Demographic, clinical, disease activity (Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP)), and radiographic data (Bath Ankylosing Spondylitis Radiology Index (BASRI) score) were compared regarding HLA-B27 status. The gene discussed is CRP; the disease is spondylitis.