HLA-B7

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.

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 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 Africian 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 at risk Costa Rican women[4] and Asian Indians[5]

Sarcoidosis

A relationship between HLA-B7 and sarcoidosis has been known for 30+ years.[6] However the association is weak and has not been reproducible in all studies. 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 was found to be increased in sarcoidosis, and further study eliminated risk contributed by A3-Cw7 and DQ6.2 indicating B7-DR15 haplotype contains risk of disease (OR = 2.5). The region of chromosome 6 contains nearly on million nucleotides so that these genes, or a closely linked gene could be involved in disease.[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]

References

  1. ↑ Marsh SG, Albert ED, Bodmer WF, et al. (2005). "Nomenclature for factors of the HLA system, 2004". Tissue Antigens. 65 (4): 301–69. doi:10.1111/j.1399-0039.2005.00379.x. PMID 15787720.
  2. ↑ derived from IMGT/HLA
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 Middleton D, Menchaca L, Rood H, Komerofsky R (2003). "New allele frequency database: http://www.allelefrequencies.net". Tissue Antigens. 61 (5): 403–7. doi:10.1034/j.1399-0039.2003.00062.x. PMID 12753660. External link in |title= (help)
  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. 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 1050484Freely accessible. PMID 7666396.
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