Orodental findings of a family with lacrimo-auriculo-dento digital (LADD) syndrome

CATSHL syndrome, a new family and phenotypic expansion

We report the case of a 12-year-old girl and her father who both had marked postnatal tall stature, camptodactyly and clinodactyly, scoliosis and juvenile-onset hearing loss. The CATSHL (CAmptodactyly - Tall stature - Scoliosis - Hearing Loss syndrome) syndrome was suspected, and molecular analysis revealed a hitherto unreported, monoallelic variant c.1861C>T (p.Arg621Cys) in FGFR3. This variant affects the same residue, but is different than, the variant p.Arg621His reported in the two families with dominant CATSHL described so far. Interestingly, peg-shaped incisors were observed in the proband, a feature never reported in CATSHL but typical of another FGFR3-related condition, LADD (Lacrimo - Auricolo - Dento - Digital) syndrome. The FGFR3 p.Arg621Cys variant seems to be a newly identified cause of CATSHL syndrome with some phenotypic overlap with the LADD syndrome.

Infigratinib, a selective FGFR1-3 tyrosine kinase inhibitor, alters dentoalveolar development at high doses

BACKGROUND

Fibroblast growth factor receptor-3 (FGFR3) gain-of-function mutations are linked to achondroplasia. Infigratinib, a FGFR1-3 tyrosine kinase inhibitor, improves skeletal growth in an achondroplasia mouse model. FGFs and their receptors have critical roles in developing teeth, yet effects of infigratinib on tooth development have not been assessed. Dentoalveolar and craniofacial phenotype of Wistar rats dosed with low (0.1 mg/kg) and high (1.0 mg/kg) dose infigratinib were evaluated using micro-computed tomography, histology, and immunohistochemistry.

RESULTS

Mandibular third molars were reduced in size and exhibited aberrant crown and root morphology in 100% of female rats and 80% of male rats at high doses. FGFR3 and FGF18 immunolocalization and extracellular matrix protein expression were unaffected, but cathepsin K (CTSK) was altered by infigratinib. Cranial vault bones exhibited alterations in dimension, volume, and density that were more pronounced in females. In both sexes, interfrontal sutures were significantly more patent with high dose vs vehicle.

CONCLUSIONS

High dose infigratinib administered to rats during early stages affects dental and craniofacial development. Changes in CTSK from infigratinib in female rats suggest FGFR roles in bone homeostasis. While dental and craniofacial disruptions are not expected at therapeutic doses, our findings confirm the importance of dental monitoring in clinical studies.

Lacrimo-auriculo-dento-digital syndrome: A novel mutation in a Korean family and review of literature

Background

Lacrimo‐auriculo‐dento‐digital (LADD) syndrome is a rare autosomal dominant disorder caused by mutations in one of the three genes: fibroblast growth factor receptor 2 (FGFR2), FGFR3, or FGF10. Affected patients have hypoplasia/aplasia of lacrimal ducts/glands, hypoplasia/aplasia of salivary glands, dental anomalies, ear anomalies, hearing loss, and digital anomalies.

Case Presentation

Proband was an 11‐year‐old male with xerostomia, xerophthalmia, and a referring diagnosis of Sjogren syndrome. He presented with microdontia, hypodontia, low‐set/cupped ear auricles, and hearing loss in the left ear.

Methods

Whole exome sequencing (WES) was performed on proband. Variations and segregation within the family were verified using Sanger sequencing.

Results

Molecular studies revealed a novel heterozygous missense mutation in exon 11 of FGFR2: c.1547C>T (p.Ala516Val), compatible with LADD syndrome.

Conclusion

To the best of our knowledge, this is the first report of a family with LADD syndrome in Korea. The combination of xerostomia and xerophthalmia, seen in patients with LADD syndrome, may be misdiagnosed as Sjogren syndrome. WES may be a useful clinical tool in ascertaining the affected gene in patients with suspected genetic disorders. Here, a literature review and summary of 23 case reports/series of LADD syndrome are presented, which may help to identify patients with this condition.

The Role of Fibroblast Growth Factors in Tooth Development and Incisor Renewal

The mineralized tissue of the tooth is composed of enamel, dentin, cementum, and alveolar bone; enamel is a calcified tissue with no living cells that originates from oral ectoderm, while the three other tissues derive from the cranial neural crest. The fibroblast growth factors (FGFs) are critical during the tooth development. Accumulating evidence has shown that the formation of dental tissues, that is, enamel, dentin, and supporting alveolar bone, as well as the development and homeostasis of the stem cells in the continuously growing mouse incisor is mediated by multiple FGF family members. This review discusses the role of FGF signaling in these mineralized tissues, trying to separate its different functions and highlighting the crosstalk between FGFs and other signaling pathways.

Prevalence of Taurodont Molars in a Selected Iranian Adult Population

Introduction:

Taurodontism is an anomaly characterized by elongated crowns and consumedly apical location of the bifurcation area. This study aimed to determine the prevalence of taurodontism in molars based on digital panoramic radiographies in eight cities of Iran.

Methods and Materials:

This descriptive cross-sectional study was conducted on 2360 digital panoramic radiographs taken for different treatment purposes. Demographic information of patients was recorded and radiographs were evaluated for presence of taurodont molars. The prevalence rates were calculated and the data were analyzed using SPSS software version 18 via paired t-test, chi square test and ANOVA.

Results:

A total of 2360 panoramic radiographs (from 51.4% male and 48.6% female patients) were evaluated and the prevalence of taurodontism was reported 22.9% (22.6% in males and 23.3% in females) (P>0.05). Its prevalence was 51.67% in the right and 48.33% in the left quadrants (P>0.05), 34.1% in the mandible and 65.9% in the maxilla (P=0.000) and 79.52% in the second and 20.48% in the first molar (P=0.000). The prevalence of hypotaurodontism, mesotaurodontism and hypertaurodontism was 84.13%, 11.07% and 4.8%, respectively.

Conclusion:

The prevalence of taurodont molars was high in Iran and it was more common in the second molars and in the maxilla. Hypotaurodontism had the highest prevalence.

Dental issues in lacrimo-auriculo-dento-digital syndrome: An autosomal dominant condition with clinical and genetic variability

BACKGROUND AND OVERVIEW

Lacrimo-auriculo-dento-digital (LADD) syndrome is an autosomal dominant disorder with variable lacrimal and salivary gland hypoplasia and aplasia, auricular anomalies and hearing loss, dental defects and caries, and digital anomalies.

CASE DESCRIPTION

The authors present the cases of 2 unrelated children with enamel defects and history of dry mouth leading to recurrent dental caries. The referring diagnoses were Sjögren disease and hypohidrotic ectodermal dysplasia, respectively. The geneticist suspected LADD syndrome, which was confirmed by means of molecular studies showing mutations of 2 genes: fibroblast growth factor receptor 2 and fibroblast growth factor 10, respectively. Similarly affected relatives indicated an autosomal dominant inheritance. These relatives needed multiple dental rehabilitations during childhood and dentures in adulthood.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Dry mouth, multiple caries, enamel defects, and abnormal tooth morphology were the reasons for seeking care from dentists. However, clinical evaluation and diagnostic imaging studies helped identify anomalies of the lacrimal and salivary glands, ears, and digits, indicating involvement of different areas of the body, compatible with LADD syndrome. Accordingly, dentists should consider genetic disorders in patients with multiple anomalies. For instance, oculodentodigital syndrome, oral-facial-digital syndrome, and LADD syndrome (among others) may have dental issues as the major clinical manifestation. Accurate identification of a particular syndrome is now commonplace with the use of genetic testing. When a patient has multiple anomalies suggestive of a syndromic condition, appropriate genetic testing can help verify the clinical diagnosis. Keeping genetics in mind helps earlier identification of other affected family members with diagnostic genetic testing and appropriate treatment; the economic advantage is to shorten the diagnostic odyssey and possibly preserve dentition.

A Case of Lacrimo-Auriculo-Dento-Digital Syndrome with Multiple Congenitally Missing Teeth

Lacrimo-auriculo-dento-digital (LADD) syndrome is an extremely rare disorder which may occur sporadically or inheritably as an autosomal dominant condition. It is characterized by defects in the lacrimal apparatus, ear problems, and dental and digital abnormalities. However, specific symptoms vary greatly among the cases with a high degree of overlap with other similar genetic disorders. Here, we describe a 7-year-old boy with LADD syndrome, clinical and radiological findings, dental treatment undertaken, and its differential diagnosis.

Complete agenesis of major salivary glands

A 4 year-old female patient was treated for persistent right-sided dacryocystitis and xerostomia. MRI was performed to screen for a dry syndrome; which resulted in the diagnosis of agenesis of the parotid and submandibular glands as well as lacrimal duct malformation. An MRI of each parent was normal. The mother's history revealed 4 days of pyrexia during the 8th week of amenorrhea. This was an isolated case, with no family history, characterized by a febrile episode during pregnancy at the period of main salivary gland genesis. Epigenetic mechanisms could be implicated.

Signaling by FGFR2b controls the regenerative capacity of adult mouse incisors

Rodent incisors regenerate throughout the lifetime of the animal owing to the presence of epithelial and mesenchymal stem cells in the proximal region of the tooth. Enamel, the hardest component of the tooth, is continuously deposited by stem cell-derived ameloblasts exclusively on the labial, or outer, surface of the tooth. The epithelial stem cells that are the ameloblast progenitors reside in structures called cervical loops at the base of the incisors. Previous studies have suggested that FGF10, acting mainly through fibroblast growth factor receptor 2b (FGFR2b), is crucial for development of the epithelial stem cell population in mouse incisors. To explore the role of FGFR2b signaling during development and adult life, we used an rtTA transactivator/tetracycline promoter approach that allows inducible and reversible attenuation of FGFR2b signaling. Downregulation of FGFR2b signaling during embryonic stages led to abnormal development of the labial cervical loop and of the inner enamel epithelial layer. In addition, postnatal attenuation of signaling resulted in impaired incisor growth, characterized by failure of enamel formation and degradation of the incisors. At a cellular level, these changes were accompanied by decreased proliferation of the transit-amplifying cells that are progenitors of the ameloblasts. Upon release of the signaling blockade, the incisors resumed growth and reformed an enamel layer, demonstrating that survival of the stem cells was not compromised by transient postnatal attenuation of FGFR2b signaling. Taken together, our results demonstrate that FGFR2b signaling regulates both the establishment of the incisor stem cell niches in the embryo and the regenerative capacity of incisors in the adult.

Case report: Presentation of lacrimo-auriculodento- digital (LADD) syndrome in a young female patient

BACKGROUND

Lacrimo-auriculo-dento-digital (LADD) syndrome (OMIM #149730) is an autosomal-dominant congenital disorder that can be caused by heterozygous mutations in the tyrosine kinase domains of the genes encoding fibroblast growth factor receptors 2 (FGFR2) and 3 (FGFR3), and has been found in association with a mutation in the FGF10 gene, which encodes an Fgfr ligand. Clinical signs vary, but the condition is characterised by involvement of the lacrimal and salivary systems, cup-shaped ears, hearing loss and dental abnormalities. Additional features may include involvement of the hands and feet with other body systems particularly the kidneys.

CASE REPORT

Previous literature on the subject has been reviewed and this case is the first presentation of LADD syndrome in the Republic of Ireland, as a sporadic case in a 12-year-old girl who exhibited a range of dental and digital anomalies.

TREATMENT

Her general medical practitioner managed her medical care whilst her oral care necessitated a multidisciplinary approach involving restorative and orthodontic elements.

FOLLOW-UP

The initial restorative phase of treatment has successfully improved the appearance of the patient's anterior teeth using direct resin composite build-ups.