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No specific autoantibody, but strongly associated with:
HLA-B27 gene (a genetic marker)
Inflammation markers (CRP, ESR) may be elevated
Spine and sacroiliac joints
May affect eyes, hips, ribs, and shoulders
Ankylosing Spondylitis (AS) is a chronic autoimmune inflammatory arthritis that primarily affects the spine and sacroiliac joints (where the spine meets the pelvis). Over time, AS can cause the vertebrae to fuse together, resulting in a rigid or curved spine, known as “bamboo spine.”
The disease can also affect other joints, eyes, and organs, and symptoms tend to appear in young adults, especially men under 40.
Chronic lower back pain, especially in the early morning or after rest
Stiffness in the hips, pelvis, or lower spine
Pain improves with movement, not with rest
Reduced flexibility in the spine
Fatigue
Inflammation in the eyes (uveitis) – causing redness, pain, or blurred vision
Pain in shoulders, ribs, knees, or feet (enthesitis – inflammation where tendons attach to bones)
AS is an autoimmune disease. The exact cause is unknown, but it’s strongly linked to:
Genetics, especially the HLA-B27 gene
Possibly triggered by infections or gut microbiome imbalance
Immune system mistakenly attacks the joints and entheses (attachment points of ligaments/tendons)
Diagnosis is based on:
Medical history and physical exam
X-rays or MRI scans to detect inflammation or spinal fusion
HLA-B27 genetic test (positive in 80–90% of AS cases)
Blood tests – may show elevated ESR or CRP (inflammation markers)
There is no cure, but treatment helps reduce symptoms and slow progression:
NSAIDs (e.g., naproxen, indomethacin) – first-line treatment
Biologic therapies – TNF inhibitors (e.g., adalimumab) or IL-17 blockers (e.g., secukinumab)
Physical therapy – to maintain posture and flexibility
Exercise and posture training
Surgery (rare, for severe joint damage or spinal deformity)
Symptoms may worsen slowly over time
With early diagnosis and proper treatment, many people maintain good mobility
Severe cases may lead to spinal fusion, breathing restriction, or loss of mobility
Eye inflammation, heart problems, or GI issues may develop in some people
Affects approximately 0.1% to 1.4% of the U.S. population
Most common in young men between ages 15 and 40
More common in people with HLA-B27 gene, especially those of Northern European descent
Spondylitis Association of America. (2023). What is Ankylosing Spondylitis?
https://www.spondylitis.org/about-spondyloarthritis/ankylosing-spondylitis/
Mayo Clinic. (2023). Ankylosing Spondylitis.
https://www.mayoclinic.org/diseases-conditions/ankylosing-spondylitis
Braun, J., & Sieper, J. (2007). Ankylosing spondylitis. The Lancet, 369(9570), 1379–1390.
https://doi.org/10.1016/S0140-6736(07)60635-7
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