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hla-b27

HLA-B27

introduction

  • Human Leukocyte Antigen (HLA) B27 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 T cells.
  • it is strongly associated with ankylosing spondylitis (AS) and other spondyloarthopathies.

prevalence of the gene

  • varies markedly in the general population.
  • 8% of Caucasians
  • 4% of North Africans,
  • 2-9% of Chinese
  • 0.1-0.5% of persons of Japanese

disease associations

  • 90% of people with ankylosing spondylitis (AS) are HLA-B27 positive, but only a fraction of people with HLA-B27 ever develop AS
  • 60% of people with spondylitis associated with inflammatory bowel disease (IBD)
  • 60% of people with psoriatic spondylitis
    • HLA-B27 is associated with the pustular form of psoriasis
    • the association of HLA-B27 in peripheral psoriatic arthritis is weak
    • in the presence of spondylitis associated with psoriasis, 60-70% of these cases are HLA-B27 positive
  • up to 50% of people who develop isolated anterior uveitis
    • 18-32% of all anterior uveitis cases in western countries and for 6-13% of all anterior uveitis cases in Asia
    • B27 positive patients tend to have 1st episode aged 20-40 years whereas B27 negative patients tend to be older at 1st presentation
  • 20-25% of people with Undifferentiated spondyloarthropathy (USpA)
hla-b27.txt · Last modified: 2013/10/10 14:55 (external edit)