# HLA-B7

HLA-B7 (B7) is an HLA-B serotype. The serotype identifies the more common HLA-B*07 gene products. (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 :
| 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 | (%) |
| | Ireland South | 17.6 |
| | Ireland Northern | 17.3 |
| | Australia New South Wales | 12.0 |
| | Croatia | 9.7 |
| | Azores S. Maria & Miguel | 9.0 |
| | Cameroon Beti | 8.6 |
| | Saudi Arabia Guraiat and Hail | 8.3 |
| | Azores Central Islands | 8.0 |
| | France South East | 7.2 |
| | Cameroon Bamileke | 7.1 |
| | Portugal Centre | 7.0 |
| | Italy North pop 1 | 6.7 |
| | Japan Central | 6.5 |
| | Czech Republic | 6.1 |
| | Uganda Kampala | 5.9 |
| | Mali Bandiagara | 5.8 |
| | Senegal Niokholo Mandenka | 5.8 |
| | India Mumbai Marathas | 4.9 |
| | Zambia Lusaka | 4.6 |
| | Zimbabwe Harare Shona | 4.6 |
| | South African Natal Zulu | 4.5 |
| | Romanian | 3.7 |
| | South Korea (3) | 3.5 |
| | Shijiazhuang Tianjian Han, China | 3.4 |
| | India North Delhi | 3.3 |
| | Kenya Luo | 2.5 |
| | China Guangzhou Han | 2.4 |
| | Mexico Chihuahua Tarahumara | 2.3 |
| | Sudanese | 2.3 |
| | Singapore Javanese Indonesians | 2.0 |
| | Spain Eastern Andalusia Gipsy | 2.0 |
| | New Caledonia | 1.9 |
| | Oman | 1.7 |
| | USA Alaska Yupik Natives | 1.6 |
| | China Beijing | 1.5 |
| | Tunisia | 1.5 |
| | Argentina Toba Rosario | 1.2 |
| | Singapore Chinese Han | 1.2 |
| | USA Arizona Pima | 1.1 |
| | American Samoa | 1.0 |
| | Japan Ainu Hokkaido | 1.0 |
| | Kenya Nandi | 1.0 |
| | Portugal South | 1.0 |
| | Singapore Riau Malay | 1.0 |
| | Singapore Thai | 1.0 |

## In disease
### Cervical cancer

HLA-B7 along with HLA-DQ8 increased risk for cervical cancer in Costa Rican and South Asian women

### Sarcoidosis

A weak relationship between HLA-B7 and sarcoidosis has been known for 30+ years, 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.

### Juvenile Spondylarthropathies

In Croatian children, two HLA-B27 alleles were found associated with disease, B*2702, B*2705. 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.

### 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.