The genetic basis of inherited anomalies of the teeth. Part 1: clinical and molecular aspects of non-syndromic dental disorders.

The genetic control of dental development represents a complex series of events, which can very schematically be divided in two pathways: specification of type, size and position of each dental organ, and specific processes for the formation of enamel and dentin. Several genes linked with early tooth positioning and development, belong to signalling pathways and have morphogenesis regulatory functions in morphogenesis of other organs where they are associated with the signalling pathways. Their mutations often show pleïotropic effects beyond dental morphogenesis resulting in syndromic developmental disorders. Some genes affecting early tooth development (MSX1, AXIN2) are associated with tooth agenesis and systemic features (cleft palate, colorectal cancer). By contrast, genes involved in enamel (AMELX, ENAM, MMP20, and KLK4) and dentin (DSPP) structures are highly specific for tooth. Mutations in these genes have been identified as causes of amelogenesis imperfecta, dentinogenesis imperfecta, dentin dysplasias and anomalies of teeth number (hypo-, oligo and anodontia), which only partially overlap with the classical phenotypic classifications of dental disorders. This review of genetic basis of inherited anomalies describes, in this first paper, the molecular bases and clinical features of inherited non-syndromic teeth disorders. And in a second part, the review focus on genetic syndromes with dental involvement.