HLA-B7
| Illustration of HLA-B with bound peptide | ||
major histocompatibility complex (human), class I, B7
| ||
| Alleles | B*0702, *0703, *0704, *0705 | |
| Structure (See HLA-B) | ||
| Alleles (See Serotyping) | ||
| Locus | chr.6 6p21.31 | |
HLA-B7 (B7) is an HLA-B serotype. The serotype identifies the more common HLA-B*07 gene products.[1] (For terminology help see: HLA-serotype tutorial) B7, previously HL-A7, was one of the first 'HL-A' antigens recognized, largely because of the frequency of B*0702 in Northern and Western Europe and the United States. B7 is found in two major haplotypes in Europe, where it reaches peak frequency in Ireland. One haplotype A3-B7-DR15-DQ1 can be found over a vast region and is in apparent selective disequilibrium. B7 is a risk factor for cervical cancer, sarcoidosis, and early-onset spondylarthropathies.Script error: No such module "Unsubst".
Serology
| B*07 | B7 | Sample |
| allele | % | size (N) |
| Template:Asterisk0702 | 98 | 10841 |
| Template:Asterisk0703 | 93 | 15 |
| Template:Asterisk0704 | 89 | 44 |
| Template:Asterisk0705 | 95 | 42 |
| Template:Asterisk0706 | 96 | 23 |
| Template:Asterisk0707 | 92 | 13 |
| Template:Asterisk0709 | 78 | 9 |
| Alleles link-out to IMGT/HLA Databease at EBI | ||
Alleles
| freq | ||
| ref. | Population | (%) |
| [3] | Ireland South | 17.6 |
| [3] | Ireland Northern | 17.3 |
| [3] | Australia New South Wales | 12.0 |
| [3] | Croatia | 9.7 |
| [3] | Azores S. Maria & Miguel | 9.0 |
| [3] | Cameroon Beti | 8.6 |
| [3] | Saudi Arabia Guraiat and Hail | 8.3 |
| [3] | Azores Central Islands | 8.0 |
| [3] | France South East | 7.2 |
| [3] | Cameroon Bamileke | 7.1 |
| [3] | Portugal Centre | 7.0 |
| [3] | Italy North pop 1 | 6.7 |
| [3] | Japan Central | 6.5 |
| [3] | Czech Republic | 6.1 |
| [3] | Uganda Kampala | 5.9 |
| [3] | Mali Bandiagara | 5.8 |
| [3] | Senegal Niokholo Mandenka | 5.8 |
| [3] | India Mumbai Marathas | 4.9 |
| [3] | Zambia Lusaka | 4.6 |
| [3] | Zimbabwe Harare Shona | 4.6 |
| [3] | South African Natal Zulu | 4.5 |
| [3] | Romanian | 3.7 |
| [3] | South Korea (3) | 3.5 |
| [3] | Shijiazhuang Tianjian Han, China | 3.4 |
| [3] | India North Delhi | 3.3 |
| [3] | Kenya Luo | 2.5 |
| [3] | China Guangzhou Han | 2.4 |
| [3] | Mexico Chihuahua Tarahumara | 2.3 |
| [3] | Sudanese | 2.3 |
| [3] | Singapore Javanese Indonesians | 2.0 |
| [3] | Spain Eastern Andalusia Gipsy | 2.0 |
| [3] | New Caledonia | 1.9 |
| [3] | Oman | 1.7 |
| [3] | USA Alaska Yupik Natives | 1.6 |
| [3] | China Beijing | 1.5 |
| [3] | Tunisia | 1.5 |
| [3] | Argentina Toba Rosario | 1.2 |
| [3] | Singapore Chinese Han | 1.2 |
| [3] | USA Arizona Pima | 1.1 |
| [3] | American Samoa | 1.0 |
| [3] | Japan Ainu Hokkaido | 1.0 |
| [3] | Kenya Nandi | 1.0 |
| [3] | Portugal South | 1.0 |
| [3] | Singapore Riau Malay | 1.0 |
| [3] | Singapore Thai | 1.0 |
In disease
Cervical cancer
HLA-B7 along with HLA-DQ8 increased risk for cervical cancer in Costa Rican [4] and South Asian women[5]
Sarcoidosis
A weak relationship between HLA-B7 and sarcoidosis has been known for 30+ years, [6] yet has not consistently been reproducible in all studies however. A common serologically defined haplotype in Europeans is HLA A3-Cw7-B7-DR15-DQ6.2 which is composed of alleles A*0301:Cw*0701:B*0702:DRB1*1501:DQA1*0102:DQB1*0602. In persistent sarcoidosis this haplotype appears elevated, further study eliminated risk contributed by A3-Cw7 and DQ6.2 indicating B7-DR15 haplotype contains risk of disease (OR = 2.5). Corresponding region of chromosome 6 contains nearly one million nucleotides thus these genes, or another closely linked gene could be involved in such massing of inflammatory granulomata.[7]
Juvenile Spondylarthropathies
In Croatian children, two HLA-B27 alleles were found associated with disease, B*2702, B*2705.[8] The study showed also B*0702 in cooperation with B*27, the HLA-B*07/B*27 combination with D6S273-134 genomic marker allele and was found not to be the result of linkage disequilibrium. B*2705 was found to be dominant allele associated.
Haemochromatosis
The HFE gene responsible for haemochromatosis is distal on chromosome 6 from HLA-A and more so from HLA-B, the distance suffices (3 million nucleotides) to allow equilibration of the loci. Nonetheless, a linkage has been found between A3-B7 haplotype and haemochromatosis. The region is almost 1.4 million nucleotides in length and contains many other genes that could be involved. A more recent study looked at a number of linked gene-alleles and found I82-2:D6S265-1:HLA-A3:D6S128-2:HLA-F1:D6S105-8 was constantly associated while B7 appeared beyond the haplotype linked to disease.[9]
Covid-19
In october 2021, a team of researcher from Centre hospitalier universitaire Sainte-Justine in Montreal, Canada, announced the discovery of HLA-B7 genetic marker as a potential cause for severe form of covid-19. While they noted that more work will be necessary to confirm this discovery, they found that individuals carrying the HLA-B7 genetic marker, which represents 35% of the population worldwide, are more likely to have a less effective immune response to covid-19.[10][11]
References
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