Method: 477 subjects from 72 pedigrees with similar cultural and behavioral habits and limited access to dental care living in the Philippines were studied. DMFT (Decayed, Missing due to caries, Filled Teeth) scores were recorded and DNA was extracted from all subjects. Sixty-one genetic variants in 13q31.1 and 128 in Xq27.1 were selected and genotyped by PCR using TaqMan chemistry. Association between caries experience and alleles was tested with the program Family-Based Association Test. In addition, we tested 1,483 subjects from our University of Pittsburgh Dental Registry and DNA Repository in order to replicate the results found in the families. Association between genetic variation and caries experience was tested using PLINK. Chi-square was used to test for deviation from Hardy- Weinberg equilibrium.
Result: Statistically significant association was found for 11 markers in 13q31.1 and 11 markers in Xq27.1 in the Philippine families. Haplotype analysis also confirmed these results. In the population from Pittsburgh, the TT genotype of marker rs4885849 in 13q31.1 was associated with high caries experience (p=0.03). In Xq27.1, differences in allele distributions depending on caries experience were observed for markers rs5931572 and rs5907426 (p=0.002 and p=0.004, respectively) and differences in genotype distributions depending on caries experience were observed for markers rs1324156, rs1324156, rs2073252, rs5931572 (p=0.03; p=0.02; p=0.03, and p=0.01, respectively).
Conclusion: Genetic factors contributing to caries experience exist in 13q31.1 and Xq27.1. Future work will focus in the identification of these factors, which will hopefully allow for the creation of new strategies to prevent and treat caries. NIH grant R01-DE018914 provided financial support. ECK and PF contributed equally to this work.