Dataset Information

Association of interleukin-1 gene variations with moderate to severe chronic periodontitis in multiple ethnicities.

ABSTRACT:

Background and objective

Genetic markers associated with disease are often non-functional and generally tag one or more functional "causative" variants in linkage disequilibrium. Markers may not show tight linkage to the causative variants across multiple ethnicities due to evolutionary divergence, and therefore may not be informative across different population groups. Validated markers of disease suggest causative variants exist in the gene and, if the causative variants can be identified, it is reasonable to hypothesize that such variants will be informative across diverse populations. The aim of this study was to test that hypothesis using functional Interleukin-1 (IL-1) gene variations across multiple ethnic populations to replace the non-functional markers originally associated with chronic adult periodontitis in Caucasians.

Material and methods

Adult chronic periodontitis cases and controls from four ethnic groups (Caucasians, African Americans, Hispanics and Asians) were recruited in the USA, Chile and China. Genotypes of IL1B gene single nucleotide polymorphisms (SNPs), including three functional SNPs (rs16944, rs1143623, rs4848306) in the promoter and one intronic SNP (rs1143633), were determined using a single base extension method or TaqMan 5' nuclease assay. Logistic regression and other statistical analyses were used to examine the association between moderate to severe periodontitis and IL1B gene variations, including SNPs, haplotypes and composite genotypes. Genotype patterns associated with disease in the discovery study were then evaluated in independent validation studies.

Results

Significant associations were identified in the discovery study, consisting of Caucasians and African Americans, between moderate to severe adult chronic periodontitis and functional variations in the IL1B gene, including a pattern of four IL1B SNPs (OR = 1.87, p < 0.0001). The association between the disease and this IL1B composite genotype pattern was validated in two additional studies consisting of Hispanics (OR = 1.95, p = 0.04) or Asians (OR = 3.27, p = 0.01). A meta-analysis of the three populations supported the association between the IL-1 genotype pattern and moderate to severe periodontitis (OR 1.95; p < 0.001). Our analysis also demonstrated that IL1B gene variations had added value to conventional risk factors in predicting chronic periodontitis.

Conclusion

This study validated the influence of IL-1 genetic factors on the severity of chronic periodontitis in four different ethnicities.

SUBMITTER: Wu X

PROVIDER: S-EPMC4183738 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundChronic periodontitis (CP) is characterized by an immune response, leading to the destruction of periodontal supporting tissue. The effect of inflammatory and genetic factors on periodontitis has been evaluated previously. The interleukin (IL-17) as an inflammation regulator seems to play a critical role in periodontitis pathogenesis. Here, in the current study, we aimed to investigate the association of -197 G > A (rs2275913) IL-17 gene promoter polymorphism with generalized severe CP in an Iranian population.Materials and methodsIn this case-control study, a total of 54 patients with periodontitis and 118 normals were enrolled. The polymerase chain reaction-restriction fragment length polymorphism technique was applied to detect IL-17 promoter rs2275913 genotypes in association with the susceptibility to severe CP. Chi-square test or Fisher's exact test was employed to compare genotype frequencies between groups. P < 0.05 were considered statistically significant.ResultsThe distribution of genotypes and alleles was in Hardy-Weinberg equilibrium. Although no significant association was observed between the risk of periodontitis and genotype frequencies under any of the inheritance models, the GG genotype was higher in healthy controls, while the AG genotype was more frequently observed in patients under the codominant model ([odd ratio [OR] = 2.14, 95% confidence interval (CI) (1.01-4.53), P = 0.13]). The frequency of AG-AA genotype was higher in patients under dominant inheritance model ([OR = 1.92, 95% CI (0.94-3.93), P = 0.068]), while GG-AA and AG genotypes were higher in healthy controls under over dominant model (OR = 0.1.95, 95% CI [0.98-3.86], P = 0.055).ConclusionThe results of this study showed that the presence of allele A and AG genotypes could be considered possible factors in increasing the risk of developing CP, although the differences of allele and genotype frequencies were remarkable but not statistically significant between the two groups.

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