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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.[citation needed]

Serology

B7 serotype recognition of Some HLA B*07 allele-group gene products[2]
B*07 B7 Sample
allele % size (N)
*0702 98 10841
*0703 93 15
*0704 89 44
*0705 95 42
*0706 96 23
*0707 92 13
*0709 78 9
Alleles link-out to IMGT/HLA Databease at EBI

Alleles

HLA B*0702 frequencies
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

  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. ^ derived from IMGT/HLA
  3. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as 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. ^ 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. ^ 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. ^ 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. ^ 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. ^ 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. ^ 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. ^ "Une découverte québécoise pourrait permettre d'identifier les patients à risque d'une forme grave de la COVID-19". 12 October 2021.
  11. ^ https://ici.radio-canada.ca/nouvelle/1830925/covid-identification-rapide-patients-risque-maladie-grave/
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