What is Ankylosing Spondylitis?
Ankylosing spondylitis (AS) is a type of inflammatory arthritis that primarily affects the spine or back. In AS, the joints and ligaments along the spine become inflamed. The inflammation produces pain and stiffness that usually begins in the lower back or buttocks, and may progress into the upper spine, chest and neck. Over time, the joints and bones (vertebrae) may grow together (fuse), causing the spine to become rigid and inflexible. Other joints, such as the hips, shoulders and knees may also be affected. AS is a systemic disease, which means it may affect organs.
Ankylosing Spondylitis Causes
The cause of ankylosing spondylitis is unknown, but genes and heredity play an important role. Scientists have discovered a gene called HLA-B27 that is found in about 90 percent of Caucasians with AS but only 8 percent of Caucasians without AS, suggesting this gene plays an important role in disease development. Some evidence suggests that AS may be triggered by an infection. Studies have focused on several bacteria that may influence the development of AS.
Who’s Affected by Ankylosing Spondylitis?
Nearly half a million people in the United States are affected by AS. The disease is more common in men than in women. Ankylosing spondylitis may develop in childhood, and boys are more likely to have it than girls. When children develop ankylosing spondylitis, symptoms usually begin in the hips, knees or heels and later progress to the spine. This disease occurs more often in Caucasians, Asian and Hispanic populations.