Association Study of IL-12B Polymorphisms Susceptibility with Ankylosing Spondylitis in Mainland Han Population

OBJECTIVE This study aims to determine whether the genetic polymorphisms of IL-12B gene is a susceptibility factor to Ankylosing spondylitis (AS) in mainland Han Chinese population. METHOD Eight single-nucleotide polymorphisms (SNPs) (rs10045431, rs11167764, rs3212227, rs6556412, rs6556416, rs6871626, rs6887695 and rs7709212) in the IL-12B gene were genotyped by iMLDR Assay technology in 400 patients [96% (384/400) HLA-B27(+)] and 395 geographically and ethnically matched healthy controls in mainland Han Chinese population. The correlation between IL-12B genetic polymorphisms and AS activity index (BASDAI, BASFI) were tested. RESULTS The significant difference was found in genotype distribution between AS and healthy controls (χ2 = 6.942, P-value = 0.031) of the SNP rs6871626. Furthermore, significant evidence was also detected under the recessive model for minor allele A. The AA genotype carrier had 1.830 fold risk compared with C allele carrier (with CC and AC genotypes) [OR (95% CI) = 1.830 (1.131-2.961), P-value = 0.014]. Nevertheless, the difference was no longer significant after Bonferroni correction. Subset analysis on cases with HLA-B27(+) did find the same results. Three genotypic groups (AA, CC and CA) in rs6871626 site was highly associated with the BASDAI and BASFI (P-value = 0.012 and P-value = 0.023, respectively), after adjustment for effect of age, sex, and disease duration, the P-value was 0.031 and 0.041, respectively. The AA genotype of rs6871626 was also significantly correlated with an increased BASDAI and BASFI compared to the AC and CC genotypes in AS patients. CONCLUSION Our findings suggest that rs6871626 may be associated AS susceptibility and with disease activity (BASDAI, BASFI) in mainland Han Chinese population.