Background: HLA-B27 is strongly associated with ankylosing spondylitis (AS), and its subtypes differ in their ethnic distribution. Studies worldwide have shown that B*2701, B*2702, B*2704, B*2705, B*2707, B*2708, B*2714, B*2715, and B*2719 are AS-predisposing subtypes, whereas B*2706 and B*2709 are reported to be negatively associated with AS. The aim of this study was to investigate HLA-B27 polymorphism and clinical features according to subtypes in Korean patients with AS.
Methods: Two hundred thirty samples from patients with impression of AS were analyzed by polymerase chain reaction using a sequence-specific primers (PCR-SSP) method. Pel-Freez SSP Unitray HLA-B*27 kit (Dynal Biotech, USA) including 16 primers was used to define HLA-B27 subtypes from B*2701 to B*2735.
Results: Among 230 samples from patients with impression of AS, 171 were HLA-B27 positive, and among 160 patients diagnosed as AS, 154 (96.3%) were HLA-B27 positive, while 17 patients not diagnosed as AS were HLA-B27 positive. Among 154 HLA-B27 positive patients with AS, 142 (92.2%) were typed as B*2705 and 9 (5.8%) were typed as B*2704. Three cases (1.9%) could be interpreted only variously because of their HLA-B27 homogeneous alleles. Between B*2705 and B*2704, no specific HLA-B27 subtype appeared to contribute to AS susceptibility (P=0.60). Difference in clinical features between B*2705 and B*2704 could not be found in this study (P>0.05).
Conclusions: This study verified that HLA-B27 (96.3%) is strongly associated with AS and identified that the major subtypes of HLA-B27 positive patients with AS in Korea are B*2705 (92.2%) and B*2704 (5.8%).