 HLA-DQ is part of the MHC class II antigen-presenting receptor (also called the human leukocyte antigen) system and distinguishes cells between self and non-self for the purposes of the immune system.The two subunits of the HLA-DQ protein are encoded by the HLA-DQA1 and HLA-DQB1 genes, located on the short arm of chromosome 6.There are seven HLA-DQ variants (DQ2 and DQ4–DQ9).