This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Joint disorders, Subject name: Orthopaedics
[{'content': 'Ankylosing spondylitis in associated with: \nSelect and explain. \nA. HLA-B27, B. HLA-B47, C. HLA-DW4/DR4, D. HLA-DR3', 'role': 'user'}, {'content': "Answer: A \nExplanation: SERONEGATIVE SPONDYLOAHROPATHIES Feature HLA B-27 positive/presence of uveitis Onset usually before 45 years age Inflammatory ahritis of spine/large peripheral joints Absence of autoantibodies (e.g. rheumatoid factor) in serum so known as seronegative -Other diseases associated with HLA-B27 positivity Mnemonic: PEARS (HLA-B27 Positive) P- Psoriatic ahritis E- Enteropathic ahritis A- Ankylosing spondylitis(>90%) R- Reiter's syndrome/ Reactive ahritis S- SAPHO Syndrome OTHER OPTIONS: HLA-DW4/DR4- A/W rheumatoid ahritis. HLA-DR3 - A/W Type 1 diabetes mellitus HLA-B47- A/W 21 hydroxylase deficiency", 'role': 'assistant'}]