The Association Between Genes and SpA in Asian

Spondyloarthritis is a family of chronic arthritis, characterized by inflammatory back pain, peripheral arthritis and enthesitis. The relationship between HLA-B27 and AS was found by a British investigator in 1973, which considerably differentiated this disease from rheumatoid arthritis. Obviously, the prevalence of ankylosing spondylitis (AS) is correlated with the B27 positive rate in general population. In the Asian countries, the B27 antigen frequency in Vietnamese, Thais, Malaysians and Indonesians ranged from 5% to 12%, which is close to or higher than in the Chinese population. In contrast, lower prevalence of HLA-B27 was found in Japanese (<1%) and Polynesians, including Taiwan aborigines (<2%). Although the B2705 and B2704 are the major subtypes in Asian people, the relationship between the prevalence of these subtypes and AS in Asians has not been demonstrated. Until now, only B2706 was considered as a “protective gene” for AS in Thai people. In addition to B27, a study of 41 B27-negative Taiwanese (Han Chinese) AS patients showed both B60 and B61 significantly increased susceptibility to AS in HLA-B27 negative patients. Also, IL1 gene cluster (IL1F10.3, IL1RN VNTR, etc) was associated with AS in Chinese. The recent study in both psoriasis (PSO) and psoriatic arthritis (PSA) in Taiwanese demonstrated HLA-B27 was significantly higher in PSA and HLA-A30, -CW6, DR7 in PSO compared with healthy control. Besides, PSO patients with the HLA-B27 and/or -CW12 have higher risk to become PSA. For USpA, the B27 frequency was 64.3% in Chinese USpA patients and 78% in Korean patients. Our group showed B27, DR12 and B60 were significantly increased in USpA patients than in control.