Dyrk1a is required for craniofacial development in Xenopus laevis

Loss of function variations in the dual specificity tyrosine-phosphorylation-regulated kinase 1 A (DYRK1A) gene are associated with craniofacial malformations in humans. Here we characterized the effects of deficient DYRK1A in craniofacial development using a developmental model, Xenopus laevis. Dyrk1a mRNA and protein were expressed throughout the developing head and both were enriched in the branchial arches which contribute to the face and jaw. Consistently, reduced Dyrk1a function, using dyrk1a morpholinos and pharmacological inhibitors, resulted in orofacial malformations including hypotelorism, altered mouth shape, slanted eyes, and narrower face accompanied by smaller jaw cartilage and muscle. Inhibition of Dyrk1a function resulted in misexpression of key craniofacial regulators including transcription factors and members of the retinoic acid signaling pathway. Two such regulators, sox9 and pax3 are required for neural crest development and their decreased expression corresponds with smaller neural crest domains within the branchial arches. Finally, we determined that the smaller size of the faces, jaw elements and neural crest domains in embryos deficient in Dyrk1a could be explained by increased cell death and decreased proliferation. This study is the first to provide insight into why craniofacial birth defects might arise in humans with variants of DYRK1A.

Craniofacial identification standards: A review of reliability, reproducibility, and implementation

There are numerous anatomical and anthropometrical standards that can be utilised for craniofacial analysis and identification. These standards originate from a wide variety of sources, such as orthodontic, maxillofacial, surgical, anatomical, anthropological and forensic literature, and numerous media have been employed to collect data from living and deceased subjects. With the development of clinical imaging and the enhanced technology associated with this field, multiple methods of data collection have become accessible, including Computed Tomography, Cone-Beam Computed Tomography, Magnetic Resonance Imaging, Radiographs, Three-dimensional Scanning, Photogrammetry and Ultrasound, alongside the more traditional in vivo methods, such as palpation and direct measurement, and cadaveric human dissection. Practitioners often struggle to identify the most appropriate standards and research results are frequently inconsistent adding to the confusion. This paper aims to clarify how practitioners can choose optimal standards, which standards are the most reliable and when to apply these standards for craniofacial identification. This paper describes the advantages and disadvantages of each mode of data collection and collates published research to review standards across different populations for each facial feature. This paper does not aim to be a practical instruction paper; since this field encompasses a wide range of 2D and 3D approaches (e.g., clay sculpture, sketch, automated, computer-modelling), the implementation of these standards is left to the individual practitioner.

First transcriptome sequencing, assembly, and annotation dataset for the freshwater angelfish, pterophyllum scalare

Cichlids are relevant to biological research for their craniofacial variations that are analogous to human structure and associated congenital anomalies. However, only a limited number of cichlids have genetic information available. Investigating cichlids and adding to the body of knowledge about them may provide better insights into studying developmental biology and craniofacial structure. The angelfish, Pterophyllum scalare, is one cichlid for which we lack genetic information including a draft transcriptome assembly. This work is the first to provide a draft transcriptome and annotation using long-read Nanopore sequencing for P. scalare. Total RNA was extracted from angelfish tissue, and a cDNA-PCR library was prepared. Sequencing was performed on a singular R.9.4.1 MinION flow cell for 84 h. Various bioinformatic tools were then employed to assemble the sequencing reads into a transcriptome. The transcriptome was then annotated against various databases. 23 million sequencing reads were collected totalling 21.9 Gb. The N50 sequencing read length was 1255 bp and the mean read length was 938. The data had an initial mean Phred score of 10.04. After assembly, the final transcriptome consists of 98,125 transcripts with a mean length of 1552 and N50 length of 2277. The transcriptome has a completeness of 80.5% as assessed by BUSCO. Functional annotation revealed pathways related to signal transduction, carbohydrate metabolism, and transcription are the most annotated in the transcriptome.

Human stem cell model of neural crest cell differentiation reveals a requirement of SF3B4 in survival, maintenance, and differentiation

In vitro modeling is a powerful approach to investigate the pathomechanisms driving human congenital conditions. Here we use human embryonic stem cells (hESCs) to model Nager and Rodriguez syndromes, two craniofacial conditions characterized by hypoplastic neural crest-derived craniofacial bones, caused by pathogenic variants of SF3B4, a core component of the spliceosome. We observed that siRNA-mediated knockdown of SF3B4 interferes with the production of hESC-derived neural crest cells, as seen by a marked reduction in neural crest gene expression. This phenotype is associated with an increase in neural crest cell apoptosis and premature neuronal differentiation. Altogether these results point at a role of SF3B4 in neural crest cell survival, maintenance, and differentiation. We propose that the dysregulation of these processes may contribute to Nager/Rodriguez syndrome associated craniofacial defects.

Stable fixation using absorbable sutures in craniofacial surgery in patients over 24 months of age-a retrospective study

PURPOSE

In craniofacial surgery, the stable fixation of transposed bone segments is crucial in order to ensure good long-term results. The use of absorbable material in fixation avoids the need for a second surgery, which would otherwise be required to remove osteosynthesis material. The authors of the present manuscript have already demonstrated that absorbable sutures ensure the stable fixation of bone segments in patients up to 24 months of age. However, it has thus far remained unclear whether stable fixation is possible in older patients by using only absorbable sutures due to the slower bone remodelling and prolonged healing time in this cohort.

METHOD

For the present study, osteosynthesis was performed in 50 patients ranging from 25.7 to 192.1 months of age (mean, 61.4 ± 21.7 months) using solely absorbable sutures (PDS II®, Ethicon, Germany). Post-operative stability and possible restrictions-such as foreign body reactions-were evaluated within clinical and radiological routine follow-ups.

RESULTS

All children demonstrated clinically and radiologically stable osteosynthesis both directly post-operatively and in follow-ups. No significant foreign body reaction could be seen.

CONCLUSION

The present study demonstrates-for the first time-that absorbable sutures with a longer absorption period are also very well suited for the fixation of bone segments in patients over 24 months of age. The sole use of absorbable sutures in children over 24 months of age is a safe procedure with nearly no foreign body reactions. The procedure enables stable and highly cost-effective osteosynthesis without altering the osteotomy design.

Comparison of methodologies for craniofacial soft-tissue cephalometrics: The value of virtual reality

BACKGROUND

Myriad options are available for plastic surgeons to perform soft-tissue analysis, which is vital to perioperative evaluation and research. Our objective is to compare the accuracy, precision, and efficiency of the available cephalometric modalities for conducting facial soft-tissue measurements.

METHODS

Twenty soft-tissue facial measurements were performed by 5 measurers with varying experiences on 5 adult subjects, using 6 methods-manual calipers, cone-beam CT, virtual reality (VR), 3D stereophotogrammetry, iPad-based 3D photogrammetry, and 2-dimensional photographs. Measurement sessions were timed and performed in triplicate, for a total of 9000 measurements. Intraclass correlation coefficient (ICC) was calculated for accuracy and one-way ANOVA was used for comparison. The coefficient of variation (CoV) was compared among groups to evaluate the precision of different methods by considering caliper measurements as the gold standard.

RESULTS

ICC among raters was 0.932, indicating excellent reliability. VR was significantly faster than other methods (137 s vs. 217 s for caliper, p < 0.001). CoV was the highest for 2D photographs and the lowest for VR (11.0 vs. 6.4, p < 0.001). The CoV of the caliper was similar to that of other methods, except for 2D photography, which was significantly higher. Measurements with the greatest absolute difference from caliper measurements, across modalities, were those around the eyes (left to right exocanthion), tragion to antitragion, and tragion to exocanthion.

CONCLUSION

2D photography is not an accurate method for cephalometric measurements. VR had the lowest variation between measurements, and was the fastest and equivalent to caliper measurements in accuracy. For studies involving a large number of cephalometrics, VR measurements may be a good option to improve study throughput.

Translation and validation of the German version of the FACE-Q paralysis module in adult patients with unilateral peripheral facial palsy

The aim was to develop and validate a German version of the FACE-Q paralysis module, a patient-reported outcome measure to assess health-related quality of life in adult patients with unilateral facial palsy. The FACE-Q craniofacial questionnaire, which includes the paralysis module, was translated. 213 patients with facial palsy completed the German FACE-Q paralysis along with the established FDI and FaCE questionnaires. Regression analyses were performed to examine the relationships between the different FACE-Q domains and patient and therapy characteristics. The FACE-Q scales had high internal consistency (Cronbach's alpha all > 0.6). High correlations were found between the FACE-Q and the FDI and FaCE (mean rho = 0.5), as well as within the FACE-Q (mean rho = 0.522). Unifactorial influences were found for all domains except Breathing (all p < 0.05). Multivariate independent predictors were found for some FACE-Q domains. Most influential predictors (> 8 subdomains): Patients who received physical therapy scored lower in ten subdomains than those who did not (all p < 0.05). Patients who had surgery scored lower in nine subdomains than patients without surgery (all p < 0.05). The German version of the FACE-Q Paralysis Module can now be used as a patient-reported outcome instrument in adult patients with facial nerve palsy.

Zebrafish raptor mutation inhibits the activity of mTORC1, inducing craniofacial defects due to autophagy-induced neural crest cell death

The mechanistic target of rapamycin (mTOR) coordinates metabolism and cell growth with environmental inputs. mTOR forms two functional complexes: mTORC1 and mTORC2. Proper development requires both complexes but mTORC1 has unique roles in numerous cellular processes, including cell growth, survival and autophagy. Here, we investigate the function of mTORC1 in craniofacial development. We created a zebrafish raptor mutant via CRISPR/Cas9, to specifically disrupt mTORC1. The entire craniofacial skeleton and eyes were reduced in size in mutants; however, overall body length and developmental timing were not affected. The craniofacial phenotype associates with decreased chondrocyte size and increased neural crest cell death. We found that autophagy is elevated in raptor mutants. Chemical inhibition of autophagy reduced cell death and improved craniofacial phenotypes in raptor mutants. Genetic inhibition of autophagy, via mutation of the autophagy gene atg7, improved facial phenotypes in atg7;raptor double mutants, relative to raptor single mutants. We conclude that finely regulated levels of autophagy, via mTORC1, are crucial for craniofacial development.

Impact of maternal topiramate ingestion on ossification of skull and appendicular bones in rat fetuses

The skull and appendicular bones are derived from different embryological sources during their development. The impact of prenatal exposure of topiramate on ossification of these bones is not adequately studied. The goal of this study was to assess the ossification patterns of the craniofacial bones and bones of the forelimbs and hindlimbs in 20-day-old rat fetuses after maternal exposure to topiramate at doses equivalent to human therapeutic doses. Three groups of Sprague-Dawley pregnant rats were used: control, topiramate 50mg/kg/day (T50) and topiramate 100mg/kg/day (T100). Topiramate was given by oral gavage from day 6 to day19 of gestation. Ossification was evaluated in the bones of 20 days fetuses after staining with Alizarin red. Results showed a significant reduction in complete ossified centers of the metacarpal, metatarsal and craniofacial bones in topiramate-exposed fetuses at both doses when compared to the control group. Also, a significant decrease in the length of ossified part of the long bones of the forelimbs and hindlimbs in topiramate-exposed fetuses at both doses was noted when compared to the control group. Crown-rump length and fetal weight were significantly decreased in topiramate treated groups compared to the control group. In all examined groups, there was a positive correlation between the crown-rump length and the lengths of humerus and femur. No abnormalities in the ossified bones and no significant changes in their ossification pattern were observed between the treated groups. In conclusion, prenatal administration of topiramate in doses equivalent to human therapeutic doses delayed ossification and development of craniofacial and appendicular bones in rat fetuses and their effects are not dose dependent at doses investigated. The implications of these findings in women who require topiramate therapy in pregnancy merit further evaluation.

A comprehensive consolidation of data on the relationship between IRF6 polymorphisms and non-syndromic cleft lip/palate susceptibility: From 79 case-control studies

BACKGROUND

Non-syndromic cleft lip with or without cleft palate (NSCL/P) is a prevalent craniofacial birth defect on a global scale. A number of candidate genes have been identified as having an impact on NSCL/P. However, the association between interferon regulatory factor 6 (IRF6) polymorphisms and NSCL/P has yielded inconsistent results, prompting the need for a meta-analysis to obtain more accurate estimates.

METHODS

We conducted a thorough screening of all relevant articles published up until November 15, 2023, in online bibliographic databases. The statistical analysis of the collected data was performed using the Comprehensive Meta-Analysis (Version 4.0) software.

RESULTS

A total of 79 case-control studies, comprising 14,003 cases and 19,905 controls, were included in our analysis. The combined data indicated that the IRF6 rs642961 and rs2235371 polymorphisms were associated with an increased risk of NSCL/P in the overall population. However, no significant association was found between the rs2013162 and rs2235375 polymorphisms and the risk of NSCL/P in the overall population. Furthermore, subgroup analyses revealed significant correlations between the IRF6 rs642961, rs2235371, and rs2235375 polymorphisms and the risk of NSCL/P based on ethnic background and country of origin. Nevertheless, the rs2013162 polymorphism plays a protective role in Caucasians and mixed populations.

CONCLUSIONS

Our collective data indicates a significant association between the rs642961 and rs2235371 polymorphisms and the risk of NSCL/P in the overall population. The rs2235375 polymorphism could influence the susceptibility to NSCL/P based on ethnic background. Meanwhile, the rs2013162 polymorphism provides protective effects in Caucasian, mixed populations, and the Brazilian population.

Dosage-dependent effects of FGFR2W290R mutation on craniofacial shape and cellular dynamics of the basicranial synchondroses

Craniosynostosis is a common yet complex birth defect, characterized by premature fusion of the cranial sutures that can be syndromic or nonsyndromic. With over 180 syndromic associations, reaching genetic diagnoses and understanding variations in underlying cellular mechanisms remains a challenge. Variants of FGFR2 are highly associated with craniosynostosis and warrant further investigation. Using the missense mutation FGFR2W290R , an effective mouse model of Crouzon syndrome, craniofacial features were analyzed using geometric morphometrics across developmental time (E10.5-adulthood, n = 665 total). Given the interrelationship between the cranial vault and basicranium in craniosynostosis patients, the basicranium and synchondroses were analyzed in perinates. Embryonic time points showed minimal significant shape differences. However, hetero- and homozygous mutant perinates and adults showed significant differences in shape and size of the cranial vault, face, and basicranium, which were associated with cranial doming and shortening of the basicranium and skull. Although there were also significant shape and size differences associated with the basicranial bones and clear reductions in basicranial ossification in cleared whole-mount samples, there were no significant alterations in chondrocyte cell shape, size, or orientation along the spheno-occipital synchondrosis. Finally, shape differences in the cranial vault and basicranium were interrelated at perinatal stages. These results point toward the possibility that facial shape phenotypes in craniosynostosis may result in part from pleiotropic effects of the causative mutations rather than only from the secondary consequences of the sutural defects, indicating a novel direction of research that may shed light on the etiology of the broad changes in craniofacial morphology observed in craniosynostosis syndromes.

BRD4 binds to active cranial neural crest enhancers to regulate RUNX2 activity during osteoblast differentiation

Cornelia de Lange syndrome (CdLS) is a congenital disorder featuring facial dysmorphism, postnatal growth deficits, cognitive disability and upper limb abnormalities. CdLS is genetically heterogeneous, with cases arising from mutation of BRD4, a bromodomain protein that binds and reads acetylated histones. In this study, we have modeled CdLS facial pathology through mouse neural crest cell (NCC)-specific mutation of BRD4 to characterize cellular and molecular function in craniofacial development. Mice with BRD4 NCC loss of function died at birth with severe facial hypoplasia, cleft palate, mid-facial clefting and exencephaly. Following migration, BRD4 mutant NCCs initiated RUNX2 expression for differentiation to osteoblast lineages but failed to induce downstream RUNX2 targets required for lineage commitment. BRD4 bound to active enhancers to regulate expression of osteogenic transcription factors and extracellular matrix components integral for bone formation. RUNX2 physically interacts with a C-terminal domain in the long isoform of BRD4 and can co-occupy osteogenic enhancers. This BRD4 association is required for RUNX2 recruitment and appropriate osteoblast differentiation. We conclude that BRD4 controls facial bone development through osteoblast enhancer regulation of the RUNX2 transcriptional program.

Preoperative sleep-disordered breathing and craniofacial abnormalities are risk factors for postoperative sleep-disordered breathing in patients undergoing skin-flap oropharyngeal reconstruction surgery for oral cavity cancer: a prospective case-control study

PURPOSE

After oropharyngeal reconstruction surgery, excessive flap volume within the oral cavity may increase the risk of pharyngeal obstruction during sleep. This prospective observational study aimed to test a hypothesis that the skin-flap oropharyngeal reconstructive surgery increases nocturnal apnea-hypopnea index (nAHI, primary variable) after surgery.

METHODS

Adult patients undergoing oropharyngeal reconstruction surgery participated in this study. The hypothesis was tested by comparing the results of portable type 4 sleep study and craniofacial assessments with lateral head and neck computed tomography scout image before and after surgery. Multiple linear regression analyses were performed to identify predictors for nAHI increase after the surgery.

RESULTS

In 15 patients, a postoperative sleep study was performed at 41 (27, 59) (median (IQR)) days after the surgery. nAHI did not increase after the surgery (mean (95% CI), 13.0 (7.2 to 18.7) to 18.4 (10.2 to 26.6) events.hour-1, p = 0.277), while apnea index significantly increased after the surgery (p = 0.026). Use of the pedicle flap for the oropharyngeal reconstruction (p = 0.051), small mandible (p = 0.008), longer lower face (0.005), and larger tongue size (p = 0.008) were independent predictors for worsening of nAHI after surgery. Hospital stay was significantly longer in patients with the pedicle flap (n = 8) than in those with the free flap (n = 7) (p = 0.014), and the period of hospital stay was directly associated with increase of nAHI after surgery (r = 0.788, p < 0.001, n = 15).

CONCLUSIONS

Oropharyngeal reconstruction surgery worsens sleep-disordered breathing in some patients with craniofacial and surgical risk factors.

TRIAL REGISTRATION

UMIN Clinical Trial Registry (UMIN000036260, March 22, 2019), https://rctportal.niph.go.jp/s/detail/um?trial_id=UMIN000036260.

Endothelin signaling in development

Since the discovery of endothelin 1 (EDN1) in 1988, the role of endothelin ligands and their receptors in the regulation of blood pressure in normal and disease states has been extensively studied. However, endothelin signaling also plays crucial roles in the development of neural crest cell-derived tissues. Mechanisms of endothelin action during neural crest cell maturation have been deciphered using a variety of in vivo and in vitro approaches, with these studies elucidating the basis of human syndromes involving developmental differences resulting from altered endothelin signaling. In this Review, we describe the endothelin pathway and its functions during the development of neural crest-derived tissues. We also summarize how dysregulated endothelin signaling causes developmental differences and how this knowledge may lead to potential treatments for individuals with gene variants in the endothelin pathway.

Spontaneous recovery of underlying bony erosion following surgical removal of craniofacial dermoid cysts in periatric patients: A prospective study

This study aimed to evaluate the spontaneous recovery of bone deformity after surgical excision of craniofacial dermoid cysts in pediatrics. Pediatric patients who underwent excision of a dermoid cyst were included in the study. A prospective analysis was conducted to evaluate the amount of bone recovery by comparing the depth of bony concavity in the preoperative and postoperative (6 months) ultrasonography. In 145 of 187 patients with preoperative imaging available, the mean size of dermoid cysts was 1.4 cm3 (range, 0.1 to 9.5), and 41.4% (60/145 cases) showed cranial bone depression. In the comparison of preoperative and postoperative ultrasonography of 30 patients, the mean depth of bony cavity decreased significantly from 4.0 to 0.9 mm (p<0.001) after a mean of 6.7 months postoperatively. There was 13.3% (4/30) of mild (≤2.0 mm), 40.0% (12/30) of moderate (>2.0 to ≤4.0 mm), and 46.7% (14/30) of severe (>4.0 mm) depression, and the concavity depth significantly decreased in all groups (p = 0.028, mild; p<0.001, moderate; p<0.001 severe). Within the limitations of the study it seems that significant recovery of cranial bone depression does take place within 6 months after excision of craniofacial dermoid cysts in pediatric patients, saving the need for immediate reconstruction.

Exposure to the aryl hydrocarbon receptor agonist dioxin disrupts formation of the muscle, nerves, and vasculature in the developing jaw

Human exposure to environmental pollutants can disrupt embryonic development and impact juvenile and adult health outcomes by adversely affecting cell and organ function. Notwithstanding, environmental contamination continues to increase due to industrial development, insufficient regulations, and the mobilization of pollutants as a result of extreme weather events. Dioxins are a class of structurally related persistent organic pollutants that are highly toxic, carcinogenic, and teratogenic. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is the most potent dioxin compound and has been shown to induce toxic effects in developing organisms by activating the aryl hydrocarbon receptor (AHR), a ligand activated transcription factor targeted by multiple persistent organic pollutants. Contaminant-induced AHR activation results in malformations of the craniofacial cartilages and neurocranium; however, the mechanisms mediating these phenotypes are not well understood. In this study, we utilized the optically transparent zebrafish model to elucidate novel cellular targets and potential transcriptional targets underlying TCDD-induced craniofacial malformations. To this end, we exposed zebrafish embryos at 4 h post fertilization to TCDD and employed a mixed-methods approach utilizing immunohistochemistry staining, transgenic reporter lines, fixed and in vivo confocal imaging, and timelapse microscopy to determine the targets mediating TCDD-induced craniofacial phenotypes. Our data indicate that embryonic TCDD exposure reduced jaw and pharyngeal arch Sox10+ chondrocytes and Tcf21+ pharyngeal mesoderm progenitors. Exposure to TCDD correspondingly led to a reduction in collagen type II deposition in Sox10+ domains. Embryonic TCDD exposure impaired development of tissues derived from or guided by Tcf21+ progenitors, namely: nerves, muscle, and vasculature. Specifically, TCDD exposure disrupted development of the hyoid and mandibular arch muscles, decreased neural innervation of the jaw, resulted in compression of cranial nerves V and VII, and led to jaw vasculature malformations. Collectively, these findings reveal novel structural targets and potential transcriptional targets of TCDD-induced toxicity, showcasing how contaminant exposures lead to congenital craniofacial malformations.

Recurred forehead osteoma disseminated after previous osteoma excision: A case report

BACKGROUND

Forehead osteoma is a commonly encountered benign facial bone tumor. Endoscopic excision of benign forehead masses is widely performed. Here, we report a rare case of recurrent forehead osteoma that disseminated after a previous osteoma excision.

CASE SUMMARY

A 54-year-old female patient had previously undergone endoscopic removal of a single forehead osteoma at 30 years of age. However, she had a recurrent osteoma around the same site and underwent another endoscopic resection at 40 years of age. During her first visit to our outpatient clinic, she presented with a cobblestone-like irregular surface on the forehead and a 3D facial bone computed tomography scan revealed a widely ragged surface of the inoculated osteoma on the outer table of the frontal bone. Under general anesthesia, we performed a radical complete excision of the disseminated osteoma through a bicoronal incision using an osteotome, chisel, mallet, and rasping. We hypothesized that the recurrence may have been caused by the inoculation of residual osteoma remnants from the previous procedure. Craniofacial surgeons should be cautious when removing osteoma particles, particularly when using an endoscopic approach.

CONCLUSION

To prevent recurrence, it is essential to conduct additional meticulous burring and a thorough inspection of the surface after copious irrigation.

ESCRT-dependent control of craniofacial morphogenesis with concomitant perturbation of NOTCH signaling

Craniofacial development is orchestrated by transcription factor-driven regulatory networks, epigenetic modifications, and signaling pathways. Signaling molecules and their receptors rely on endo-lysosomal trafficking to prevent accumulation on the plasma membrane. ESCRT (Endosomal Sorting Complexes Required for Transport) machinery is recruited to endosomal membranes enabling degradation of such endosomal cargoes. Studies in vitro and in invertebrate models established the requirements of the ESCRT machinery in membrane remodeling, endosomal trafficking, and lysosomal degradation of activated membrane receptors. However, investigations during vertebrate development have been scarce. By ENU-induced mutagenesis, we isolated a mouse line, Vps25ENU/ENU, carrying a hypomorphic allele of the ESCRT-II component Vps25, with craniofacial anomalies resembling features of human congenital syndromes. Here, we assessed the spatiotemporal dynamics of Vps25 and additional ESCRT-encoding genes during murine development. We show that these genes are ubiquitously expressed although enriched in discrete domains of the craniofacial complex, heart, and limbs. ESCRT-encoding genes, including Vps25, are expressed in both cranial neural crest-derived mesenchyme and epithelium. Unlike constitutive ESCRT mutants, Vps25ENU/ENU embryos display late lethality. They exhibit hypoplastic lower jaw, stunted snout, dysmorphic ear pinnae, and secondary palate clefting. Thus, we provide the first evidence for critical roles of ESCRT-II in craniofacial morphogenesis and report perturbation of NOTCH signaling in craniofacial domains of Vps25ENU/ENU embryos. Given the known roles of NOTCH signaling in the developing cranium, and notably the lower jaw, we propose that the NOTCH pathway partly mediates the craniofacial defects of Vps25ENU/ENU mouse embryos.

Craniofacial Growth and Development: A Primer for the Facial Trauma Surgeon

Understanding craniofacial growth and development is important in the management of facial trauma in the growing pediatric patient. This manuscript is a review of craniofacial growth and development and clinical implications of pediatric facial fractures.

Developmental origin of the mammalian premaxilla

The evolution of jaws has played a major role in the success of vertebrate expansion into a wide variety of ecological niches. A fundamental, yet unresolved, question in craniofacial biology is about the origin of the premaxilla, the most distal bone present in the upper jaw of all amniotes. Recent reports have suggested that the mammalian premaxilla is derived from embryonic maxillary prominences rather than the frontonasal ectomesenchyme as previously shown in studies of chicken embryos. However, whether mammalian embryonic frontonasal ectomesenchyme contributes to the premaxillary bone has not been investigated and a tool to trace the contributions of the frontonasal ectomesenchyme to facial structures in mammals is lacking. The expression of the Alx3 gene is activated highly specifically in the frontonasal ectomesenchyme, but not in the maxillary mesenchyme, from the beginning of facial morphogenesis in mice. Here, we report the generation and characterization of a novel Alx3CreERT2 knock-in mouse line that express tamoxifen-inducible Cre DNA recombinase from the Alx3 locus. Tamoxifen treatment of Alx3CreERT2/+;Rosa26mTmG/+ embryos at E7.5, E8.5, E9.5, and E10.5, each induced specific labeling of the embryonic medial nasal and lateral nasal mesenchyme but not the maxillary mesenchyme. Lineage tracing of Alx3CreERT2-labeled frontonasal mesenchyme from E9.5 to E16.5 clearly showed that the frontonasal mesenchyme cells give rise to the osteoblasts generating the premaxillary bone. Furthermore, we characterize a Dlx1-Cre BAC transgenic mouse line that expresses Cre activity in the embryonic maxillary but not the frontonasal mesenchyme and show that the Dlx1-Cre labeled embryonic maxillary mesenchyme cells contribute to the maxillary bone as well as the soft tissues lateral to both the premaxillary and maxillary bones but not to the premaxillary bone. These results clearly demonstrate the developmental origin of the premaxillary bone from embryonic frontonasal ectomesenchyme cells in mice and confirm the evolutionary homology of the premaxilla across amniotes.

Craniofacial developmental biology in the single-cell era

The evolution of a unique craniofacial complex in vertebrates made possible new ways of breathing, eating, communicating and sensing the environment. The head and face develop through interactions of all three germ layers, the endoderm, ectoderm and mesoderm, as well as the so-called fourth germ layer, the cranial neural crest. Over a century of experimental embryology and genetics have revealed an incredible diversity of cell types derived from each germ layer, signaling pathways and genes that coordinate craniofacial development, and how changes to these underlie human disease and vertebrate evolution. Yet for many diseases and congenital anomalies, we have an incomplete picture of the causative genomic changes, in particular how alterations to the non-coding genome might affect craniofacial gene expression. Emerging genomics and single-cell technologies provide an opportunity to obtain a more holistic view of the genes and gene regulatory elements orchestrating craniofacial development across vertebrates. These single-cell studies generate novel hypotheses that can be experimentally validated in vivo. In this Review, we highlight recent advances in single-cell studies of diverse craniofacial structures, as well as potential pitfalls and the need for extensive in vivo validation. We discuss how these studies inform the developmental sources and regulation of head structures, bringing new insights into the etiology of structural birth anomalies that affect the vertebrate head.

Intrauterine exposure to nicotine through maternal vaping disrupts embryonic lung and skeletal development via the Kcnj2 potassium channel

Smoking cigarettes during pregnancy is associated with adverse effects on infants including low birth weight, defective lung development, and skeletal abnormalities. Pregnant women are increasingly turning to vaping [use of electronic (e)-cigarettes] as a perceived safer alternative to cigarettes. However, nicotine disrupts fetal development, suggesting that like cigarette smoking, nicotine vaping may be detrimental to the fetus. To test the impact of maternal vaping on fetal lung and skeletal development in mice, pregnant dams were exposed to e-cigarette vapor throughout gestation. At embryonic day (E)18.5, vape exposed litter sizes were reduced, and some embryos exhibited growth restriction compared to air exposed controls. Fetal lungs were collected for histology and whole transcriptome sequencing. Maternally nicotine vaped embryos exhibited histological and transcriptional changes consistent with impaired distal lung development. Embryonic lung gene expression changes mimicked transcriptional changes observed in adult mouse lungs exposed to cigarette smoke, suggesting that the developmental defects may be due to direct nicotine exposure. Fetal skeletons were analyzed for craniofacial and long bone lengths. Nicotine directly binds and inhibits the Kcnj2 potassium channel which is important for bone development. The length of the maxilla, palatal shelves, humerus, and femur were reduced in vaped embryos, which was further exacerbated by loss of one copy of the Kcnj2 gene. Nicotine vapor exposed Kcnj2KO/+ embryos also had significantly lower birth weights than unexposed animals of either genotype. Kcnj2 mutants had severely defective lungs with and without vape exposure, suggesting that potassium channels may be broadly involved in mediating the detrimental developmental effects of nicotine vaping. These data indicate that intrauterine nicotine exposure disrupts fetal lung and skeletal development likely through inhibition of Kcnj2.

Calvarial hyperpigmentation

Background

Osseous hyperpigmentation of the calvarium is an extremely rare finding with only few reported cases in literature.

Case Description

The case is of a 59-year-old Caucasian male who presented with an acute history of generalized tonic clonic seizures and progressive weakness of the right upper limb. He had a background history of a malignant melanoma which had been resected from his left external acoustic meatus 4 weeks prior. Neuroimaging of the brain showed an intra-axial space-occupying lesion in his left parietal lobe with no associated osseous changes. A left mini parietal craniotomy was performed which revealed black discoloration of the parietal bone. The lesion was successfully resected and the bone flap was secured back in place. The patient was discharged on the 4th day postoperatively with no complications. The unusual finding of black discoloration of the calvarium was found to be secondary to adolescent tetracycline use.

Conclusion

Calvarial hyperpigmentation is a phenomenon encountered incidentally and will often come as surprise for surgeons. Once encountered, thorough history taking and examination should be done to investigate the cause.

Identification of a heterogeneous and dynamic ciliome during embryonic development and cell differentiation

Primary cilia are nearly ubiquitous organelles that transduce molecular and mechanical signals. Although the basic structure of the cilium and the cadre of genes that contribute to ciliary formation and function (the ciliome) are believed to be evolutionarily conserved, the presentation of ciliopathies with narrow, tissue-specific phenotypes and distinct molecular readouts suggests that an unappreciated heterogeneity exists within this organelle. Here, we provide a searchable transcriptomic resource for a curated primary ciliome, detailing various subgroups of differentially expressed genes within the ciliome that display tissue and temporal specificity. Genes within the differentially expressed ciliome exhibited a lower level of functional constraint across species, suggesting organism and cell-specific function adaptation. The biological relevance of ciliary heterogeneity was functionally validated by using Cas9 gene-editing to disrupt ciliary genes that displayed dynamic gene expression profiles during osteogenic differentiation of multipotent neural crest cells. Collectively, this novel primary cilia-focused resource will allow researchers to explore longstanding questions related to how tissue and cell-type specific functions and ciliary heterogeneity may contribute to the range of phenotypes associated with ciliopathies.

Superficial temporal artery injury and delayed post-cranioplasty infection

OBJECTIVE

Complications after cranioplasty after decompressive craniectomy (DC) have been reported to be as high as 40%. The superficial temporal artery (STA) is at substantial risk for injury in standard reverse question-mark incisions that are typically used for unilateral DC. The authors hypothesize that STA injury during craniectomy predisposes patients to post-cranioplasty surgical site infection (SSI) and/or wound complication.

METHODS

A retrospective study of all patients at a single institution who underwent cranioplasty after decompressive craniectomy and who underwent imaging of the head (computed tomography angiogram, magnetic resonance imaging with intravenous contrast, or diagnostic cerebral angiography) for any indication between the two procedures was undertaken. The degree of STA injury was classified and univariate statistics were used to compare groups.

RESULTS

Fifty-four patients met inclusion criteria. Thirty-three patients (61%) had evidence of complete or partial STA injury on pre-cranioplasty imaging. Nine patients (16.7%) developed either an SSI or wound complication after cranioplasty and, among these, four (7.4%) experienced delayed (>2 weeks from cranioplasty) complications. Seven of 9 patients required surgical debridement and cranioplasty explant. There was a stepwise but non-significant increase in post-cranioplasty SSI (STA present: 10%, STA partial injury: 17%, STA complete injury: 24%, P=0.53) and delayed post-cranioplasty SSI (STA present: 0%, STA partial injury: 8%, STA complete injury: 14%, P=0.26).

CONCLUSIONS

There is a notable but statistically non-significant trend toward increased rates of SSI in patients with complete or partial STA injury during craniectomy.

Craniofacial and Dental Manifestations in Pediatric Patients with Achondroplasia: A Case Report and Clinical View

Aim

The aim of this case report is to describe the dentofacial manifestations of achondroplasia and highlight concerns associated with dental management of pediatric patients with achondroplasia.

Background

Achondroplasia is the most common form of skeletal dysplasia (dwarfism) with clinical manifestations including disproportionate limb shortening and stunted stature. The craniofacial characteristics of achondroplasia are relative macrocephaly, depression of the nasal bridge, and maxillary hypoplasia. Special precautions are necessary during dental management of pediatric patients with achondroplasia due to a large head size, implanted shunts, airway obstruction, and difficulty in head control.

Case description

A 6 years and 7 months male, the patient was diagnosed with achondroplasia, currently receiving vitamin D, no known drug allergy, and a mixed dentition stage with multiple caries, mouth breather, and a high risk of further caries based on a caries risk assessment due to poor oral hygiene. As the patient was uncooperative and required extensive dental care, dental rehabilitation was conducted under general anesthesia using oral intubation due to nasal obstruction. Future examinations were planned for every 3 months.

Conclusion

The current case demonstrated that the characteristics of achondroplasia might cause respiratory, neurological, skeletal, orthodontic, and psychological difficulties. Pediatric dentists who treat these patients must be able to detect these characteristics and difficulties, as dental treatment is limited by practical issues associated with this condition.

Clinical significance

The characteristic features of achondroplasia are attributed to skeletal, respiratory, neurologic, orthodontic, and psychosocial issues. The dentist should be aware of the features of achondroplasia, which can potentially restrict dental management.

How to cite this article

Almutiry A, Alotaibi F, Almutiry B, et al. Craniofacial and Dental Manifestations in Pediatric Patients with Achondroplasia: A Case Report and Clinical View. Int J Clin Pediatr Dent 2023;16(2):409-415.

Wnt/β-Catenin Signaling in Craniomaxillofacial Osteocytes

PURPOSE OF REVIEW

There is a growing appreciation within the scientific community that cells exhibit regional variation. Whether the variation is attributable to differences in embryonic origin or anatomical location and mechanical loading has not been elucidated; what is clear, however, is that adult cells carry positional information that ultimately affects their functions. The purpose of this review is to highlight the functions of osteocytes in the craniomaxillofacial (CMF) skeleton as opposed to elsewhere in the body, and in doing so gain mechanistic insights into genetic conditions and chemically-induced diseases that particularly affect this region of our anatomy.

RECENT FINDINGS

In the CMF skeleton, elevated Wnt/β-catenin signaling affects not only bone mass and volume, but also mineralization of the canalicular network and osteocyte lacunae. Aberrant elevation in the Wnt/β-catenin pathway can also produce micropetrosis and osteonecrosis of CMF bone, presumably due to a disruption in the signaling network that connects osteocytes to one another, and to osteoblasts on the bone surface.

Successful therapeutic intervention in new mouse models of frizzled 2-associated congenital malformations

Frizzled 2 (FZD2) is a transmembrane Wnt receptor. We previously identified a pathogenic human FZD2 variant in individuals with FZD2-associated autosomal dominant Robinow syndrome. The variant encoded a protein with a premature stop and loss of 17 amino acids, including a region of the consensus dishevelled-binding sequence. To model this variant, we used zygote microinjection and i-GONAD-based CRISPR/Cas9-mediated genome editing to generate a mouse allelic series. Embryos mosaic for humanized Fzd2W553* knock-in exhibited cleft palate and shortened limbs, consistent with patient phenotypes. We also generated two germline mouse alleles with small deletions: Fzd2D3 and Fzd2D4. Homozygotes for each allele exhibit a highly penetrant cleft palate phenotype, shortened limbs compared with wild type and perinatal lethality. Fzd2D4 craniofacial tissues indicated decreased canonical Wnt signaling. In utero treatment with IIIC3a (a DKK inhibitor) normalized the limb lengths in Fzd2D4 homozygotes. The in vivo replication represents an approach for further investigating the mechanism of FZD2 phenotypes and demonstrates the utility of CRISPR knock-in mice as a tool for investigating the pathogenicity of human genetic variants. We also present evidence for a potential therapeutic intervention.

Predictive model for preoperative risk calculation of cerebrospinal fluid leak after resection of midline craniofacial mass lesions

Background

Complex anterior skull base defects produced by resection of mass lesions vary in size and configuration and may be extensive. We analyzed the largest single-center series of midline craniofacial lesions extending intra- and extracranially. The study aims at the development of a predictive model for preoperative measurement of the risk of the postoperative cerebrospinal fluid (CSF) leak based on patients' characteristics and surgical plans.

Methods

166 male and 149 female patients with mean age 40,5 years (1 year and - 81 years) operated for benign and tumor-like midline craniofacial mass lesions were retrospectively analyzed using logistic regression method (Ridge regression algorithm was selected). The overall CSF leak rate was 9.6%. The ROSE algorithm and 'glmnet' software suite in R were used to overcome the cohort's disbalance and avoid overtraining the model.

Results

The most influential modifiable negative predictor of the postoperative CSF leak was the use of extracranial and combined approaches. Use of transbasal approaches, gross total resection, utilization of one or two vascularized flaps for skull base reconstruction were the foremost modifiable predictors of a good outcome. Criterium of elevated risk was established at 50% with a specificity of the model as high as 0.83.

Conclusions

The performed study has allowed for identifying the most significant predictors of postoperative CSF leak and developing an effective formula to estimate the risk of this complication using data known for each patient. We believe that the suggested web-based online calculator can be helpful for decision making support in off-pattern clinical situations.

Early and long-term skull growth after surgical correction for sagittal synostosis in relation to the occurrence of papilledema

OBJECTIVE

Stagnation of skull growth is correlated with papilledema in craniosynostosis. In this retrospective cohort study, we describe the postoperative skull growth after surgical correction for sagittal synostosis and its relation to the development of papilledema.

METHODS

Patients with isolated sagittal synostosis at our center between 2005 and 2012 were included. Occipitofrontal circumference (OFC) was analyzed, at 3 time points (preoperative, 2 years postoperative, and last OFC measurement) and 3 phases (initial postoperative growth, long-term growth, and overall growth), and related to papilledema on fundoscopy.

RESULTS

In total, 163 patients were included. The first time interval showed a decline in skull growth, with subsequent stabilization at long term. Papilledema occurred postoperatively in 10 patients. In these patients, the OFC at 2 years and at last follow-up (T3) were significantly smaller than in patients without papilledema. A larger OFC resulted in a decreased odds of developing papilledema at both postoperative time points (at T2 (OR = 0.40, p = 0.01) and at T3 (OR 0.29, p < 0.001)). Sensitivity and specificity analysis indicated that an OFC below 0.25 SD at T2 (sensitivity 90%, specificity 65%) and below 0.49 at T3 (sensitivity 100%, specificity 60%) are related to the occurrence of papilledema.

CONCLUSION

A small OFC is correlated with the occurrence of papilledema. A decline in OFC within 2 years postoperatively is common in sagittal synostosis and is acceptable up to a value of 0.25SD. Patients with an OFC at last follow-up of less than 0.5SD are at risk for developing papilledema.

Complications arising from clinical application of composite polycaprolactone/bioactive glass ceramic implants for craniofacial reconstruction: A prospective study

This study aimed to demonstrate the in vitro performance of a novel polymer-ceramic composite incorporating polycaprolactone (PCL) and bioactive glass (BGS-7), and investigate its clinical outcomes in craniofacial reconstruction. After preparation of the material, the biochemical properties of the composite PCL/BGS-7 implant were tested to evaluate apatite formation in simulated body fluid (SBF). Changes in the implant surface after soaking in the SBF were determined using field-emission scanning electron microscopy. For clinical application of the implant, patients with craniofacial defects were prospectively enrolled to receive three-dimensional (3D)-printed PCL/BGS-7 implants. Clinical outcomes were investigated by reviewing postoperative complications, including wound problems, allergic responses, hematoma, seroma, implant displacement, and bone union. The accuracy of reconstruction was assessed by measuring the surface error between the reconstructed and mirrored models. Upon exposure of the PCL/BGS-7 implant to SBF, apatite particles were actively developed on the surface of the PCL/BGS-7 sample, showing favorable bone-binding capacity. Regarding the clinical application, seven patients with craniofacial defects were included. The clinical outcome was favorable in terms of complications, except in one patient, who presented with delayed wound healing due to previous irradiation. The patients showed improvements in symmetry, with a significant change in mean ± SD surface error between preoperative (5 ± 3 mm) and postoperative (1.5 ± 0.65 mm) status (p = 0.018). Wthin the limitations of the study it seems that the PCL/BGS-7 implants might be a relevant option for repairing craniofacial bone defects, owing to its favorable bone-binding property and clinical safety, with few complications.

Anabolic actions of parathyroid hormone in a hypophosphatasia mouse model

Hypophosphatasia, the rare heritable disorder caused by TNAP enzyme mutations, presents wide-ranging severity of bone hypomineralization and skeletal abnormalities. Intermittent PTH (1-34) increased long bone volume in Alpl^-/- mice but did not alter the skull phenotype. PTH may have therapeutic value for adults with TNAP deficiency-associated osteoporosis.

INTRODUCTION

Hypophosphatasia is the rare heritable disorder caused by mutations in the tissue non-specific alkaline phosphatase (TNAP) enzyme leading to TNAP deficiency. Individuals with hypophosphatasia commonly present with bone hypomineralization and skeletal abnormalities. The purpose of this study was to determine the impact of intermittent PTH on the skeletal phenotype of TNAP-deficient Alpl^-/- mice.

METHODS

Alpl-/- and Alpl+/+ (wild-type; WT) littermate mice were administered PTH (1-34) (50 µg/kg) or vehicle control from days 4 to 12 and skeletal analyses were performed including gross measurements, micro-CT, histomorphometry, and serum biochemistry.

RESULTS

Alpl^-/- mice were smaller with shorter tibial length and skull length compared to WT mice. Tibial BV/TV was reduced in Alpl^-/- mice and daily PTH (1-34) injections significantly increased BV/TV and BMD but not TMD in both WT and Alpl^-/- tibiae. Trabecular spacing was not different between genotypes and was decreased by PTH in both genotypes. Serum P1NP was unchanged while TRAcP5b was significantly lower in Alpl^-/- vs. WT mice, with no PTH effect, and no differences in osteoclast numbers. Skull height and width were increased in Alpl^-/- vs. WT mice, and PTH increased skull width in WT but not Alpl^-/- mice. Frontal skull bones in Alpl^-/- mice had decreased BV/TV, BMD, and calvarial thickness vs. WT with no significant PTH effects. Lengths of cranial base bones (basioccipital, basisphenoid, presphenoid) and lengths of synchondroses (growth plates) between the cranial base bones, plus bone of the basioccipitus, were assessed. All parameters were reduced (except lengths of synchondroses, which were increased) in Alpl^-/- vs. WT mice with no PTH effect.

CONCLUSION

PTH increased long bone volume in the Alpl^-/- mice but did not alter the skull phenotype. These data suggest that PTH can have long bone anabolic activity in the absence of TNAP, and that PTH may have therapeutic value for individuals with hypophosphatasia-associated osteoporosis.

Alkaline Phosphatase Profile of Patients with Fibro-Osseous Lesions

INTRODUCTION

Although some studies on craniofacial fibro-osseous lesions have assayed serum alkaline phosphatase levels of affected patients, the findings of these reports are often inconclusive. The aim of this study was to determine the association between the serum ALP levels of individuals with craniofacial fibro-osseous lesions (CFOLs) and treatment outcome.

MATERIALS AND METHODS

Consecutive patients who presented at the Ahmadu Bello University Teaching Hospital, Zaria from May, 2016 to December, 2017 with lesions histologically diagnosed as CFOLs. The Speight and Carlos' (2006) classification of CFOLs was adopted, and the serum ALP level of patients and their age- and- gender matched apparently healthy controls were measured at presentation, and repeated at the 3rd and 6th post-operative months for subjects only. Treatment outcomes were assessed 6 months post treatment.

RESULTS

Fifty cases of CFOLs were recorded with a male preponderance, while fibrous dysplasia was the most prevalent lesion, and the maxilla was the most affected jaw (62%). Only 11 subjects had elevated serum ALP levels at presentation, and the mean serum ALP level of subjects with CFOLs was higher (341.2 ± 198.1 IU/L) than that of their age-and gender-matched controls (190.7 ± 110.2 IU/L). With the exception of subjects whose lesions recurred, there was a decrease in the mean serum ALP levels of subjects by the 3rd (245 ± 170.2 IU/L) and 6th (240.5 ± 172.7 IU/L) months post-treatment. Thirty three subjects had elimination of lesions, while three cases each recurred or developed morbidity.

CONCLUSION

The treatment outcomes of patients with fibrous dysplasia appear to be associated with their serum ALP level. Therefore, serial serum ALP level monitoring suggested in the management of patients with fibrous dysplasia of the craniofacial region.

Craniofacial sutures: Signaling centres integrating mechanosensation, cell signaling, and cell differentiation

Cranial sutures are dynamic structures in which stem cell biology, bone formation, and mechanical forces interface, influencing the shape of the skull throughout development and beyond. Over the past decade, there has been significant progress in understanding mesenchymal stromal cell (MSC) differentiation in the context of suture development and genetic control of suture pathologies, such as craniosynostosis. More recently, the mechanosensory function of sutures and the influence of mechanical signals on craniofacial development have come to the forefront. There is currently a gap in understanding of how mechanical signals integrate with MSC differentiation and ossification to ensure appropriate bone development and mediate postnatal growth surrounding sutures. In this review, we discuss the role of mechanosensation in the context of cranial sutures, and how mechanical stimuli are converted to biochemical signals influencing bone growth, suture patency, and fusion through mediation of cell differentiation. We integrate key knowledge from other paradigms where mechanosensation forms a critical component, such as bone remodeling and orthodontic tooth movement. The current state of the field regarding genetic, cellular, and physiological mechanisms of mechanotransduction will be contextualized within suture biology.

Posterior Calvarial Distraction in older paediatric population: single centre paediatric neurosurgery craniofacial unit outcomes

PURPOSE

Posterior calvarial distraction (PCD) is a safe and effective technique used to increase cranial vault volume and therefore reduce intracranial pressure in children with complex craniosynostosis. Optimal timing and method used for PCD is controversial. This procedure is usually performed in children younger than 2 years. Literature regarding calvarial distraction in older children is sparse and limited. We report our single-centre experience with PCD in children aged 6 and above to outline the applications, benefits and challenges of employing this technique in an older paediatric population.

METHODS

A retrospective analysis of a database on craniofacial cases from 2006 to 2021 was performed. Patients undergoing PCD were identified and children aged 6 and above at the time of operation were included. Data on demographics and clinical outcomes were obtained from electronic records and relevant imaging was reviewed. All cases were reviewed prior to a decision for surgery by the multidisciplinary craniofacial team (composed of neurosurgery, maxillofacial and plastics teams) and underwent surgery in our paediatric craniofacial centre.

RESULTS

Overall, 98 PCD cases were identified during the study period, of which 20 cases were identified as having undergone PCD at age 6 or above with mean age of 8.8 years (range 6-18). The most common indication was pansynostosis associated with raised intracranial pressure. Four cases had calvarial remodelling previously and represented with symptoms of raised intracranial pressure sometime after their initial surgery requiring PCD as rescue procedure. Average duration of inpatient stay was 5.85 days. The average duration of follow-up was 3.5 years (0.3 to 11 years). Mean distraction distance achieved was 22.5 mm (18-29 mm). Five patients experienced complications related to wound infection or distractor. Follow-up assessment in all patients demonstrated evidence of vault expansion and symptomatic improvement and resolution of intracranial pressure signs. Comparison with younger cohort did not reveal any difference in any parameters except lower rate of transfusion in the older cohort compared to young cohort (5% vs 38%).

CONCLUSION

Posterior calvarial distraction in older children is safe and effective for vault expansion and treatment of raised intracranial pressure in selected cases. A multidisciplinary craniofacial team approach is crucial for appropriate case selection and management in order to optimise outcomes.

Management of Sagittal and Lambdoid Craniosynostosis: Open Cranial Vault Expansion and Remodeling

The prevalence of sagittal and lambdoid suture craniosynostosis differs considerably, as they are notably the most and least prevalent sutures involved in isolated suture craniosynostosis, respectively. The goals of reconstructing the cranial vault in both entities is the same: to release the fused suture, expand cranial volume, restore normal head shape and morphology, and allow for normal growth of the cranial vault. With regards to sagittal suture synostosis, opinions vary on whether reconstruction should focus on either the anterior or poster cranial vault. In contrast, the poster cranial vault is always targeted in lambdoid suture craniosynostosis.

First Italian experience using the automated craniofacial gestalt analysis on a cohort of pediatric patients with multiple anomaly syndromes

Background

In this study, we used the novel DeepGestalt technology powered by Face2Gene (FDNA Inc., MA, USA) in suggesting a correct diagnosis based on the facial gestalt of well-known multiple anomaly syndromes. Only molecularly characterized pediatric patients were considered in the present research.

Subjects and methods

A total of 19 two-dimensional (2D) images of patients affected by several molecularly confirmed craniofacial syndromes (14 monogenic disorders and 5 chromosome diseases) and evaluated at the main involved Institution were analyzed using the Face2Gene CLINIC application (vs.19.1.3). Patients were cataloged into two main analysis groups (A, B) according to the number of clinical evaluations. Specifically, group A contained the patients evaluated more than one time, while in group B were comprised the subjects with a single clinical assesment. The algorithm’s reliability was measured based on its capacity to identify the correct diagnosis as top-1 match, within the top-10 match and top-30 matches, only based on the uploaded image and not any other clinical finding or HPO terms. Failure was represented by the top-0 match.

Results

The correct diagnosis was suggested respectively in 100% (8/8) and 81% (9/11) of cases of group A and B, globally failing in 16% (3/19).

Conclusion

The tested tool resulted to be useful in identifying the facial gestalt of a heterogeneous group of syndromic disorders.

This study illustrates the first Italian experience with the next generation phenotyping technology, following previous works and providing additional observations.

Snrpb is required in murine neural crest cells for proper splicing and craniofacial morphogenesis

Heterozygous mutations in SNRPB, an essential core component of the five small ribonucleoprotein particles of the spliceosome, are responsible for cerebrocostomandibular syndrome (CCMS). We show that Snrpb heterozygous mouse embryos arrest shortly after implantation. Additionally, heterozygous deletion of Snrpb in the developing brain and neural crest cells models craniofacial malformations found in CCMS, and results in death shortly after birth. RNAseq analysis of mutant heads prior to morphological defects revealed increased exon skipping and intron retention in association with increased 5′ splice site strength. We found increased exon skipping in negative regulators of the P53 pathway, along with increased levels of nuclear P53 and P53 target genes. However, removing Trp53 in Snrpb heterozygous mutant neural crest cells did not completely rescue craniofacial development. We also found a small but significant increase in exon skipping of several transcripts required for head and midface development, including Smad2 and Rere. Furthermore, mutant embryos exhibited ectopic or missing expression of Fgf8 and Shh, which are required to coordinate face and brain development. Thus, we propose that mis-splicing of transcripts that regulate P53 activity and craniofacial-specific genes contributes to craniofacial malformations.

This article has an associated First Person interview with the first author of the paper.

Summary: We report the first mouse model for cerebrocostomandibular syndrome, showing that mis-splicing of transcripts that regulate P53 activity and craniofacial-specific genes contributes to craniofacial malformations.

Global Epidemiology of Craniosynostosis: A Systematic Review and Meta-Analysis

OBJECTIVE

Craniosynostosis leads to craniofacial deformity and may result in raised intracranial pressure, neurocognitive deficits, and psychosocial issues if left untreated. The global epidemiology of craniosynostosis is unknown. We conducted a meta-analysis to estimate global birth prevalence.

METHODS

PubMed, Embase, and Scopus were searched. Articles were screened by title and abstract and then full text. Meta-analysis of birth prevalence was conducted. Birth prevalence figures were combined with metrics detailing the number of births in 2019 to estimate the number of children worldwide born with craniosynostosis annually.

RESULTS

Of 1378 resultant articles, 24 studies were included, including 20 providing data for craniosynostosis overall and 9 for nonsyndromic craniosynostosis. World Health Organization regions of included studies were 9 (37.5%) European Region, 8 (33.3%) Region of the Americas, 4 (16.7%) Western Pacific region, 2 (8.3%) African Region, and 1 (4.2%) Eastern Mediterranean Region. Lower middle-income countries represented only 4% of study manuscripts. The overall birth prevalence of craniosynostosis was 5.9 per 10,000 live births (20 studies; 95% confidence interval [CI]: 3.9, 8.4; I² = 100%). The birth prevalence of nonsyndromic craniosynostosis was 5.2 per 10,000 live births (9 studies; 95% CI: 3.4, 7.3; I² = 98%). The number of children born globally with craniosynostosis in 2019 was estimated to be 84,665 (95% CI: 55,965, 120,540), including 72,857 (95% CI: 47,637, 120,280) with nonsyndromic craniosynostosis.

CONCLUSIONS

Craniosynostosis is a common condition that affects the neurocognitive and craniofacial skeletal development of children worldwide. Initiatives to scale up capacity for craniosynostosis epidemiologic research and clinical care are warranted, particularly in low- and middle-income countries.

Cellular and molecular mechanisms of EPH/EPHRIN signaling in evolution and development

The EPH receptor tyrosine kinases and their signaling partners, the EPHRINS, comprise a large class of cell signaling molecules that plays diverse roles in development. As cell membrane-anchored signaling molecules, they regulate cellular organization by modulating the strength of cellular contacts, usually by impacting the actin cytoskeleton or cell adhesion programs. Through these cellular functions, EPH/EPHRIN signaling often regulates tissue shape. Indeed, recent evidence indicates that this signaling family is ancient and associated with the origin of multicellularity. Though extensively studied, our understanding of the signaling mechanisms employed by this large family of signaling proteins remains patchwork, and a truly "canonical" EPH/EPHRIN signal transduction pathway is not known and may not exist. Instead, several foundational evolutionarily conserved mechanisms are overlaid by a myriad of tissue -specific functions, though common themes emerge from these as well. Here, I review recent advances and the related contexts that have provided new understanding of the conserved and varied molecular and cellular mechanisms employed by EPH/EPHRIN signaling during development.

Spironolactone affects cardiovascular and craniofacial development in zebrafish embryos (Danio rerio)

Spironolactone, a potassium-sparing diuretic and aldosterone antagonist, is a mineralocorticoid hormone commonly prescribed to patients suffering from heart failure, hirsutism, dermatological afflictions, and hypertension. Interestingly, relatively little work has been done on the development of vertebrate embryos after exposure to this compound. Here, we treat zebrafish embryos with spironolactone at 10^-6 M, 10^-7 M, or 10^-8 M, and observe them after three to seven days of exposure. While no effect was observed in mortality, we did detect differences in cardiovascular development at 3 dpf and craniofacial development at 5 dpf. At 10^-6 M, smaller atria, ventricles, and blood vessels were observed. The highest concentrations also caused a longer ceratohyal/Meckel's distance, longer palatoquadrate, and smaller angles between the palatoquadrate and both the ceratohyal and Meckel's. Further research of spironolactone's effects on embryonic development could lead to a better understanding of the compound resulting in improved public and environmental health.

Auriculocondylar syndrome 2 results from the dominant-negative action of PLCB4 variants

Auriculocondylar syndrome 2 (ARCND2) is a rare autosomal dominant craniofacial malformation syndrome linked to multiple genetic variants in the coding sequence of phospholipase C β4 (PLCB4). PLCB4 is a direct signaling effector of the endothelin receptor type A (EDNRA)-Gq/11 pathway, which establishes the identity of neural crest cells (NCCs) that form lower jaw and middle ear structures. However, the functional consequences of PLCB4 variants on EDNRA signaling is not known. Here, we show, using multiple signaling reporter assays, that known PLCB4 variants resulting from missense mutations exert a dominant-negative interference over EDNRA signaling. In addition, using CRISPR/Cas9, we find that F0 mouse embryos modeling one PLCB4 variant have facial defects recapitulating those observed in hypomorphic Ednra mouse models, including a bone that we identify as an atavistic change in the posterior palate/oral cavity. Remarkably, we have identified a similar osseous phenotype in a child with ARCND2. Our results identify the disease mechanism of ARCND2, demonstrate that the PLCB4 variants cause craniofacial differences and illustrate how minor changes in signaling within NCCs may have driven evolutionary changes in jaw structure and function. This article has an associated First Person interview with the first author of the paper.

The outcome of targeted NGS screening in patients with syndromic forms of sagittal and pansynostosis - IL11RA is an emerging core-gene for pansynostosis

Here, we have studied the prevalence and spectrum of genetic alterations in syndromic forms of sagittal and pansynostosis. Eighteen patients with sagittal synostosis (isolated or combined with other synostoses, except coronal) or pansynostosis were phenotypically assessed by retrospective analysis of medical records, three-dimensional computed tomography skull reconstructions, and registered photos. Patient DNAs were analyzed using a targeted next-generation sequencing (NGS) panel including 63 craniosynostosis (CS) related genes. Pathogenic and likely pathogenic variants were found in 72% of the cases, mainly affecting FGFR2, TWIST1, IL11RA, and SKI. Two patients that were negative at NGS screening - one with a supernumerary marker chromosome with duplication of 15q25.2q26.3 and one with a pathogenic PHEX variant - were identified using microarray and single gene analysis, respectively. The overall diagnostic rate in the cohort was thus 83%. We identified two novel likely pathogenic variants in FGFR2 (NM_022970.3: c.811_812delGGinsCC, p.Gly271Pro) and TWIST1 (NM_000474.3: c.476T  >  A, p.Leu159His), and a novel variant of unclear phenotypic significance in RUNX2 (NM_001024630.3: c.340G > A, p.Val114Ile) which could suggest a modulatory effect. Notably, we also identified three new patients with pansynostosis and a Crouzon-like phenotype with IL11RA mutation. Targeted NGS using a broad panel of CS-related genes is a simple and powerful tool for detecting pathogenic mutations in patients with syndromic forms of CS and multiple suture involvement, in particular pansynostosis. Our results provide additional evidence of an association between pansynostosis and IL11RA, an emerging core gene for autosomal recessive CS.

Endoscopic surgery for intraconal orbital tumors

Traditionally, external craniofacial approaches have been used for orbital tumor resection. Over the last 30 years, endoscopic sinonasal and skull base techniques have become widely used throughout the world. These experiences paved the way for the extension of transnasal endoscopic techniques to the intraconal orbit. Transnasal endoscopic intraconal surgery has several advantages regarding morbidity and outcome as compared with purely external approaches. However, the anatomical knowledge and experience of the surgeon is crucial for the success of the surgery. Endoscopic approaches for intraconal tumor removal are feasible for medial and inferior lesions as well as for lesions lateral to the optic nerve provided they remain inferior to the "plane of resectability" and no optic nerve retraction is required. As intraorbital tumors are rare, new international staging systems including CHEER (Cavernous Hemangioma Exclusively Endonasal Resection) and ORBIT (Orbital Resection by Intranasal Technique) help to standardize safety, efficacy, and outcome.

Craniofacial characteristics in Van der Woude syndrome

AIM

To describe the particular craniofacial characteristics of Van der Woude syndrome(VWS) patients compared to patients with a non-syndromic cleft(CG1) and to a malocclusive healthy population(CG2).

MATERIAL AND METHODS

Retrospective case-control study. A sample of 110matched-patients was recruited(VWS(n=7),CG1(n=49),CG2(n=49)).Subsequently, 37 radiometric-variables were analysed and the dental-skeletal ages were determined. The intra/inter-observer method errors were quantified.Descriptive statistics were computed, and different inferential analysis tests were used depending on the normality of the data(Chi-square-test,Fisher-exact-test,paired-Student'sT-test,Mann-Whitney´s-test)(p-value<0.05).Pairwise comparisons were corrected by Bonferroni´s criteria.

RESULTS

VW-patients presented specific craniofacial characteristics and morphology. A marked tendency to the vertical growth pattern was found in VW-patients compared to CG1-CG2(p<0.001); at the sagittal level, skeletal class II caused by mandibular retrognathism, with a greatly increased ANB angle compared to CG1(p=0.042). Dental analysis showed that the lower incisor was more retruded and retroclined(p<0.05 in all cases)and the interincisal angulation was increased(p<0.001(CG2)).At the profile level, an open nasolabial angle(p=0.040;CG1) and a more protruding lower lip with respect to the Sn-Pg plane(p=0.040(CG1);p=0.044(CG2))were observed.

CONCLUSIONS

VW-patients present particular characteristics in the facial skeletal structures. There is a critical necessity to increase the evidence regarding specific clinical features and orofacial pathology of rare diseases such as VWS, which will help to these minorities to gain access in the future to a better quality of care with precise treatment and diagnostic necessities.

Skeletal Stem Cell Isolation from Cranial Suture Mesenchyme and Maintenance of Stemness in Culture

Skeletal stem cells residing in the suture mesenchyme are responsible for calvarial development, homeostatic maintenance, and injury-induced repair. These naïve cells exhibit long-term self-renewal, clonal expansion, and multipotency. They possess osteogenic abilities to regenerate bones in a cell-autonomous manner and can directly replace the damaged skeleton. Therefore, the establishment of reliable isolation and culturing methods for skeletal stem cells capable of preserving their stemness promises to further explore their use in cell-based therapy. Our research team is the first to isolate and purify skeletal stem cells from the calvarial suture and demonstrate their potent ability to generate bone at a single-cell level. Here, we describe detailed protocols for suture stem cell (SuSC) isolation and stemness maintenance in culture. These methods are extremely valuable for advancing our knowledge base of skeletal stem cells in craniofacial development, congenital deformity, and tissue repair and regeneration.

An efficient miRNA knockout approach using CRISPR-Cas9 in Xenopus

In recent years CRISPR-Cas9 knockouts (KO) have become increasingly ultilised to study gene function. MicroRNAs (miRNAs) are short non-coding RNAs, 20-22 nucleotides long, which affect gene expression through post-transcriptional repression. We previously identified miRNAs-196a and -219 as implicated in the development of Xenopus neural crest (NC). The NC is a multipotent stem-cell population, specified during early neurulation. Following EMT, NC cells migrate to various points in the developing embryo where they give rise to a number of tissues including parts of the peripheral nervous system, pigment cells and craniofacial skeleton. Dysregulation of NC development results in many diseases grouped under the term neurocristopathies. As miRNAs are so small, it is difficult to design CRISPR sgRNAs that reproducibly lead to a KO. We have therefore designed a novel approach using two guide RNAs to effectively 'drop out' a miRNA. We have knocked out miR-196a and miR-219 and compared the results to morpholino knockdowns (KD) of the same miRNAs. Validation of efficient CRISPR miRNA KO and phenotype analysis included use of whole-mount in situ hybridization of key NC and neural plate border markers such as Pax3, Xhe2, Sox10 and Snail2, q-RT-PCR and Sanger sequencing. To show specificity we have also rescued the knockout phenotype using miRNA mimics. MiRNA-219 and miR-196a KO's both show loss of NC, altered neural plate and hatching gland phenotypes. Tadpoles show gross craniofacial and pigment phenotypes.

Appropriateness of standard cephalometric norms for the assessment of dentofacial characteristics in patients with cleidocranial dysplasia

OBJECTIVES

Cleidocranial dysplasia (CCD) is a rare skeletal syndrome affecting craniofacial and dental development. As a consequence, conventional cephalometric landmarks may not be valid for CCD patients, and the appropriateness of norms used for the general population should be critically discussed.

METHODS

Five patients 9- to 22-year-old (three females, two males) with CCD were included. Lateral-cephalograms, orthopantomographies, and intra-oral photos were retrospectively analysed. Lateral-cephalograms of 50 normal controls (ten for each CCD patient) matched for age and sex were selected from an online database. Cephalometric measurements of each CCD patients were compared with average values of matched controls using Wilcoxon signed-rank test for paired values (α = 0.05).

RESULTS

In CCD patients, a shortening of the cranial base was present (ΔSN = -17.1 mm, p = 0.043). Thus, the mandible (ΔSNPg = +9.5°, p = 0.043) and the maxilla (ΔSNA = +11.2°, p = 0.043) showed protrusion compared to the cranial base, despite a reduced maxillary (ΔCo-A = -15.1 mm, p = 0.043) and mandibular (ΔCo-Gn = -15.2 mm, p = 0.080) length. The mandibular divergence was reduced (ΔSN/GoGn = -6.4°, p = 0.043), a reduced overbite was present (ΔOverbite = -2.9 mm, p = 0.043), and the interincisal angle was increased (ΔInterincisalAngle = +13.7°, p = 0.043), mainly due to retro-inclination of lower incisors.

CONCLUSIONS

Standard cephalometric norms for the assessment of horizontal jaw position may not be applicable to CCD patients because of a reduced anterior cranial base length compared to normal subjects. Vertical relationships may not be affected, and mandibular hypodivergency was confirmed.