While the exact cause of AS remains unknown, genetic factors play a significant role in its development. Research has identified the human leukocyte antigen-B27 (HLA-B27) gene as a key genetic marker associated with AS. However, it is important to note that not all individuals with the HLA-B27 gene will develop the condition, and conversely, some individuals without the gene may still experience AS. This suggests that other genes and environmental factors contribute to the manifestation of the disease, adding to its complexity.