title: Interleukin-18 gene polymorphisms and rheumatoid arthritis: a meta-analysis.
abstract: Interleukin-18 (IL-18) is a member of the IL-1 superfamily that enhances both innate and acquired immune responses. IL-18 is highly expressed in sera, synovial fluids and synovial tissues of patients with RA, and these IL-18 levels are correlated with RA disease activity, indicating an important role of IL-18 in the pathogenesis of RA. Several studies have examined the association of IL-18 gene polymorphisms with RA, but these studies have shown inconclusive and controversial results. To verify the association between IL-18 gene polymorphism and susceptibility to RA, we conducted a meta-analysis of all relevant reports cited in MEDLINE/PubMed before October 2012. A meta-analysis on the association between the IL-18 rs1946518 SNP and RA was performed for 2944 patients with RA and 2377 controls from 7 published studies and a meta-analysis on the association between the IL-18 rs187238 SNP and RA was performed for 1319 patients with RA and 1211 controls from 5 published studies. In addition, 2 studies involving 1873 RA patients and 1092 controls were considered in the meta-analysis of the association between the IL-18 rs360722 SNP and RA. No significant association was found between two IL-18 SNPs (rs1946518 and rs187238) and RA susceptibility in all subjects. In subgroup analysis stratified by ethnicity, there was still no significant association between these two IL-18 SNPs and RA susceptibility. However, the frequency of the T allele at rs360722 was found to be significantly lower in patients with RA compared with controls, although this finding was based on only 2 studies. The results of our meta-analysis suggest that IL-18 rs360722 SNP is only associated with RA susceptibility. However, due to only two studies included in our meta-analysis, large-scale well designed studies should be considered in future studies to confirm the exact role of IL-18 rs360722 SNP in RA susceptibility.
authors.affiliation: Rheumatology, College of Medicine, Korea University, 126-1, Anam-Dong 5-Ga, Sungbuk-Ku, Seoul 136-705, South Korea. jjdjmesy@korea.ac.kr
authors.forename: Jong Dae
authors.initials: JD
authors.lastname: Ji
authors.forename: Won Jin
authors.initials: WJ
authors.lastname: Lee
mesh_terms: D000483:Alleles; D001172:Arthritis, Rheumatoid / Q000208:ethnology / Q000235:genetics*; D016208:Databases, Factual; D005787:Gene Frequency; D056726:Genetic Association Studies / Q000379:methods; D020022:Genetic Predisposition to Disease; D005828:Genetics, Population / Q000379:methods; D015894:Genome, Human; D006801:Humans; D020382:Interleukin-18 / Q000235:genetics*; D016017:Odds Ratio; D020641:Polymorphism, Single Nucleotide; D017594:Publication Bias
chemical_list: D020382:Interleukin-18