A group of rheumatic diseases characterized by axial and/or peripheral arthritis and enthesitis (inflammation at the bony insertion of tendons and ligaments)
- Enthesitis-related arthritis
- Ankylosing spondylitis (AS)
- Psoriatic arthritis
- Inflammatory bowel disease–associated arthropathy
- Reactive arthritis
- Spondyloarthritis accounts for 15–20% of juvenile arthritis or more.
- Nonradiographic axial spondyloarthritis (male = female)
- AS typically affects adolescent boys (male-to-female ratio is 2 to 3:1).
Prevalence of AS mirrors that of HLA-B27 in a population
- European descent 8% HLA-B27+ and 0.5% AS
- HLA-B27 associated
- Risk of developing ERA with HLA-B27 is approximately 1–3%. Usually, there is a family history of a male relative with the disease.
- HLA-B27–positive with a family history of AS have a 10-fold increased risk of AS compared to HLA-B27–positive person with no family history.
- Inflammatory synovitis of joints and inflammation at sites of ligament and tendon attachment to bone (entheses).
- Progression to ankylosis is a result of calcification of the anterior and posterior longitudinal ligaments of the spine.
- Autoimmune or autoinflammatory arthritis of unknown etiology, likely multifactorial
- Microbiome may play a role in disease.
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