Interactions of lymphotoxin alpha (TNF-beta), angiotensin-converting enzyme (ACE), and endothelin-1 (ET-1) gene polymorphisms in adult periodontitis

Background: Adult periodontitis is a complex multifactorial disease whose e tiology is not well defined. To investigate whether the genes encoded withi n the HLA class III region may confer susceptibility to periodontitis, poly morphisms in the ET-1 and TNF-beta genes were analyzed together with the I/ D polymorphism of the ACE gene. Methods: We determined allele and genotype frequencies of the NcoI bi-allel ic polymorphism of the TNF-beta gene, the I/D (insertion/deletion) polymorp hism of the ACE gene, and the TaqI polymorphism of the ET-1 gene in 63 Cauc asian patients with adult periodontitis and 95 orally healthy controls. Results: We found a significant difference in a 3 locus combination of geno types between patients and controls (P <0.05). In the next analyses, no sig nificant differences were found in allele frequencies of single genes, but we did find a significant difference in the genotype distribution between c ases and controls for TNF-<beta> (P<0.03). Differences were also observed f or 2 locus combinations of ACE and TNF-<beta> genotypes (P <0.03), and the ET-1 and TNF-<beta> (P <0.05) genes. Evidence of deviation from Hardy-Weinb erg equilibrium was observed in the periodontitis group for TNF-<beta>, wit h an absence of the B1B1 homozygotes in patients. Conclusions: This study is of an exploratory nature. Considering the number of significant results, however, at least a part of the observed associati ons may obviously be real and our findings suggest that interactions of the TNF-beta, ET-1, and ACE genes may be involved in susceptibility to adult p eriodontitis.