Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Ankylosing Spondylitis ?
    ### Response:
    Ankylosing spondylitis is a type of arthritis of the spine. It causes inflammation between your vertebrae, which are the bones that make up your spine, and in the joints between your spine and pelvis. In some people, it can affect other joints.    AS is more common and more severe in men.
    