Ankylosing spondylitis (AS) is an autoimmune disease which affects collagen structures, specifically the joints between the vertebrae of the spine. The joints and ligaments that normally permit the spine to move become inflamed and stiff. The bones of the spine may grow together, causing the spine to become rigid and inflexible. Other joints such as the hips, shoulders, knees, or ankles also may become involved. Symptoms of ankylosing spondylitis appear most frequently in young men between the ages of 16 and 35. It is less common in women, whose symptoms are often milder and more difficult to diagnose. About 5% of ankylosing spondylitis cases begin in childhood; boys are more likely to have it than girls. When children develop ankylosing spondylitis, it usually begins in the hips, knees, bottoms of the heels or big toes and may later progress to involve the spine.

The gene is present in 8% of white Americans and 2-3% of African Americans. About 1% of the adult population has this condition and, as expected, the disease is three times more common in whites than in African Americans.

Heredity seems to play a role in determining who if affected: approximately one in five sufferers have a relative with the same disorder. A gene called HLA-B27 that is present in over 90% of people with ankylosing spondylitis; of those who inherit the gene, 10-15% will fall victim to the condition.

Almost all sufferers can expect to lead normal and productive lives. Despite the chronic nature of the illness, only a few people will become severely disabled; the management of pain and the control of inflammation can reduce the daily problems that may occur. By watching posture and body position and by doing exercises daily, an individual can control many of the effects of the disease.

In extreme cases, the inflammation can cause the sacroiliac and vertebral bones to fuse or grow together. When this occurs, the normal flexibility of the spine, including the neck, is lost and the whole spine becomes rigid. Similarly, the bones in the chest may fuse, causing a loss of normal chest expansion when breathing. The hips, shoulders, knees, or ankles also may become inflamed and painful and eventually lose their mobility. The heels may become affected, making it uncomfortable to stand or walk on hard surfaces.

Ankylosing spondylitis is a systemic disease, meaning it can affect the entire body in some people. It can cause fever, loss of appetite, and fatigue, and it can damage other organs besides the joints, such as the lungs, heart and eyes. Inflammation can occur where the heart and aorta connect leading to possible enlargement of the aorta. Most often, however, only the lower back is involved.

Doctors usually base their diagnosis on symptoms and X-rays showing inflammation of the sacroiliac joints at the back of the pelvis. If symptoms or X-rays suggest ankylosing spondylitis but the diagnosis is uncertain, your doctor may perform a blood test to check for the HLA-B27 gene.

Although Reiter's Syndrome is not mentioned on Ebringer's site, it is his opinion that, after a couple of years, RS becomes AS, as the same mechanism is involved.