HLA-DRB4 belongs to the HLA class II beta chain paralogues. This class II molecule is a heterodimer consisting of an alpha (DRA) and a beta (DRB) chain, 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. Diseases associated with HLA-DRB4 include Halo Nevi and Polyarticular Juvenile Idiopathic Arthritis. Among its related pathways are Hematopoietic cell lineage and G-protein signaling N-RAS regulation pathway.