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The signs and symptoms of ankylosing spondylitis often appear gradually, with peak onset being between 20 and 30 years of age. Initial symptoms are usually a chronic dull pain in the lower back or gluteal region combined with stiffness of the lower back.
Low back pain is the first symptom in more than 75% of patients. In some patients, the symptoms are more in the buttock. Over time, the patient experiences limited spinal mobility. One of the keys to the diagnosis of ankylosing spondylitis is identifying features of inflammatory low back pain.