Assessment of genotyping tools applied in genetic susceptibility studies of periodontal disease: A systematic review.

OBJECTIVE: A systematic review to evaluate the various genotyping tools and study strategies employed to define genetic susceptibility to periodontitis. METHODS: The review was performed in accordance with Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. The search for publications referring to the genetic bases of periodontal disease was performed on the MEDLINE-PubMed and Cochrane Library databases, on trials registers, and on the web pages of regulatory agencies. RESULTS: We found 2439 potentially eligible articles, of which only 25 satisfied the established inclusion criteria and were processed for data extraction. The review revealed marked heterogeneity between studies, caused in part by the lack of a universally accepted definition for periodontitis phenotypes and by the variety of genotyping tools available. The most commonly used technique was genotyping candidate genes. CONCLUSION: The few rigorous studies that have been published on genetic susceptibility to periodontitis are subject to severe methodological bias due to their design and the genotyping tools employed. Despite their limitations, candidate gene studies continue to be the predominant methodological approach, rather than genome-wide association studies. Further studies must be designed using a universally accepted, validated diagnostic criterion for periodontitis, analysing multiple genes and polymorphisms in combination with rare variants.