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What is the percentage of patients with ankylosing spondylitis who have HLA-B27 negative blood testing?
Ankylosing spondylitis is strongly associated with the HLA-B27 gene. Testing is positive in over 90% of Caucasians. A negative test could be found in approximately 10% of Caucasian patients with the disease. The relationship is less strong in Blacks with only 50% of patients having a positive test.