HLA-DQB1

Major histocompatibility complex, class II, DQ beta 1, also known as HLA-DQB1, is a human gene and also denotes the genetic locus which contains this gene.cite web | title = Entrez Gene: HLA-DQB1 major histocompatibility complex, class II, DQ beta 1| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=3119| accessdate = ] The protein encoded by this gene is one of two proteins that are required to form the DQ heterodimer, a cell surface receptor essential to the function of the immune system.

Function

HLA-DQB1 belongs to the HLA class II beta chain paralogues. This 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).

Gene struture and polymorphisms

The beta chain is approximately 26-28 kDa and it contains 6 exons. Exon one encodes the leader peptide, exons 2 and 3 encode the two extracellular protein domains, exon 4 encodes the transmembrane domain and exon 5 encodes 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 4 different molecules. Typing for these polymorphisms is routinely done for bone marrow transplantation.cite journal | author = Lau M, Terasaki PI, Park MS | title = International Cell Exchange, 1994 | journal = Clin Transpl | volume = | issue = | pages = 467–88 | year = 1994 | pmid = 7547576 | doi = | url = | issn = ]

Disease association

Diabetes

Several alleles of HLA-DQB1 are associated with an increased risk of developing type 1 diabetes.cite journal | author = Todd JA | title = Genetic control of autoimmunity in type 1 diabetes | journal = Immunol. Today | volume = 11 | issue = 4 | pages = 122–9 | year = 1990 | month = April | pmid = 2187469 | doi = | url = | issn = ] cite journal | author = Todd JA | title = Genetics of type 1 diabetes | journal = Pathol. Biol. | volume = 45 | issue = 3 | pages = 219–27 | year = 1997 | month = March | pmid = 9296067 | doi = | url = | issn = ] cite journal | author = Redondo MJ, Fain PR, Eisenbarth GS | title = Genetics of type 1A diabetes | journal = Recent Prog. Horm. Res. | volume = 56 | issue = | pages = 69–89 | year = 2001 | pmid = 11237226 | doi = 10.1210/rp.56.1.69 | url = | issn = | accessdate = ] The locus also has the genetic name IDDM1 as it is the highest genetic risk for type 1 diabetes. Again the DQB1*0201 and DQB1*0302 alleles, particularly the phenotype DQB1*0201/*0302 has a high risk of late onset type 1 diabetes. The risk is partially shared with the HLA-DR locus (DR3 and DR4 serotypes).

Coeliac disease

Celiac1 is a genetic name for DQB1, the HLA DQB1*0201, *0202, and *0302 encode genes that mediate the autoimmune coeliac disease. Homozygotes of DQB1*0201 have a higher risk of developing the coeliac disease, relative to any other genetic locus.cite journal | author = Murray JA, Moore SB, Van Dyke CT, "et al" | title = HLA DQ gene dosage and risk and severity of celiac disease | journal = Clin. Gastroenterol. Hepatol. | volume = 5 | issue = 12 | pages = 1406–12 | year = 2007 | month = December | pmid = 17919990 | doi = 10.1016/j.cgh.2007.08.013 | url = | issn = ]

Multiple sclerosis

Certain HLA-DQB1 alleles are also linked to a modest increased risk of multiple sclerosis.cite journal | author = Dyment DA, Sadovnick AD, Ebers GC, Sadnovich AD | title = Genetics of multiple sclerosis | journal = Hum. Mol. Genet. | volume = 6 | issue = 10 | pages = 1693–8 | year = 1997 | pmid = 9300661 | doi = 10.1093/hmg/6.10.1693 | url = | issn = ] cite journal | author = Schmidt H, Williamson D, Ashley-Koch A | title = HLA-DR15 haplotype and multiple sclerosis: a HuGE review | journal = Am. J. Epidemiol. | volume = 165 | issue = 10 | pages = 1097–109 | year = 2007 | month = May | pmid = 17329717 | doi = 10.1093/aje/kwk118 | url = | issn = ]

Narcolepsy

Other HLA-DQB1 alleles are associated with a predisposition to narcolepsy.cite journal | author = Kadotani H, Faraco J, Mignot E | title = Genetic studies in the sleep disorder narcolepsy | journal = Genome Res. | volume = 8 | issue = 5 | pages = 427–34 | year = 1998 | month = May | pmid = 9582188 | doi = 10.1101/gr.8.5.427 | url = | issn = | accessdate = ]

Alleles

ee also

* Major histocompatibility complex
* Human leukocyte antigen
* HLA-DQ

References

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