Correlation of interleukin-6-174 GC and interleukin-6-572 GC gene polymorphisms with periodontal disease in an Iranian population.

Abstract

Periodontal disease has a multifactorial etiology. A combination of microbial agents and environmental, habitual, systemic, and genetic risk factors is responsible for the development of periodontal disease. Host immune response causes the destruction of tooth-supporting structure and eventual tooth loss. This study aimed to assess the correlation of interleukin 6 (IL-6) -174-GC and IL-6-572-GC gene polymorphisms with periodontal disease in an Iranian population. This case-control analytical study was conducted on 129 subjects presenting to the laboratory of Taleghani Hospital. Subjects underwent clinical and periodontal examinations and divided into five groups of healthy, gingivitis and mild, moderate and severe periodontitis. Blood samples (2 ml) were obtained. Genomic DNA was extracted manually using the salting-out method. IL-6 sequence amplification was performed using polymerase chain reaction with three thermal protocols. Digested products were analyzed by electrophoresis through 2% agarose gel using Gel Red staining. Data were analyzed using Chi-square, Kruskal-Wallis, and Mann-Whitney tests, and P < 0.05 was considered significant. The frequency of GG polymorphism at IL-6-174 and IL-6-572 genomic regions was 51.2% and 71.3%, respectively. The frequency of IL-6-572-GG polymorphism was significantly greater than that of IL-6-572-GC polymorphism (P < 0.001). Comparison of the mean and maximum pocket depth and clinical attachment level, as well as bleeding on probing percentage, revealed significant differences between the healthy controls and periodontitis patients (P < 0.001). The frequency percentages of GC and GG polymorphisms were almost equal in the healthy, gingivitis, and periodontitis groups. In other words, the frequency of the two polymorphisms was not significantly different between the health and disease states (P = 0.065 for IL-6-572 and P = 0.63 for IL-6-174). This study found no association between IL-6-174 and IL-6-572 gene polymorphisms and periodontitis in the studied population.