This review addresses the multi-causal etiology of periodontitis, in which genetic factors play a role. The various proposed causes for periodontitis always play a role simultaneously, but the relative contribution of each of these, varies from case to case. In young individuals often with aggressive periodontitis (AgP) a stronger contribution from genetic factors is apparent, while in older individuals often with chronic periodontitis (CP), the relative contribution of the established subgingival biofilms (environmental factors) and life style factors (e.g. smoking, stress, diet), play a more dominant role in the phenotype of the disease.Nevertheless always some genetic susceptibility is present, for CP estimated at 25%.Periodontitis is therefore a complex disease, i.e. it behaves in a nonlinear fashion. Actually the disease progression rate fluctuates, where the disease sometimes moves into an aberrant state of host response and then swings back into a resolving state; in between, a settlement zone is present where essentially no differences are found for immunological parameters between cases with periodontitis and healthy controls. The genotype determines part of this fluctuation and the extent of it. The disease is polygenic, i.e. multiple genetic variants in multiple genes determine the phenotype, but there are individual and ethnic differences in the genes involved. We are still at the early stage to have identified the involved genes, in comparisons to other chronic diseases, we need to count on it that at least 100 causative genes across various global populations exist in AgP and CP. To date, the genetic variations firmly and repeatedly associated with periodontitis in some populations are found within the following genes: ANRIL, COX2, IL1, IL10, DEFB1, while many proposed periodontitis candidate genes have not been firmly proven or replicated.
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KeypointsPeriodontitis is a multi-causal disease, with each of the causal factors playing a role but the relative contribution of these vary form case to case.The disease behaves in a nonlinear fashion, with periods of aberrant host response to periods within an active disease resolving state.To date only a few of the multitude of possible genetic factors for periodontitis are identified.
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