<prompt> Which of the following inflammatory condition has 90 association with HLA-B27?Ankylosing spondylitisPsoriasisReitersRheumatoid ahritis  <response>: Ankylosing spondylitis AS is defined by the presence of sacroiliitis on X-ray and other structural changes on spine X-rays, which may eventually progress to bony fusion of the spine. There is a male-to-female ratio of about 3 : 1. In Europe, more than 90 of those affected are HLA-B27-positive Caucasian HLA-B27 population prevalence is 9. The overall prevalence of AS is below 0.5 in most populations. Over 75 of patients are able to remain in employment and enjoy a good quality of life. Even if severe ankylosis develops, functional limitation may not be marked, as long as the spine is fused in an erect posture. Ref Davidsons 23e p1030 