What is ankylosing spondylitis (AS)?
Ankylosing spondylitis (AS) is a condition that mainly affects the spine. The joints of the neck, back and pelvis become inflamed, causing pain and stiffness. The sacroiliac joints are commonly affected in AS. These joints connect the base of your spine (sacrum) to your pelvis. Other joints, such as the hips and shoulders, can also be involved. AS can also affect other parts of the body, such as the eyes, skin, bowel and lungs. The symptoms of AS usually begin between the ages of 15 and 45 years.
What are the symptoms?
The symptoms of AS vary from person to person. The most common are: • pain and stiffness in the back, buttocks or neck • symptoms worse after rest (for example, in the early morning) and relieved with exercise • pain in tendons (which connect muscles to bones) and ligaments (which connect bones to each other), often felt as pain at the front of the chest, back of the heel or underneath the foot.
What causes it?
It is not known what causes AS. Unlike other types of back pain, AS isn’t caused by particular jobs, activities or injuries. You are more likely to get AS if you have a history of it in your family. There is a gene called HLA-B27 that is associated with AS. Almost nine out of ten people with AS test positive for this gene. However HLA-B27 is present in 8% of the general population, including healthy people without AS. Recently, two new genes (IL23R and ARTS1) have also been found to be associated with ankylosing spondylitis.
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