Ankylosing Spondylitis (AS) Explained
What is Ankylosing Spondylitis?
AS is a chronic inflammatory disorder that can often be progressive. AS involves pain and inflammation primarily of the spine and sacroiliac joints (area where your spine meets your pelvis).
What are the symptoms of AS?
AS has a wide range of symptoms. While patients may not have all of these symptoms, the most common include:
- Lower back pain that is worse after you have slept or been inactive
- Pain and stiffness in your hips
- Joint pain and inflammation in your shoulders and knees
- Limited range of motion in your spine and hips
- Restricted expansion of your chest
- Neck pain
According to a 2002 survey by the Spondylitis Association of America, over 60% of AS patients say they have difficulty walking, getting into a car, or sleeping.
Who gets AS?
AS affects between 150,000 and 300,000 Canadians (as many as 1 in 100). AS is 3 times more common in men than women. AS typically affects young people, with symptoms usually beginning between the ages of 15 and 40. Onset after age 40 is uncommon.
What causes AS?
The cause of AS is unknown, but as genetic studies continue, researchers believe that the gene for Human Leukocyte Antigen B27 (HLA-B27) may be a significant factor. It is thought that HLA-B27 interacts with other proteins, altering the body's normal immune response.
HLA-B27 does not cause AS, but it is present in 90-95% of people who suffer from AS. However, just having the gene does not mean you will definitely get AS. Fewer than 25% of people with the HLA-B27 gene develop AS. For this reason, other factors besides HLA-B27 are thought to predispose you to AS. These may be genetic, environmental, and possibly even bacterial.
