Dento-maxillo-facial phenotype and implants-based oral rehabilitation in Ectodermal Dysplasia with WNT10A gene mutation: report of a case and literature review

The fundamentals of WNT10A

Human wingless-type MMTV integration site family member 10A (WNT10A) is a secreted glycoprotein that is involved in signaling pathways essential to ectodermal organogenesis and tissue regeneration. WNT10A was first linked to human disorders in 2006, demonstrating a WNT10a variant to be associated with cleft lip with/without cleft palate. Numerous publications have since then identified the importance of WNT10A in the development of ectodermal appendages and beyond. In this review, we provide information on the structure of the WNT10A gene and protein, summarize its expression patterns in different animal models and in human, and describe the identified roles in tissue and organ development and repair in the different animal model organisms. We then correlate such identified functions and working mechanisms to the pathophysiology of a spectrum of human diseases and disorders that result from germline loss-of-function mutations in WNT10A, including ectodermal dysplasia (ED) syndromes Odonto-oncho-dermal dysplasia (OODD), Schöpf-Schulz-Passarge syndrome (SSPS), and selective tooth agenesis, as well as pathological conditions like fibrosis and carcinogenesis that can be correlated with increased WNT10A activity (Section 5).

A novel WNT10A variant impairs the homeostasis of alveolar bone mesenchymal stem cells

OBJECTIVES

To explore the influence of a novel WNT10A variant on bone mineral density, proliferation, and osteogenic differentiation capacities of alveolar bone mesenchymal stem cells in humans.

SUBJECTS AND METHODS

Whole-exome sequencing and Sanger sequencing were utilized to detect gene variants in a family with non-syndromic tooth agenesis (NSTA). The panoramic mandibular index was calculated on the proband with WNT10A variant and normal controls to evaluate bone mineral density. Alveolar bone mesenchymal stem cells from the proband with a novel WNT10A variant and normal controls were isolated and cultured, then proliferation and osteogenic differentiation capacities were evaluated and compared.

RESULTS

We identified a novel WNT10A pathogenic missense variant (c.353A > G/p. Tyr118Cys) in a family with NSTA. The panoramic mandibular index of the proband implied a reduction in bone mineral density. Moreover, the proliferation and osteogenic differentiation capacities of alveolar bone mesenchymal stem cells from the proband with WNT10A Tyr118Cys variant were significantly decreased.

CONCLUSIONS

Our findings broaden the spectrum of WNT10A variants in patients with non-syndromic oligodontia, suggest an association between WNT10A and the proliferation and osteogenic differentiation of alveolar bone mesenchymal stem cells, and demonstrate that WNT10A is involved in maintaining jaw bone homeostasis.

Oligodontia in the Clinical Spectrum of Syndromes: A Systematic Review

The aim of this systematic review was to describe the clinical and genetic features of syndromes showing oligodontia as a sign. The review was performed according to the PRISMA 2020 checklist guidelines, and the search was conducted using PubMed, Scopus, Lilacs, Web of science, Livivo, and EMBASE and supplemented by a gray literature search on Google Scholar and ProQuest, applying key terms relevant to the research questions. The systematic review identified 47 types of syndromes in 83 studies, and the most common was hypohidrotic ectodermal dysplasia, which was reported in 24 patients in 22 studies. Other common syndromes that reported oligodontia included Axenfeld-Rieger syndrome, Witkop's syndrome, Ellis-van Creveld syndrome, blepharocheilodontic syndrome, and oculofaciocardiodental syndrome. The X-linked mode of inheritance was the most reported (n = 13 studies), followed by the autosomal dominant (n = 13 studies). The review describes the main syndromes that may have oligodontia as a clinical sign and reinforces the need for orodental-facial examining for adequate diagnosis and treatment of the affected patients. Molecular analysis in order to better understand the occurrence of oligodontia is imperative.

Reduced bone dimension in patients affected by oligodontia: A retrospective study on maxillary and mandibular CBCT

AIM

Oligodontia (OD) is a rare developmental condition characterized by the absence of six or more teeth. Dental implant placement may be challenging due to anatomical factors. This study aims to evaluate the alveolar bone dimensions in OD patients compared with controls.

MATERIALS AND METHODS

On maxillary and mandibular cone-beam computed tomography (CBCT), bone height and width were measured at every tooth and edentulous site. The distance to the inferior alveolar nerve was also measured. Fifty-three OD patients (40 maxillary and 32 mandibular CBCT) and 82 controls (51 maxillary and 31 mandibular CBCT) were compared using mixed models.

RESULTS

Compared with those in OD patients, maxillary permanent teeth and edentulous sites showed significantly higher mean height in control patients (incisive-canine site height: +2.12 mm; edentulous incisive-canine site height: +4.46 mm [p > .001]). For the mandibular permanent teeth, mean height was higher in controls than in OD patients at the incisive-canine (+3.82 mm [p > .001]) and premolar areas (+2.06 mm [p > .001]). Only edentulous incisive-canine sites were significantly different between controls and OD patients (mean: +0.52 mm [p > .001]). Changes in alveolar nerve position were observed in case of molar agenesis.

CONCLUSION

Maxillary and mandibular bone dimensions are reduced in OD patients compared with controls both in sites with permanent teeth and in edentulous areas.

Surgical bone augmentation procedures for oral rehabilitation of patients with oligodontia: A review with a systematic approach

Oligodontia is a developmental dental anomaly defined by the absence of 6 or more permanent teeth, excluding the third molars. We performed a review with a systematic approach and proposed a guideline for the choice of the bone augmentation surgery. The different bone augmentation technique terms were searched in the PubMed and Science Direct database. Clinical studies were eligible if they reported on pre-implant surgery in patients with oligodontia. The database search yielded 400 studies after duplicates removed. Thirty studies were finally included, involving 410 patients. Sixty-three sinus lifts were performed in 37 patients with no failure. Thirteen out of 33 patients with iliac bone transplantation and two out of 24 with parietal bone transplantation had resorption, one out of 4 patients who received allogeneic bone block had complete failure. Seventy-eight patients underwent guided bone regeneration, none had bone loss. No failure was found with the alveolar distraction osteogenesis technique. Four out of thirteen patients developed permanent hypoesthesia after inferior alveolar nerve transposition. The cumulative implant survival rate was 94.4% after bone augmentation procedures. Extensive edentulous areas should be grafted with parietal bone, as iliac grafts present a greater risk of resorption. Smaller edentulous areas should be treated by endobuccal harvesting or guided bone regeneration. Osteogenesis distraction and nerve transposition are effective surgeries for medium-to-large mandibular edentulous spaces. The implant survival rate is not significantly different between implants placed in grafted and nongrafted bone, the appropriate choice of bone augmentation technique can reduce the risk of peri‑implant bone resorption.

Association between tooth agenesis and cancer: a systematic review

The congenital absence of multiple teeth may share the same genetic background of the development of some types of cancer. Objective: This systematic review aimed to investigate the possible association between dental agenesis and cancer, and the perspective of agenesis as an early predictor for cancer risk. Methodology: The electronic databases PubMed, Scopus, Web of Science, Cochrane Library, LILACS, and OpenGrey were searched and the risk of bias was evaluated using the Newcastle-Ottawa tool. The GRADE tool was used to evaluate the certainty of the evidence. Results: Six studies met the eligibility criteria. A positive co-occurrence between ovarian cancer and hypodontia was found in two articles. Three studies evaluated the association between dental agenesis and colorectal cancer and only one showed common genes for these conditions. One paper found individuals with hypodontia had a higher risk of family history of cancer. Five studies had a fair quality and one a good quality. The certainty of evidence was classified as very low. Conclusion: Notwithstanding the limited scientific evidence, there may be a possible association between dental agenesis and cancer due to genes involved in both conditions. Agenesis of multiple teeth could be an early indicator of cancer risk. Nevertheless, studies with a better level of evidence are needed to confirm this possible association.

LEF1 haploinsufficiency causes ectodermal dysplasia

Ectodermal dysplasias are a family of genodermatoses commonly associated with variants in the ectodysplasin/NF-κB or the Wnt/β-catenin pathways. Both pathways are involved in signal transduction from ectoderm to mesenchyme during the development of ectoderm-derived structures. Wnt/β-catenin pathway requires the lymphoid enhancer-binding factor 1 (LEF1), a nuclear mediator, to activate target gene expression. In mice, targeted inactivation of the LEF1 gene results in a complete block of development of multiple ectodermal appendages. We report two unrelated patients with 4q25 de novo deletion encompassing LEF1, associated with severe oligodontia of primary and permanent dentition, hypotrichosis and hypohidrosis compatible with hypohidrotic ectodermal dysplasia. Taurodontism and a particular alveolar bone defect were also observed in both patients. So far, no pathogenic variants or variations involving the LEF1 gene have been reported in human. We provide further evidence for LEF1 haploinsufficiency role in ectodermal dysplasia and delineate its clinical phenotype.

Dental implants in patients with ectodermal dysplasia: A systematic review

PURPOSE

This study sought to assess the clinical outcome and survival rate of oral implants placed in individuals with ectodermal dysplasia (ED), based on previously published studies.

METHODS

An electronic search without time restrictions was undertaken in 5 databases (PubMed/Medline, Web of Science, ScienceDirect, J-Stage, Lilacs). Descriptive statistics, Kaplan Meier estimator and implant failure probability were calculated.

RESULTS

90 publications were included, reporting 228 ED patients that received 1472 implants (1392 conventional, 47 zygomatic, 33 mini-implants). Mean age of the patients was 20.2 ± 6.8 years (2-56). Patients had a mean of 3.2 ± 2.5 maxillary and 2.1 ± 2.6 mandibular permanent teeth (min-max, 0-14). Patients received a mean of 8.2 ± 3.8 implants (1-20). Most implants were placed in the third decade of life, 24.6% of the implants were placed in children (0-17 years of age). 1391 implants had information on follow-up (72 failures, 5.2%). The 20-year CSR was 84.6%. The probability of failure was 4.5% (95%CI 3.5%-5.6%, p < 0.001). Additional treatments performed were Le Fort I (99 implants, 20 patients, 3.5% failed), grafting (497 implants, 77 patients, 5.2% failed), distraction osteogenesis (79 implants, 16 patients, 10.1% failed). Mean follow-up was 42.9 ± 41.9 months (min-max, 2-240).

CONCLUSIONS

Dental implants placed in ED patients, either infants or adults, present a high survival rate (20-year CSR 84.6%).

Prosthetic rehabilitation of patients with hypohidrotic ectodermal dysplasia: A systematic review

Hypohidrotic ectodermal dysplasia (HED) comprises a large group of inherited disorders of ectodermal structures, characterised by hypo- or anhidrosis, hypotrichosis and hypo- or oligo- or anodontia. We aimed to systematically assess the spectrum of prosthodontic approaches with regard to the patients' age and to provide clinical implications for practicing dentists. An electronic and manual search was conducted in four databases (Medline, LIVIVO, Cochrane Library, Web of Science Core Collection). Publications of multiple study designs written in English or German without data restrictions, reporting on prosthodontic treatment of patients diagnosed with HED and afflicted with oligo- or anodontia, were included. In total, 75 articles on 146 patients were analysed according to the patients' age. In children aged 2-17 years, removable full or partial (over)dentures represented standard treatment. In the mandible, implant-supported removable dentures on two interforaminal implants presented an alternative, already in young childhood. In cases with more than six teeth per jaw, also fixed (resin) bridges were used, frequently after orthodontic treatment. In adults, fixed or removable reconstructions with the help of up to eight implants per jaw, usually placed after bone augmentation procedures, were standard. Ten case reports/series with long-term follow-up illustrated the need for consistent maintenance including denture renewals. Prosthodontic rehabilitation should start in early childhood and needs to be revised in accordance with the patients' growth. Treatment should be carried out by a multidisciplinary team addressing variable demands in different age groups.

Impacted Lower Second Permanent Molars at the Ramus and Coronoid Process: A New Clinical Symptom of the WNT10A Mutation in Ectodermal Dysplasia

AIM

Hidrotic ectodermal dysplasia (ED) with the WNT10A mutation produces variable dentofacial symptoms. The aim of this study was to describe a new clinical symptom, i.e., specific to the WNT10A mutation in hidrotic ED. The study investigated the migratory trend of the lower second permanent molars to the ramus or coronoid process. To the best of authors' knowledge, no data in the literature describe this trend in cases of hidrotic ED.

MATERIALS AND METHODS

A three-generation family pedigree was established for seven families after the diagnosis of hidrotic ED in a 10-year-old boy. Thereafter, a genetic and clinical study was conducted on three families with at least one individual affected by hidrotic ED (20 individuals). We selected the children with molar germs 37 and 47. The eruption axes of these germs were then traced on the panoramic images at the initial time (T0) and 1 year later (T0 + 1 year), and the deviations between these axes were measured.

RESULTS

A significant familial consanguinity was shown. Eight subjects presented with the hidrotic ED phenotype. Among them, three individuals carried germs 37 and 47. Over time, the measured deviations between the eruption axes of the latter displayed, in the majority of the cases, a distal inclination toward the ramus.

LIMITATIONS

A larger sample size is mandatory to assess the frequencies and treatment modalities.

CONCLUSION

The presence of germs in the lower second permanent molars in patients with hidrotic ED is an important clinical symptom that should be monitored to detect and prevent ectopic migration of these teeth.

CLINICAL SIGNIFICANCE

In hidrotic ED cases, the study of the presence of the second lower permanent germs must include clinical and radiological examinations. Establishing an inter-ceptive treatment is necessary to prevent the migration of the molars in question.How to cite this article: Sfeir E, Aboujaoude S. Impacted Lower Second Permanent Molars at the Ramus and Coronoid Process: A New Clinical Symptom of the WNT10A Mutation in Ectodermal Dysplasia. Int J Clin Pediatr Dent 2017;10(4):363-368.

Gene screening facilitates diagnosis of complicated symptoms: A case report

Gene mutation has an important role in disease pathogenesis; therefore, genetic screening is a useful tool for diagnosis. The present study screened pathogenic genes, ectodysplasin A (EDA) and lamin A/C (LMNA), in a patient with suspected syndromic hearing impairment and various other symptoms including tooth and skin abnormalities. Large-scale sequencing of 438 deafness-associated genes and whole-genome sequencing was also performed. The present findings did not identify copy number variation and mutations in EDA; therefore, excluding the possibility of EDA-initiated ectodermal dysplasia syndrome. A synonymous mutation in LMNA, possibly due to a splicing abnormality, did not elucidate the pathogenesis of Hutchinson-Gilford progeria syndrome. Whole-genome sequencing revealed copy number variations or mutations in various candidate genes which may elucidate part of the symptoms observed. The copy number variations and mutations were also used to identify single nucleotide variations (SNVs) in crystallin mu (CRYM), RAB3 GTPase activating protein catalytic subunit 1 (RAB3GAP1) and Wnt family member 10A (WNT10A), implicated in deafness, hypogonadism and tooth/skin abnormalities, respectively. The importance of an existing SNV in CRYM and a novel SNV in RAB3GAP1 in pathogenesis remains to be further elucidated. The WNT10A p.G213S mutation was confirmed to be the etiological cause of tooth agenesis and ectodermal dysplasia as previously described. It was concluded that a mutation in WNT10A may be the reason for some of the symptoms observed in the patient; however, other genes may also be involved for other symptoms. The findings of the present study provide putative gene mutations that require further investigation in order to determine their roles in pathogenesis.

Management of rare diseases of the Head, Neck and Teeth: results of a French population-based prospective 8-year study

BACKGROUND

In the last ten years, national rare disease networks have been established in France, including national centres of expertise and regional ones, with storage of patient data in a bioinformatics tool. The aim was to contribute to the development and evaluation of health strategies to improve the management of patients with rare diseases. The objective of this study has been to provide the first national-level data concerning rare diseases of the head, neck and teeth and to assess the balance between demand and supply of care in France.

METHODS

Centres of expertise for rare diseases record a minimum data set on their clinical cases, using a list of rare Head, Neck and Teeth diseases established in 2006. The present analysis focuses on 2008 to 2015 data based on the Orphanet nomenclature. Each rare disease RD "case" was defined by status "affected" and by the degree of diagnostic certainty, encoded as: confirmed, probable or non-classifiable. Analysed parameters, presented with their 95% confidence intervals using a Poisson model, were the following: time and age at diagnosis, proportions of crude and standardized RD prevalence by age, gender and geographical site. The criteria studied were the proportions of patients in Paris Region and the "included cases geography", in which these proportions were projected onto the other French Regions, adjusting for local populations.

RESULTS

In Paris Region, estimated prevalence of these diseases was 5.58 per 10,000 inhabitants (95% CI 4.3-7.1). At December 31st 2015, 11,342 patients were referenced in total in France, of whom 7294 were in Paris Region. More than 580 individual clinical entities (ORPHA code) were identified with their respective frequencies. Most abnormalities were diagnosed antenatally. Nearly 80% of patients recorded come to Paris hospitals to obtain either diagnosis, care or follow up. We observed that the rarer the disease, the more patients were referred to Paris hospitals.

CONCLUSIONS

A health network covering a range of aspects of the rare diseases problematic from diagnostics to research has been developed in France. Despite this, there is still a noticeable imbalance between health care supply and demand in this area.

Odonto-onycho-dermal dysplasia in a patient homozygous for a WNT10A nonsense mutation and mild manifestations of ectodermal dysplasia in carriers of the mutation

Background

Odonto-onycho-dermal dysplasia (OODD) is a rare form of ectodermal dysplasia characterized by severe oligodontia, onychodysplasia, palmoplantar hyperkeratosis, dry skin, hypotrichosis, and hyperhidrosis of the palms and soles. The ectodermal dysplasias resulting from biallelic mutations in the WNT10A gene result in highly variable phenotypes, ranging from isolated tooth agenesis to OODD and Schöpf-Schulz-Passarge syndrome (SSPS).

Case presentation

We identified a female patient, with consanguineous parents, who was clinically diagnosed with OODD. Genetic testing showed that she was homozygous for a previously reported pathogenic mutation in the WNT10A gene, c.321C > A, p.Cys107*. The skin and nail abnormalities were for many years interpreted as psoriasis and treated accordingly. A thorough clinical examination revealed hypotrichosis and hyperhidrosis of the soles and dental examination revealed agenesis of permanent teeth except the two maxillary central incisors. Skin biopsies from the hyperkeratotic palms and soles showed the characteristic changes of eccrine syringofibroadenomatosis, which has been described in patients with ectodermal dysplasias. Together with a family history of tooth anomalies, this lead to the clinical suspicion of a hereditary ectodermal dysplasia.

Conclusion

This case illustrates the challenges of diagnosing ectodermal dysplasia like OODD and highlights the relevance of interdisciplinary cooperation in the diagnosis of rare conditions.

The Gene Network Underlying Hypodontia

Mammalian tooth development is a precise and complicated procedure. Several signaling pathways, such as nuclear factor (NF)-κB and WNT, are key regulators of tooth development. Any disturbance of these signaling pathways can potentially affect or block normal tooth development, and presently, there are more than 150 syndromes and 80 genes known to be related to tooth agenesis. Clarifying the interaction and crosstalk among these genes will provide important information regarding the mechanisms underlying missing teeth. In the current review, we summarize recently published findings on genes related to isolated and syndromic tooth agenesis; most of these genes function as positive regulators of cell proliferation or negative regulators of cell differentiation and apoptosis. Furthermore, we explore the corresponding networks involving these genes in addition to their implications for the clinical management of tooth agenesis. We conclude that this requires further study to improve patients' quality of life in the future.