Ankylosing spondylitis is a form of arthritis affecting the spine. It is an inflammatory disease that over time causes vertebrae in your spine to fuse, become rigid & make the body bent forwards. One of the Human leukocyte antigens (HLA) present on the surface of lymphocytes (white blood cells) namely HLA-B27 is associated in 79% patients suffering from this disease. HLA-B27 is also seen in about 8% of normal population. It is also associated with certain eye disorders with arthritis like Reiter’s syndrome.