HLA-B7

HLA-B7

HLA-B7

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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.[citation needed]

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

Serology

B7 serotype recognition of Some HLA B*07 allele-group gene products[2]
B*07B7 Sample
allele %size (N)
*07029810841
*07039315
*07048944
*07059542
*07069623
*07079213
*0709789
Alleles link-out to IMGT/HLA Databease at EBI

Alleles

HLA B*0702 frequencies
freq
ref.Population(%)
[3]Ireland South17.6
[3]Ireland Northern17.3
[3]Australia New South Wales12.0
[3]Croatia9.7
[3]Azores S. Maria & Miguel9.0
[3]Cameroon Beti8.6
[3]Saudi Arabia Guraiat and Hail8.3
[3]Azores Central Islands8.0
[3]France South East7.2
[3]Cameroon Bamileke7.1
[3]Portugal Centre7.0
[3]Italy North pop 16.7
[3]Japan Central6.5
[3]Czech Republic6.1
[3]Uganda Kampala5.9
[3]Mali Bandiagara5.8
[3]Senegal Niokholo Mandenka5.8
[3]India Mumbai Marathas4.9
[3]Zambia Lusaka4.6
[3]Zimbabwe Harare Shona4.6
[3]South African Natal Zulu4.5
[3]Romanian3.7
[3]South Korea (3)3.5
[3]Shijiazhuang Tianjian Han, China3.4
[3]India North Delhi3.3
[3]Kenya Luo2.5
[3]China Guangzhou Han2.4
[3]Mexico Chihuahua Tarahumara2.3
[3]Sudanese2.3
[3]Singapore Javanese Indonesians2.0
[3]Spain Eastern Andalusia Gipsy2.0
[3]New Caledonia1.9
[3]Oman1.7
[3]USA Alaska Yupik Natives1.6
[3]China Beijing1.5
[3]Tunisia1.5
[3]Argentina Toba Rosario1.2
[3]Singapore Chinese Han1.2
[3]USA Arizona Pima1.1
[3]American Samoa1.0
[3]Japan Ainu Hokkaido1.0
[3]Kenya Nandi1.0
[3]Portugal South1.0
[3]Singapore Riau Malay1.0
[3]Singapore Thai1.0

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

  1. [1]
    Marsh, S. G.; Albert, E. D.; Bodmer, W. F.; Bontrop, R. E.; Dupont, B.; Erlich, H. A.; Fernández-Viña, M.; Geraghty, D. E.; Holdsworth, R.; Hurley, C. K.; Lau, M.; Lee, K. W.; Mach, B.; Maiers, M.; Mayr, W. R.; Müller, C. R.; Parham, P.; Petersdorf, E. W.; Sasazuki, T.; Strominger, J. L.; Svejgaard, A.; Terasaki, P. I.; Tiercy, J. M.; Trowsdale, J. (2010). "Nomenclature for factors of the HLA system, 2010". Tissue Antigens. 75 (4): 291–455. doi:10.1111/j.1399-0039.2010.01466.x. PMC 2848993. PMID 20356336.
  2. [2]
    derived from IMGT/HLA
  3. [3]
    Middleton D, Menchaca L, Rood H, Komerofsky R (2003). "New allele frequency database". Tissue Antigens. 61 (5): 403–7. doi:10.1034/j.1399-0039.2003.00062.x. PMID 12753660.
  4. [4]
    Wang SS, Wheeler CM, Hildesheim A, et al. (November 2001). "Human leukocyte antigen class I and II alleles and risk of cervical neoplasia: results from a population-based study in Costa Rica". J. Infect. Dis. 184 (10): 1310–4. doi:10.1086/324209. PMID 11679920.
  5. [5]
    Bhattacharya P, Sengupta S (October 2007). "Predisposition to HPV16/18-related cervical cancer because of proline homozygosity at codon 72 of p53 among Indian women is influenced by HLA-B*07 and homozygosity of HLA-DQB1*03". Tissue Antigens. 70 (4): 283–93. doi:10.1111/j.1399-0039.2007.00894.x. PMID 17767549.
  6. [6]
    Rybicki BA, Iannuzzi MC (March 2004). "Sarcoidosis and human leukocyte antigen class I and II genes: it takes two to tango?". Am. J. Respir. Crit. Care Med. 169 (6): 665–6. doi:10.1164/rccm.2401005. PMID 15003948.
  7. [7]
    Grunewald J, Eklund A, Olerup O (March 2004). "Human leukocyte antigen class I alleles and the disease course in sarcoidosis patients". Am. J. Respir. Crit. Care Med. 169 (6): 696–702. CiteSeerX 10.1.1.321.2788. doi:10.1164/rccm.200303-459OC. PMID 14656748.
  8. [8]
    Harjacek M, Margetić T, Kerhin-Brkljacić V, Martinez N, Grubić Z (2008). "HLA-B*27/HLA-B*07 in combination with D6S273-134 allele is associated with increased susceptibility to juvenile spondyloarthropathies". Clin. Exp. Rheumatol. 26 (3): 498–504. PMID 18578977.
  9. [9]
    Raha-Chowdhury R, Bowen DJ, Burnett AK, Worwood M (June 1995). "Allelic associations and homozygosity at loci from HLA-B to D6S299 in genetic haemochromatosis". J. Med. Genet. 32 (6): 446–52. doi:10.1136/jmg.32.6.446. PMC 1050484. PMID 7666396.
  10. [10]
    "Une découverte québécoise pourrait permettre d'identifier les patients à risque d'une forme grave de la COVID-19". 12 October 2021.
  11. [11]
    https://ici.radio-canada.ca/nouvelle/1830925/covid-identification-rapide-patients-risque-maladie-grave/
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