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What is Ankylosing Spondylitis? Explanation & Causes

November 3, 2017

Ankylosing spondylitis, or AS, is a form of chronic inflammatory arthritis affecting the back or spine. For some patients, the condition starts between the teens and 30s. Ankylosing spondylitis is characterized by pain and stiffness in the lower back as the joints and ligaments within the spine become inflamed.

Who’s Affected by Ankylosing Spondylitis?

Ankylosing spondylitis forms during teen or young adult years. Most patients with the disease began having symptoms before age 30 and it affects patients for the rest of their lives. About twice as many men as women are diagnosed with ankylosing spondylitis.


The cause of AS is unknown. It’s likely that genes (passed from parents to children) and the environment both play a role in a patient developing an AS diagnosis. Scientists have discovered a gene called HLA-B27 that is found in about 90 percent of Caucasian patients with AS but only 8 percent of Caucasian patients without AS, suggesting a genetic link.


In some cases, it develops so gradually that you may not notice it. The symptoms may come and go, and improve or get worse, over many years. If you've had consistent low back pain for more than three months, talk to your doctor. Symptoms of ankylosing spondylitis include:
  • Neck pain
  • Stiffness that is worse in the morning
  • A reduction in pain and stiffness with physical activity
  • Fatigue
  • A hunched posture
  • Difficulty taking a deep breath (if the disease has affected the ribs)

Long-Term Effects


Ankylosing Spondylitis can also create inflammation in your joints (arthritis). These symptoms include:
  • Pain when moving the affected joint
  • Joint tenderness during an examination
  • Swelling and warmth in the affected area


Fatigue is a common symptom of untreated AS. It can make you feel tired and lacking in energy.

Additional Warnings

Smokers who have ankylosing spondylitis (AS) have more spinal damage than non-smokers with the same level of disease activity. Having the disease is also linked to an increased risk of heart disease and stroke.

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