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Thread: HLA-B27 : distribution map and associated medical conditions

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    1 out of 1 members found this post helpful.

    Post HLA-B27 : distribution map and associated medical conditions

    Here is a map showing the allele frequency of HLA-B27. The maximum frequencies are observed among the Saami (20% in northern Sweden, 15% in Norway), then in the rest of Fennoscandia, in Belgium, England and Scotland.

    HLA-B27 is the most routinely tested HLA types by doctors because carrying this allele greatly increases the risk of developing ankylosing spondylitis (AS), and other associated inflammatory diseases referred to as "spondyloarthropathies". About 12% of B27 carriers will develop this debilitating autoimmune disease of the lower axial spine and nearby joints. The onset of the disease is typically between 15 and 25 years old and there is no cure at present.

    You can check if you carry the allele for HLA-B27 if you tested your genome with 23andMe, Geno 2.0 or FamilyFinder. The SNP for HLA-B*27:05, the most common variant in Europe, is rs6919835 (the A allele means carrier). I have checked ancient genomes from Haak et al 2015, and only one sample (Neolithic Spain) was positive for B27.

    Last edited by Maciamo; 21-04-15 at 18:41.
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    Thank You very much

    I was checked positive for this allele after some unexplained back pain. My doctor told me that this gene is common in northern population.
    My ancestry is from Erzrum ( today Turkey ) they came to Eastern Armenia before 1915.

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    1 out of 1 members found this post helpful.
    Thank you for this! I tested postive for HLA-B27 first while registering for the marrow donor list through a non-genetic antigen test, and then later, with a medical genetic test which confirmed my commercial SNP array test results.

    I am rs6919835=GG and therefore rs6919835=A does not mean the person is positive for HLA-B27.

    Commonly tested HLA-B27 tag SNPs are:
    rs13202464=G
    rs4349859=A


    Of all the ancient DNA samples in Gedmatch, only Ajvide58 (Gedmatch ID F99924) from the Pitted Ware Culture of the Scandinavian Hunter-Gatherers, c. 5000 years ago, appears to carry HLA-B27.

    Ajvide58 is likley to carry the specific HLA-B*27:0502 allele, which is the subtype common among the Saami and Northern Europeans in general.

    A roundabout way of imputing whether someone carries HLA-B27 (or perhaps the Northern European HLA-B*27:0502) is to see if they are a match (especially a phased match) of F999924 Ajvide58 at approximately the following region. (Use 50 SNPs and 1 cM for the one-to-one matching parameters in Gedmatch):
    6 27,833,481 32,703,038 1.4 245

    Both 23andMe and DNA.land "paint" this segment as "Finnish" and a person who carries HLA-B27:05 may come out as "4% Finnish" in their ancestry estimates.

    HLA-B27 is particularly common among Native Americans from North America. (However, Clovis Anzick-1 and Kennewick Man didn't carry it.)

    Various subtypes of HLA-B27 have different risks for HLA-B27 Syndromes, including Ankylosing Spondylitis. HLA-B*27:09, found in Sardinia, and HLA-B*27:06 common in Southeast Asia, do not carry a risk for HLA-B27 syndromes.

    In Europe, HLA-B*27:02 is common among Mediterranean populations (outside of Sardinia). HLA-B*27:04 is common among Chinese, East Asian, and Native American populations.

    Along with the other common HLA-B*27 alleles worldwide, the most common HLA-B*27:05 (Northern Europe), HLA-B*27:02 (the Mediterreanean) HLA-B*27:04 (East Asia and Native Americans) are associated with HLA-B27 Syndromes and disease risks.

    The risk for HLA-B27 Syndromes is not greater for homozygous individuals than carriers of a single allele.

    More info about HLA-B27:

    SNPedia: HLA-B27
    snpedia .com/index.php/HLA-B27#Commonly_tested:

    Medscape: HLA-B27 Syndromes
    emedicine.medscape .com/article/1201027-overview

    HLA-B27: The Facts
    hlab27 .com/hlab27.aspx

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    There are also studies regarding a protective role in AIDS/HIV:
    HLA-B27 is known for its strong association with inflammatory spondyloarthropathies (SpA), a group of rheumatic diseases. Apart from playing its role in the onset of these inflammatory diseases, HLA-827 is so ubiquitous in the world that the carrying of this gene must have also have an advantage. There are some indications that a beneficial effect can be found as a less severe course of viral infections among B27-carriers. The literature on this subject was reviewed and revealed a favorable course of infection with influenza virus, herpes simplex type 2 virus, Epstein-Barr virus and, even more interesting, a protective effect of HLA-B27 in the progression of HIV infections. The course of HIV infection differs among individuals and is thought to be partly related to host-factor variability, reflecting broad genetic heterogeneity. The polymorphic human leukocyte antigens (HLA) are herein analyzed intensively with respect to this relationship. Cytotoxic T lymphocyte (CTL) responses, activated by HLA antigen presentation, are implicated in the control of HIV replication. An immunological explanation for the protective role for HLA B27 in HIV disease is that B27+ patients have a specific and strong CTL response against the p24 epitope, a conservative HIV protein that does not easily mutate. Some HLA genes seen in long-term non-progressors (LTNP) (>10 years disease free) are associated with a favorable prognosis. One of the alleles found predominantly in LTNPs is HLA-B27. More genetic factors seem to influence disease progression in HIV infections. Therefore, it would be interesting to further explore the influence of the genetic make up of these HIV-infected individuals. Knowledge of the immunogenetic profile might give clues for the individual course of the HIV infection, may influence the development of drug-resistant viruses and will possibly lead to a tailored therapeutic strategy in HIV-infected persons.

    More: https://www.ncbi.nlm.nih.gov/pubmed/15332431

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    Very interesting. In terms of medical conditions associated:
    Here is a study regarding the protective role of HLA-B27 and hepatitis C as well as HIV:

    https://www.ncbi.nlm.nih.gov/pubmed/21302207

    The human leukocyte antigen (HLA) B27 has been linked to rheumatic diseases such as ankylosing spondylitis nearly 40 years ago, but its role in pathogenesis remains unclear. Apart from this association, HLA-B27 has a positive effect in two of the most threatening human viral infections: in HIV infection, HLA-B27 positive patients have low viral loads, CD4+ T cell counts decline slowly and AIDS progresses slowly. In acute hepatitis C virus (HCV) infection, HLA-B27 is associated with a very high rate of spontaneous viral clearance. The mechanisms of protection by HLA-B27 in HIV and HCV infection have been characterized in the recent years and will be discussed in this article.

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