HLA-B27 Subtypes in Korean Patients with Ankylosing Spondylitis

Park, Kyung Sun; Kang, So Young; Lee, Woo In

Abstract

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%).