Which of the following inflammatory condition has 90% association with HLA-B27?: (A) Ankylosing spondylitis, (B) Psoriasis, (C) Reiters, (D) Rheumatoid ahritis
Answer is A. 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