Chronic periodontitis (CP) is an inflammatory disease affecting tooth supporting structures in response to bacterial dental plaque causing irreversible tissue destruction. Cyclooxygenase-2 (COX-2) is an effective mediator in the pathogenesis of periodontitis. Polymorphisms in the COX-2 gene may contribute to its overexpression and increased disease susceptibility. To evaluate the association between -1195 A/G single nucleotide polymorphism (SNP) in the promotor area of the cyclooxygenase-2(COX-2) gene and severity of chronic periodontitis in a sample of Iraqi population. -1195A/ G COX-2 SNP was investigated in 70 chronic periodontitis (CP) cases and 30 healthy controls. CP cases composed of 2 subgroups (35 moderate CP cases and 35 severe CP cases). Genotyping of -1195A/G SNP was performed using polymerase chain reaction-Restriction fragment length polymorphism (PCR-RFLP). Genotypes distributions were compared using Chi-square and their association with disease risk were assessed using odd ratios. Allele G carriers were significantly more prevalent in the CP cases compared to controls (P = 0.041) and the risk for CP was 1.6 times more in allele G carriers compared to non-carriers. Additional subgroup investigation revealed that there was a non-significant difference in genotype distribution and allele frequency of -1195A/G SNP between controls and moderate CP cases (P = 0.983), while there was a significantly higher frequency of allele G in severe CP cases compared to controls and moderate CP cases and the risk of having severe CP was 2.36 times higher in allele G carriers. Allele G of the COX2-1195 single nucleotide polymorphism may be a risk factor for severe chronic periodontitis.
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