transforming-growth-factor-alpha and Anodontia

Dental agenesis is the most common developmental anomaly in humans and is frequently associated with several other oral abnormalities. Whereas the incidence of missing teeth may vary considerably depending on dentition, gender, and demographic or geographic profiles, distinct patterns of agenesis have been detected in the permanent dentition. These frequently involve the last teeth of a class to develop (I2, P2, M3) suggesting a possible link with evolutionary trends. Hypodontia can either occur as an isolated condition (non-syndromic hypodontia) involving one (80% of cases), a few (less than 10%) or many teeth (less than 1%), or can be associated with a systemic condition or syndrome (syndromic hypodontia), essentially reflecting the genetically and phenotypically heterogeneity of the condition. Based on our present knowledge of genes and transcription factors that are involved in tooth development, it is assumed that different phenotypic forms are caused by different genes involving different interacting molecular pathways, providing an explanation not only for the wide variety in agenesis patterns but also for associations of dental agenesis with other oral anomalies. At present, the list of genes involved in human non-syndromic hypodontia includes not only those encoding a signaling molecule (TGFA) and transcription factors (MSX1 and PAX9) that play critical roles during early craniofacial development, but also genes coding for a protein involved in canonical Wnt signaling (AXIN2), and a transmembrane receptor of fibroblast growth factors (FGFR1). Our objective was to review the current literature on the molecular mechanisms that are responsible for selective dental agenesis in humans and to present a detailed overview of syndromes with hypodontia and their causative genes. These new perspectives and future challenges in the field of identification of possible candidate genes involved in dental agenesis are discussed.

Topics: Anodontia; Axin Protein; Cytoskeletal Proteins; Humans; MSX1 Transcription Factor; Odontogenesis; PAX9 Transcription Factor; Phenotype; Receptor, Fibroblast Growth Factor, Type 1; Syndrome; Transforming Growth Factor alpha

Tooth agenesis affects 20% of the world population, and maxillary lateral incisors agenesis (MLIA) is one of the most frequent subtypes, characterized by the absence of formation of deciduous or permanent lateral incisors. Odontogenesis is a complex mechanism regulated by sequential and reciprocal epithelial-mesenchymal interactions, controlled by activators and inhibitors involved in several pathways. Disturbances in these signaling cascades can lead to abnormalities in odontogenesis, resulting in alterations in the formation of the normal teeth number. Our aim was to study a large number of genes encoding either transcription factors or key components in signaling pathways shown to be involved in tooth odontogenesis. We selected 8 genes-MSX1, PAX9, AXIN2, EDA, SPRY2, TGFA, SPRY4, and WNT10A-and performed one of the largest case-control studies taking into account the number of genes and variants assessed, aiming at the identification of MLIA susceptibility factors. We show the involvement of PAX9, EDA, SPRY2, SPRY4, and WNT10A as risk factors for MLIA. Additionally, we uncovered 3 strong synergistic interactions between MLIA liability and MSX1-TGFA, AXIN2-TGFA, and SPRY2-SPRY4 gene pairs. We report the first evidence of the involvement of sprouty genes in MLIA susceptibility. This large study results in a better understanding of the genetic components and mechanisms underlying this trait.

Topics: Adenine; Anodontia; Axin Protein; Case-Control Studies; Cytosine; Ectodysplasins; Female; Fibroblast Growth Factors; Gene Frequency; Genetic Predisposition to Disease; Genotype; Guanine; Haplotypes; Humans; Incisor; Intracellular Signaling Peptides and Proteins; Linkage Disequilibrium; Male; Maxilla; Membrane Proteins; MSX1 Transcription Factor; Nerve Tissue Proteins; Odontogenesis; PAX9 Transcription Factor; Polymorphism, Single Nucleotide; Risk Factors; Thymine; Tooth, Deciduous; Transforming Growth Factor alpha; Wnt Proteins

Phenotypic characteristics expressed in syndromes give clues to the factors involved in the cause of isolated forms of the same defects. We investigated two genes responsible for craniofacial syndromes, FGFR1 and IRF6, in a collection of families with isolated tooth agenesis. Cheek swab samples were obtained for DNA analysis from 116 case/parent trios. Probands had at least one developmentally missing tooth, excluding third molars. In addition, we studied 89 cases and 50 controls from Ohio to replicate any positive findings. Genotyping was performed by kinetic polymerase chain-reaction or TaqMan assays. Linkage disequilibrium analysis and transmission distortion of the marker alleles were performed. The same variants in the IRF6 gene that are associated with isolated orofacial clefts are also associated with human tooth agenesis (rs861019, P = 0.058; rs17015215-V274I, P = 0.0006; rs7802, P = 0.004). Mutations in IRF6 cause Van der Woude and popliteal pterygium syndromes. The craniofacial phenotypic characteristics of these syndromes include oral clefts and preferential tooth agenesis of incisors and premolars, besides pits on the lower lips. Also it appears that preferential premolar agenesis is associated with FGFR1 (P = 0.014) and IRF6 (P = 0.002) markers. There were statistically significant data suggesting that IRF6 interacts not only with MSX1 (P = 0.001), but also with TGFA (P = 0.03).

Topics: Adolescent; Adult; Algorithms; Alleles; Anodontia; Child; Family Health; Female; Gene Frequency; Genetic Markers; Genetic Predisposition to Disease; Genotype; Haplotypes; Humans; Interferon Regulatory Factors; Linkage Disequilibrium; Male; Middle Aged; MSX1 Transcription Factor; Polymorphism, Single Nucleotide; Receptor, Fibroblast Growth Factor, Type 1; Transforming Growth Factor alpha

In this study, we sought to determine the association between tooth agenesis and DNA sequence variation in the genes MSX1 and PAX9 in an ethnically diverse human population. Since cleft lip/palate is also associated with both tooth agenesis and the gene TGFA, we included TGFA in the analysis as well. Cheek swab samples were obtained for DNA analysis from 116 case/parent trios. Probands had at least one developmentally missing tooth, excluding third molars. Genotyping was performed by single-strand conformational polymorphism or kinetic polymerase chain-reaction assays. Transmission distortion of the marker alleles and DNA sequence analysis was performed. Results showed that tooth agenesis is associated with markers of the genes MSX1 and TGFA. No mutations were found in MSX1 or PAX9 coding regions. There were statistically significant data suggesting that MSX1 interacts with PAX9. These findings suggest that MSX1, PAX9, and TGFA play a role in isolated dental agenesis.

Topics: Adolescent; Adult; Alleles; Anodontia; Base Pairing; Child; DNA-Binding Proteins; Exons; Female; Genetic Markers; Genotype; Haplotypes; Homeodomain Proteins; Humans; Introns; Male; Middle Aged; MSX1 Transcription Factor; PAX9 Transcription Factor; Polymerase Chain Reaction; Polymorphism, Single-Stranded Conformational; Sequence Analysis, DNA; Transcription Factors; Transforming Growth Factor alpha

The purpose of this study was to determine whether the candidate genes previously studied in subjects with cleft lip, cleft palate, or both are associated with hypodontia outside the region of the cleft.. One hundred twenty subjects from the Iowa Craniofacial Anomalies Research Center were selected based on the availability of both dental records and genotype information.. The type of orofacial clefting and type and location of dental anomalies (missing teeth, supernumerary teeth, or peg laterals) were assessed by dental chart review and radiographic examination. Genotype analysis of candidate genes was performed using polymerase chain reaction/single-strand conformation polymorphism analysis.. The prevalence of hypodontia in this sample was 47.5%, with 30.0% of subjects having missing teeth outside the cleft. There was a positive association between subjects with cleft lip or cleft lip and palate who had hypodontia outside the cleft region (compared with noncleft controls) and both muscle segment homeo box homolog 1 (MSX1) (p =.029) and transforming growth factor beta 3 (TGFB3) (p =.024). It was not possible in this analysis to determine whether this association was specifically associated with orofacial clefting combined with hypodontia or whether it was due primarily to the clefting phenotype.. In this sample, there was a significantly greater incidence of hypodontia outside the cleft region in subjects with cleft lip and palate, compared with cleft lip only or cleft palate only. Cleft lip and/or palate with hypodontia outside the cleft region was positively associated with both TGFB3 and MSX1, compared with noncleft controls.

Topics: Anodontia; Chi-Square Distribution; Child; Cleft Lip; Cleft Palate; DNA-Binding Proteins; Gene Frequency; Genetic Markers; Homeodomain Proteins; Humans; MSX1 Transcription Factor; PAX9 Transcription Factor; Polymerase Chain Reaction; Polymorphism, Single-Stranded Conformational; Statistics, Nonparametric; Transcription Factors; Transforming Growth Factor alpha; Transforming Growth Factor beta; Transforming Growth Factor beta3