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Aim: We aimed to assess the association of different genotypes with increased aggressive periodontitis susceptibility by studying functional relevant variants in the pathogen-recognition receptor Toll-like receptor 4 (TLR4) and variants in the promoter region of the pro-inflammatory cytokine interleukin-18 (IL-18)., Material and Methods: One hundred and eleven patients with aggressive periodontitis and 80 periodontally healthy controls were genotyped for four functional variants in the TLR4 gene (c.896A>G and c.1196C>T) and in the IL-18 promoter (c.-368G>C and c.-838C>A). The genotype and allele frequencies, as well as the frequency of combined genotypes were compared between study groups., Results: There were no statistical differences in genotype and allele frequencies within the four variants between the groups. All study subjects were further classified into carriers and non-carriers of at least one variant of both genes. The logistic regression analysis adjusted for gender and smoking showed no association between carrier status of at least one variant of both genes and periodontal status (OR=1.41, 95% CI: 0.43-4.70)., Conclusions: Our results reject the hypothesis that functionally relevant IL-18 and TLR4 gene mutations have a major effect on aggressive periodontitis susceptibility alone or in combination.

Aim: The autosomal-recessive Papillon-Lefèvre syndrome (PLS) is characterized by severe aggressive periodontitis, combined with palmoplantar hyperkeratosis, and is caused by mutations in the Cathepsin C (CTSC) gene. This study aimed to identify CTSC mutations in different PLS phenotypes, including atypical forms and isolated pre-pubertal aggressive periodontitis (PAP)., Material and Methods: Thirteen families with different phenotypes were analysed by direct sequencing of the entire coding region and the regulatory regions of CTSC. The function of novel mutations was tested with enzyme activity measurements., Results: In 11 of 13 families, 12 different pathogenic CTSC mutations were found in 10 typical PLS patients, three atypical cases and one PAP patient. Out of four novel mutations, three result in protein truncation and are thus considered to be pathogenic. The homozygous c.854C>T nucleotide exchange (p.P285L) was associated with an almost complete loss of enzyme activity. The observed phenotypic heterogeneity could not be associated with specific genotypes., Conclusions: The phenotypic variability of the PLS associated with an identical genetic background may reflect the influence of additional genetic or environmental factors on disease characteristics. CTSC mutation analyses should be considered for differential diagnosis in all children suffering from severe aggressive periodontitis.

Cathepsin C (CTSC) mutations are known to cause Papillon-Lefèvre syndrome. The aim of this study was to examine the association of CTSC genotype with susceptibility to non-syndromic aggressive periodontitis. The CTSC gene was analyzed in 110 persons with generalized aggressive periodontitis in comparison with 78 control individuals, after identifying different variants in a cohort of 100 persons. Five out of 19 discovered variants were included in this association study, representing 5 single-nucleotide polymorphism groups in tight linkage disequilibrium. The relevance of genotypes on enzyme function was examined. The carrier frequency of the missense variant p.I453V was significantly increased in persons with disease compared with healthy control individuals (17.3% vs. 6.4%, p < 0.05). CTSC activity in leukocytes from individuals harboring this variant was significantly reduced (119.8 ΔOD/min*105 cells, 95% confidence interval 17.4-174.9, p = 0.018). No influence of promoter variants was found on mRNA expression. The results support the hypothesis that CTSC gene variants contribute to increased susceptibility in generalized aggressive periodontitis. [ABSTRACT FROM AUTHOR]

Objective: The CARD15 gene encodes a protein that acts as an intracellular receptor of bacterial products, thus playing an important role in the innate immune response. Recently, CARD15 gene variants have been identified as a cause of increased susceptibility to Crohn's disease. The present study aimed to examine a potential association of CARD15 gene variants with aggressive periodontitis susceptibility. Material and Methods: The three main known CARD15 gene variants (p.R702W, p.G908R, and p.L1007fsX1008) were analysed by direct sequencing of exon 4, 8, and 11 of the gene in a total of 86 generalized aggressive periodontitis patients in comparison with 67 healthy controls. Results: The mutant allele frequencies of the CARD15 variants were low in the generalized aggressive periodontitis group as well as in the control group and not significantly different (R702W: 3.5% versus 5.2%; G908R: 1.7% versus 1.5%; L1007fsX1008: 5.2% versus 4.5%). Two rare variants (A755V and R791Q), previously described only in patients with other inflammatory diseases, were observed in three patients having aggressive periodontitis but not in controls. Conclusions: Unlike in Crohn's disease, our results did not show an association between the three main CARD15 mutations and aggressive periodontitis. The role of rare variants remains unclear. [ABSTRACT FROM AUTHOR]