<qa>  What is the first time x-rays will be taken of the pelvis, lowerThose enrolled in the study will return to the NIH Clinical Center at 6, 12, 18, 24, 30, 36, 42, 48, 54, and 60 months after screening for examination of the joints, measurement of flexibility of the spine, and a blood test. They will also complete symptoms assessment and coping questionnaires. At the first study visit screening visit, x-rays will be taken of the pelvis, lower back, and neck, if recent X-rays within 1 year are not available. These x-ray studies will be repeated on all patients every two years during the study at 24 and 48 months after screening. 