Interleukin-6 receptor gene polymorphisms and periodontitis in a non-smoking Japanese population

• Published in: Journal of clinical periodontology 2006-10, Vol.33 (10), p.704-709
• Main Authors: Galicia, Johnah C., Tai, Hideaki, Komatsu, Yasutaka, Shimada, Yasuko, Ikezawa, Ikuyo, Yoshie, Hiromasa
• Format: Article
• Language: English
• Subjects: Adenine; Adult; Aged; Alanine - genetics; Alleles; Aspartic Acid - genetics; Biomarkers - analysis; case-control; Cytosine; Dentistry; Exons - genetics; Female; Genetic Variation - genetics; Genotype; Humans; IL-6 receptor; Japan; Japanese; Linkage Disequilibrium - genetics; Male; Middle Aged; periodontitis; Periodontitis - genetics; Periodontitis - immunology; Polymorphism, Genetic - genetics; Polymorphism, Single Nucleotide - genetics; Promoter Regions, Genetic - genetics; Receptors, Interleukin-6 - genetics; SNP
• ISSN: 0303-6979; 1600-051X
• DOI: 10.1111/j.1600-051X.2006.00978.x

Aim: The indispensable role of interleukin‐6 receptor (IL‐6R) in regulating IL‐6 responses has been clearly established. We have previously reported that IL6R polymorphisms strongly influenced the serum levels of soluble IL‐6R. In this study, we investigated the association between these genetic variations and periodontitis. Material and Methods: Among the seven novel IL6R single‐nucleotide polymorphisms (SNPs) reported, we genotyped two important sites: the +48892 A/C in exon 9 and the −183 G/A in the promoter region. The SNP in exon 9 results in Asp→Ala substitution in the proteolytic cleavage site of IL‐6Rα. In total, 212 periodontitis cases and 210 healthy controls were genotyped using polymerase chain reaction, restriction fragment length polymorphisms and direct sequencing methods. Results: Analysis of the genotype distribution of the +48892 A/C SNP in periodontitis patients and in controls revealed a suggestive association with aggressive (p=0.04) and chronic periodontitis (p=0.04). In addition, the carriage rate for the A allele was significantly higher in chronic periodontitis patients [p=0.02, odds ratio (OR)=2.25]. No association was found in the −183 G/A SNP. The two markers were in linkage disequilibrium (LD) (|D′|=0.53). Conclusion: The IL6R+48892 A/C polymorphism could act as a risk factor for periodontitis; however, further association and biological studies are needed.