Evidence for association between a Toll-like receptor 4 gene polymorphism and moderate/severe periodontitis in the Japanese population

Background and Objective: Chronic periodontitis is an inflammatory disease caused by bacteria in subgingival pockets. Because Toll-like receptor 2 and Toll-like receptor 4 have been shown to play an important role in the recognition of periodontal pathogens, we investigated the relevance of genetic variations in TLR2 and TLR4 to susceptibility to periodontitis. A total of 97 patients with chronic periodontitis and 100 control subjects were examined for mutations in TLR2 and TLR4. Case-control analysis was performed using individual single nucleotide polymorphisms detected during the mutation search. The missense mutations reported previously in TLR2 (677 Arg>Trp and 753 Arg>Gln) and in TLR4 (299 Asp>Gly and 399 Thr>Ile) were not detected in 97 of the Japanese patients with chronic periodontitis or in 100 of the Japanese control subjects. Nine single nucleotide polymorphisms were identified in exons of TLR2 and TLR4. The case-control analysis revealed that the frequency of the C/C genotype at base-pair position +3725 in TLR4 was significantly higher in both the moderate and the severe periodontitis patient group than in the control group. A genetic variation of TLR4 might be associated with moderate and severe periodontitis in the Japanese population.