha chain paralogues. The class II molecule is a heterodimer consisting of an alpha (DQA) and a beta chain (DQB), both anchored in the membrane. It plays a central role in the immune system by presenting peptides derived from extracellular proteins. Class II molecules are expressed in antigen presenting cells (APC: B Lymphocytes, dendritic cells, macrophages). The alpha chain is approximately 33-35 kDa. It is encoded by 5 exons; exon 1 encodes the leader peptide, exons 2 and 3 encode the two extracellular domains, and exon 4 encodes the transmembrane domain and the cytoplasmic tail. Within the DQ molecule both the alpha chain and the beta chain contain the polymorphisms specifying the peptide binding specificities, resulting in up to four different molecules. Typing for these polymorphisms is routinely done for bone marrow transplantation.