Attention has been paid to the role of IL-1 in the pathogenesis of the disease, and to the significance of a genetic test, investigating the presence of composite two polymorphisms of IL-1 gene, as a risk factor for severe periodontitis.
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).
The polymorphisms observed in IL-1α(+4845) and IL-1β(+3954) single nucleotide polymorphisms (SNPs), was significantly different among the study groups (healthy controls, mild, moderate and severe periodontitis with p<0.05, d.f.=1.
Study inclusion criteria focused on the analytic framework originally proposed for the IL-1 genetic effect in which overexpression of inflammatory mediators is hypothesized to result in more severe periodontitis in response to a bacterial challenge.
At T(2), a genetic test to determine the IL-1 genotype and genetic susceptibility for severe periodontal disease was performed for all 60 patients, and they were classified as IL-1 genotype positive (G+) or negative (G-) according to the test results.
Cross-sectional studies have demonstrated that a specific polymorphism (allele 2 of both IL-1A +4845 and IL-1B +3954) in the IL-1 gene cluster has been associated with an increased susceptibility to severe periodontal disease and to an increased bleeding tendency during periodontal maintenance.
Former moderate smokers (>5 pk/yr and <10 pk/yr) who were IL-1 genotype negative were at increased odds ratio of having moderate to severe periodontal disease of 7.43 (95% CI: 1.20-46.20) compared to non-smokers or former light smokers who were IL-1 genotype negative.
Two polymorphisms located at +4845 bp in the IL-1 alpha region and at +3954 bp in the IL-1 beta region were evaluated by a polymerase chain reaction method; 35.3% of the examined subjects were positive for specific combinations of allotypes of the IL-1 gene complex previously associated with an increased risk for severe periodontitis.
Polymorphisms in the IL-1A gene are correlated with levels of interleukin-1alpha protein in gingival crevicular fluid of teeth with severe periodontal disease.
This study demonstrates that specific genetic markers, that have been associated with increased IL-1 production, are a strong indicator of susceptibility to severe periodontitis in adults.