page_title: HLA-DQ2
section_title: DQ2 isoforms and DQ2 haplotypes
hierarchical_section_title: HLA-DQ2 / DQ2 isoforms and DQ2 haplotypes
caption_attribution_description: English: Image shows the result of isoform pairing with the DQ2.2/DQ2.5 phenotype. The haplotypes, top and bottom are inherited one from each parent (gender is unimportant). The genes produce isoform polypeptides that are free to pair on the surface. The density of DQ2.5 and DQ2.2 increase because of both cis and trans-pairing of DQA1*0501 with DQB1*0201 and DQB1*0202. The two B1*02 genes differ outside of the functional regions, and are functionally equivalent.
context_page_description: HLA-DQ2 is a serotype group within HLA-DQ serotyping system. The serotype is determined by the antibody recognition of β² subset of DQ β-chains. The β-chain of DQ is encoded by HLA-DQB1 locus and DQ2 are encoded by the HLA-DQB1*02 allele group. This group currently contains two common alleles, DQB1*0201 and DQB1*0202. HLA-DQ2 and HLA-DQB1*02 are almost synonymous in meaning. DQ2 β-chains combine with α-chains, encoded by genetically linked HLA-DQA1 alleles, to form the cis-haplotype isoforms. These isoforms, nicknamed DQ2.2 and DQ2.5, are also encoded by the DQA1*0201 and DQA1*0501 genes, respectively.
  DQ2 is most common in Western Europe, North Africa and East Africa. Highest frequencies are observed in parts of Spain and Ireland; this distribution correlates with the frequency of two of the most prevalent autoimmune diseases. There is also an increase in DQB1*0201 in Central Asia, peaking in Kazakhstan and declining slowly west to east into China and finally Southeast Asia. DQA1*0501: DQB1*0201. DQ2.5 is one of the most predisposing factors for autoimmune disease.
  DQ2.5 is encoded, often, by a haplotype associated with a large number of diseases.
caption: Isoform pairings in DQ2.5/DQ2.2 results in two functionally unique isoform
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