Comparison of clinical features in HLA-B27 positive and negative patients with ankylosing spondylitis.

The clinical features of ankylosing spondylitis (AS) were compared in 63 HLA-B 27 positive (+) and 15 B27 negative (-) individuals with this disease. There were no differences in age at onset, functional class, degree of deformity, pain, severity of X-ray changes, or frequency of peripheral joint involvement or of reconstructive orthopedic surgery. These data demonstrated that skeletal manifestations of AS were essentially the same in B27(+) and (-) patients, and provide no evidence for the speculation that AS in B27(-) patients is milder or is a different disease from that occurring in B27(+) patients. On the other hand, acute anterior uveitis was found to be significantly more common in B27(+) patients, a fact suggesting that the "uveitis of AS" may in fact be an independent condition occurring in B27(+) individuals, rather than a manifestation of AS per se.