Ankylosing Spondylosis is a form of chronic inflammation of the spine and the sacroiliac (SI) joints. The SI joints are located in the low back at the junction of spine and hip. Chronic inflammation in these areas causes pain and stiffness in and around the spine. Over the period of time, chronic spinal inflammation (spondylitis) can lead to a complete cementing together (fusion) of the vertebrae, a process referred to as ankylosis. Ankylosis leads to loss of mobility of the spine. Ankylosing spondylitis is also a systemic rheumatic disease, meaning it can affect other tissues throughout the body. Accordingly, it can cause inflammation in or injury to other joints away from the spine, as well as other organs, such as the eyes, heart, lungs, and kidneys. Ankylosing spondylitis shares many features with several other arthritis conditions, such as Psoriatic Arthritis, Reactive Arthritis, and arthritis associated With Crohn's Disease and Ulcerative Colitis. Each of these arthritic conditions can cause disease and inflammation in the spine, other joints, eyes, skin, mouth, and various organs. In view of their similarities and tendency to cause inflammation of the spine, these conditions are collectively referred to as "Spondyloarthropathies." The tendency to develop ankylosing spondylitis is believed to be genetically inherited, and the majority (nearly 90%) of patients with ankylosing spondylitis is born with the HLA-B27 gene. Blood tests help to detect the HLA-B27 gene marker. The characteristics of the gene marker HLA-B27 are being further understood. There are now seven different subtypes of HLA-B27 known to be present.