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Carpenter syndrome (CRPTS) is a rare autosomal recessive condition caused by biallelic variants in genes that encode negative regulators of hedgehog signalling (RAB23 [CRPT1] or, more rarely, MEGF8 [CRPT2]), and is characterised by craniosynostosis, polysyndactyly, and other congenital abnormalities. We describe a further six families comprising eight individuals with MEGF8-associated CRPT2, increasing the total number of reported cases to fifteen, and refine the phenotype of CRPT2 compared to CRPT1. The core features of craniosynostosis, polysyndactyly and (in males) cryptorchidism are almost universal in both CRPT1 and CRPT2. However, laterality defects are present in nearly half of those with MEGF8-associated CRPT2, but are rare in RAB23-associated CRPT1. Craniosynostosis in CRPT2 commonly involves a single midline suture in comparison to the multi-suture craniosynostosis characteristic of CRPT1. No patient to date has carried two MEGF8 gene alterations that are both predicted to lead to complete loss-of-function, suggesting that a variable degree of residual MEGF8 activity may be essential for viability and potentially contributing to variable phenotypic severity. These data refine the phenotypic spectrum of CRPT2 in comparison to CRPT1 and more than double the number of likely pathogenic MEGF8 variants in this rare disorder., (© 2024. The Author(s).)

The fibroblast growth factor (FGF)/FGF receptor (FGFR) signaling pathway plays important roles in the development and growth of the skeleton. Apert syndrome caused by gain-of-function mutations of FGFR2 results in aberrant phenotypes of the skull, midface, and limbs. Although short limbs are representative features in patients with Apert syndrome, the causative mechanism for this limb defect has not been elucidated. Here we quantitatively confirmed decreases in the bone length, bone mineral density, and bone thickness in the Apert syndrome model of gene knock-in Fgfr2 S252W/+ (EIIA-Fgfr2 S252W/+ ) mice. Interestingly, despite these bone defects, histological analysis showed that the endochondral ossification process in the mutant mice was similar to that in wild-type mice. Tartrate-resistant acid phosphatase staining revealed that trabecular bone loss in mutant mice was associated with excessive osteoclast activity despite accelerated osteogenic differentiation. We investigated the osteoblast-osteoclast interaction and found that the increase in osteoclast activity was due to an increase in the Rankl level of osteoblasts in mutant mice and not enhanced osteoclastogenesis driven by the activation of FGFR2 signaling in bone marrow-derived macrophages. Consistently, Col1a1-Fgfr2 S252W/+ mice, which had osteoblast-specific expression of Fgfr2 S252W, showed significant bone loss with a reduction of the bone length and excessive activity of osteoclasts was observed in the mutant mice. Taken together, the present study demonstrates that the imbalance in osteoblast and osteoclast coupling by abnormally increased Rankl expression in Fgfr2 S252W/+ mutant osteoblasts is a major causative mechanism for bone loss and short long bones in Fgfr2 S252W/+ mice., (© 2022 The Authors. Journal of Cellular Physiology published by Wiley Periodicals LLC.)

Sutures separate the flat bones of the skull and enable coordinated growth of the brain and overlying cranium. The coronal suture is most commonly fused in monogenic craniosynostosis, yet the unique aspects of its development remain incompletely understood. To uncover the cellular diversity within the murine embryonic coronal suture, we generated single-cell transcriptomes and performed extensive expression validation. We find distinct pre-osteoblast signatures between the bone fronts and periosteum, a ligament-like population above the suture that persists into adulthood, and a chondrogenic-like population in the dura mater underlying the suture. Lineage tracing reveals an embryonic Six2+ osteoprogenitor population that contributes to the postnatal suture mesenchyme, with these progenitors being preferentially affected in a Twist1+/-; Tcf12+/- mouse model of Saethre-Chotzen Syndrome. This single-cell atlas provides a resource for understanding the development of the coronal suture and the mechanisms for its loss in craniosynostosis., (© 2021. The Author(s).)

BACKGROUND Pfeiffer syndrome (PS) is a fibroblast growth factor receptor (FGFR)-associated craniosynostosis syndrome, characterized by abnormally broad and medially deviated thumbs and great toes. Tracheal cartilage sleeve (TCS) is associated with several FGFR-associated craniosynostosis syndromes, including PS. TCS is an airway malformation in which the tracheal cartilage rings fuse with each other to form a sleeve of cartilage. CASE REPORT The patient was a 4-year-old girl with PS, TCS, and abnormal hyperplasia of non-fused intrapulmonary cartilages. The patient showed cranial dysplasia on prenatal ultrasonography. At birth, a cloverleaf skull in association with hydrocephalus and digital malformations was apparent. These findings were consistent with PS type 2. The diagnosis of PS type 2 was confirmed from a genetic test detecting a FGFR2 mutation (Y340C). During the clinical course, she underwent several surgeries, including ventriculoperitoneal shunts, sequential cranioplasty surgeries, and tracheotomy due to upper airway abnormalities. At 4 years old, she died of multiple organ failure following aspiration pneumonia. The autopsy revealed that the tracheal cartilages had fused with each other, resulting in a condition called TCS, in which the cartilage rings and tracheal ligaments were absent. The lungs were poorly aerated, and the dilated bronchi had thickened walls surrounded by many cartilage fragments, mainly at the hilum. These cartilages tended to overlap at both ends, did not fuse, and were greatly altered in size and shape. CONCLUSIONS We report the results of autopsy for PS with the first histopathological findings for the lungs and other visceral organs.

Background: The diagnostic process for uncommon disorders with similar manifestations is complicated and requires newer technology, like gene sequencing for a correct diagnosis., Main Body: We described two brothers clinically diagnosed with Carpenter syndrome, which is a condition characterized by the premature fusion of certain skull bones (craniosynostosis), abnormalities of the fingers and toes, and other developmental problems, for which they underwent craniotomies. However, whole exome sequencing analysis concluded a novel pathological variation in the ATRX chromatin remodeler gene and protein remodeling demonstrated structural variations that decreased the function, giving a completely different diagnosis to these patients., Conclusion: Our study focuses on the importance of using newer technologies, such as whole exome sequencing analysis, in patients with ambiguous phenotypes., (© 2021. The Author(s).)

Midface hypoplasia is a major manifestation of Apert syndrome. However, the tissue component responsible for midface hypoplasia has not been elucidated. We studied mice with a chondrocyte-specific Fgfr2 S252W mutation (Col2a1-cre; Fgfr2 S252W/+ ) to investigate the effect of cartilaginous components in midface hypoplasia of Apert syndrome. In Col2a1-cre; Fgfr2 S252W/+ mice, skull shape was normal at birth, but hypoplastic phenotypes became evident with age. General dimensional changes of mutant mice were comparable with those of mice with mutations in EIIa-cre; Fgfr2 S252W/+ , a classic model of Apert syndrome in mice. Col2a1-cre; Fgfr2 S252W/+ mice showed some unique facial phenotypes, such as elevated nasion, abnormal fusion of the suture between the premaxilla and the vomer, and decreased perpendicular plate of the ethmoid bone volume, which are related to the development of the nasal septal cartilage. Morphological and histological examination revealed that the presence of increased septal chondrocyte hypertrophy and abnormal thickening of nasal septum is causally related to midface deformities in nasal septum-associated structures. Our results suggest that careful examination and surgical correction of the nasal septal cartilage may improve the prognosis in the surgical treatment of midface hypoplasia and respiratory problems in patients with Apert syndrome.

Polydactyly is a limb malformation and can occur as nonsyndromic polydactyly, syndromic polydactyly, or along with other limb defects. A few genes have been identified that cause various forms of syndromic and nonsyndromic polydactyly, of which GLI3 has been extensively explored. In the present study, GLI3 gene was screened by direct resequencing in 15 polydactyly cases with or without other anomalies. GLI3 screening revealed two novel pathogenic variants, NM_000168.6:c.3414delC [p.(H1138Qfs*68)] and NM_000168.6:c.1862C>T [p.(P621L)], found in two unrelated cases of familial complex pre- and postaxial polysyndactyly and sporadic Greig cephalopolysyndactyly syndrome (GCPS), respectively. The first pathogenic GLI3 variant, NM_000168.6:c.3414delC, causes premature protein truncation at the C-terminal domain of GLI3. Alternatively, the second pathogenic variant, NM_000168.6:c.1862C>T, lies in the DNA binding domain of GLI3 protein and may affect its hydrophobic interaction with DNA. Both pathogenic GLI3 variants had reduced transcriptional activity in HEK293 cells that likely had led to haploinsufficiency and, consequently, the clinical phenotypes. Overall, the present study reports a novel familial case of complex pre- and postaxial polysyndactyly and the underlying novel pathogenic GLI3 variant expanding the clinical criteria for GLI3 mutational spectrum to complex pre- and postaxial polysyndactyly. Furthermore, this study also reports a novel GLI3 pathogenic variant linked to GCPS, highlighting the known genotype-phenotype correlation., (© 2020 Wiley Periodicals LLC.)

Aim: To assess the long-term outcomes of our management protocol for Saethre-Chotzen syndrome, which includes one-stage fronto-orbital advancement., Method: All patients born with Saethre-Chotzen syndrome between January 1992 and March 2017 were included. Evaluated parameters included occipital frontal head circumference (OFC), fundoscopy, neuroimaging (ventricular size, tonsillar position, and the presence of collaterals/an abnormal transverse sinus), polysomnography, and ophthalmological outcomes. The relationship between papilledema and its associated risk factors was evaluated with Fisher's exact test., Results: Thirty-two patients (21 females, 11 males) were included. Median (SD) age at first surgery was 9.6 months (3.1mo) for patients who were primarily referred to our center (range: 3.6-13.0mo), the median (SD) age at last follow-up was 13 years (5y 7mo; range: 3-25y). Seven patients had papilledema preoperatively, which recurred in two. Two patients had papilledema solely after first surgery. Second cranial vault expansion was indicated in 20%. Thirteen patients had an OFC deflection, indicating restricted skull growth, one patient had ventriculomegaly, and none developed hydrocephalus. Eleven patients had emissary veins, while the transverse sinus was aberrant unilaterally in 13 (hypoplastic n=10 and absent n=3). Four patients had mild tonsillar descent, one of which was a Chiari type I malformation. Four patients had obstructive sleep apnoea (two mild, one moderate, and one severe). An aberrant transverse sinus was associated with papilledema (p=0.01)., Interpretation: Single one-stage fronto-orbital advancement was sufficient to prevent intracranial hypertension for 80% of our patients with Saethre-Chotzen syndrome. Follow-up should focus on OFC deflection and venous anomalies., (© 2020 The Authors. Developmental Medicine & Child Neurology published by John Wiley & Sons Ltd on behalf of Mac Keith Press.)

Rationale: Apert syndrome (AS) is an autosomal dominant inheritance pattern of the most severe craniosynostosis syndrome. AS is characterized by synostosis of cranial sutures and acrocephaly, including brachycephaly, midfacial hypoplasia, and syndactyly of the hands and feet. Patients with AS often present with craniosynostosis, severe syndactyly, and skin, skeletal, brain, and visceral abnormalities., Patient Concerns: A pregnant Chinese woman presented with a fetus at 23 + 5 weeks of gestation with suspected AS in a prenatal ultrasound examination. Following ultrasound, the pregnancy underwent spontaneous abortion. Gene sequencing was performed on the back skin of the dead fetus., Diagnosis: The diagnosis of AS was confirmed on the basis of clinical manifestations of the fetus, and a de novo mutation in the fibroblast growth factor receptor 2 (FGFR2) gene was identified., Interventions: The couple finally chose to terminate the pregnancy based on the ultrasonic malformations and the risk of the parents having a neonate with AS in the future is small. However, any future pregnancy must be assessed by prenatal diagnosis., Outcomes: The dead fetus presented with bilateral skull deformation. Additionally, there were bilateral changes to the temporal bone caused by inwards movement leading to concave morphology, a "clover" sign, and syndactyly from the index finger/second toe to the little finger/little toe. AS was diagnosed by genetic testing, which showed a p.S137W (c.410C>G, chr10:123279677) mutation in the FGFR2 gene., Lessons: Clinicians should be aware that there are a variety of ultrasound findings for AS. Therefore, genetic testing should be used when appropriate to confirm diagnosis of AS.

Background: Apert syndrome causes normal or enlarged intracranial volume overall as patients grow. This study aimed to trace the segmental anterior, middle, and posterior cranial fossae volume and structural morphology in these patients, to help discern a more focused and individualized surgical treatment plan for patients with Apert syndrome., Methods: This study included 82 preoperative computed tomographic scans (Apert, n = 32; control, n = 50) divided into five age-related subgroups. The scans were measured using image processing and three-dimensional modeling software., Results: The middle cranial fossa volume was increased and was the earliest change noted. It was increased by 45 percent (p = 0.023) compared with controls before 6 months of age and remained increased into adulthood (161 percent, p = 0.016), with gradually increasing severity. The anterior and posterior cranial fossae volumes also increased, by 35 percent (p = 0.032) and 39 percent (p = 0.007), respectively. Increased depth of cranial fossae contributed most to the increase in volumes of patients with Apert syndrome, with correlation coefficients of 0.799, 0.908, and 0.888 for anterior, middle, and posterior cranial fossa, respectively. The intracranial volume was increased 12 percent (p = 0.098) across the entire test age range (0 to 26 years old), but only had statistical significance during the age range of 6 to 18 years (22 percent, p = 0.001)., Conclusions: Malformation of the middle cranial fossa is an early, perhaps the initial, pivotal cranial morphologic change in Apert syndrome. Increased cranial fossae depth is an inherent characteristic of the maldevelopment. Normalization of cranial volume and circumference overall may not achieve a normal skull structure, as it does not correct regional craniocerebral disproportion.

Apert syndrome is a rare genetic disorder that manifests as craniosynostosis, craniofacial and limb dysmorphic features. Mutations in fibroblast growth factor receptor 2 (FGFR2) gene account for almost all cases. Given the impact it can have throughout life, prenatal management becomes a challenge. A healthy 33-year-old woman, gravida 4, para 0, was referred to routine ultrasound at 22 weeks of gestation. Atypical cranial morphology with prominent forehead, ocular proptosis, hypertelorism and mitten hands were detected. Genetic investigation revealed an FGFR2 gene mutation (c.755C>G(p.Ser252Trp)), confirming the diagnosis. Magnetic resonance showed brachycephaly, turricephaly and cortical malformation. Following counselling, parents requested medical termination of pregnancy. Macroscopic features were consistent with ultrasound findings. This case emphasises the importance of early diagnosis to provide the best family counselling and prenatal management. A multidisciplinary team, consisting of an obstetrician with ultrasonography experience, a medical geneticist and a fetal pathologist, should conduct these cases., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Apert syndrome is frequently combined with respiratory insufficiency, because of the midfacial deformity which, in turn, is influenced by the malformation of the skull base. Respiratory impairment resulting from Apert syndrome is caused by multilevel limitations in airway space. Therefore, this study evaluated the segmented nasopharyngeal and laryngopharyngeal anatomy to clarify subcranial anatomy in children with Apert syndrome and its relevance to clinical management., Methods: Twenty-seven patients (Apert syndrome, n = 10; control, n = 17) were included. All of the computed tomographic scans were obtained from the patients preoperatively, and no patient had confounding disease comorbidity. Computed tomographic scans were analyzed using Surgicase CMF. Craniometric data relating to the midface, airway, and subcranial structures were collected. Statistical significance was determined using t test analysis., Results: Although all of the nasal measurements were consistent with those of the controls, the nasion-to-posterior nasal spine, sphenethmoid-to-posterior nasal spine, sella-to-posterior nasal spine, and basion-to-posterior nasal spine distances were decreased 20 (p < 0.001), 23 (p = 0.001), 29 (p < 0.001), and 22 percent (p < 0.001), respectively. The distance between bilateral gonions and condylions was decreased 17 (p = 0.017) and 18 percent (p = 0.004), respectively. The pharyngeal airway volume was reduced by 40 percent (p = 0.01)., Conclusion: The airway compromise seen in patients with Apert syndrome is attributable more to the pharyngeal region than to the nasal cavity, with a gradually worsening trend from the anterior to the posterior airway, resulting in a significantly reduced volume in the hypopharynx.

Background: Saethre-Chotzen Syndrome (SCS) is an autosomal dominant syndrome that occurs due to a mutation or deletion of the Twist1 gene at chromosome 7p21. Our aim was to conduct a morphometric analysis of the craniofacial features in the mouse associated with a Twist1 +/- mutation., Methods: Micro-computed imaging was conducted for the skulls of forty skeletally mature mice, equally distributed by sex (male and female) and two genotypes (Twist1 +/- or murine model of SCS; and Twist1 +/+ or wild-type). A morphometric analysis was carried out for eight parameters for the maxillary-zygomatico-temporal region, 10 parameters for the mandible and three parameters for teeth from three-dimensional reconstructions., Results: Compared with wild-type, the murine model of SCS showed these trends: (1) maxillary-zygomatico-temporal region, significantly shorter length and width posteriorly (p<0.05), (2) mandible, significantly reduced height and width (p<0.05), and (3) teeth, significantly shorter height, shorter mesio-distal width but longer bucco-lingual width (p<0.05). In the murine model of SCS, the key morphological variations included incomplete ossification of the temporal bone and zygomatic arch, twisting and/or incomplete ossification of the palatal process of the maxilla, premaxilla and the ventral nasal concha, as well as bifid coronoid processes., Conclusions: The skeletal and dental alterations in the height, length and width provide a foundation for large-scale phenomics studies, which will improve existing knowledge of the Twist1 signalling cascade. This is relevant given the predicted shift towards minimally invasive molecular medical treatment for craniosynostosis., (Copyright © 2019 Elsevier GmbH. All rights reserved.)

Introduction: We present the CT scan-derived turricephaly index (TI) as a quotient of the maximal occipito-frontal length of the skull to the distance from the centre of the sella to the highest point on the vertex as a validated tool for assessing turricephaly and evaluating surgical techniques aimed at reducing it., Materials and Methods: Measurements taken from CTs of non-operated children with Apert syndrome and age-matched controls were analysed using Centricity PACS system (from the lateral scout image) and the thick-sliced Osirix tool. CTs from non-operated children with Apert syndrome were used to investigate the natural history of their turricephaly both as a group and individually., Results: There was statistically significant agreement between measurements taken from the CT scout and Osirix for 42 control children (R 2  = 0.97) and 42 children with Apert syndrome (R 2  = 0.98) and between two separate observers. There was a statistically significant difference (p < 0.001) between CT scout-derived TI value between controls (1.73 ± 0.12, range 1.46-1.99) and Apert children (1.42 ± 0.15, range 1.13-1.73). Analysis of 113 CTs of 65 non-operated children with Apert syndrome showed a decrease in turricephaly with age (positive spearman correlation: r = 0.50, p < 0.001). Analysis of 37 CTs of those with multiple (>2) CT's showed a similar decrease in turricephaly in the individual child (p < 0.001)., Conclusions: TI derived from the CT scout view provides a simple, objective and validated method for assessing turricephaly. We recommend it for monitoring and for the prospective evaluation of reconstructive techniques in children with complex/syndromic craniosynostosis., (Copyright © 2018 European Association for Cranio-Maxillo-Facial Surgery. All rights reserved.)

Complicated craniofacial malformations interfacing with multiple intracellular regulatory mechanisms, lead to ambiguous growth patterns in Apert syndrome. This study aims to explore the chronology and pathogenesis of the development of craniofacial anatomic relationships and to verify the positional correlates between skull and facial structures in Apert syndrome. Fifty-four computed tomography scans (Apert, n = 18; control, n = 36) were included and divided into 3 age subgroups. Craniofacial 3-dimensional cephalometries were analyzed by Materialize software. The angle between sella-nasion plane and maxillary plane widens 7.74° (P = 0.003) prior to 6 months of age; thereafter, this widening increases by 10.36° (P < 0.001) in 6 months to 2 years of age, and remains increased by 8.9° (P = 0.046) throughout childhood. The angle between Frankfort horizontal plane and maxillary plane widens 5.17° (P = 0.022) before 6 months. Angles SNA, SNB, and ANB showed decreases, averaging 12.23° (P < 0.001), 5.19° (P = 0.004), and 6.72° (P = 0.001), respectively. The linear measurements showed synchronicity and continuing deformity into adulthood. Between 6 months to 2 years of age, the distance from sella to nasion (S-N), anterior nasal spine (S-ANS), and posterior nasal spine (S-PNS) decreased 8% (P = 0.006), 16% (P < 0.001), and 19% (P = 0.002), respectively, and remained shortened into adulthood. The angulation changes occur earlier in development than linear distance reduction in Apert syndrome patients compared with controls. Angular adjustments were not sufficient to maintain normal cranial base length. Facial deformity of Apert syndrome temporally begins with the midface, and affects orbit and mandible later in life.

Background: Apert syndrome is a rare form of syndromic craniosynostosis, also known as acrocephalosyndactyly, which is a disorder characterized by a unique set of craniofacial, hand, and foot abnormalities. Diagnosis is made through a genetic analysis, where the mutation of FGFR2, Ser252Trp, and Pro253Arg confirms the diagnosis., Case Presentation: Although craniosynostosis is the most common characteristic in clinical presentation, we present an atypical case of a one-and-a-half-year-old girl with Apert syndrome confirmed by genetic testing but without craniosynostosis.

Apert syndrome is characterized by the severe craniofacial deformities. The subsequent process of skeletal maldevelopment is likely to be influenced by multiple interactions at several levels, at a given time. In this study, we aimed to explore the evolution of cranial basal dysmorphology and the chronology of these deformities in Apert syndrome, by objectively analyzing three-dimensional measurements. Fifty-four CT scans from unoperated patients (Apert, n = 18; control, n = 36) were included in this study, with age range from 3 days to 24 years. Before 6 months of age, Apert's anterior cranial base was widened 60%. Between 6 months and 2 years of age, the whole cranial base length, anterior cranial base length and posterior cranial base length decreased 8%, 8% and 14%, respectively. The greater sphenoid wing angle was wider by 26.0°, and continued into adulthood. The cranial base angles did not produce significant changes throughout life. The extra cranial distances synchronously and almost proportionally shortened after later infancy. The anterior and posterior cranial base length shortened at an almost proportional rate. The malformations of the skull vault are additive effects with cranial base fusion on skull length restriction, but the angulation of the skull base is virtually normal., (Copyright © 2018 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

Background: Apert syndrome is characterized by craniosynostosis and bony syndactyly of the hands and feet. The cause of Apert syndrome is a single nucleotide substitution mutation (S252W or P253R) in fibroblast growth factor receptor 2 (FGFR2). Clinical experience suggests increased production of saliva by Apert syndrome patients, but this has not been formally investigated. FGFR2 signaling is known to regulate branching morphogenesis of the submandibular glands (SMGs). With the Apert syndrome mouse model (Ap mouse), we investigated the role of FGFR2 in SMGs and analyzed the SMG pathology of Apert syndrome., Results: Ap mice demonstrated significantly greater SMG and sublingual gland (SMG/SLG complex) mass/body weight and percentage of parenchyma per unit area of the SMG compared with control mice. Furthermore, gene expression of Fgf1, Fgf2, Fgf3, Pdgfra, Pdgfrb, Mmp2, Bmp4, Lama5, Etv5, and Dusp6 was significantly higher in the SMG/SLG complex of Ap mice. FGF3 and BMP4 exhibited altered detection patterns. The numbers of macrophages were significantly greater in SMGs of Ap mice than in controls. Regarding functional evaluations of the salivary glands, no significant differences were observed., Conclusions: These results suggest that the gain-of-function mutation in FGFR2 in the SMGs of Ap mice enhances branching morphogenesis. Developmental Dynamics 247:1175-1185, 2018. © 2018 Wiley Periodicals, Inc., (© 2018 Wiley Periodicals, Inc.)

Cranial sutures separate the skull bones and house stem cells for bone growth and repair. In Saethre-Chotzen syndrome, mutations in TCF12 or TWIST1 ablate a specific suture, the coronal. This suture forms at a neural-crest/mesoderm interface in mammals and a mesoderm/mesoderm interface in zebrafish. Despite this difference, we show that combinatorial loss of TCF12 and TWIST1 homologs in zebrafish also results in specific loss of the coronal suture. Sequential bone staining reveals an initial, directional acceleration of bone production in the mutant skull, with subsequent localized stalling of bone growth prefiguring coronal suture loss. Mouse genetics further reveal requirements for Twist1 and Tcf12 in both the frontal and parietal bones for suture patency, and to maintain putative progenitors in the coronal region. These findings reveal conservation of coronal suture formation despite evolutionary shifts in embryonic origins, and suggest that the coronal suture might be especially susceptible to imbalances in progenitor maintenance and osteoblast differentiation., Competing Interests: CT, MT, DF, MB, RM, JC No competing interests declared, (© 2018, Teng et al.)

Midface dysgenesis is a feature of more than 200 genetic conditions in which upper airway anomalies frequently cause respiratory distress, but its etiology is poorly understood. Mouse models of Apert and Crouzon craniosynostosis syndromes exhibit midface dysgenesis similar to the human conditions. They carry activating mutations of Fgfr2 , which is expressed in multiple craniofacial tissues during development. Magnetic resonance microscopy of three mouse models of Apert and Crouzon syndromes revealed decreased nasal passage volume in all models at birth. Histological analysis suggested overgrowth of the nasal cartilage in the two Apert syndrome mouse models. We used tissue-specific gene expression and transcriptome analysis to further dissect the structural, cellular and molecular alterations underlying midface and upper airway dysgenesis in Apert Fgfr2 +/S252W mutants. Cartilage thickened progressively during embryogenesis because of increased chondrocyte proliferation in the presence of Fgf2 Oral epithelium expression of mutant Fgfr2, which resulted in a distinctive nasal septal fusion defect, and premature facial suture fusion contributed to the overall dysmorphology. Midface dysgenesis in Fgfr2 -related craniosynostosis is a complex phenotype arising from the combined effects of aberrant signaling in multiple craniofacial tissues., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2018. Published by The Company of Biologists Ltd.)

The earliest developmental origins of dysmorphologies are poorly understood in many congenital diseases. They often remain elusive because the first signs of genetic misregulation may initiate as subtle changes in gene expression, which are hard to detect and can be obscured later in development by secondary effects. Here, we develop a method to trace back the origins of phenotypic abnormalities by accurately quantifying the 3D spatial distribution of gene expression domains in developing organs. By applying Geometric Morphometrics to 3D gene expression data obtained by Optical Projection Tomography, we determined that our approach is sensitive enough to find regulatory abnormalities that have never been detected previously. We identified subtle but significant differences in the gene expression of a downstream target of a Fgfr2 mutation associated with Apert syndrome, demonstrating that these mouse models can further our understanding of limb defects in the human condition. Our method can be applied to different organ systems and models to investigate the etiology of malformations., Competing Interests: NM, RM, JS, SM, MY, AR, JS, LR, KK, JR, JS No competing interests declared, (© 2018, Martínez-Abadías et al.)

Saethre-Chotzen syndrome (SCS), associated with TWIST-1 mutations, is characterized by premature fusion of cranial sutures. TWIST-1 haploinsufficiency, leads to alterations in suture mesenchyme cellular gene expression patterns, resulting in aberrant osteogenesis and craniosynostosis. We analyzed the expression of the TWIST-1 target, Tyrosine kinase receptor c-ros-oncogene 1 (C-ROS-1) in TWIST-1 haploinsufficient calvarial cells derived from SCS patients and calvaria of Twist-1 del/+ mutant mice and found it to be highly expressed when compared to TWIST-1 wild-type controls. Knock-down of C-ROS-1 expression in TWIST-1 haploinsufficient calvarial cells derived from SCS patients was associated with decreased capacity for osteogenic differentiation in vitro. Furthermore, treatment of human SCS calvarial cells with the tyrosine kinase chemical inhibitor, Crizotinib, resulted in reduced C-ROS-1 activity and the osteogenic potential of human SCS calvarial cells with minor effects on cell viability or proliferation. Cultured human SCS calvarial cells treated with Crizotinib exhibited a dose-dependent decrease in alkaline phosphatase activity and mineral deposition, with an associated decrease in expression levels of Runt-related transcription factor 2 and OSTEOPONTIN, with reduced PI3K/Akt signalling in vitro. Furthermore, Crizotinib treatment resulted in reduced BMP-2 mediated bone formation potential of whole Twist-1 del/+ mutant mouse calvaria organotypic cultures. Collectively, these results suggest that C-ROS-1 promotes osteogenic differentiation of TWIST-1 haploinsufficient calvarial osteogenic progenitor cells. Furthermore, the aberrant osteogenic potential of these cells is inhibited by the reduction of C-ROS-1. Therefore, targeting C-ROS-1 with a pharmacological agent, such as Crizotinib, may serve as a novel therapeutic strategy to alleviate craniosynostosis associated with aberrant TWIST-1 function., (© 2018 Wiley Periodicals, Inc.)

Background: A proper balance between the activator and the repressor form of GLI3, a zinc-finger transcription factor downstream of hedgehog signaling, is essential for proper development of various organs during development. Mutations in different domains of the GLI3 gene underlie several congenital diseases including Greig cephalopolysyndactyly syndrome (GCPS) and Pallister-Hall syndrome (PHS)., Case Presentation: Here, we describe the case of an overlapped phenotype of these syndromes with agenesis of the gallbladder and the pancreas, bearing a c.2155 C > T novel likely pathogenic variant of GLI3 gene by missense point mutation causing p.P719S at the proteolytic cleavage site., Conclusions: Although agenesis of the gallbladder and the pancreas is uncommon in GLI3 morphopathy, a slight difference in the gradient or the balance between activator and repressor in this case may hinder sophisticated spatial and sequential hedgehog signaling that is essential for proper development of gallbladder and pancreas from endodermal buds.

There are many surgical techniques for craniosynostosis. However, the indications for and timing of surgery still remain unclarified. Most of the skull growth in craniosynostosis is completed in the first year, and the bone is strong enough to undergo distraction osteogenesis. However, previous reports showed that patients operated on before 1 year of age had better IQ than those operated later in life. This report aims to consider the best timing for cranial expansion and surgical strategy for Apert syndrome. From January 2002 to December 2011, 13 patients with Apert syndrome were operated on and were followed up for more than 5 years. Nine patients underwent operations before 1 year of age (early surgery group) and three patients underwent operations later in life (late surgery group). They underwent fronto-orbital advancement for primary surgery. We evaluated postoperative developmental quotient every year and cephalic index (CI) measured by three-dimensional computerized tomography (3D-CT) at the age over 5 years retrospectively. Eleven of 13 patients improved their developmental quotient scores, with no significant intergroup differences. The CI evaluation showed cases with remnant brachycephalic deformity in both groups. Two patients with remnant plagiocephalic deformities tend to have primary surgery early in life compared to the others. Thus the delay in primary surgery had little influence on psychological development. We conclude that the primary surgery can be delayed unless the intracranial pressure needs to be controlled. In addition, fronto-orbital advancement could not sufficiently improve the brachycephalic appearance, other procedures like posterior vault distraction might be better alternatives., (© 2017 Japanese Teratology Society.)

FGFR1 plays an important role in the development of the nervous system as well as the regulation of the skeletal development and bone homeostasis. Mutations in FGFR1 genes affect skull development, specifically suture and synchondrosis, resulting in craniosynostosis and facial abnormalities. We examined subjects with normal skull morphology for genetic polymorphisms that might be associated with normal craniofacial variations. Genomic DNA was obtained from 216 Japanese and 227 Korean subjects. Four FGFR1 SNPs, namely, rs881301, rs6996321, rs4647905, and rs13317, were genotyped. These SNPs were tested for association with craniofacial measurements obtained from lateral and posteroanterior cephalometries, in which principle component analysis was performed to compress the data of the craniofacial measurements. We observed that SNPs rs13317 and rs6996321 were correlated with the overall head size and midfacial development, indicating that FGFR1 SNPs played crucial roles in the normal variation of human craniofacial morphology. Subjects with the derived alleles of SNPs rs13317 and rs6996321 had a small face and a facial pattern associated with a retruded midface and relatively wide-set eyes. These facial features were similar to but were milder than those of individuals with Pfeiffer syndrome, which is caused by a dysfunctional mutation in FGFR1., Competing Interests: The authors have declared that no competing interests exist.

Apert syndrome - acrocephalosyndactyly - is a rare autosomal dominant disorder representing 1:65 000 cases of living newborns. Characteristic malformations of the Apert syndrome are early craniostenosis, microviscerocranium and II-V finger syndactyly of hand and toes with proximal phalanx of the bilateral thumb "in delta". It is difficult to determine prenatal diagnosis in the second quarter, when examining the morphology of fetal signs; the dysmorphism signs appeared in the third pregnancy quarter. We present here the case of a newborn with Apert syndrome that was born prematurely in our Clinic after a monitored pregnancy, where there was issued a suspicion of cranio-facial dysmorphism, malposition and malformation of the feet and hands in the third quarter of prenatal pregnancy. The diagnosis of Apert syndrome was placed on clinical signs, laboratory and genetic tests. The clinical outcome of the baby in the maternity was favorable, the therapeutic management being established by a multidisciplinary team. Immediate complications were due to the case of prematurity: respiratory distress syndrome and the characteristics of the syndrome: micrognathia and naso-facial dysmorphism, syndactyly, bilateral foot metatarsus adductus.

Apert Syndrome (AS) is one of the most severe forms of craniosynostosis. It is caused by gain-of-function mutations in the receptor fibroblast growth factor receptor 2 (FGFR2), which leads to ligand-receptor promiscuity. Here, we aimed to better understand the behavior of mesenchymal stem cells (MSCs) and of fibroblastoid cells, cellular populations that are part of the suture complex, when stimulated with different fibroblast growth factors (FGFs). We also aimed to verify whether FGFR2 specificity loss due to AS mutations would change their signaling behavior. We tested this hypothesis through cell proliferation and differentiation assays and through gene expression profiling. We found that FGF19 and FGF10 increase proliferation of fibroblastoid cells harboring the FGFR2 p.S252W mutation, but not of mutant MSCs. FGF19 and FGF10 were associated with different expression profiles in p.S252W cells. Further, in accordance to our gene expression microarray data, FGF19 decreases bone differentiation rate of mutant fibroblastoid cells and increases bone differentiation rate of MSCs. This effect in osteogenesis appears to be mediated by BMP signaling. The present data indicate that non-natural FGFR2 ligands, such as FGF10 and FGF19, are important factors in the pathophysiology of AS. Further research is needed to determine the role of modulation of MSC proliferation or use of FGF19 or anti-BMP2 as inhibitors of osteogenesis in AS subjects' cells, and whether these findings can be used in the clinical management of AS.

Background: Greig cephalopolysyndactyly syndrome (GCPS) is an uncommon entity characterised by polysyndactyly and craniofacial features. The syndrome is not defined by classic signs. Instead there is a high variability in phenotypes observed. This is due to the large number of different mutations in the glioma-associated oncogene 3 (GLI3) that can give rise to the syndrome. We present a case series of five un-related individuals with GCPS treated in our hand surgery unit with different phenotype presentations of GCPS., Conclusion: An awareness of the diversity in phenotypes is important for diagnosis and early referral for genetic confirmation and counselling.

This article reviews the prenatal diagnosis of those syndromes in which craniosynostosis is a key feature. Although not an exhaustive list, the authors highlight conditions that may be encountered with some regularity, especially in a higher volume fetal imaging center. Rare conditions are also discussed. Normal sutural anatomy and development are first reviewed, followed by a discussion of specific syndromes, the salient imaging findings, and pathologic as well as postnatal correlations when possible., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: To describe the subtle clinical features, genetic considerations, and management of progressive postnatal pansynostosis, a rare form of multisutural craniosynostosis that insidiously occurs after birth and causes inconspicuous cranial changes. Design, Participants, Setting : The study is a retrospective chart review of all patients diagnosed with progressive postnatal pansynostosis at a major craniofacial center between 2000 and 2009. Patients with kleebattschädel were excluded., Results: Nineteen patients fit our inclusion criteria. Fifteen patients had a syndromic diagnosis: Crouzon syndrome (n = 8), Saethre-Chotzen syndrome (n = 5), and Pfeiffer syndrome (n = 2). With the exception of one patient with moderate turricephaly, all patients had a relatively normal head shape with cranial indices ranging from 0.72 to 0.93 (mean, 0.81). Patients were diagnosed at an average of 32.4 months; craniosynostosis was suspected based on declining percentile head circumference (n = 14), detection of an apical prominence (n = 12), papilledema (n = 7), and worsening exorbitism (n = 3). Nearly all patients had evidence of increased intracranial pressure., Conclusion: Progressive postnatal pansynostosis is insidious; diagnosis is typically delayed because the clinical signs are subtle and appear gradually. All infants or children with known or suspected craniosynostotic disorder and a normal head shape should be carefully monitored; computed tomography is indicated if there is any decrease in percentile head circumference or symptoms of intracranial pressure.

Pfeiffer syndrome (MIM: #101600) is a rare autosomal dominant disorder classically characterized by limb and craniofacial anomalies. It is caused by heterozygous mutations in the fibroblast growth factor receptors types 1 and 2 (FGFR1 and FGFR2). We applied a next generation sequencing (NGS) panel approach comprising all 2877 genes currently known to be causative for one or more Mendelian diseases combined with the phenotype based computational tool PhenIX (Phenotypic Interpretation of eXomes). We report on a patient presenting with multiple anomalies of hands and feet including brachydactyly and symphalangism. No clinical diagnosis could be established based on the clinical findings and testing of several genes associated with brachydactyly and symphalangism failed to identify mutations. Via next generation sequencing (NGS) panel approach we then identified a novel de novo missense FGFR2 mutation affecting an amino acid reported to be mutated in Pfeiffer syndrome. Since our patient shows typical radiological findings of Pfeiffer syndrome in hands and feet but at the same time lacks several characteristic features such as clinical signs of craniosynostosis and prominent eyes we suggest introducing the term "FGFR2 associated phenotypes" for similar cases. Our results highlight the emerging role of combined NGS and phenotype based bioinformatics strategies to establish clinical diagnoses., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

Apert syndrome (AS) is a frequent acrocephalosyndactyly, with autosomal dominant inheritance. AS has been associated with mutations in fibroblast growth factor receptor 2 (FGFR2), and approximately 99% of cases show 2 of the frequent mutations located in exon IIIa (Ser252Trp or Pro253Arg). The purpose of the present study was to describe the mutations in exon IIIa of FGFR2 in Mexican AS patients and the relationships with clinical features. Exon IIIa of FGFR2 from 6 AS patients was amplified by polymerase chain reaction. Mutations in exon IIIa of the FGFR2 gene were identified by digestion with the restriction endonuclease Bstx1 and polyacrylamide gel electrophoresis. PCR fragments were cloned into the PCR 2.1 vector, and both DNA strands were sequenced using the T7 promoter and M13 universal cloning region oligonucleotides. Sequence alignment was performed using the MEGA software version 5. The patients' major clinical features included craniosynostosis, hypertelorism, proptosis, otitis media, midfacial hypoplasia, rhizomelic shortening, and hyperhidrosis. Mutation S252W was present in 4 patients, while the other 2 patients had P253R. In conclusion, either S252W or P253R mutations were present independently in AS patients; however, the 2 mutations were not found together. None of the clinical features were associated with any of the mutations, suggesting that other mutations may be involved in the development of this syndrome.

Apert syndrome (AS) is a type of autosomal dominant disease characterized by premature fusion of the cranial sutures, severe syndactyly, and other abnormalities in internal organs. Approximately 70% of AS cases are caused by a single mutation, S252W, in fibroblast growth factor receptor 2 (FGFR2). Two groups have generated FGFR2 knock-in mice Fgfr2S252W/+ that exhibit features of AS. During the present study of AS using the Fgfr2S252W/+ mouse model, an age-related phenotype of bone homeostasis was discovered. The long bone mass was lower in 2 month old mutant mice than in age-matched controls but higher in 5 month old mutant mice. This unusual phenotype suggested that bone marrow-derived mesenchymal stem cells (BMSCs), which are vital to maintain bone homeostasis, might be involved. BMSCs were isolated from Fgfr2S252W/+ mice and found that S252W mutation could impair osteogenic differentiation BMSCs but enhance mineralization of more mature osteoblasts. A microarray analysis revealed that Wnt pathway inhibitors SRFP1/2/4 were up-regulated in mutant BMSCs. This work provides evidence to show that the Wnt/β-catenin pathway is inhibited in both mutant BMSCs and osteoblasts, and differentiation defects of these cells can be ameliorated by Wnt3a treatment. The present study suggested that the bone abnormalities caused by deregulation of Wnt pathway may underlie the symptoms of AS.

Pfeiffer syndrome is an autosomal dominant disorder classically characterized by craniosynostosis, facial dysmorphism and limb anomalies. The majority of cases are caused by mutations in the fibroblast growth factor receptor 2 (FGFR2) gene. A specific, rare mutation p.Pro252Arg, located between the second and third extracellular immunoglobulin-like domain of FGFR1, is associated with mild clinical signs. We report on a three-generation family with five members having a heterozygous FGFR1 p.Pro252Arg mutation. Phenotypic features within the family showed high variability from the apparently normal skull and limbs to the characteristic brachycephaly and digital anomalies. The typical features of Pfeiffer syndrome appeared only in the third generation allowing us to unveil the syndrome in several further family members in two previous generations. Variable expressivity can complicate the recognition of Pfeiffer syndrome, principally the mild type 1, requiring careful phenotyping and genetic counseling., (© 2014 Wiley Periodicals, Inc.)

Background: The spheno-occipital synchondrosis is an important driver of facial and cranial base growth. The current study characterizes its fusion in patients with Apert, Crouzon, and Pfeiffer syndromes and correlates early fusion with the presence, and degree, of midface hypoplasia., Methods: A retrospective case-control study was performed of all syndromic patients treated between 1996 and 2012. Case computed tomographic scans and age- and sex-matched control scans were analyzed as demonstrating either open, partially fused, or completely fused synchondroses, and patient age at each scan was recorded. Midface hypoplasia as determined by sella-nasion-A point angle measurement at the time of midface surgery was correlated to fusion status., Results: Fifty-four patients with 206 computed tomographic scans met inclusion criteria. Two hundred six age- and sex-matched control scans were also identified. Average age at computed tomographic scanning was 6.1 years. The earliest ages of partial and complete fusion were 1.1 and 7.0 years, respectively, among cases; and 6.2 and 12.7 years, respectively, among controls. The odds of synchondrosis fusion in case computed tomographic scans was 66.0 times that of controls (95 percent CI, 9.2 to 475.5 times that of controls; p < 0.000001). Average age of synchondrosis fusion was 3.5 years (range, 0.5 to 6.0 years). Average sella-nasion-A point angle at the time of midface surgery was 67.5 degrees (range, 58 to 76 degrees), with a positive correlation between earlier age of fusion and more severe midface hypoplasia (p = 0.028)., Conclusions: The spheno-occipital synchondrosis fuses earlier in syndromic patients compared with age-matched controls. Moreover, there is a positive correlation between earlier fusion and degree of midface hypoplasia, although definitive causality cannot be concluded. This is the first study to demonstrate such a correlation in human subjects., Clinical Question/level of Evidence: Risk, II.

Apert syndrome is one of the craniosynostosis syndromes which, due to its association with other skeletal anomalies, is also known as acrocephalosyndactyly. It is a rare congenital anomaly which stands out from other craniosynostosis due to its characteristic skeletal presentations.

Background: Midface retrusion is the hallmark of the syndromic dysostoses (i.e., Crouzon and Apert). Lack of forward projection and/or structural deficiency could be responsible, but neither has been adequately assessed three-dimensionally. The authors examined both the cranial base/facial interface and the midface volume to provide an understanding of the etiopathogenesis of midface deficiency., Methods: Children with computed tomographic scans in the absence of any surgical intervention were included. Demographic information was recorded for three groups: Apert, Crouzon, and control. Scans were digitized and manipulated using Materialise software (Surgicase CMF). Craniometric data relating to the midface and sphenoid were collected. Volumetric assessment of the midface was tabulated. Statistical analysis was performed using the t test., Results: Thirty-six scans were included (control, n=17; Crouzon/Apert, n=19). All children were in the early mixed dentition stage. The anterior cranial fossa proved to be shorter and wider in Crouzon/Apert patients compared with controls. The cranial base angles (N-S-BA, N-S-SO, N-SO-BA, S-SO-BA, and N-S-AR) were not statistically different across the groups. The Crouzon/Apert group showed angles more obtuse between the greater wings of the sphenoid, and more obtuse (more splayed) between the pterygoid plates. Nasion-sella-pterygomaxillary fissure angle was more obtuse (flatter) in the Crouzon/Apert group. There was no volumetric difference in the maxilla, zygoma, and sphenoid comparing the Crouzon/Apert group to controls., Conclusions: Midface retrusion in the Crouzon/Apert group is associated with altered sphenoid morphology (widened and retruded pterygoid plates), with a flatter and wider maxilla, suggesting diminished growth inferiorly and anteriorly. There is no volumetric deficiency in Crouzon/Apert patients compared with controls., Clinical Question/level of Evidence: Risk, II.

Background: The birth prevalence of Apert syndrome is estimated at 1:64,500 and accounts for about 4.5 % of all craniosynostosis with a male/female ratio equal to 1:1. It is associated to allelic mutations in the fibroblast growth factor receptor 2 (FGFR2) gene. Majority cases are sporadic. Prenatal ultrasound diagnosis is based on the detection of abnormal cranial shape, midfacial hypoplasia and bilateral syndactyly of hands and feet, hypertelorism, and exorbitism. Other abnormalities includes central nervous system anomalies, congenital heart diseases, cleft palate, and urogenital diseases., Case Report: A 37-year-old Caucasian woman, gravida 2, para 1, was referred to our center of Prenatal Diagnosis for routine ultrasound at 21 weeks of gestation. We detected irregular head shape, dolicocephaly, prominent forehead, bilateral mild ventriculomegaly, suspicion of partial agenesis of the corpus callosum, hypertelorism, and midfacial hypoplasia, with a depressed nasal bridge and syndactyly, prompting a suspicion for Apert syndrome. Magnetic resonance excluded agenesis of corpus callosum and confirmed bilateral mild ventriculomegaly. A follow-up ultrasound, performed at 23 weeks, confirmed the anomalies showed in the previous scan. An amniocentesis was performed. The results showed a normal male karyotype, while the molecular genetic test confirmed a mutation in FGFR2 gene. Fetus macroscopic analysis showed compatible features., Conclusions: Our case underlines the complementary role of ultrasound and magnetic resonance imaging in the early prenatal diagnosis of Apert syndrome.

Background: Apert syndrome (AS) is characterized by craniosynostosis, midfacial hypoplasia, and bony syndactyly. It is an autosomal dominantly inherited disease caused by point mutations (S252W or P253R) in fibroblast growth factor receptor (FGFR) 2. These mutations cause activation of FGFR2 depending on ligand binding. Recently, an AS mouse model, Fgfr2(+/) (S252W) , showed phenotypes similar to those of AS patients. We previously reported that the soluble form of FGFR2(S252W) (sFGFR2IIIc(S252W) ) efficiently inhibits enhanced osteoblastic differentiation caused by FGFR2 activation in AS in vitro, presumably because FGFs binding to FGFRs is interrupted. In this study, we developed Fgfr2(+/) (S252W) (Ap) mice expressing the sFGFR2IIIc(S252W) protein, and we investigated the effects of sFGFR2IIIc(S252W) on AS-like phenotypes., Results: In Ap mice, the coronal suture (CS) was fused prematurely at P1. In addition, the mice exhibited a widened interfrontal suture (IFS) with ectopic bone and thickened cartilage formation. In Fgfr2(+/) (S252W) sFGFR2IIIc(S252W) (Ap/Sol) mice, the CS was similar to that of wild-type mice. Ap/Sol mice did not show any ectopic bone or cartilage formation in the IFS, but showed a wider IFS than that of the wild-type mice., Conclusions: sFGFR2IIIc(S252W) may partially prevent craniosynostosis in the Apert mouse model by affecting the CS and IFS in vivo., (Copyright © 2013 The Authors Developmental Dynamics published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.)

A S252W mutation of fibroblast growth factor receptor 2 (FGFR2), which is responsible for nearly two-thirds of Apert syndrome (AS) cases, causes retarded development of the skeleton and skull malformation resulting from premature fusion of the craniofacial sutures. We utilized a Fgfr2(+/S252W) mouse (a knock-in mouse model mimicking human AS) to demonstrate decreased bone mass due to reduced trabecular bone volume, reduced bone mineral density, and shortened growth plates in the long bones. In vitro bone mesenchymal stem cells (BMSCs) culture studies revealed that the mutant mice showed reduced BMSC proliferation, a reduction in chondrogenic differentiation, and reduced mineralization. Our results suggest that these phenomena are caused by up-regulation of p38 and Erk1/2 phosphorylation. Treatment of cultured mutant bone rudiments with SB203580 or PD98059 resulted in partial rescue of the bone growth retardation. The p38 signaling pathway especially was found to be responsible for the retarded long bone development. Our data indicate that the S252W mutation in FGFR2 directly affects endochondral ossification, resulting in growth retardation of the long bone. We also show that the p38 and Erk1/2 signaling pathways partially mediate the effects of the S252W mutation of FGFR2 on long bone development.

Saethre–Chotzen syndrome is a very rare autosomal dominant congenital disorder characterized by craniosynostosis and acrocephalosyndactyly. It is caused by a mutation in TWIST1, located on chromosome 7p21. A shortage of functional TWIST1 protein affects the development and maturation of cells in the skull, face, and limbs. The patient described in this report displayed craniofacial features classic for Saethre–Chotzen syndrome, including craniosynostosis, low-set ears, small pinna with prominent crura, a high-arched palate, and a simian crease on the left hand. He did not have the limb anomalies commonly seen in patients with Saethre–Chotzen syndrome, and the results of conventional chromosome analysis were normal. However, results of a microarray-based comparative genomic hybridization (array CGH) study confirmed the karyotype of46,XY.7p21.1p15.3(15,957,375-20,331,837)x1, a region that includes TWIST1. Subsequent fluorescent in situ hybridization analysis confirmed this result. No other chromosome was involved in the rearrangement. This case illustrates the important contribution of array CGH to the identification of TWIST microdeletions, even in a patient not showing the phenotype typical of Saethre–Chotzen syndrome.

Craniosynostosis is one of the most common craniofacial disorders encountered in clinical genetics practice, with an overall incidence of 1 in 2,500. Between 30% and 70% of syndromic craniosynostoses are caused by mutations in hotspots in the fibroblast growth factor receptor (FGFR) genes or in the TWIST1 gene with the difference in detection rates likely to be related to different study populations within craniofacial centers. Here we present results from molecular testing of an Australia and New Zealand cohort of 630 individuals with a diagnosis of craniosynostosis. Data were obtained by Sanger sequencing of FGFR1, FGFR2, and FGFR3 hotspot exons and the TWIST1 gene, as well as copy number detection of TWIST1. Of the 630 probands, there were 231 who had one of 80 distinct mutations (36%). Among the 80 mutations, 17 novel sequence variants were detected in three of the four genes screened. In addition to the proband cohort there were 96 individuals who underwent predictive or prenatal testing as part of family studies. Dysmorphic features consistent with the known FGFR1-3/TWIST1-associated syndromes were predictive for mutation detection. We also show a statistically significant association between splice site mutations in FGFR2 and a clinical diagnosis of Pfeiffer syndrome, more severe clinical phenotypes associated with FGFR2 exon 10 versus exon 8 mutations, and more frequent surgical procedures in the presence of a pathogenic mutation. Targeting gene hot spot areas for mutation analysis is a useful strategy to maximize the success of molecular diagnosis for individuals with craniosynostosis., (© 2013 Wiley Periodicals, Inc.)

The aim of this study was to compare changes in dental arch morphology between patients with Crouzon syndrome or Apert syndrome and controls. Children between 4 and 14 yr of age with Crouzon syndrome (n = 40) or Apert syndrome (n = 28) were compared with non-syndromic controls (n = 457) in terms of arch widths, depths, and length dimensions. Multilevel statistical modeling techniques were used to evaluate changes over time. Dental arch dimensions were found to be smaller in patients with Crouzon syndrome or Apert syndrome compared with control subjects. Maxillary intercanine width for patients with Apert syndrome were increased, whilst other arch width variables showed no change. Patients with Crouzon syndrome showed increases in maxillary intercanine width, whilst intermolar width showed no change over time. Dental arch dimensions in syndromic patients were thus found to be consistently smaller than in control subjects between 4 and 14 yr of age, implying that patients with Crouzon syndrome and Apert syndrome had a diminished growth potential., (© 2013 Eur J Oral Sci.)

Syndromic craniosynostose exhibit variable clinical and genetic heterogeneity. Many of this disorders are caused by mutations in the fibroblast growth factor receptor genes: FGFR2, FGFR3 (encoding fibroblast growth factor receptors), TWIST1 (functions as an upstream regulator of FGFRs) and EFNB1 (gene encoding fibrillin1). However recent advances in molecular genetics have led to a discover of other genes implicated in different craniosynostosis syndromes., (Copyright © 2012 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.)

Apert syndrome is a congenital disorder characterized by severe skull malformations and caused by one of two missense mutations, S252W and P253R, on fibroblast growth factor receptor 2 (FGFR2). The molecular bases underlying differential Apert syndrome phenotypes are still poorly understood and it is unclear why cleft palate is more frequent in patients carrying the S252W mutation. Taking advantage of Apert syndrome mouse models, we performed a novel combination of morphometric, histological and immunohistochemical analyses to precisely quantify distinct palatal phenotypes in Fgfr2(+/S252W) and Fgfr2(+/P253R) mice. We localized regions of differentially altered FGF signaling and assessed local cell patterns to establish a baseline for understanding the differential effects of these two Fgfr2 mutations. Palatal suture scoring and comparative 3D shape analysis from high resolution μCT images of 120 newborn mouse skulls showed that Fgfr2(+/S252W) mice display relatively more severe palate dysmorphologies, with contracted and more separated palatal shelves, a greater tendency to fuse the maxillary-palatine sutures and aberrant development of the inter-premaxillary suture. These palatal defects are associated with suture-specific patterns of abnormal cellular proliferation, differentiation and apoptosis. The posterior region of the developing palate emerges as a potential target for therapeutic strategies in clinical management of cleft palate in Apert syndrome patients.

Craniosynostosis, the premature fusion of the cranial sutures, is a heterogeneous disorder with a prevalence of ∼1 in 2,200 (refs. 1,2). A specific genetic etiology can be identified in ∼21% of cases, including mutations of TWIST1, which encodes a class II basic helix-loop-helix (bHLH) transcription factor, and causes Saethre-Chotzen syndrome, typically associated with coronal synostosis. Using exome sequencing, we identified 38 heterozygous TCF12 mutations in 347 samples from unrelated individuals with craniosynostosis. The mutations predominantly occurred in individuals with coronal synostosis and accounted for 32% and 10% of subjects with bilateral and unilateral pathology, respectively. TCF12 encodes one of three class I E proteins that heterodimerize with class II bHLH proteins such as TWIST1. We show that TCF12 and TWIST1 act synergistically in a transactivation assay and that mice doubly heterozygous for loss-of-function mutations in Tcf12 and Twist1 have severe coronal synostosis. Hence, the dosage of TCF12-TWIST1 heterodimers is critical for normal coronal suture development.

Background: The authors catalogued phenotypic variability among children with Apert syndrome, reviewed surgical outcomes (particularly with respect to their treatment goals of avoiding preventable developmental delays and reducing operative interventions), and examined correlations that might stimulate improved treatment paradigms., Methods: A case series review of all Apert syndrome patients, treated by a single surgeon, including phenotypic variations, mutational analyses, developmental assessments, and surgical treatments, was performed., Results: Over a 20-year period, 135 Apert syndrome patients were treated (32 percent from birth). A fairly even distribution of mutations was noted (S252W, n = 20; P253R, n = 18). Of 268 hands, 60 percent were type I, 21 percent were type II, and 19 percent were type III. Fifty percent had palatal anomalies. Three separate skull configuration types were identified, and 29 percent had acquired Chiari malformations, 24 percent had anomalies of the septum pellucidum, and 12 percent had anomalies of the corpus callosum. Cranial and midfacial procedures were performed significantly earlier at outside centers (6.2 months versus 12.6 months, and 5.3 years versus 7.5 years). No significant correlations were noted between development and gene mutation, hand or skull phenotypes, intracranial anomalies, and timing of initial skull surgery. A significant correlation was noted between adverse development and ventriculoperitoneal shunts, tracheostomies, and more operative interventions. Higher development strongly correlated with treatment at our center from birth., Conclusion: Treatment goals focused on the prevention of avoidable developmental delays (from raised intracranial pressure and sleep apnea) and reducing operative interventions may potentially improve developmental outcomes., Clinical Question/level of Evidence: Therapeutic, III.

Apert syndrome (Acrocephalosyndactyly type I; AS) is a rare but well-known autosomal dominant disorder characterized by craniosynostosis, midface hypoplasia, bony/cutaneous syndactyly of fingers and toes as well as a variety of associated congenital anomalies involving the brain, heart, limbs and other organ systems. We report the case of a fetus with molecularly confirmed Apert syndrome and additional fusion of the thalamic nuclei. Various central nervous system anomalies, have been reported in patients with AS. However, as far as we know cases of fused thalami in Apert syndrome have never been reported so far.