Expanding the genetic spectrum of tooth agenesis using whole-exome sequencing

Main genetic entities associated with tooth agenesis

BACKGROUND

Tooth agenesis refers to the absence of one or more of the deciduous or permanent teeth. Tooth agenesis results from a series of disrupted reciprocal ectodermal mesenchymal interactions taking place during the early stages of tooth development.

METHODS

A narrative literature review was performed to describe the main genetic syndromes associated with tooth agenesis.

RESULTS AND CONCLUSIONS

The etiology of congenital tooth agenesis is multifactorial and include genetic, epigenetic, and environmental influences. Syndromes associated with chromosomal alterations, ectodermal dysplasia, Axenfeld-Rieger syndrome, oral-facial cleft syndromes, and syndromes with cancer predisposition are among the main entities presenting with tooth agenesis.

CLINICAL RELEVANCE

Tooth agenesis disorders can affect the masticatory function and cause disfigurement leading to physiological and psychological complications. Early recognition of these entities is crucial to guide the management of the patient and to provide families with the appropriate genetic counseling.

Exploring the genetics, mechanisms, and therapeutic innovations in non-syndromic tooth agenesis

Tooth agenesis is the congenital absence of one or more teeth in the normal series due to failures during dental development in the odontogenesis process. Although tooth development mechanisms are more precise in the literature, the etiology of non-syndromic tooth agenesis remains partially unknown. Mutations in genes that regulate the transcription factors involved in tooth development are associated with this condition. Despite advances in genetic research, questions remain about whose understanding might enable more precise and customized treatments. This study aimed to explain the molecular mechanisms associated with non-syndromic tooth agenesis and treatment progression regarding the condition in genetics. The search was non-systematic and performed in MedLine (via PubMed). The inclusion criteria were observational and experimental studies published in English, Portuguese, and Spanish, with open access and without time restrictions. The data analysis was narrative/descriptive. Fifty-three articles were selected. The primary genes associated with non-syndromic tooth agenesis identified in the study include PAX9 and MSX1 - essential for molar and premolar formation; WNT10A and WNT10B - involved in cell signaling during odontogenesis; AXIN2 - related to the regulation of cell control and colorectal cancer risk; EDA and EDAR - crucial for ectodermal structures; and BMP4 - regulates cell differentiation and morphogenesis. These lesions directly affect tooth formation and quantity. Understanding these genetic foundations and the molecular mechanisms of tooth agenesis is essential to improve diagnosis, develop customized therapies, and enhance patients' quality of life. Continuous research is critical to establish genetic-based therapeutic innovations.

Eight EDA mutations in Chinese patients with tooth agenesis and genotype-phenotype analysis

OBJECTIVE

Tooth agenesis is a common craniofacial malformation, which is often associated with gene mutations. The purpose of this research was to investigate and uncover ectodysplasin A (EDA) gene variants in eight Chinese families affected with tooth agenesis.

METHODS

Genomic DNA was extracted from tooth agenesis families and sequenced using whole-exome sequencing. The expression of ectodysplasin A1 (EDA1) protein was studied by western blot, binding activity with receptor was tested by pull-down and the NF-κB transcriptional activity was analyzed by Dual luciferase assay.

RESULTS

Eight EDA missense variants were discovered, of which two (c.T812C, c.A1073G) were novel. The bioinformatics analysis indicated that these variants might be pathogenic. The tertiary structure analysis revealed that these eight variants could cause structural damage to EDA proteins. In vitro functional studies demonstrated that the variants greatly affect protein stability or impair the EDA-EDAR interaction; thereby significantly affecting the downstream NF-κb transcriptional activity. In addition, we summarized the genotype-phenotype correlation caused by EDA variants and found that EDA mutations leading to NSTA are mostly missense mutations located in the TNF domain.

CONCLUSION

Our results broaden the variant spectrum of the EDA gene associated with tooth agenesis and provide valuable information for future genetic counseling.

i-Dent: A virtual assistant to diagnose rare genetic dental diseases

Rare genetic diseases are difficult to diagnose and this translates in patient's diagnostic odyssey! This is particularly true for more than 900 rare diseases including orodental developmental anomalies such as missing teeth. However, if left untreated, their symptoms can become significant and disabling for the patient. Early detection and rapid management are therefore essential in this context. The i-Dent project aims to supply a pre-diagnostic tool to detect rare diseases with tooth agenesis of varying severity and pattern. To identify missing teeth, image segmentation models (Mask R-CNN, U-Net) have been trained for the automatic detection of teeth on patients' panoramic dental X-rays. Teeth segmentation enables the identification of teeth which are present or missing within the mouth. Furthermore, a dental age assessment is conducted to verify whether the absence of teeth is an anomaly or a characteristic of the patient's age. Due to the small size of our dataset, we developed a new dental age assessment technique based on the tooth eruption rate. Information about missing teeth is then used by a final algorithm based on the agenesis probabilities to propose a pre-diagnosis of a rare disease. The results obtained in detecting three types of genes (PAX9, WNT10A and EDA) by our system are very promising, providing a pre-diagnosis with an average accuracy of 72 %.

Treatment strategy for patient with non-syndromic tooth agenesis: a case report and literature review

BACKGROUND

Non-syndromic tooth agenesis (NSTA) is a type of ectodermal dysplasia (ED) in which patients with non-syndromic oligodontia may only affect teeth. No pathological findings were found in other tissues of the ectodermal. Herein, we report a case of a NSTA patient with severe dental anxiety and poor oral health.

CASE PRESENTATION

A 5-year-old boy without systemic diseases presented as a patient with oligodontia, extensive caries, and periapical periodontitis. Molecular genetic analysis found a mutation in the Ectodysplasin A (EDA) gene, confirming the diagnosis of NSTA.

CONCLUSION

Tooth agenesis (TA) is the most common ectodermal developmental abnormality in humans. Non-syndromic oligodontia patients often seek treatment in the department of stomatology. Because of their complex oral conditions, these patients should be provided with a systematic and personalized treatment plan.

Identification of novel candidate genes associated with non-syndromic tooth agenesis in Mongolian families

OBJECTIVES

This study aimed to identify genetic variants associated with non-syndromic tooth agenesis (TA) in nine families from Mongolia using whole-exome sequencing (WES) and bioinformatics analysis.

MATERIAL AND METHODS

The study enrolled 41 participants, including three inherited and six non-inherited families. WES analysis was performed on 14 saliva samples from individuals with non-syndromic TA. The potential candidate genes were identified through variant filtering and segregation analysis. The filtered variants were then analyzed in silico mutation impact analysis.

RESULTS

WES analysis identified 21 variants associated with TA, and 5 of these variants met all filtering criteria. These variants were located in the exome region of MAST4, ITGA6, PITX2, CACNA1S, and CDON genes. The variant in PITX2 was found in eight participants from inherited and non-inherited families, while the MAST4 variant was identified in 6 participants from inherited families.

CONCLUSIONS

The study identified various genetic variant candidates associated with TA in different family groups, with PITX2 being the most commonly identified. Our findings suggest that MAST4 may also be a novel candidate gene for TA due to its association with the Wnt signaling pathway. Additionally, we found that five candidate genes related to focal adhesion and calcium channel complex were significant and essential in tooth development.

CLINICAL RELEVANCE

Identifying new pathogenic genes associated with TA can improve our understanding of the molecular mechanisms underlying the disease, leading to better diagnosis, prevention, and treatment. Early detection of TA based on biomarkers can improve dental management and facilitate orthodontic and prosthetic treatment.

The EDA/EDAR/NF-κB pathway in non-syndromic tooth agenesis: A genetic perspective

Non-syndromic tooth agenesis (NSTA) is one of the most common dental developmental malformations affected by genetic factors predominantly. Among all 36 candidate genes reported in NSTA individuals, EDA, EDAR, and EDARADD play essential roles in ectodermal organ development. As members of the EDA/EDAR/NF-κB signaling pathway, mutations in these genes have been implicated in the pathogenesis of NSTA, as well as hypohidrotic ectodermal dysplasia (HED), a rare genetic disorder that affects multiple ectodermal structures, including teeth. This review provides an overview of the current knowledge on the genetic basis of NSTA, with a focus on the pathogenic effects of the EDA/EDAR/NF-κB signaling pathway and the role of EDA, EDAR, and EDARADD mutations in developmental tooth defects. We also discuss the phenotypic overlap and genetic differences between NSTA and HED. Ultimately, this review highlights the importance of genetic analysis in diagnosing and managing NSTA and related ectodermal disorders, and the need for ongoing research to improve our understanding of these conditions.