Ankylosing Spondylitis Definition

Arthritis can affect any joint in the body. Ankylosing spondylitis is a type of arthritis that targets the spine. The joints and ligaments that normally function to mobilize the vertebrae become inflamed and can produce significant pain and stiffness.

Although it is most commonly found in young men aged 15 to 30, ankylosing spondylitis has been diagnosed in women and children. Nearly all patients diagnosed with ankylosing spondylitis carry an identical copy of the gene HLA-B27. The gene is a marker for susceptibility to developing AS, but not all individuals with a positive test for HLA-B27 develop AS.

The condition is characterized by a posture that is curved forward, brittle vertebrae prone to fracture, and although most cases are mild it can lead to permanent disability and immobility. Early diagnosis and treatment are critical, as ankylosing spondylitis is a progressive type of arthritis that can cause fusion of spinal segments.