A meta analysis of MMP 9 promoter 1562 C/T polymorphism on susceptibility of chronic periodontitis
BackgroundAlthough many studies have focused on the association of the MMP 9 promoter 1562 C/T polymorphism with the susceptibility and/or severity of chronic periodontitis (CP) results have been inconsistent. Therefore, a meta analysis of all eligible studies was performed to derive a more precise estimation of the association between this polymorphism and CP risk.MethodsAll relevant studies were identified through a database search in PubMed, Medline, and Web of Science. All the full text studies with appropriate analytical design, published in English, which evaluated the association of MMP 9 promoter 1562C/T polymorphism with CP risk using validated genotyping methods, and with non duplicated data were selected for this study. A fixed effect model was used to calculate pooled ORs in the absence of heterogeneity across included trials (P 0.1 and I2 50 otherwise the random effect model was applied.ResultsIn an overall meta analysis, pooled ORs revealed that T variant in the MMP 9 promoter 1562 C/T polymorphism was associated with a significantly decreased risk for CP under all comparison models. In subgroup analyses by ethnicity, pooled ORs showed that a significant association of the MMP 9 promoter 1562 C/T polymorphism with CP risk was only detected in Caucasians and Asians but not in mixed population. In the subgroup analysis by severity of CP, pooled ORs indicated that T allele of the MMP 9 promoter 1562 C/T polymorphism was associated with decreased susceptibility to severe CP while there was no significant association between this polymorphism and moderate CP.ConclusionsOur meta analysis showed that T allele in the MMP 9 promoter 1562 C/T polymorphism might be a protective factor for CP, especially in Caucasians and Asians. Moreover, there was a significant association of the MMP 9 promoter 1562 C/T polymorphism with decreased susceptibility to severe CP, while the allelic and/or genotype distributions of this polymorphism were not associated with moderate CP.
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