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.