Ankylosing spondylitis is an arthritis that causes inflammation in some parts of the spine. Ankylosing means rigid or stiff. Spondyl means spine, and itis means inflammation. The disease causes inflammation in the spine that results in stiffness and pain. It may damage the joint between the hip bone and spine, called the sacroiliac joint. It may also form bony bridges between vertebrae in the spine, fusing the bones. Additionally, the bones in the chest may also fuse.
Almost 95% of people with AS have a human leukocyte antigen-B gene (HLA-B) variation. It is either a changed or mutated gene that produces a protein called HLA-B27. It increases the risk of disease. Most people with a mutated HLA-B gene do not get AS.
Having one of the conditions may also increase the risk of-
The signs of Ankylosing spondylitis typically appear between 17 and 45, commonly in younger children and older adults. The pain usually starts in the lower back and goes on and off.
Some people have constant pain, while others experience milder symptoms like-