This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Which of the following is having a 90% associated with HLA B27 
Select and explain. 
A. Ankylosing spondylitis, B. Rheumatoid ahritis, C. Psoriasis, D. Reiter's syndrome
A: Ankylosing spondylitis
Answer: A: Ankylosing spondylitis 
Explanation: Ref Robbins 9/e p205 A positive result meansHLA-B27 was found in your blood. You may have a higher-than-average risk of ceain autoimmune diseases, such as ankylosing spondylitis and reactive ahritis.