Familial autosomal dominant severe ankyloglossia with tooth abnormalities

Effectiveness of Myofunctional Therapy in Ankyloglossia: A Systematic Review

Ankyloglossia is a pathology of the tongue in which the frenulum appears anchored to the floor of the mouth. The treatment of choice for this pathology is frenectomy, but myofunctional therapy is emerging in recent years as a complement to surgical intervention. This systematic review aims to synthesize the scientific evidence and assess its quality regarding the use of myofunctional therapy in ankyloglossia. The Cochrane Central Register of Controlled Trials, Physiotherapy Evidence Database, Pubmed, Web of Science and Scopus were searched. Study quality was determined using the PEDro scale, STROBE statement and single-case experimental design scale. Eleven studies were selected. Based on the studies included in this review, surgery is more effective than myofunctional therapy, although better results are achieved if both are combined. Improvements have been found in maternal pain, weight gain of babies, duration of breastfeeding, tongue mobility, strength and endurance, sleep apnea, mouth breathing and snoring, quality of life, clenching teeth, myofascial tension, pain after surgery and speech sound production. These findings must be taken with caution because of the small number of articles and their quality. Future clinical trials using larger sample sizes and with higher methodological quality are needed.

Role of LGR5-positive mesenchymal cells in craniofacial development

Leucine Rich Repeat Containing G Protein-Coupled Receptor 5 (LGR5), a Wnt pathway member, has been previously recognised as a stem cell marker in numerous epithelial tissues. In this study, we used Lgr5-EGFP-CreERT2 mice to analyse the distribution of LGR5-positive cells during craniofacial development. LGR5 expressing cells were primarily located in the mesenchyme adjacent to the craniofacial epithelial structures undergoing folding, such as the nasopharyngeal duct, lingual groove, and vomeronasal organ. To follow the fate of LGR5-positive cells, we performed lineage tracing using an inducible Cre knock-in allele in combination with Rosa26-tdTomato reporter mice. The slight expansion of LGR5-positive cells was found around the vomeronasal organ, in the nasal cavity, and around the epithelium in the lingual groove. However, most LGR5 expressing cells remained in their original location, possibly supporting their signalling function for adjacent epithelium rather than exerting their role as progenitor cells for the craniofacial structures. Moreover, Lgr5 knockout mice displayed distinct defects in LGR5-positive areas, especially in the reduction of the nasopharyngeal duct, the alteration of the palatal shelves shape, abnormal epithelial folding in the lingual groove area, and the disruption of salivary gland development. The latter defect manifested as an atypical number and localisation of the glandular ducts. The gene expression of several Wnt pathway members (Rspo1-3, Axin2) was altered in Lgr5-deficient animals. However, the difference was not found in sorted EGFP-positive cells obtained from Lgr5 +/+ and Lgr5 -/- animals. Expression profiling of LGR5-positive cells revealed the expression of several markers of mesenchymal cells, antagonists, as well as agonists, of Wnt signalling, and molecules associated with the basal membrane. Therefore, LGR5-positive cells in the craniofacial area represent a very specific population of mesenchymal cells adjacent to the epithelium undergoing folding or groove formation. Our results indicate a possible novel role of LGR5 in the regulation of morphogenetic processes during the formation of complex epithelial structures in the craniofacial areas, a role which is not related to the stem cell properties of LGR5-positive cells as was previously defined for various epithelial tissues.

Binder's phenotype with ankyloglossia: Report of a rare inherited association in an Indian female

Binder's syndrome, a rare congenital malformation of nasomaxillary complex, first described in 1962, has a hexad of characteristic clinical and radiographic features consisting of arhinoid face, intermaxillary hypoplasia with malocclusion, abnormal position of nasal bones, atrophy of nasal mucosa, reduced or absent anterior nasal spine and hypoplastic/absent frontal sinus. The typical facies due to mid-face hypoplasia may also be accompanied by other midline malformations such as cleft palate, spinal, skeletal and cardiac abnormalities. It is usually sporadic, of unknown etiology although various environmental and genetic mechanisms are implicated due to few familial cases predominantly in the Swedish population. A case of inherited Binder's syndrome is presented in an Indian female patient with an unusual finding of ankyloglossia (AG). The development of the anterior nasal spine and AG are chronologically related as they both occur during the 5^th–6^th weeks of gestation. The possible etiopathogenetic mechanisms for this rare association are reviewed.

Sox2 Controls Periderm and Rugae Development to Inhibit Oral Adhesions

In humans, ankyloglossia and cleft palate are common congenital craniofacial anomalies, and these are regulated by a complex gene regulatory network. Understanding the genetic underpinnings of ankyloglossia and cleft palate will be an important step toward rational treatment of these complex anomalies. We inactivated the Sry (sex-determining region Y)-box 2 (Sox2) gene in the developing oral epithelium, including the periderm, a transient structure that prevents abnormal oral adhesions during development. This resulted in ankyloglossia and cleft palate with 100% penetrance in embryos examined after embryonic day 14.5. In Sox2 conditional knockout embryos, the oral epithelium failed to differentiate, as demonstrated by the lack of keratin 6, a marker of the periderm. Further examination revealed that the adhesion of the tongue and mandible expressed the epithelial markers E-Cad and P63. The expanded epithelia are Sox9-, Pitx2-, and Tbx1-positive cells, which are markers of the dental epithelium; thus, the dental epithelium contributes to the development of oral adhesions. Furthermore, we found that Sox2 is required for palatal shelf extension, as well as for the formation of palatal rugae, which are signaling centers that regulate palatogenesis. In conclusion, the deletion of Sox2 in oral epithelium disrupts palatal shelf extension, palatal rugae formation, tooth development, and periderm formation. The periderm is required to inhibit oral adhesions and ankyloglossia, which is regulated by Sox2. In addition, oral adhesions occur through an expanded dental epithelial layer that inhibits epithelial invagination and incisor development. This process may contribute to dental anomalies due to ankyloglossia.