Candidate gene sequencing reveals mutations causing hypoplastic amelogenesis imperfecta.

Objective: Amelogenesis imperfecta (AI) is a rare hereditary disorder affecting the quality and quantity of the tooth enamel. The purpose of this study was to identify the genetic etiology of hypoplastic AI families based on the candidate gene approach.

Materials And Methods: We recruited three Turkish families with hypoplastic AI and performed a candidate gene screening based on the characteristic clinical feature to find the pathogenic genetic etiology.

Porcine Amelogenin : Alternative Splicing, Proteolytic Processing, Protein - Protein Interactions, and Possible Functions.

Amelogenin is the major secretory product of ameloblasts and is critical for proper tooth enamel formation. Amelogenin isoforms and their cleavage products comprise over 80% of total secretory stage enamel protein. We have isolated and characterized four secreted amelogenin isoforms from developing porcine enamel : P190 (27-kDa), P173 (25-kDa), P132 (18-kDa) and P56 (6.

Dentinogenesis and Dentin Sialophosphoprotein (DSPP).

Dentin sialophosphoprotein (DSPP) is critical for proper mineralization of tooth dentin, and understanding its structure and function should yield important insights into how dentin biomineralization is controlled. During the recent six years, I have focused on characterizing DSPP-derived proteins isolated from developing porcine teeth. Porcine DSPP is expressed and secreted by odontoblasts and is processed by BMP-1, MMP-20 and MMP-2 into three main parts: dentin sialoprotein (DSP), dentin glycoprotein (DGP), and dentin phosphoprotein (DPP).

Dentin Sialophophoprotein (DSPP) and Dentin.

The revolution in genetics disclosed the types of malformations that occur when expression of a particular gene is lost. In the case of tooth dentin, mutations in the two genes encoding type I collagen cause osteogenesis imperfecta, a bone condition that often includes dentin malformations. Besides collagen, there are a number of non-collagenous proteins in dentin.

Proteomics and genetics of dental enamel.

The initiation of enamel crystals at the dentino-enamel junction is associated with the expression of dentin sialophosphoprotein (DSPP, a gene normally linked with dentin formation), three 'structural' enamel proteins--amelogenin (AMELX), enamelin (ENAM), and ameloblastin (AMBN)--and a matrix metalloproteinase, enamelysin (MMP20). Enamel formation proceeds with the steady elongation of the enamel crystals at a mineralization front just beneath the ameloblast distal membrane, where these proteins are secreted. As the crystal ribbons lengthen, enamelysin processes the secreted proteins.

Novel MSX1 frameshift causes autosomal-dominant oligodontia.

Can kindreds with tooth agenesis caused by MSX1 or PAX9 mutations be distinguished by their phenotypes? We have identified an MSX1second bicuspids and mandibular central incisors. The dominant phenotype is apparently due to haploinsufficiency. We analyzed patterns of partial tooth agenesis in seven kindreds with defined MSX1 mutations and ten kindreds with defined PAX9 mutations.

ENAM mutations in autosomal-dominant amelogenesis imperfecta.

To date, 4 unique enamelin gene (ENAM) defects have been identified in kindreds with amelogenesis imperfecta. To improve our understanding of the roles of enamelin in normal enamel formation, and to gain information related to possible genotype/phenotype correlations, we have identified 2 ENAM mutations in kindreds with hypoplastic ADAI, 1 novel (g.4806A>C, IVS6-2A>C) and 1 previously identified (g.

Mutational hot spot in the DSPP gene causing dentinogenesis imperfecta type II.

The current system for the classification of hereditary defects of tooth dentin is based upon clinical and radiographic findings and consists of two types of dentin dysplasia (DD) and three types of dentinogenesis imperfecta (DGI). However, whether DGI type III should be considered a distinct phenotype or a variation of DGI type II is debatable. In the 30 years since the classification system was first proposed, significant advances have been made regarding the genetic etiologies of inherited dentin defects.

Amelogenin p.M1T and p.W4S mutations underlying hypoplastic X-linked amelogenesis imperfecta.

Mutations in the human amelogenin gene (AMELX, Xp22.3) cause a phenotypically diverse set of inherited enamel malformations. We hypothesize that the effects of specific mutations on amelogenin protein structure and expression will correlate with the enamel phenotype, clarify amelogenin structure/function relationships, and improve the clinical diagnosis of X-linked amelogenesis imperfecta (AI).