High frequencies of HLA-B27 in Chinese patients with suspected of ankylosing spondylitis.

This study was performed to investigate the frequency of human leukocyte antigen (HLA)-B27 in Chinese patients with suspected of ankylosing spondylitis (AS) and to assess the clinical significance of HLA-B27 typing. A total of 1,016 patients suspected of AS were classified into six groups based on one major AS-related clinical manifestation. HLA-B27 was determined by polymerase chain reaction using sequence-specific primers. The frequency of B27 ranged between 24.3 and 46.7% among the patient groups, significantly higher than in healthy controls (2.4%). In the same group, the frequency of B27 in young (< or = 40 years) and in male patients was significantly higher than in the old and in female (P < 0.01). During a 1-year follow-up, 102 subjects were definitely diagnosed as AS, but only one B27(-) patient. Of the 102 definite patients, 69 (67.6%) definite patients were distributed in group 1 (low back pain and stiffness) with the higher incidence (28.5%) of AS. The incidence of AS in the same group was found with a similar pattern to the frequency of B27, in male and young patients significantly greater, except groups 4 and 6 (peripheral arthritis and alteration of skin). These findings confirm that HLA-B27 is one of sensitive diagnostic tools for early AS and suggest that there was a remarkable clinical significance of HLA-B27 typing in Chinese patients suspected of AS, particularly a young man who presents with low back pain and stiffness for > 3 months.