Ankylosing spondylitis is a protracted inflammatory condition that can affect various joints of the body including the eyes and intestines, but most frequently it targets the spine. Doctors classify it as a variety of spinal arthritis to clearly distinguish it from common back injuries. It is also potentially much more harmful than common back problems because it may eventually impede the patient’s mobility and damage their eyesight. There is clear evidence that genetic factors influence which individuals develop this disease. Studies link it with the HLA-B27 gene. It usually first appears in the teenage years with males three times more likely to develop it than females.