Are mTOR and Endoplasmic Reticulum Stress Pathway Genes Associated with Oral and Bone Diseases?

The purpose of this cohort study was to identify associations between combined oral and bone disease phenotypes and genes present in cell regulatory pathways. The studied pathways play important roles in cellular growth, proliferation, differentiation, and homeostasis. DNA samples extracted from whole saliva of 3,912 individuals were genotyped and these data analyzed according to dental caries experience, periapical lesions, periodontitis, osteoporosis, or temporomandibular joint discomfort. Samples were obtained from the Dental Registry and DNA Repository project at the University of Pittsburgh. Twenty-seven polymorphisms in eight genes related to mTOR or endoplasmic reticulum stress pathways were selected for genotyping. Allele frequencies and Hardy-Weinberg equilibrium were calculated. Analyses were performed comparing genotypes between affected and unaffected individuals for each phenotype, as well as for the associated phenotypes combined. For all analyses, we used the software PLINK with an alpha of 0.002. Borderline associations with multiple variants of several genes were found, suggesting that both pathways may be involved in the susceptibility to multiple conditions affecting the oral cavity and bones. When combining patients that had concomitant dental caries, periodontitis, and periapical pathology, several markers in RHEB showed statistically significant association. Multiple conditions affecting bone and teeth (i.e., dental caries, periodontitis, periapical lesion formation, and osteoporosis) appear to share similar underlying genetic etiological factors, which allow us to hypothesize that instead of individually, they should be studied in conjunction in human populations.