Mapping of candidate gene(s) influencing dental caries susceptibility in mice

Objectives: It has been reported that mouse strain differences in susceptibility to dental caries are strongly associated with genetic factors. Recently, we demonstrated that genetic factors related to caries inducing ability are located on chromosomes 7, 8 and 11 [Ohta, 2005]. Hence the present study was conducted to identify the region that would include the candidate gene influencing dental caries susceptibility in mice.

Methods: Quantitative Trait Loci (QTL) analysis was performed on the genetic crosses of BALB/cJ mice (caries – susceptible strain) and C3H/HeJ (caries – resistant strain). F2 intercross [(BALB x C3H) X (BALB x C3H)] mice were obtained by mating the mice in our laboratory. A total of 20 microsatellite markers and two gene markers were used for genotyping. Interval mapping was performed with the use of MapManager QTXb19.

Results:Based on the permutation test, the LRS scores used for detecting suggestive/significant associations with the caries score were 8.4/15.9. From the results of interval mapping, In chromosome 11, LRS scores showed higher than significant level around the region 33.9cM from the centromere between D11Mit26 and D11Mit262 (D11Mit26 LRS, 18.5; D11Mit339 LRS,16.8; D11Mit177 LRS,16.6; D11Mit262 LRS,17.3). In chromosome 7, LRS score showed a higher than suggestive level, the peak score was located in the region 50 cM from the centromere (D7Mit126 LRS, 14.4). In chromosome 8, LRS score showed a higher than suggestive level, the peak score was located in the region 38.4 cM from the centromere (D8Mit78 LRS, 13.8).

Conclusions:These results suggest that the major gene(s) responsible for caries susceptibility are located in the specific region on chromosome 11.