Ankylosing spondylitis
Ankylosing spondylitis (AS), also known as Morbus Bechterew or radiographic axial spondyloarthritis, is a chronic inflammatory disease that primarily affects the sacroiliac joints and spine. Progressive inflammation can lead to pain, stiffness, reduced mobility, and, in some patients, spinal fusion.
The genetic factor strongly associated with ankylosing spondylitis is HLA-B*27 (HLA-B27), a variant within the human leukocyte antigen (HLA) system. Approximately 60–90% of patients with axial spondyloarthritis carry HLA-B27, making it one of the strongest known genetic associations with a common human disease.
Importantly, HLA-B27 is a risk factor rather than a diagnostic marker. Many healthy individuals carry HLA-B27 and never develop ankylosing spondylitis.
Ankylosing spondylitis typically begins in early adulthood, often between the ages of 15 and 40 years. The most common symptoms include:
- Chronic inflammatory back pain
- Morning stiffness
- Improvement with exercise and activity
- Pain in the sacroiliac joints
- Reduced spinal mobility
- Fatigue
As the disease progresses, inflammation may lead to new bone formation and fusion of vertebrae (ankylosis), resulting in reduced flexibility of the spine.
AS is a systemic disease and may also affect tissues outside the musculoskeletal system. Common extra-articular manifestations include:
- Acute anterior uveitis (eye inflammation)
- Psoriasis
- Inflammatory bowel disease (Crohn’s disease or ulcerative colitis)
- Peripheral arthritis
These associated conditions reflect the shared immune mechanisms underlying the spondyloarthritis disease spectrum.
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