Background In western countries, prevalence of HLA-B27 antigen is highly associated with ankylosing spondylitis (AS) (1). Recent study pointed out the prevalence of HLA-B27 antigens in geographically adjacent regions may vary (2). In Tokyo area, it has been reported that HLA-B27 prevalence of Japanese patients with AS was 83% (3). However, HLA-B27 prevalence of patients with AS in some areas outside of Tokyo is perceived to be lower than that of Tokyo, but the prevalence is unknown.
Objectives To compare the prevalence of the HLA-B locus in geographically adjacent Japanese patients with AS and to assess the clinical symptoms.
Methods In this retrospective study, patients with spondylarthritis in the Shinonoi General Hospital, Nagano Prefecture were diagnosed as having AS based upon the modified New York diagnostic criteria. The HLA-B locus was assessed with the polymerase chain reaction using sequence specific primers. Peripheral arthritis was determined by physical examination; the Mander Enthesis Index (MEI) was used for assessing enthesitis. Familial records of spondylarthritis/rheumatic disease were also obtained. X-ray was used to assess sacroiliac arthritis, bamboo spine and syndesmophytes. The HLA-B locus for 492 healthy people was obtained from the Central Bone Marrow Data Center (4). Chi-square test was used for statistical comparisons.
Results A total of 148 patients with AS were included in the study (54 males and 94 females). The HLA-B loci were positive for B7 (15 patients), B13 (2), B27 (2), B35 (23), B39 (19), B44 (25), B46 (14), B51 (25), B52 (38), B54 (16), B59 (8), B60 (13), B61 (2), and B62 (23). Compared with the healthy population, the prevalences of HLA-B35, B39, B 44, B 46, B 51, B 52, B 61, and B 62 were high (p<0.05). However, HLA-B7, B13, B27, B54, and B60 were not different from healthy subjects and HLA-B39, B51, and B52 exhibited lower probabilities of occurrence. The clinical symptoms of patients with AS were 94.6% MEI positive, 47.3% had peripheral arthritis, 10.8% had bamboo spine, and 16.2% exhibited syndesmophytes. Comorbidity was present in 11.5% for SAPHO syndrome, 2.7% for uveitis, and 2.0% for inflammatory bowel disease. Familial history was present in 6.1% for spondylarthritis, and 10.8% for rheumatic disease.
Conclusions The prevalence of HLA-B27 positive patients among patients with AS in the province was extremely low compared with that of western countries and was similar to the healthy Japanese population. However, the prevalence was low compared with that of the Tokyo area; with a separating distance of approximately 170 kilometers. However, the prevalences of HLA-B39, B51, and B52 were higher than those of the healthy population, suggesting that the results present unique features of Japanese patients with AS.
John D. et al, Curr Opin Rheumatol 2001; 13:265–272.
Merashli M. et al, Ann Rheum Dis 2013; 72(Suppl 3):957.
Yamaguchi A, et al, Arthritis Rheum 1995; 38(11):1672-1677.
Tanaka H, et al, Clin Transplant 1996; 139-144.
Disclosure of Interest : None declared