The causes of ankylosing spondylitis are currently considered to be the following three factors: 1, genetic factors, ankylosing spondylitis has a significant family gathering phenomenon, related to genetics. The main reason is that the family carries the human leukocyte antigen B27, and if you go to the hospital and have a positive blood test for B27, you are prone to ankylosing spondylitis. 2. Infectious factors, which are inflammatory infections in other parts of the body, can trigger ankylosing spondylitis, such as inflammation of the urinary tract, inflammation of the digestive tract, inflammation of the reproductive tract, i.e., the usual urethritis, enteritis, cervicitis, etc., can trigger ankylosing spondylitis.