Ankylosing spondylitis

HLA-B27

Ankylosing spondylitis is a chronic inflammatory disease of the spine. More than 90 percent of patients carry HLA-B27, a class I type. Conversely, only a small fraction of B27 carriers develop the disease, which is why the marker alone does not decide.

Why B27 stands out

Few diseases are so tightly bound to a single HLA allele. Discussed are a faulty folding of the B27 molecule, the presentation of certain peptides and interactions with the microbiome. The exact mechanism is not yet fully resolved.

Context

A positive B27 result raises the probability markedly but must be read in the context of symptoms, imaging and course. Many healthy people carry B27. Genome shows the type as technical evidence.

What Genome measures. Whether HLA-B27 is present in the HLA class I typing, as a strong risk and context marker.

Related topics

HLA and autoimmunityHLA typing

Sources

  1. 1Reveille, 2012 Genetics of spondyloarthritis beyond the MHC. Nature Reviews Rheumatology 8:296–304. doi.org/10.1038/nrrheum.2012.41
  2. 2Brown et al., 2016 Genetics of ankylosing spondylitis: insights into pathogenesis. Nature Reviews Rheumatology 12:81–91. doi.org/10.1038/nrrheum.2015.133