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Ankylosing Spondylitis Causes

The cause of ankylosing spondilitis as with all autoimmune diseases is unknown, but genetic factors seem to play a role. The disease starts with intermittent hip and/or lower-back pain that is worse at night, in the morning, or after inactivity. While the cause is unknown doctors have noticed that some things can trigger it.

Back pain begins in the sacroiliac joint (between the pelvis and the spine) and may progress to include the lumbosacral spine and the thoracic spine (chest portion of the spine).

Pain may be eased by assuming a bent posture. Limited expansion of the chest occurs because of the involvement of the joints between the ribs. The symptoms may worsen, go into remission, or stop at any stage.

Ankylosing spondylitis is a progressive disease and once developed it will lead to deterioration of bone and cartilage can lead to fusion in the spine or peripheral joints, affecting mobility. It can be extremely painful and crippling. The heart, the lungs, and the eyes may also become affected.


The disease most frequently begins between age 20 and 40, but may begin before age 10. It affects more males than females. Risk factors include a family history of ankylosing spondylitis and male gender. About 0.21% of Americans over age 15 are affected.

Ankylosing Spondylitis Causes - Infections

Ankylosing spondylitis may be triggered by certain types of bacterial or viral infections that activate an immune response that does not shut off after the infection is healed. The immune system then attacks the body's own tissue. A disorder caused by the body's own immune system is called an autoimmune disease.

Ankylosing Spondylitis Causes - Genetic markers

Genetic markers are protein molecules found on the surfaces of cells. The HLA markers enable the body's immune system to distinguish between "self" and "other."

  • About 95% of people who have ankylosing spondylitis also have a genetic marker known as human leukocyte antigen-B27 (HLA-B27).
  • About eight people in 100 among American Caucasians are born with the HLA-B27 gene. The gene is much less common among African Americans.

Modified 6-10-2013 Information compiled from the National Institutes of Health






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Arthritis can develop as a result of an infection. For example, bacteria that cause gonorrhea or Lyme disease can cause arthritis. Infectious arthritis can cause serious damage, but usually clears up completely with antibiotics. Scleroderma is a systemic disease that involves the skin, but may include problems with blood vessels, joints, and internal organs. Fibromyalgia syndrome is soft-tissue rheumatism that doesn't lead to joint deformity, but affects an estimated 5 million Americans, mostly women. The approximate number of cases in the United States of some common forms of arthritis. is an informational out reach of the Consumer Health Information Network. It is our goal to provide up to date information about arthritis and other inflammatory and bone conditions in a easy to understand format.

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