Which of the following is NOT linked to HLA-B27?

• A. Reactive Arthritis
• B. Rheumatoid Arthritis
• C. Psoriatic Arthritis
• D. Ankylosing Spondylitis

Answer: (B)

HLA-B27 is a genetic marker most strongly associated with seronegative spondyloarthropathies, including ankylosing spondylitis, reactive arthritis, and psoriatic arthritis. In these conditions, HLA-B27 positivity is common and helps explain the inflammatory pattern seen in the spine and joints, and it can be linked to ocular inflammation such as anterior uveitis in some patients. Rheumatoid arthritis, by contrast, is not linked to HLA-B27. Its genetic risk is more closely tied to other HLA alleles, particularly HLA-DRB1 with the shared epitope, and to autoantibodies like rheumatoid factor and anti-CCP. Therefore, rheumatoid arthritis is not associated with HLA-B27, making it the item that does not fit with the others.