Genetic aspects of oral disorder

Deciphering the relative roles of heredity and environmental factors (“nature vs. nurture”) in the pathogenesis of dental caries and diseases of the periodontium has occupied clinical and basic researchers for decades. Success in the endeavor has come more easily in the case of caries; the complex interactions that occur between host-response mechanisms and mutative microbiologic pathogens in periodontal disease have made elucidation of genetic factors in disease susceptibility more difficult. A critical discussion of the evidence for a hereditary component in oral disorders is presented, also from a historical perspective. Recent researches on genetic analyses in periodontal research are also being discussed, with an eye toward a future in which persons who are at risk, i.e., genetically predisposed to periodontal disease may be identified and targeted for interventional strategies. Present studies are clarifying previously unrecognized genetic and phenotypic heterogeneities and attempting to unravel the complex interactions between genes and environment by applying new statistical modelling approaches to twin and family data. Linkage studies using highly polymorphic DNA markers are providing a means of locating candidate genes, including quantitative trait loci (QTL). The most important conclusion of this review is: while phenotype is inevitably the result of both genetic and environmental factors, there is irrefutable evidence for a significant genetic influence in many periodontal and occlusal variables.