It is a chronic inflammatory connective tissue disease that affects the axial skeleton and central joints including the TMJ. It is also called as Marie strumpell disease and rheumatic spondylitis. The disease is more common in men and often run in families. It is mostly diagnosed in late adolescence or early adulthood. Over time, it fuses vertebrae together by limiting movement.
The cause is usually unknown and it occurs due to a combination of genetic and environmental factors. It is believed to be due to this specific antigen known as HLA-B27. Tumor necrosis factor -alpha and IL-1 is also implicated in this disease.