HLA-B7 (B7) is an HLA- B

serotype A serotype or serovar is a distinct variation within a species of bacteria or virus or among immune cells of different individuals. These microorganisms, viruses, or cells are classified together based on their surface antigens, allowing the ep ...

. 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 Cervical cancer is a cancer arising from the cervix. It is due to the abnormal growth of cells that have the ability to invade or spread to other parts of the body. Early on, typically no symptoms are seen. Later symptoms may include abnormal ...

sarcoidosis Sarcoidosis (also known as ''Besnier-Boeck-Schaumann disease'') is a disease involving abnormal collections of inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph nodes. Less commonly af ...

, and early-onset spondylarthropathies.

Serology

Alleles

In disease

Cervical cancer

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

Sarcoidosis

A weak relationship between HLA-B7 and

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 Human leukocyte antigen (HLA) B27 (subtypes B*2701-2759) is a class I surface antigen encoded by the B locus in the major histocompatibility complex (MHC) on chromosome 6 and presents antigenic peptides (derived from self and non-self antigens) to ...

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 The Centre hospitalier universitaire Sainte-Justine (CHU Sainte-Justine) is the largest mother and child centre in Canada and one of the four most important pediatric centres in North America. It is affiliated with the Université de Montréal, lo ...

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.https://ici.radio-canada.ca/nouvelle/1830925/covid-identification-rapide-patients-risque-maladie-grave/

References

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