Which HLA type is most strongly associated with reactive arthritis?

• A. HLA-B27 positivity
• B. HLA-B7 positivity
• C. Rheumatoid factor positivity
• D. Anti-CCP positivity

Answer: (A)

Reactive arthritis is part of the seronegative spondyloarthropathies, and the strongest genetic association is with HLA-B27. This antigen is present at a much higher frequency in people who develop reactive arthritis after a GI or GU infection, and its presence can influence disease features and course, though it’s not required for diagnosis. HLA-B7 does not have a notable link to this condition. Rheumatoid factor and anti-CCP antibodies are typical markers of rheumatoid arthritis and are usually negative in reactive arthritis, reflecting the seronegative nature of this group.