HLA-DQ2

HLA-DQ2 (DQ2) is a serotype group within HLA-DQ (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.

HLA-DQ2
Illustration of HLA-DQ2.5 with deamidated gliadin peptide in the binding pocket.1s9v​
Polymer typeMHC Class II, DQ
Cis-haplotype Haplotype
isoform subtype DQA1 DQB1
DQ α2β2 DQ2.2 *0201 *0202
DQ α3β2 DQ2.3 *0303 *0202
DQ α5β2 DQ2.5 *0501 *0201

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. This haplotype, HLA A1-B8-DR3-DQ2, is associated with diseases in which HLA-DQ2 has suspect involvement. Direct involvement of DQ2 is certain in coeliac disease (also known as celiac disease).

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