Premature Fusion Of Cranial Sutures Research Articles

Convolutional neural network-based classification of craniosynostosis and suture lines from multi-view cranial X-rays

Early and precise diagnosis of craniosynostosis (CSO), which involves premature fusion of cranial sutures in infants, is crucial for effective treatment. Although computed topography offers detailed imaging, its high radiation poses risks, especially to children. Therefore, we propose a deep-learning model for CSO and suture-line classification using 2D cranial X-rays that minimises radiation-exposure risks and offers reliable diagnoses. We used data comprising 1,047 normal and 277 CSO cases from 2006 to 2023. Our approach integrates X-ray-marker removal, head-pose standardisation, skull-cropping, and fine-tuning modules for CSO and suture-line classification using convolution neural networks (CNNs). It enhances the diagnostic accuracy and efficiency of identifying CSO from X-ray images, offering a promising alternative to traditional methods. Four CNN backbones exhibited robust performance, with F1-scores exceeding 0.96 and sensitivity and specificity exceeding 0.9, proving the potential for clinical applications. Additionally, preprocessing strategies further enhanced the accuracy, demonstrating the highest F1-scores, precision, and specificity. A qualitative analysis using gradient-weighted class activation mapping illustrated the focal points of the models. Furthermore, the suture-line classification model distinguishes five suture lines with an accuracy of > 0.9. Thus, the proposed approach can significantly reduce the time and labour required for CSO diagnosis, streamlining its management in clinical settings.

Genetic Association Between Blood Metabolites and Craniosynostosis: A Mendelian Randomization Study.

Craniosynostosis is a congenital disorder characterized by the premature fusion of cranial sutures, leading to abnormal skull development and potential neurodevelopmental complications. The role of metabolic influences in craniosynostosis remains underexplored. This study investigates the causal relationship between specific blood metabolites and the risk of craniosynostosis using a 2-sample Mendelian randomization (MR) approach. Genetic instruments were selected from a genome-wide association study on blood metabolites and craniosynostosis data from the FinnGen database. The MR analysis was conducted using inverse variance weighted regression as the primary method, with MR-Egger and weighted median methods as sensitivity analyses. Additional tests for pleiotropy and heterogeneity were performed to validate the robustness of the findings. The analysis identified significant associations between elevated levels of gamma-glutamylglycine [odds ratio (OR) = 2.379, 95% CI = 1.261-4.488, P = 0.007], N6-acetyllysine (OR = 2.731, 95% CI = 1.081-6.901, P = 0.034), phosphocholine (OR = 2.205, 95% CI = 1.226-3.658, P = 0.038) and glycine (OR = 2.118, 95% CI = 1.226-3.658, P = 0.007) with an increased risk of craniosynostosis. Conversely, higher levels of 3-hydroxy-2-methylpyridine sulfate (OR = 0.411, 95% CI = 0.1717-0.988, P = 0.047) and 5,6-dihydrothymine (OR = 0.293, 95% CI = 0.098-0.876, P = 0.028) were associated with reduced risk. Sensitivity analyses confirmed the robustness of these findings, with no significant evidence of pleiotropy or heterogeneity detected. This study provides evidence that specific blood metabolites may causally influence the risk of craniosynostosis, suggesting potential metabolic pathways that could be targeted for therapeutic intervention. These findings help to develop metabolite-based strategies for the prevention and treatment of craniosynostosis.

Cranial bone microarchitecture in a mouse model for syndromic craniosynostosis.

Crouzon syndrome is a congenital craniofacial disorder caused by mutations in the Fibroblast Growth Factor Receptor 2 (FGFR2). It is characterized by the premature fusion of cranial sutures, leading to a brachycephalic head shape, and midfacial hypoplasia. The aim of this study was to investigate the effect of the FGFR2 mutation on the microarchitecture of cranial bones at different stages of postnatal skull development, using the FGFR2C342Y mouse model. Apart from craniosynostosis, this model shows cranial bone abnormalities. High-resolution synchrotron microtomography images of the frontal and parietal bone were acquired for both FGFR2C342Y/+ (Crouzon, heterozygous mutant) and FGFR2+/+ (control, wild-type) mice at five ages (postnatal days 1, 3, 7, 14 and 21, n = 6 each). Morphometric measurements were determined for cortical bone porosity: osteocyte lacunae and canals. General linear model to assess the effect of age, anatomical location and genotype was carried out for each morphometric measurement. Histological analysis was performed to validate the findings. In both groups (Crouzon and wild-type), statistical difference in bone volume fraction, average canal volume, lacunar number density, lacunar volume density and canal volume density was found at most age points, with the frontal bone generally showing higher porosity and fewer lacunae. Frontal bone showed differences between the Crouzon and wild-type groups in terms of lacunar morphometry (average lacunar volume, lacunar number density and lacunar volume density) with larger, less dense lacunae around the postnatal age of P7-P14. Histological analysis of bone showed marked differences in frontal bone only. These findings provide a better understanding of the pathogenesis of Crouzon syndrome and will contribute to computational models that predict postoperative changes with the aim to improve surgical outcome.

Mercedes Benz pattern craniosynostosis associated with Chiari malformation type 1: A case report of a rare condition

Introduction: Craniosynostosis results from the premature fusion of cranial sutures and is classified as complex when it affects multiple sutures. The abnormal and rare fusion of the sagittal and bilateral lambdoid sutures is known as the Mercedes-Benz (CMB) pattern responsible for up to 0.7% of craniosynostoses. It's characterized by flattening of the occipital bone and sub-lambdoid depression. Additionally, the Arnold-Chiari malformation, one of the anomalies associated, occurs due to the junction of deformities in the posterior fossa and rhombencephalon. Type 1 (CM1) is the most incident and less severe, represented by the pointed shape of the cerebellar tonsils. Objective: The objective of this article is to report a rare case presentation of Mercedes Benz pattern Craniosynostosis associated with Arnold Chiari malformation Case presentation: Male patient, 11 months old, diagnosed with CMB associated with CM1, presenting with anterior turribrachycephaly and occipital brachycephaly. The diagnosis was made after the 10th month of life, with typical findings on computed tomography and cerebellar tonsil herniation (CTH) on magnetic resonance imaging (MRI). No signs of neurodevelopmental delay were observed, and there is no history of cranial malformations in the family. At 11 months, the patient underwent neurosurgery involving cranial parietal remodeling to correct craniosynostosis, along with posterior fossa decompression to address CM1. Conclusion: Neurosurgical techniques like parietal remodeling and posterior decompression, despite their complexity, play a central role in addressing CMB. It's crucial to discuss this rare condition to ensure early diagnosis and treatment, facilitating an efficient approach and preventing potential later consequences.

Perioperative Care for Children With Syndromic Craniofacial Synostosis Undergoing Le Fort III Surgery: A Retrospective Cohort Study.

To present characteristics, surgical variables, complications, and postoperative care in pediatric patients with craniofacial synostosis undergoing Le Fort III osteotomy. Craniofacial synostoses are a group of genetic syndromes that result in premature fusion of cranial and facial sutures, leading to craniofacial deformities and associated complications. Midface advancement through Le Fort III osteotomy is the most frequent surgical option for these conditions. Retrospective monocentric cohort study including patients with syndromic craniofacial synostosis who underwent Le Fort III osteotomy between 2009 and 2022 in a specialized referral center. Data collection encompassed surgical time, blood loss, intraoperative transfusions, fluid balance, and postoperative parameters such as duration of invasive mechanical ventilation and intensive care unit (ICU) length of stay. Twenty-six children were included in the analysis. The median surgical time was 345 minutes (300-360), with an estimated blood loss of 15 (9.9-24) mL/kg. Patients required a median transfusion of 12.63 (7.1-24.5) mL/kg of packed red blood cells and 19.82 (11.1-33) mL/kg of fresh frozen plasma. Intraoperative fluid balance was + 12.5 (0.8-22.8) mL/kg, with a median infusion of 30.4 (23.9-38.7) mL/kg of crystalloids. All patients were transferred to the ICU after surgery to ensure a safe environment for extubation. The median duration of mechanical ventilation in the ICU was 30 (20.25-45) hours, and postoperative ICU length of stay was 2 (2-4) days, and complications were infrequent, with only one extubation failure recorded. Le Fort III osteotomy in craniofacial synostosis patients may be characterized by a complex perioperative course. A multidisciplinary approach in the care of these patients allows for minimizing complications in the perioperative phase. Further research is needed to enhance perioperative management in this unique patient population.

Fronto-Orbital Advancement Using Computer-Aided Surgical Simulation: 2-Dimensional Operative Video

Craniosynostosis is a developmental anomaly resulting from the premature fusion of cranial sutures, with an estimated incidence of 1 per 2000 to 1 per 2500 births. 1 Surgical options for correction include open calvarial vault reconstruction, and more recently, endoscopic-assisted repairs that have been introduced to mitigate blood loss and hospital stay, 2 although these remain understudied. In this operative video (Video), the authors present the case of an 11-month-old girl with right-sided coronal craniosynostosis that was treated with coronal cranial vault reconstruction with fronto-orbital advancement using computer-aided surgical simulation (KLS Martin Group), which has been studied previously with acceptable results when comparing the preoperative plan to the postoperative outcome. 3 The patient was seen in follow-up at 1 month and 6 months and remained neurologically intact, continuing to meet all her developmental milestones appropriately. The patient's guardians consented to performance of the procedure and publication of the images. Institutional review board approval was deemed unnecessary. The participants and any identifiable individuals consented to publication of his/her images.

Quantifying dysmorphologies of the neurocranium using artificial neural networks.

Craniosynostosis, a congenital condition characterized by the premature fusion of cranial sutures, necessitates objective methods for evaluating cranial morphology to enhance patient treatment. Current subjective assessments often lead to inconsistent outcomes. This study introduces a novel, quantitative approach to classify craniosynostosis and measure its severity. An artificial neural network was trained to classify normocephalic, trigonocephalic, and scaphocephalic head shapes based on a publicly available dataset of synthetic 3D head models. Each 3D model was converted into a low-dimensional shape representation based on the distribution of normal vectors, which served as the input for the neural network, ensuring complete patient anonymity and invariance to geometric size and orientation. Explainable AI methods were utilized to highlight significant features when making predictions. Additionally, the Feature Prominence (FP) score was introduced, a novel metric that captures the prominence of distinct shape characteristics associated with a given class. Its relationship with clinical severity scores was examined using the Spearman Rank Correlation Coefficient. The final model achieved excellent test accuracy in classifying the different cranial shapes from their low-dimensional representation. Attention maps indicated that the network's attention was predominantly directed toward the parietal and temporal regions, as well as toward the region signifying vertex depression in scaphocephaly. In trigonocephaly, features around the temples were most pronounced. The FP score showed a strong positive monotonic relationship with clinical severity scores in both scaphocephalic (ρ = 0.83, p < 0.001) and trigonocephalic (ρ = 0.64, p < 0.001) models. Visual assessments further confirmed that as FP values rose, phenotypic severity became increasingly evident. This study presents an innovative and accessible AI-based method for quantifying cranial shape that mitigates the need for adjustments due to age-specific size variations or differences in the spatial orientation of the 3D images, while ensuring complete patient privacy. The proposed FP score strongly correlates with clinical severity scores and has the potential to aid in clinical decision-making and facilitate multi-center collaborations. Future work will focus on validating the model with larger patient datasets and exploring the potential of the FP score for broader applications. The publicly available source code facilitates easy implementation, aiming to advance craniofacial care and research.

Exploring Different Management Modalities of Nonsyndromic Craniosynostosis.

Craniosynostosis is an atypical skull shape characterized by the premature fusion of cranial sutures. It is one of the most common congenital anomalies encountered by craniofacial surgeons, with a prevalence of one in every 2000-2500 births.Itis classifiedinto two main types: syndromic and nonsyndromic. In syndromic, thepatient presents with other abnormalities involving the trunk, face, or extremities.While innonsyndromicthe only anomy is the premature fusion,which usually involvesone suture; the most common subtypes are unicoronal, sagittal, bicoronal, metopic, and lambdoid.As a consequence, premature fusion before its natural time restricts the space for the brain to grow, increases intracranial pressure, causes damage to the brain tissue, and affectsthe development of the child.This review comprehensively provides a detailed overview of nonsyndromic craniosynostosisand aimsto highlight the importance of early and accuratediagnosis,and determining the most suitable intervention, whether surgical or conservative modalities. The optimal treatment approach produces the most favorable aesthetic and functional outcomes.

Whole genome sequencing identifies associations for nonsyndromic sagittal craniosynostosis with the intergenic region of BMP2 and noncoding RNA gene LINC01428

Craniosynostosis (CS) is a major birth defect resulting from premature fusion of cranial sutures. Nonsyndromic CS occurs more frequently than syndromic CS, with sagittal nonsyndromic craniosynostosis (sNCS) presenting as the most common CS phenotype. Previous genome-wide association and targeted sequencing analyses of sNCS have identified multiple associated loci, with the strongest association on chromosome 20. Herein, we report the first whole-genome sequencing study of sNCS using 63 proband-parent trios. Sequencing data for these trios were analyzed using the transmission disequilibrium test (TDT) and rare variant TDT (rvTDT) to identify high-risk rare gene variants. Sequencing data were also examined for copy number variants (CNVs) and de novo variants. TDT analysis identified a highly significant locus at 20p12.3, localized to the intergenic region between BMP2 and the noncoding RNA gene LINC01428. Three variants (rs6054763, rs6054764, rs932517) were identified as potential causal variants due to their probability of being transcription factor binding sites, deleterious combined annotation dependent depletion scores, and high minor allele enrichment in probands. Morphometric analysis of cranial vault shape in an unaffected cohort validated the effect of these three single nucleotide variants (SNVs) on dolichocephaly. No genome-wide significant rare variants, de novo loci, or CNVs were identified. Future efforts to identify risk variants for sNCS should include sequencing of larger and more diverse population samples and increased omics analyses, such as RNA-seq and ATAC-seq.

Yoda1 opens the lymphatic path for craniosynostosis therapy.

The rediscovery of meningeal lymphatic vessels (MLVs) has sparked research interest in their function in numerous neurological pathologies. Craniosynostosis (CS) is caused by a premature fusion of cranial sutures during development. In this issue of the JCI, Matrongolo and colleagues show that Twist1-haploinsufficient mice that develop CS exhibit raised intracranial pressure, diminished cerebrospinal fluid (CSF) outflow, and impaired paravascular CSF-brain flow; all features that were associated with MLV defects and exacerbated pathology in mouse models of Alzheimer's disease. Activation of the mechanosensor Piezo1 with Yoda1 restored MLV function and CSF perfusion in CS models and in aged mice, opening an avenue for further development of therapeutics.

Insights into craniosynostosis management in low- and middle-income countries: A narrative review of outcomes, shortcomings and paediatric neurosurgery capacity.

Craniosynostosis, marked by premature cranial suture fusion, necessitates prompt intervention to avert developmental, neurological, and aesthetic issues. While high-income countries have advanced in managing this condition, low- and middle-income countries grapple with substantial healthcare access disparities. This narrative review explores current craniosynostosis management in low- and middle-income countries. The review focused on studies published between 2008 and 2023. The focus was neurosurgical outcomes, and the search utilised databases like PubMed, EMBASE, Google Scholar, the Cochrane Library and Scopus, incorporating specific keywords and phrases. An in-depth analysis of 21 included studies reveals noteworthy positive outcomes, including low mortality, successful corrections and sustained efficacy. These advancements stem from enhanced pre-operative strategies, surgical techniques and postoperative care. Nonetheless, challenges persist, encompassing complications, mortality, reoperations, and treatment disparities, particularly in low- and middle-income countries constrained by financial and expertise limitations. The enhancement of clinical practice and the formulation of effective policies in the future entail several key strategies. These include the reinforcement of specialised healthcare infrastructure and diagnostic capabilities, the ongoing training and retention of neurosurgeons, the improvement of funding mechanisms, and the promotion of equitable access. Additionally, a crucial focus is placed on fortifying paediatric neurosurgical care in low- and middle-income countries. The recommendations underscore the importance of collaborative initiatives, the development of specialised healthcare infrastructure, and the implementation of strategic policies to not only advance pediatric neurosurgical care but also to address existing gaps in management.

Ribosome biogenesis controls cranial suture MSC fate via the complement pathway in mouse and human iPSC models

Disruption of global ribosome biogenesis selectively affects craniofacial tissues with unclear mechanisms. Craniosynostosis is a congenital craniofacial disorder characterized by premature fusion of cranial suture(s) with loss of suture mesenchymal stem cells (MSCs). Here we focused on ribosomopathy disease gene Snord118, which encodes a small nucleolar RNA (snoRNA), to genetically disturb ribosome biogenesis in suture MSCs using mouse and human induced pluripotent stem cell (iPSC) models. Snord118 depletion exhibited p53 activation, increased cell death, reduced proliferation, and premature osteogenic differentiation of MSCs, leading to suture growth and craniosynostosis defects. Mechanistically, Snord118 deficiency causes translational dysregulation of ribosomal proteins and downregulation of complement pathway genes. Further complement pathway disruption by knockout of complement C3a receptor 1 (C3ar1) exacerbated MSC and suture defects in mutant mice, whereas activating the complement pathway rescued MSC cell fate and suture growth defects. Thus, ribosome biogenesis controls MSC fate via the complement pathway to prevent craniosynostosis.

Meningeal lymphatics stem cognitive decline in craniosynostosis.

Craniosynostosis is a congenital craniofacial disorder where premature fusion of cranial sutures causes elevated intracranial pressure and neurological deficits. In this issue of Cell Stem Cell, Ma etal. demonstrate that replenishing skull progenitor cells alleviates intracranial pressure elevations in craniosynostosis by restoring the meningeal lymphatic system, improving neurocognitive function.

Evaluating Tranexamic Acid Administration in Cranial Vault Reconstruction: The Experience of an Academic Center in the Deep South

Background: In infants with craniosynostosis, cranial vault reconstruction is performed to prevent sequela of premature fusion of cranial sutures. Open correction puts patients at risk for complications of major blood loss. We evaluated the impact of tranexamic acid (TXA) in children undergoing open surgical repair of a variety of types of craniosynostosis. Methods: A retrospective review of 102 infants who underwent open cranial vault reconstruction between January 2015 and December 2020 at a tertiary referral hospital was performed. The patients were stratified into TXA or non-TXA based on usage. Outcome measures included volume of blood transfused, perioperative blood loss and any adverse effects were noted. Results: In this cohort 42% of patients were treated with TXA. There was no significant difference between the patient demographics of TXA and non-TXA cohorts with the majority classified as Sagittal Craniosynostosis ( P = .1062), an average weight of 8.89 ± 1.37 kg, and age of 9.02 ± 2.02 months at time of surgery. The non-TXA cohort had longer length of hospital stay ( P = .04). The TXA cohort had an average 100 ml decrease in surgical drain output over the course of their hospital stay ( P = .02). Overall surgical complication was 14% ( P = .18) and clinical outcomes were not significantly different between the cohorts. Conclusions: The receipt of TXA in the interoperative period in patients with craniosynostosis undergoing cranial vault remodeling was associated with a decreased surgical drain output and length of stay.

FRI285 Evidence For ZIC1 As A Novel Gene For Isolated Hypogonadotropic Hypogonadism With Phenotypic Pleiotropic Intersection With Cerebellar Malformation

Abstract Disclosure: J. Cassin: None. D.L. Keefe: None. K.E. Sung: None. C.C. Bojo: None. G. Santiago: None. L. Plummer: None. K.B. Salnikov: None. S.B. Seminara: None. R. Balasubramania: None. P.L. Mellon: None. Isolated Hypogonadotropic Hypogonadism (IHH) is a condition marked by absent pubertal development and low sex steroids in the setting of low/normal gonadotropins. Mutations in known IHH genes only explain &amp;lt;50% of the genetic etiology suggesting significant missing heritability in IHH. To explore this missing IHH heritability, we examined whole exome sequencing data from approximately 1400 IHH probands for rare genetic variants in novel genes that are enriched in IHH patients. We identified four IHH probands with rare, novel heterozygous variants in ZIC1 (p.H134Rfs*21, p.Y287X, p.E299K, p.S413Y), a gene encoding C2H2-type zinc finger protein (rare variant enrichment p &amp;lt;0.0001 for both truncating and missense alleles). Prior literature review show that heterozygous deletions affecting the ZIC1 gene have been linked to Dandy Walker malformation [DWM], a cerebellar malformation, while gain-of-function ZIC1 single nucleotide variants have been linked to coronal craniosynostosis (premature cranial suture fusion). Notably, two IHH subjects with novel ZIC1 variants in our cohort exhibited posterior fossa abnormalities (DWM [p.H134Rfs*21] and ventriculomegaly [E299K]) but none had any cranial suture defects. Given the above genetic enrichment, phenotypic overlap between DWM and IHH, and ZIC1’s known high expression in the hypothalamus, we explored whether ZIC1 regulates the expression of hypothalamic releasing factors. We determined that ZIC1 overexpression increases GNRH1 luciferase expression in the immortalized GnRH cell line, GT1-7. We next explored whether the rare ZIC1 variants identified in the four IHH probands would affect this phenotype. We discovered that three of the four ZIC1 variants significantly reduced GNRH1-luciferase expression. Of those, one truncating mutation, p.H134Rfs*21, resulted in lower ZIC1 protein content in the cell and failure to localize to the nucleus, suggesting a hypomorphic mechanism of action. These findings implicate ZIC1 variants as putatively causal for IHH. Further studies will define the precise ZIC1 transcriptional targets that relate to ZIC1’s pleotropic effects on GnRH transcription, neuronal function, cerebellar development, and cranial suture fusion. Presentation: Friday, June 16, 2023

Concurrent impact of de novo mutations on cranial and cortical development in nonsyndromic craniosynostosis.

Nonsyndromic craniosynostosis (nsCS), characterized by premature cranial suture fusion, is considered a primary skull disorder in which impact on neurodevelopment, if present, results from the mechanical hindrance of brain growth. Despite surgical repair of the cranial defect, neurocognitive deficits persist in nearly half of affected children. Therefore, the authors performed a functional genomics analysis of nsCS to determine when, where, and in what cell types nsCS-associated genes converge during development. The authors integrated whole-exome sequencing data from 291 nsCS proband-parent trios with 29,803 single-cell transcriptomes of the prenatal and postnatal neurocranial complex to inform when, where, and in what cell types nsCS-mutated genes might exert their pathophysiological effects. The authors found that nsCS-mutated genes converged in cranial osteoprogenitors and pial fibroblasts and their transcriptional networks that regulate both skull ossification and cerebral neurogenesis. Nonsyndromic CS-mutated genes also converged in inhibitory neurons and gene coexpression modules that overlapped with autism and other developmental disorders. Ligand-receptor cell-cell communication analysis uncovered crosstalk between suture osteoblasts and neurons via the nsCS-associated BMP, FGF, and noncanonical WNT signaling pathways. These data implicate a concurrent impact of nsCS-associated de novo mutations on cranial morphogenesis and cortical development via cell- and non-cell-autonomous mechanisms in a developmental nexus of fetal osteoblasts, pial fibroblasts, and neurons. These results suggest that neurodevelopmental outcomes in nsCS patients may be driven more by mutational status than surgical technique.

Delineation of craniosynostosis in Saudi Arabia

Craniosynostosis (CS) is defined as an early premature fusion of cranial sutures resulted to congenital skull deformity and affecting approximately 1 in 2500 children.

Application and development of orthognathic surgery in treatment of syndromic craniosynostosis

To summarize the application and recent development of orthognathic surgery in treating syndromic craniosynostosis. The related literature at home and abroad in recent years was extensively reviewed, and the indications, routine procedures, and protocols of orthognathic surgery in the treatment of syndromic craniosynostosis were summarized and analyzed. Craniosynostosis is a common congenital craniofacial malformation. Syndromic craniosynostosis usually involves premature fusion of multiple cranial sutures and is associated with other deformities. Orthognathic surgery is the necessary and effective means to improve the midfacial hypoplasia and malocclusion. Le Fort I osteotomy combined with sagittal split ramus osteotomy are the common surgical options. Orthognathic surgery should combine with craniofacial surgery and neurosurgery, and a comprehensive long-term evaluation should be conducted to determine the best treatment plan. Orthognathic surgery plays an important role in the comprehensive diagnosis and treatment of syndromic craniosynostosis. The development of digital technology will further promote the application and development of orthognathic surgery in the treatment of syndromic craniosynostosis.

Craniosynostosis in Patients With X-Linked Hypophosphatemia: A Review.

Craniosynostosis is a rare condition of skull development, manifesting during fetal and early infant development, and is usually congenital. Craniosynostosis secondary to metabolic disorders, such as X-linked hypophosphatemia (XLH), is less common and is typically diagnosed later than congenital craniosynostosis. XLH is a rare, progressive, and lifelong hereditary phosphate-wasting disorder characterized by loss of function of the phosphate-regulating endopeptidase homologue, X-linked gene, which is associated with premature fusion of cranial sutures due to abnormal phosphate metabolism (hypophosphatemia) and altered bone mineralization or elevated levels of fibroblast growth factor 23. This targeted literature review of 38 articles seeks to provide an overview of craniosynostosis in individuals with XLH. The objectives of this review are to increase awareness of the prevalence, presentation, and diagnosis of craniosynostosis in XLH; examine the spectrum of craniosynostosis severity in XLH; discuss the management of craniosynostosis in those with XLH; recognize the complications for patients with XLH; and identify what is known about the burden of craniosynostosis for individuals with XLH. The presentation of craniosynostosis in individuals with XLH tends to manifest slightly later than congenital craniosynostosis and can vary in severity and appearance, making diagnosis difficult and resulting in inconsistent clinical outcomes. Consequently, craniosynostosis in patients with XLH is an underreported and potentially underrecognized condition. There have been no studies investigating the effects of craniosynostosis on the quality of life of people with XLH. Despite a growing awareness among researchers and experienced clinicians, there are still improvements to be made in general awareness and timely diagnosis of craniosynostosis in XLH. The XLH community would benefit from further study into the prevalence of craniosynostosis, the effect of XLH medical therapy on the development of craniosynostosis, and the effects of craniosynostosis on quality of life. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Augmentation of BMP Signaling in Cranial Neural Crest Cells Leads to Premature Cranial Sutures Fusion through Endochondral Ossification in Mice.

Craniosynostosis is a congenital anomaly characterized by the premature fusion of cranial sutures. Sutures are a critical connective tissue that regulates bone growth; their aberrant fusion results in abnormal shapes of the head and face. The molecular and cellular mechanisms have been investigated for a long time, but knowledge gaps remain between genetic mutations and mechanisms of pathogenesis for craniosynostosis. We previously demonstrated that the augmentation of bone morphogenetic protein (BMP) signaling through constitutively active BMP type 1A receptor (caBmpr1a) in neural crest cells (NCCs) caused the development of premature fusion of the anterior frontal suture, leading to craniosynostosis in mice. In this study, we demonstrated that ectopic cartilage forms in sutures prior to premature fusion in caBmpr1a mice. The ectopic cartilage is subsequently replaced by bone nodules leading to premature fusion with similar but unique fusion patterns between two neural crest-specific transgenic Cre mouse lines, P0-Cre and Wnt1-Cre mice, which coincides with patterns of premature fusion in each line. Histologic and molecular analyses suggest that endochondral ossification in the affected sutures. Both in vitro and in vivo observations suggest a greater chondrogenic capacity and reduced osteogenic capability of neural crest progenitor cells in mutant lines. These results suggest that the augmentation of BMP signaling alters the cell fate of cranial NCCs toward a chondrogenic lineage to prompt endochondral ossification to prematurely fuse cranial sutures. By comparing P0-Cre;caBmpr1a and Wnt1-Cre;caBmpr1a mice at the stage of neural crest formation, we found more cell death of cranial NCCs in P0-Cre;caBmpr1a than Wnt1-Cre;caBmpr1a mice at the developing facial primordia. These findings may provide a platform for understanding why mutations of broadly expressed genes result in the premature fusion of limited sutures. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.