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Association between vitamin D receptor polymorphisms and periodontitis: a meta-analysis.

BACKGROUND
The purpose of the meta-analysis is to explore the association between vitamin D receptor polymorphisms (including four gene loci: Taq-I, Bsm-I, Apa-I, and Fok-I) for susceptibility to periodontitis (either chronic [CP] or aggressive [AP]). Up to now, there has been only one systematic review focusing on this topic. We obtained some different findings compared with the previously published literature.


METHODS
Nineteen case-control studies were identified through a search of multiple electronic databases (from January 1, 1999 to June 30, 2011). The pooled odds ratios (ORs) and 95% confidence intervals (CIs) using codominant, dominant, and recessive genetic models from meta-analysis were the main outcome measure. The Harbord test was used to detect the publication bias for each group.


RESULTS
Eighteen identified articles met the eligibility criteria. Through overall analyses, no statistical association was found between polymorphisms of the four gene loci and periodontitis. However, based on subgroup analyses, a significant association between the Taq-I variants and CP rather than AP was shown in Asians (OR = 0.590; 95% CI = 0.425, 0.818) but not in whites (OR = 0.823; 95% CI = 0.637, 1.063). No statistically significant association was found between polymorphisms of Bsm-I and Apa-I with either AP or CP. The Fok-I polymorphism showed a statistical association with AP (OR = 1.583; 95% CI = 1.157, 2.166) instead of CP (OR = 1.081; 95% CI = 0.638, 1.830) in Asians.


CONCLUSIONS
The results of the present meta-analysis indicate the following: 1) the mutant allele t of the Taq-I locus may be a protective factor for CP but not for AP in Asians, although this was not true in whites; 2) the mutant allele F of the Fok-I locus appeared to be a risk factor for AP rather than CP in Asians; and 3) Bsm-I and Apa-I polymorphisms were found to have no significant associations with susceptibility to periodontitis (CP/AP).