Amelogenesis imperfecta: Gener, proteiner og fænotyper

English summary Amelogenesis imperfecta: Genes, proteins, and phenotypes Nor Tannlegeforen Tid 2013; 123: 712-19 Introduction - Traditionally, amelogenesis imperfecta (AI) is identified and classified based on changes in the clinical appearance of the enamel. The enamel may be discolored, soft and hypoplastic to varying degrees, and exhibit radiological changes often with reduced X-ray contrast. Recent research enables classification of amelogenesis imperfecta on the basis of genetic defects, which contributes to a better understanding of both the enamel protein function during amelogenesis, and the pathogenesis of the disease. Objective - This article reviews genes and proteins, in which error coding is known or suspected to participate in the AI pathogenesis. The general protein functions are listed briefly to the extent that are known. Materials and method - PubMed was searched without language restrictions until 2012. Keywords: amelogenesis imperfecta, amelogenesis, amelogenin, ameloblastin, amelin, sheathlin, enamelin, tuftelin, dentin sialophosphoprotein, dentin sialoprotein, dentin glycoprotein, dentin phosphoprotein, dentin matrix protein-1, enamelysin, kallikrein-4, dlx3 and combinations of these. Results - A number of proteins with different function are involved in amelogenesis. The immature enamel contain amelogenins and non-amelogenins. If there are errors in protein formation or function, of one or more of these proteins, the clinical representation of the disease often reflects the stage during amelogenesis where the fault show up. Changes of the protein function determine the degree and nature of the enamel malformation. Conclusion - The phase of enamel formation where an AI gene and protein error appears and amelogenesis is disturbed - during stages of respectively secretion, mineralization or maturation of enamel matrix - is mirrored directly in the clinical AI phenotypes with either hypoplastic, hypomineralisation, or hypomaturation enamel type. Mixed AI types may appear.