Which disease is not typically associated with HLA-B27?

HLA-B27 is a specific human leukocyte antigen that is strongly associated with several autoimmune and inflammatory conditions, particularly those affecting the spine and joints. Each of the other conditions listed—reactive arthritis, ankylosing spondylitis, and anterior uveitis—have a well-established connection to HLA-B27 positivity.

In the case of psoriatic arthritis, while it can be associated with HLA-B27 in some patients, it is not nearly as strong or definitive as the associations seen with the other listed conditions. Psoriatic arthritis is more commonly linked to other genetic markers and is influenced by a wide range of factors including psoriasis, which does not have the same clear-cut relationship with HLA-B27.

Consequently, while HLA-B27 may appear in some cases of psoriatic arthritis, it is not considered a typical or dominant association, making this option stand out as the disease that does not fit with the others in terms of its strong association with the HLA-B27 antigen.