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Ankylosing Spondylitis, Rheumatologic Perspective

AS Rheumatologic Fact

  • Ankylosing spondylitis (AS) is a type of arthritis that causes inflammation of the spine and the sacroiliac joints (joints between the lowest end of the spine, the sacrum, and the pelvis).
  • The affected joints and ligaments become swollen and painful, leading to stiffness in the back and neck.
  • As the disease progresses, the vertebrae can fuse together, making the spine rigid and inflexible, eventually making the joints immovable.
  • Ankylosing spondylitis can also affect other joints away from the spine as well as cause inflammation of tendons and ligaments.
  • Ankylosing spondylitis affects a very small percentage of the population. It most commonly affects young males, but females can be affected. Females often experience a somewhat less severe form of the disease.
  • The usual age of onset is from the late teens to 40 years of age.
  • Some people with ankylosing spondylitis have onset of symptoms when younger than 16 years. This form of AS is referred to as juvenile-onset ankylosing spondylitis.

AS Rheumatologic Causes

A combination of genetic and environmental factors is believed to cause ankylosing spondylitis, but the exact cause is unknown. Studies have shown that most people with ankylosing spondylitis have the gene for HLA-B27. A person with the gene for HLA-B27 is not guaranteed to develop ankylosing spondylitis; however, having the gene increases the likelihood of developing ankylosing spondylitis. It is felt that in some people, infection of the intestines with certain bacteria (such as Klebsiella) may trigger an reaction to cause the joint inflammation in people with the gene for HLA-B27, eventually leading to the development of ankylosing spondylitis.

Medically Reviewed by a Doctor on 5/9/2016

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