Compromised actin dynamics underlie the orofacial cleft in Baraitser-Winter Cerebrofrontofacial syndrome with a variant in ACTB.

Craniofacial anomalies encompassing the orofacial cleft are associated with > 30% of systemic congenital malformations. Baraitser-Winter Cerebrofrontofacial syndrome (BWCFF) is a rare genetic disorder attributed to variants in the actin beta (ACTB) or actin gamma genes that are correlated with a range of craniofacial abnormalities, including cleft lip and/or palate. The underlying pathological mechanism of BWCFF remains elusive, and it is necessary to investigate the etiology of orofacial clefts in patients with BWCFF. In this study, we identified a missense variant (c.1043C > T: p.S348L) in the ACTB gene of a patient with BWCFF and concomitant cleft lip and palate. Furthermore, we performed functional assessments of this variant using various disease models such as the MDCK cell line and Xenopus laevis. These models revealed a compromised capacity of mutated ACTB to localize to the epithelial junction, consequently affecting the behavior of epithelial cells. Additionally, we discovered that the mutated ACTB exhibited an impaired ability to bind PROFILIN1, a critical factor in actin polymerization. This defective ability may contribute to the molecular etiology of aberrant epithelial cell adhesion and migration, resulting in orofacial cleft formation in BWCFF.

Craniofacial and dental characteristics of three Japanese individuals with genetically diagnosed SATB2-associated syndrome.

Craniofacial defects are one of the most frequent phenotypes in syndromic diseases. More than 30% of syndromic diseases are associated with craniofacial defects, which are important for the precise diagnosis of systemic diseases. Special AT-rich sequence-binding protein 2 (SATB2)-associated syndrome (SAS) is a rare syndromic disease associated with a wide variety of phenotypes, including intellectual disability and craniofacial defects. Among them, dental anomalies are the most frequently observed phenotype and thus becomes an important diagnostic criterion for SAS. In this report, we demonstrate three Japanese cases of genetically diagnosed SAS with detailed craniofacial phenotypes. The cases showed multiple dental problems, which have been previously reported to be linked to SAS, including abnormal crown morphologies and pulp stones. One case showed a characteristic enamel pearl at the root furcation. These phenotypes add new insights for differentiating SAS from other disorders.

Development of dentition: From initiation to occlusion and related diseases.

BACKGROUND: The development of dentition begins in the embryonic oral cavity and progresses in the branchial arches and alveolar bone. Continuous cellular and molecular crosstalk occurs during crown formation, after which the tooth germ begins to migrate apically through the alveolar process into the oral cavity. It eventually comes in contact with its antagonist in the contralateral jaw to establish functional occlusion. Any defect in either step can result in delayed tooth development, the spectrum of which varies from a congenitally missing tooth to an impacted tooth (infraocclusion) with an eruption problem, both of which can impair oral function. HIGHLIGHT: Congenitally missing teeth or eruption problems may result from genetic mutations. Several different mutations have been identified, each causing a distinct phenotype. Thus, it is imperative that medical providers understand the fundamentals of these genetic principles that govern such dental diseases. CONCLUSION: In this review, we focus on several diseases, including congenitally missing teeth and tooth eruption problems. We review these diseases with aspect to their association with a particular syndrome, as well as independently in a non-syndromic capacity. We also review previously identified genetic mutations and discuss the possible mechanisms that cause individual phenotypes by analyzing previous investigations. We also discuss future prospects of how genetic diagnosis and precision medicine could impact the clinical environment in the field of dentistry. ETHICAL APPROVAL: Present study has been carried out in accordance with The Code of Ethics of the World Medical Association and approved by Institutional Review Board of Osaka University Graduate School of Dentistry.