Association of IL-1 gene complex members with ankylosing spondylitis in Chinese Han population

P>There are reports of IL-1 complex gene polymorphisms in ankylosing spondylitis (AS; MIM 106300), but the results have been inconsistent among populations. Moreover, few studies examine the association between IL-1 complex gene polymorphisms and clinical symptoms of AS patients. We investigated polymorphisms of IL-1 complex with AS in the Chinese Han population in this study. Chinese Han AS patients and ethnically matched healthy controls were genotyped for five single nucleotide polymorphisms (IL1 beta+3953, beta-511, F10.3, RN.4, RN.6/1) and the IL1RN.VNTR of IL-1 gene cluster. Allele, Genotype and haplotype frequencies were compared between cases and controls by SHEsis software. The frequency of allele C of the marker IL1F10.3 was significantly increased in AS patients versus controls [p = 0.001, odds ratio (OR) = 1.54, 95% confidence interval (CI) = 1.19-1.20; p = 0.002, respectively]. Strong linkage disequilibrium was identified between IL1B-511, IL1B+3953 and RN4 in both patients and healthy controls (D' > 0.95). Haplotypes of pairs of these markers (6) were also significantly associated with AS. The strongest associations observed was between allele combination B-511-T/B+3953-C/F10.3-C/RN4-T/RN2VNTR-1/RN6.1-C and AS (p = 3.32 x 10-5, OR = 4.41, 95% CI=2.1-9.3). Clinical manifestation showed week association between RN2VNTR A2 allele and risk of peripheral arthritis (OR = 0.2, 95% CI = 0.07-0.91). The IL-1 gene cluster is associated with AS in Chinese population. This finding provides strong statistical support for the previously observed relationship and indicates possible association between clinical manifestation and genetic factor.