Genetics factor play an important role in causing ankylosing spondylitis. Specifically, people who have the gene marker called SLA B27 are at increased risk of having ankylosing spondylitis. In addition, environmental risk factors have been shown to increase your risk of AS. One such theory states that an imbalance and dysregulation of the gut microbiome, which is a term used to describe the collection of millions of bacteria in our gut, can be a contributing factor in causing ankylosing spondylitis. A combination of genetic risk with the environmental triggers leads to the immune dysregulation and abnormal joint inflammation. Such inflammation leads to unusual extra bone formation which is a key features of this condition.