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10-03-2013 | Genetics | Article

Interleukin-6 variants predispose to periodontitis in Chinese Han population


Free abstract

medwireNews: Two single nucleotide polymorphisms in the genes for interleukin (IL)-6 and its receptor contribute to genetic susceptibility to chronic periodontitis in the Northwestern Chinese Han population, report researchers from Gansu Province in China.

The team, led by Xiao-dong Xie from Lanzhou University, reports that IL-6 -1363 G/T genotype GG may increase the risk for chronic periodontitis, while IL-6R +48892 A/C genotype CC appears to protect against it.

The study included 199 patients (116 men) of Northwestern Chinese origin with severe chronic periodontitis, aged an average of 38 years, and 216 healthy, matched control individuals.

As described in Oral Diseases, analysis of genomic DNA revealed no differences between periodontitis patients and controls in the distribution of genotype or allele frequencies for the IL-6 -572 G/C or the IL-6R -183 G/A polymorphisms.

By contrast, the frequencies of the G allele and the GG genotype for IL-6 -1363 G/T were significantly higher in cases than controls. Indeed, the GG genotype was associated with a 2.8-fold increased odds for chronic periodontitis, after adjusting for age and gender.

Conversely, the frequency of IL-6R +48892 A/C genotype CC was much higher in healthy controls than the periodontitis patients, with an odds ratio for the condition of 0.32.

Further analysis showed that IL-6R -183 G/A and +48892 A/C were in weak linkage disequilibrium, and the IL-6R haplotype A+48892/A-183 was also protective against periodontitis when compared with presence of the other haplotypes, at an odds ratio of 0.72.

The authors explain that the polymorphisms affect expression of IL-6 and IL-6R, which are key to inflammatory pathways and also in particular are involved in osteoclast differentiation and bone resorption, processes that are important in the pathogenesis of periodontitis.

"In summary, our data suggested that IL-6 and IL-6R polymorphisms were associated with chronic periodontitis," write the authors, "and it was important for the interaction of IL-6 and IL-6R in the pathogenesis of chronic periodontitis."

"However, further studies with larger numbers of patients of different ethnic groups are required for further evaluation and confirmation of our findings," they conclude.

By Caroline Price, Senior medwireNews Reporter

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