Enthesitis-related arthritis (ERA) is classified according to the International League of Associations for Rheumatology (ILAR) criteria in the JIA subgroup as arthritis and enthesitis lasting longer than 6 weeks in children under the age of 16, or arthritis or enthesitis plus two of the following: tenderness of the sacroiliac joint or inflammatory back pain, the
HLA-B27 positivity, the onset of arthritis in boys older than 6, anterior uveitis, and a family history of ankylosing spondylitis (AS), ERA, sacroiliitis with inflammatory bowel disease (IBD), or anterior uveitis in at least one first-degree relative (1).
AS has no known cause, but the presence of a certain gene,
HLA-B27, increases the risk.
People who have the
HLA-B27 gene are at greatly increased risk of developing the disease.
It is based on sacroillitis on X-ray or MRI plus SPA features or
HLA-B27.
(4,5,6) The diagnosis of HLA-B27-associated AAU is based on clinical findings and positive
HLA-B27 antigen test after ruling out other infectious or inflammatory diseases.
Around ninety percent of individuals with AS have a genetic marker called
HLA-B27. This gene, however, does not need to be positive to have AS.
Most people with AS have a gene called
HLA-B27. In most cases, the gene is ruled out as an absolute cause of Ankylosing Spondylitis, but it contributes to it.
If a person is seronegative, one marker for rheumatoid arthritis is
HLA-B27, a protein found in white blood cells that contributes to immune function disruption.
The authors discovered a new gene on chromosome 5 specific for PsA and not for psoriasis, in addition to the well-known
HLA-B27 gene, another PsA-specific gene.
HLA-B27 and psoriatic disease: a modern view of an old relationship.
SpAs are a group of disorders characterized by positive Human Leukocyte Antigene-B27 (
HLA-B27) and inflammation of the axial skeleton or peripheral joints.