Causes
Experts are not sure what is responsible for ankylosis spondylitis, but they believe it is associated with the genes. Most people with this condition possess genes that produce a protein called HLA-B27. Doctors believe it sends a message to the immune systems to fight off some common bacteria in the body and increase the symptoms of AS.
Risk factors
Your sex
Men have a higher chance of developing ankylosing spondylitis than women. It affects men harder than women. Most women develop a mild version of ankylosing spondylitis known as non-radiographic axial spondylarthritis
Your heredity
In most cases, people who have ankylosing spondylitis have the HLA-B27 gene. However, so many people have this gene and never develop ankylosing spondylitis.
Your age
This condition begins in your teens and young adulthood. Over 80 percent of cases start before the age of 30 and 95 percent by age 45.