HLA-DQ7#DQ7.5

Serotyping efficiency. The serotyping efficiency of DQ7 toward DQB1*0301 is reasonably good, but still results in some false negatives, for *0304 the typing efficiency is poor and cross-reaction with DQ8 is relatively high.

DQB1*0301 is the major DQ7 allele

DQB1*0301 appears to be associated with lupus anticoagulant.{{cite journal |vauthors=Arnett FC, Olsen ML, Anderson KL, Reveille JD | title = Molecular analysis of major histocompatibility complex alleles associated with the lupus anticoagulant | journal = J. Clin. Invest. | volume = 87 | issue = 5 | pages = 1490–5 | year = 1991 | pmid = 1673688 | doi =10.1172/JCI115158 | pmc = 295227 }}

DQB1*0304 is the minor DQ7 allele

DQ haplotypes of this serotype are formed between the cis-chromosomal genes of the DQA1 locus.

This includes DQA1*0301, *0302, *0303, *0401, *0505, *0601.

There is a rather large degree of disequilibration about DQA1*0301 suggesting that this is one of the older and more established HLA DQB1* alleles in Eurasia. The intron structure of DQB1 suggest that DQB1*0301 DQB1*0302/*0303 split occurred before DQB1*0302/*0303, the distribution of *03 in Africa suggest that recombination DQA1*03:DQB1*0301 are primarily the result of recombination events that have occurred in Africa. A recent study of myasthenia gravis in Houston confirms the presence of A*0505:B*0301 in Nigeria. B1*0301 and A1*03 haplotypes are found at relatively high frequencies in SE Asia and Austronesia, also indicating that it is well established in the exo-African population.

The DQ7.3 haplotype can be formed by DQA1*0301:DQB1*0301, DQA1*0302:DQB1*0301, DQA1*0303:DQB1*0301. In the west, the DQA1*0303:DQB1*0301 haplotype appears to be more common.

The gene products of all 3 function similarly and subunits are interchangeable. In the literature, older DNA tests recognize DQA1*0303 as DQA1*0302, and still oldest DNA tests recognize all three as DQA1*03 or DQA1*0301.

DQA1*0303:DQB1*0301 may be involved in narcolepsy.{{cite journal |vauthors=Hong SC, Lin L, Lo B, etal | title = DQB1*0301 and DQB1*0601 modulate narcolepsy susceptibility in Koreans | journal = Hum. Immunol. | volume = 68 | issue = 1 | pages = 59–68 | year = 2007 | pmid = 17207713 | doi = 10.1016/j.humimm.2006.10.006}} DQ7.3 appears to be associated with oral ulcerations and gingival disease {{cite journal | pmid = 8052655 | volume=91 | issue=16 | title=Common major histocompatibility complex class II markers in clinical variants of cicatricial pemphigoid. | date=Aug 1994 | journal=Proc Natl Acad Sci U S A | pages=7747–51 | doi=10.1073/pnas.91.16.7747 | pmc=44479 | vauthors=Yunis JJ, Mobini N, Yunis EJ, Alper CA, Deulofeut R, Rodriguez A, Foster CS, Marcus-Bagley D, Good RA, Ahmed AR| bibcode=1994PNAS...91.7747Y | doi-access=free }}

DQA1*0401:DQB1*0301 (DQ7.4) This haplotype is found in Siberia, Africa but also at low levels in Western Europe.

DQA1*0505:DQB1*0301 (DQ7.5) was gene-typed as DQA1*0501:DQB1*0301 until it was recognized that there was amino acid sequence variant in the preprocessed DQA1* gene product (proto-α-chain polypeptide encoded DQA1*0505). This proto-alpha, once processed, is identical to the DQA1*0501 encoded α-chain once it is processed. Almost 100% of DQ7.5 haplotypes carry the DQA1*0505 allele.{{cite journal |vauthors=Pera C, Delfino L, Longo A, Pistillo MP, Ferrara GB | title = Novel associations among HLA-DQA1 and -DQB1 alleles, revealed by high-resolution sequence-based typing (SBT) | journal = Tissue Antigens | volume = 55 | issue = 3 | pages = 275–9 | year = 2000 | pmid = 10777105 | doi =10.1034/j.1399-0039.2000.550313.x | url = https://zenodo.org/record/1231460 }} The DR5-DQ7.5 is common in the Southeastern Europe and the Levant, with DQ7.5 reaching a haplotype frequency of 40% in Lebanon. Its high level is probably not by chance, the haplotype appears to protect against juvenile diabetes, which appears to be more common among cereal eating peoples.{{cite journal |vauthors=Almawi WY, Wakim-Ghorayeb SF, Arekat MR, etal | title = Association of selective HLA class II susceptibility-conferring and protective haplotypes with type 2 diabetes in patients from Bahrain and Lebanon | journal = Clin. Vaccine Immunol. | volume = 13 | issue = 11 | pages = 1296–8 | year = 2006 | pmid = 16988007 | doi = 10.1128/CVI.00206-06 | pmc = 1656545}} Cereals were first domesticated in the Near and Middle East more than 10,000 years ago and selection may explain DQ7.5's higher frequencies. (See: Triticeae)

The processed alpha subunit of DQA1*0505 is identical to that of DQA1*0501, but some slight differences in the association with autoimmune disease are observed, possibly as a result of linked DR and DQB1 genes. DQA1*0505 can play into celiac disease under two circumstances. First it can increase risk when DQ2.5 is present, although current studies indicate that it marginally increases risk relative to DQB1*0202 in DQ2.5 cis haplotype. DQA1*0505, without DQ2, is found in a small percentage of coeliac disease (without DQ2 or DQ8).{{cite journal |vauthors=Karell K, Louka AS, Moodie SJ, etal |title=HLA types in celiac disease patients not carrying the DQA1*05-DQB1*02 (DQ2) heterodimer: results from the European Genetics Cluster on Celiac Disease |journal=Hum. Immunol. |volume=64 |issue=4 |pages=469–77 |year=2003 |pmid=12651074 |doi= 10.1016/S0198-8859(03)00027-2}}

DQ7.5 is found also high in frequency in the new world, but with DR types less commonly encountered in the old world. DQA1*05 allele is not clear in the new world. DQB1*0301 may be under current positive selection in the human population, at least in areas where DQ2.5 and DQ8 are high, as it confers resistance to type 1 diabetes. For hepatitis type B, DQ7 is associated with persistence but for C, DQ7 is associated with clearance.{{cite journal |vauthors=Singh R, Kaul R, Kaul A, Khan K | title = A comparative review of HLA associations with hepatitis B and C viral infections across global populations | journal = World J. Gastroenterol. | volume = 13 | issue = 12 | pages = 1770–87 | year = 2007 | pmid = 17465466 | doi = 10.3748/wjg.v13.i12.1770| pmc = 4149952 | doi-access = free }} DQA1*0505, DQB1*0301 appear to increase the risk for melanoma in the Spanish population however this may have a linkage to more recent fair skinned migrants. DQB1*0301 is also associated with allergic fungal sinusitis, human papillomavirus (HPV) induced warts, limited cutaneous systemic sclerosis in Africans, and primary sclerosing cholangitis in Southern Europeans. DQB1*0301 is also predisposing in narcolepsy. DQB1*0301 does not to play a role in any frequently occurring autoimmune disease and its presence in the near east and suppressed frequencies of coeliac disease and Type 1 diabetes in these regions is suggestive that it has a positive selection in Post-Mesolithic cereal based societies in the Western Eurasia.

DQB1*0301 appears to be more associated with early onset myasthenia

gravis in Japanese than DQ8, and was also found along with DQB1*0304 to be associated with Chinese MG. DQ7 or associated DR types may play a role in rheumatoid arthritis. In celiac disease the DQ7 (A*0505/1) can mediate celiac disease when HLA DQ2.2 is also present. HLA DQB1*0301 in Turks is associated with Thymoma but the risk may be associated with HLA class I loci.

DQA1*0601:DQB1*0301 (DQ7.6) is a globally rare haplotype, however it is found at high frequencies in the South Pacific and along the West Pacific rim. DQB1*0301 appears to be uniquely linked to DQA1*0601. DQ7.6 is positively associated with asthma,{{cite journal |vauthors=Guo X, Ni P, Li L | title = [Association between asthma and the polymorphism of HLA-DQ genes] | language = zh | journal = Zhonghua Jie He He Hu Xi Za Zhi | volume = 24 | issue = 3 | pages = 139–41 | year = 2001 | pmid = 11802952 }} pauciarticular juvenile arthritis without anti-nuclear antibodies,{{cite journal |vauthors=Donn RP, Thomson W, Pepper L, etal | title = Antinuclear antibodies in early onset pauciarticular juvenile chronic arthritis (JCA) are associated with HLA-DQB1*0603: a possible JCA-associated human leucocyte antigen haplotype | journal = Br. J. Rheumatol. | volume = 34 | issue = 5 | pages = 461–5 | year = 1995 | pmid = 7788177 | doi =10.1093/rheumatology/34.5.461 }} DQ7.6 is negatively associated (Protective against) juvenile diabetes,{{cite journal |vauthors=Chuang LM, Jou TS, Wu HP, etal | title = HLA DQA1 genotypes and its interaction with HLA DQB1 in Chinese IDDM living in Taiwan | journal = Proc. Natl. Sci. Counc. Repub. China B | volume = 19 | issue = 2 | pages = 73–9 | year = 1995 | pmid = 7624445 }} liver and spleen disease in Schistosoma japonicum infection,{{cite journal |vauthors=Waine GJ, Ross AG, Williams GM, Sleigh AC, McManus DP | title = HLA class II antigens are associated with resistance or susceptibility to hepatosplenic disease in a Chinese population infected with Schistosoma japonicum | journal = Int. J. Parasitol. | volume = 28 | issue = 4 | pages = 537–42 | year = 1998 | pmid = 9602373 | doi =10.1016/S0020-7519(98)00020-4 }} pulmonary tuberculosis.{{cite journal |vauthors=Vejbaesya S, Chierakul N, Luangtrakool K, Srinak D, Stephens HA | title = Associations of HLA class II alleles with pulmonary tuberculosis in Thais | journal = Eur. J. Immunogenet. | volume = 29 | issue = 5 | pages = 431–4 | year = 2002 | pmid = 12358854 | doi =10.1046/j.1365-2370.2002.00352.x }}

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