Analysis of RANKL gene polymorphism (rs9533156 and rs2277438) in Iranian patients with chronic periodontitis and periimplantitis

Objective: RANK/OPG/RANKL pathway plays a significant role in osteoclastogenesis, osteoclast activation, and regulation of bone resorption. The aim of this study was to investigate the association of RANKL gene polymorphisms (rs9533156 and rs2277438) with chronic periodontitis and peri-implantitis in an Iranian population. Design: 77 patients with chronic periodontitis, 40 patients with peri-implantitis and 89 periodontally healthy patients were enrolled in this study. 5cc of blood was obtained from the cephalic vein of subjects arms and transferred into tubes containing EDTA. Genomic DNA was extracted using Miller's Salting Out technique. The DNA was transferred into 96 division plates, transported to Kbioscience Institute in United Kingdom and analyzed using the Kbioscience Competitive Allele Specific PCR (KASP) technique. Differences in the frequencies of genotypes and alleles in the disease and control groups were analyzed using Chi-square and Fisher's exact statistical tests. Results: Comparison of frequency of alleles in SNP rs9533156 of RANKL gene between the chronic periodontitis group with the control and peri-implantitis groups revealed statistically significant differences (P = 0.024 and P = 0.027, respectively). Comparison of genotype expression of SNP rs9533156 on RANKL gene between the peri-implantitis group with chronic periodontitis and control groups revealed statistically significant differences (P = 0.001); the prevalence of CT genotype was significantly higher amongst the chronic periodontitis group. Regarding SNP rs2277438 of RANKL gene, comparison of prevalence of genotypes and frequency of alleles did not reveal any significant differences (P = 0.641/P = 0.537, respectively). Conclusions: The results of this study indicate that CT genotype of rs9533156 RANKL gene polymorphism was significantly associated with peri-implantitis, and may be considered as a genetic determinant for peri-implantitis. (C) 2012 Elsevier Ltd. All rights reserved.