Crouzon syndrome: Genetic and intervention review

A unique presentation of Crouzon-like syndrome: Complex craniosynostosis in the absence of genetic mutations or familial predisposition - A case report

Background

Crouzon syndrome is a rare genetic disorder characterized by premature fusion of skull sutures during skull development, resulting in various craniofacial abnormalities and complex craniosynostosis is a condition in which more than one such sutures of the skull fuse prematurely.

Case Description

Herein, we present a case of a 5-year-old male diagnosed with Crouzon-like syndrome and complex craniosynostosis involving multiple cranial sutures, including metopic, sagittal, coronal (right and left), and lambdoid sutures, and without any identifiable mutations on karyotyping. The patient underwent successful surgical intervention with a satisfactory outcome, highlighting the importance of early diagnosis and intervention to prevent or minimize associated neurological manifestations and craniofacial abnormalities.

Conclusion

Our case report underscores the involvement of multiple cranial sutures in complex craniosynostosis and the absence of identifiable mutations or family history of similar craniofacial abnormalities, providing important insights into the diagnosis and management of this condition.

Crouzon Syndrome Spanning Three Generations: Advances in the Treatment of Syndromic Midface Deficiency

Background

Crouzon syndrome is an autosomal dominant genetic disorder characterized by craniosynostosis, midface retrusion, and exophthalmos. Over the past century, the treatment of craniofacial disorders like Crouzon syndrome has evolved significantly.

Methods

An institutional review board-approved retrospective study was conducted to ascertain the treatment of three individuals with Crouzon syndrome from one family, complemented with a series of literature searches to examine the evolution of craniofacial surgical history.

Results

Dr. David Williams Cheever developed the Le Fort I level to correct malocclusion, maxillomandibular malformations, and midface hypoplasia. Later, Dr. Paul Tessier introduced the Le Fort II and III osteotomies to treat syndromic midface hypoplasia. In 1978, Dr. Fernando Ortiz-Monasterio and Dr. Antonio Fuente del Campo published the first series of monobloc osteotomies, allowing for simultaneous correction of supraorbital and midface malformations, although complicated by blood loss and high infection rates. In 1992, McCarthy et al introduced the concept of gradual distraction to the craniofacial skeleton. In 1995, Polley et al performed the first monobloc advancement using external distraction. Subsequently, in 1997, Polley and Figueroa introduced a rigid external distraction device with multiple vector control to manage severe cleft maxillary hypoplasia. The technique was further refined and applied to treat syndromic midface hypoplasia, reducing complication rates. Currently, either external or internal distraction approaches are used to safely treat this challenging group of patients.

Conclusion

The treatment of syndromic midface deficiency has significantly evolved over the past 50 years, as evidenced by this report of three generations of Crouzon syndrome.

Meticulous and Early Understanding of Congenital Cranial Defects Can Save Lives

BACKGROUND

Omitting the early closure of the cranial sutures in newly born children is not an uncommon practice. We describe the natural history of several unrelated children and adults from two unrelated families. These children were born with variable clinical manifestations: craniofacial asymmetry, ocular proptosis, floppiness, and progressive deceleration in cognitive development. None of these children underwent a cranial sutures assessment. False diagnoses of positional plagiocephaly, neonatal thyrotoxicosis, congenital muscular atrophy, and hydrocephalus were given to the parents. This sort of malpractice was the reason behind a sequence of devastating pathological events that occurred in the lifetime of these children and adults.

MATERIAL AND METHODS

This was a multigenerational study of two unrelated families. In total, we studied three children (aged 7-19 years) and three adults (aged 40-52 years) from two families. The children from the first family were referred to our departments because of pre-pubertal scoliosis, kyphoscoliosis, and early-onset osteoarthritis. Reading the clinical histories of these children signified apparent clinical misconceptions. For instance, craniofacial asymmetry was misinterpreted as positional plagiocephaly and treated by means of helmet molding therapy. Ocular proptosis was given the false diagnosis of neonatal thyrotoxicosis. Floppiness (hypotonia) was misdiagnosed as congenital muscular dystrophy. The index case from the second family showed progressive deceleration in his cognitive development, associated with signs of increased intracranial pressure. The only diagnosis was Dandy-Walker malformation. We documented every patient in accordance with the clinical and radiological phenotypic characterizations. The genotype characterization followed accordingly.

RESULTS

All patients in family (I) manifested a phenotype consistent to a certain extent with the clinical phenotype of Shprintzen-Goldberg syndrome (SGS), though the intensity of spine deformities was greater than has been described in the literature. The second family showed a constellation of Marfanoid habitus, craniosynostosis, increased intracranial pressure, hydrocephalus, Dandy-Walker malformation, seizures, and intellectual disability. The overall clinical phenotype was consistent but not fully diagnostic of craniosynostosis-Dandy-Walker-malformation hydrocephalus syndrome. The early closure of the sutures was totally different from one patient to another, including the premature closure of the metopic, coronal, squamosal, and sagittal sutures. One patient from family (II) underwent the implementation of a shunt system at the age of 3 years, unfortunately passing over the pre-existing craniosynostosis. In addition to skeletal deformities, a history of seizures and severe intellectual disability was recorded. The proband underwent chromosomal karyotyping, the FISH test, and whole-exome sequencing.

CONCLUSION

The purpose of this study was fivefold. Firstly, to gain a meticulous understanding in order to differentiate between positional plagiocephaly, hypotonia, and congenital exophthalmos and their connections to abnormal craniofacial contours was and still is our first and foremost concern. Secondly, we aimed to characterize craniosynostosis, seizures, intellectual disabilities, and hydrocephalus associated with Marfanoid habitus, which were clearly demonstrated in our patients. Thirdly, we aimed to address the imperative for interpretations of clinical and radiological phenotypes and relate these tools to etiological understanding, which is an essential basis for diagnosis in the majority of long-term pediatric admissions. Fourthly, we aimed to assess the impacts of the missed early closure by the pediatricians and pediatric neurologists, which added a heavy pathological burden on these patients and their families. Fifthly, we aimed to identify whether early and diligent recognition can assist in cranial vault remodeling via surgical intervention to halt premature cranial suture fusions and can possibly alter the devastating course and the complications of the synostosed sutures.

An unusual presentation of bilateral optic pathway glioma in Crouzon Syndrome

Crouzon Syndrome is a genetic craniosynostosis disorder associated with a high risk of ophthalmologic sequelae secondary to structural causes. However, ophthalmologic disorders due to intrinsic nerve aberrations in Crouzon Syndrome have not been described. Optic pathway gliomas (OPGs) are low grade gliomas that are intrinsic to the visual pathway, frequently associated with Neurofibromatosis type 1 (NF-1). OPGs involving both optic nerves without affecting the optic chiasm are rarely seen outside of NF-1. We report an unusual case of bilateral optic nerve glioma without chiasmatic involvement in a 17-month-old male patient with Crouzon Syndrome without any clinical or genetic findings of NF-1. This case suggests that close ophthalmologic follow up and orbital MRIs may benefit patients with Crouzon Syndrome.

Crouzon syndrome complicated with binocular strabismus and extraocular muscle fibrosis: a case report

BACKGROUND

Crouzon syndrome, a rare genetic disorder characterized by premature closure of coronal sutures, results in skull and facial deformities along with abnormal brain and ocular development.

CASE PRESENTATION

Here, we report a case of a 27-year-old ethnic han male patient who presented with complex binocular strabismus secondary to Crouzon syndrome. At the time of surgery, extraocular muscles were found to be fibrotic and results of the pathological examination revealed degeneration of muscle fibers, which were replaced by adipose tissue. The entire exome sequencing DNA testing indicated that the patient and his father possessed the fibroblast growth factor receptor 2 (FGFR2) gene c.G812T:p.G271V heterozygous mutation. Binocular strabismus corrective surgery was performed in this patient with a satisfactory outcome.

CONCLUSIONS

This case demonstrates that Crouzon syndrome patients can show an FGFR2 gene c.G812T:p.G271V mutation and display clinical symptoms such as extraocular muscle fibrosis, exotropia, exophthalmos, and a pointed head deformity.

Crouzon syndrome and the eye: An overview

The current literature review aims to evaluate the ocular findings and associated ophthalmic features in Crouzon syndrome. Craniosynostoses are syndromes characterized by premature fusion of sutures of the skull and Crouzon syndrome is the most common of the craniosynostosis syndromes. Early fusion of sutures results in craniofacial anomalies, including abnormalities of the orbits. To prepare this review of the ophthalmic findings in this disorder, an organized search on online databases such as PubMed, Scopus, Cochrane Library, and Ovid was carried out. The key terms searched were "Crouzon", "craniosynostosis", "eye" and "ophthalmic", and 51 research items were found. A total of 17 articles were included after scrutiny of the databases and a further 25 articles were added after augmented search. A detailed review was performed from the final 42 articles. A comprehensive description of associated anomalies is given along with the author's own technique of surgical management in cases with Crouzon syndrome having bilateral luxation bulbi with exposure keratopathy. However, for optimum management of cranial and oculo-facial dysmorphisms, a multidisciplinary team of specialists is required.

Crouzon syndrome in a fraternal twin: A case report and review of the literature

BACKGROUND

Crouzon syndrome (CS; OMIM 123500) is an autosomal dominant inherited craniofacial disorder caused by mutations in the fibroblast growth factor receptor 2 (FGFR2) gene. CS is characterized by craniofacial dysostosis, exophthalmos, and facial anomalies with hypoplastic maxilla and relative mandibular prognathism.

CASE SUMMARY

Our report involves a 6-year-old fraternal twin boy with many caries in the oral cavity who presented with characteristic features of CS based on clinical and radiographic examinations along with Sanger sequencing. The fraternal girl did not show any abnormalities indicating CS. Carious teeth and poor oral hygiene were managed promptly through administering appropriate behavior guidance, orthodontic treatment was planned, and preventive procedures were described.

CONCLUSION

CS could occur in a fraternal twin caused by a de novo mutation of the FGFR2 gene. Oral hygiene instruction, preventive programs on oral hygiene, orthodontic treatment, and maxillary osteotomy were required for treatment.

Computed tomography findings of Crouzon syndrome: A case report

Crouzon syndrome is a genetic condition characterized by a premature fusion of skull sutures resulting in head and facial deformities. Crouzon syndrome is usually suspected at birth through physical examination or in the antenatal period via ultrasonographic assessment. Once Crouzon syndrome is suspected, advanced imaging methods such as three-dimensional computed tomography must be requested, showing early signs of cranial sutures fusion. In this paper, we present a case of a six-year-old girl who was taken to a pediatrician control appointment due to abnormal facies. During the physical examination, a suspicion of Crouzon syndrome was raised. Therefore, a head computed tomography was requested, showing asymmetrical calvarium thickening, diffuse indentation of the inner table of the skull, and moderate hydrocephalus with a big cyst in the posterior fossa. Due to these findings, the patient was remitted to maxillofacial surgery for further evaluation; however, the medical appointment could not be achieved as a consequence of the poor medical insurance of the girl. This paper aims to describe and discuss the computed tomography findings of Crouzon syndrome.

Posterior Vault Distraction Outcomes in Patients with Severe Crouzon Syndrome Resulting from Ser347Cys and Ser354Cys Mutations

BACKGROUND

In this study, the authors present the outcomes of 4 patients with a severe form of Crouzon syndrome characterized by mutation of fibroblast growth factor receptor 2 (FGFR2) c.1040 C > G p.Ser347Cys or the pathogenic c.1061C > G p.Ser354Cys variant of FGFR2, who underwent posterior vault distraction osteogenesis (PVDO) to alleviate elevated intracranial pressure.

METHODS

Patients with diagnosed Crouzon syndrome who were found by genetic testing to have an FGFR2 c.1040 C > G p.Ser347Cys mutation or the c.1061C > G p.Ser354Cys variant were included. Outcome data and presence of hydrocephalus, Chiari Malformation type I (CMIs), and the presence/absence of a tracheostomy were recorded.

RESULTS

Three patients with the FGFR2 c.1040 C > G p.Ser347Cys mutation and 1 with the pathogenic FGFR2 c.1061C > G p.Ser354Cys variant were identified as having characteristics of severe Crouzon syndrome. The mean age at PVDO was 15 months and the mean posterior advancement was 20 mm. All 4 patients experienced sufficient relief of the elevated intracranial pressure from the PVDO to prevent the need for shunt placement, stabilize the ventricular dimensions (n = 2), and resolve the CMIs (n = 2). Intracranial pressure screening ruled out malignant cerebrospinal fluid volume increase.

CONCLUSIONS

PVDO effectively prevented hydrocephalus and resolved CMIs, successfully alleviating intracranial pressure and maximizing clinical outcomes for patients with severe Crouzon syndrome.

FGFR3 overactivation in the brain is responsible for memory impairments in Crouzon syndrome mouse model

Crouzon syndrome with acanthosis nigricans (CAN, a rare type of craniosynostosis characterized by premature suture fusion and neurological impairments) has been linked to a gain-of-function mutation (p.Ala391Glu) in fibroblast growth factor receptor 3 (FGFR3). To characterize the CAN mutation's impact on the skull and on brain functions, we developed the first mouse model (Fgfr3A385E/+) of this syndrome. Surprisingly, Fgfr3A385E/+ mice did not exhibit craniosynostosis but did show severe memory impairments, a structurally abnormal hippocampus, low activity-dependent synaptic plasticity, and overactivation of MAPK/ERK and Akt signaling pathways in the hippocampus. Systemic or brain-specific pharmacological inhibition of FGFR3 overactivation by BGJ398 injections rescued the memory impairments observed in Fgfr3A385E/+ mice. The present study is the first to have demonstrated cognitive impairments associated with brain FGFR3 overactivation, independently of skull abnormalities. Our results provide a better understanding of FGFR3's functional role and the impact of its gain-of-function mutation on brain functions. The modulation of FGFR3 signaling might be of value for treating the neurological disorders associated with craniosynostosis.

Syndromic Hydrocephalus

Hydrocephalus, the abnormal accumulation and impaired circulation/clearance of cerebrospinal fluid, occurs as a common phenotypic feature of a diverse group of genetic syndromes. In this review, we outline the genetic mutations, pathogenesis, and accompanying symptoms underlying syndromic hydrocephalus in the context of: L1 syndrome, syndromic craniosynostoses, achondroplasia, NF 1/2, Down's syndrome, tuberous sclerosis, Walker-Warburg syndrome, primary ciliary dyskinesia, and osteogenesis imperfecta. Further, we discuss emerging genetic variants associated with syndromic hydrocephalus.

Reducing the Burden of Care: Multidisciplinary Management of Late-Manifested Crouzon Syndrome—A Case Report

The therapy of patients with Crouzon syndrome involves a multidisciplinary team. In most cases, this therapy is extensive, time-consuming, and exhausting for the patient. This case report illustrates a temporally coordinated therapy plan that succeeds in reducing the burden of care. Showing typical extraoral characteristics of Crouzon syndrome, the patient had a frontal and left-sided crossbite, and impaction of the maxillary canines. Multidisciplinary therapy included the extraction of multiple teeth, midface distraction at Le Fort III level, and alignment of the impacted teeth. Before starting, during, and after completion of the treatment, the patient’s oral health-related quality of life was assessed using COHIP-19. The combination of different treatment steps significantly reduced the duration of therapy. The therapy improved not only the patient’s oro- and craniofacial function, but also the patient’s facial appearance in a short treatment period. The patient’s quality of life improved considerably during this time. In the treatment of severe craniofacial anomalies, the highest priority should be given to keeping the burden of care low. All measures should encourage young patients’ appropriate psychosocial development despite extensive therapies, ensuring at the same time medically satisfactory treatment results.

Development and validation of an expanded targeted sequencing panel for non-invasive prenatal diagnosis of sporadic skeletal dysplasia

Background

Skeletal dysplasia (SD) is one of the most common inherited neonatal disorders worldwide, where the recurrent pathogenic mutations in the FGFR2, FGFR3, COL1A1, COL1A2 and COL2A1 genes are frequently reported in both non-lethal and lethal SD. The traditional prenatal diagnosis of SD using ultrasonography suffers from lower accuracy and performed at latter gestational stage. Therefore, it remains in desperate need of precise and accurate prenatal diagnosis of SD in early pregnancy. With the advancements of next-generation sequencing (NGS) technology and bioinformatics analysis, it is feasible to develop a NGS-based assay to detect genetic defects in association with SD in the early pregnancy.

Methods

An ampliseq-based targeted sequencing panel was designed to cover 87 recurrent hotspots reported in 11 common dominant SD and run on both Ion Proton and NextSeq550 instruments. Thirty-six cell-free and 23 genomic DNAs were used for assay developed. Spike-in DNA prepared from standard sample harboring known mutation and normal sample were also employed to validate the established SD workflow. Overall performances of coverage, uniformity, and on-target rate, and the detecting limitations on percentage of fetal fraction and read depth were evaluated.

Results

The established targeted-seq workflow enables a single-tube multiplex PCR for library construction and shows high amplification efficiency and robust reproducibility on both Ion Proton and NextSeq550 platforms. The workflow reaches 100% coverage and both uniformity and on-target rate are > 96%, indicating a high quality assay. Using spike-in DNA with different percentage of known FGFR3 mutation (c.1138 G > A), the targeted-seq workflow demonstrated the ability to detect low-frequency variant of 2.5% accurately. Finally, we obtained 100% sensitivity and 100% specificity in detecting target mutations using established SD panel.

Conclusions

An expanded panel for rapid and cost-effective genetic detection of SD has been developed. The established targeted-seq workflow shows high accuracy to detect both germline and low-frequency variants. In addition, the workflow is flexible to be conducted in the majority of the NGS instruments and ready for routine clinical application. Taken together, we believe the established panel provides a promising diagnostic or therapeutic strategy for prenatal genetic testing of SD in routine clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-021-01063-1.

The need to belong: Subjective experiences of living with craniofacial conditions and undergoing appearance-altering surgery

The purpose of this study was to better understand how individuals with craniofacial conditions experience living with visible differences and make sense of appearance-altering surgery. We conducted semi-structured qualitative interviews with 11 adults with Goldenhar or Crouzon syndrome. Interviews were analysed using a hermeneutic-phenomenological approach to thematic analysis. Our analysis revealed the following overarching theme, To see myself as other people see me, which encompassed three main themes: a) Striving to fit in, b) Altering the way I look and c) Support from family and friends. The participants' sense of their own appearance seemed to be connected to how they perceived others to evaluate their appearance. All had experienced negative reactions from others. They experienced themselves as different and had a desire to belong. All participants had undergone appearance-altering surgery, hoping that by changing appearance, they would reduce negative reactions and feel more connected to and accepted by other people. The process of undergoing appearance-changing surgery was experienced as challenging, and participants wished for a dialogue with surgeons which included psychological and emotional aspects of changing appearance. A better understanding of how to strengthen positive identity processes and feelings of belongingness should be a key focus of future research.

Severe craniolacunae and upper and lower extremity anomalies resulting from Crouzon syndrome, FGFR2 mutation, and Ser347Cys variant

Crouzon syndrome is a rare form of syndromic craniosynostosis (SC) characterized by premature fusion of the cranial and facial sutures, elevated intracranial pressure, varying degrees of ocular exposure due to exorbitism, and airway compromise caused by midface retrusion. Craniolacunae and upper and lower extremity anomalies are not frequently found in Crouzon syndrome. We present a girl with Crouzon syndrome caused by c.1040 C > G, p.Ser347Cys, a pathogenic mutation in the FGFR2 gene with atypical characteristics, including craniolacunae resembling severe Swiss cheese type of bone formation, and upper and lower extremity anomalies which are more commonly associated with Pfeiffer syndrome patients. Distinguishing between severe Crouzon syndrome patients and patients who have mild and/or moderate Pfeiffer syndrome can be challenging even for an experienced craniofacial surgeon. An accurate genotype diagnosis is essential to distinguishing between these syndromes, as it provides predictors for neurosurgical complications and facilitates appropriate family counseling related to long-term outcomes.

Comprehensive management of Crouzon syndrome: A case report with three-year follow-up

Crouzon syndrome is one of the most common craniosynostosis facial syndromes caused by a mutation in the fibroblast growth factor receptor 2 (FGFR2) gene. Less commonly, there is a mutation of the FGFR3 gene which results in Crouzon syndrome syndrome with acanthosis nigricans. It involves the premature fusion of sutures of the cranial vault, base, orbital and maxillary region. The clinical presentation of this congenital deformity depends on the pattern and timing of sutural fusion. The present report describes the features and management of this syndrome in an 18-year-old woman. The patient presented with a hypoplastic maxilla, deficient midface, exorbitism due to shallow orbits, severe crowding and bilateral crossbite. A multidisciplinary approach involving orthodontics and surgical intervention with distraction osteogenesis brought about marked improvement in the facial profile, occlusion and upper airway. The aesthetics and function were greatly enhanced, and the results were found to be stable at the end of three years.

Extremity anomalies associated with Robinow syndrome

Robinow syndrome, a rare genetic disorder, is characterized by skeletal dysplasia with, among other anomalies, extremity and hand anomalies. There is locus heterogeneity and both dominant and recessive inheritance. A detailed description of associated extremity and hand anomalies does not currently exist due to the rarity of this syndrome. This study seeks to document the hand anomalies present in Robinow syndrome to allow for improved rates of timely and accurate diagnosis. A focused assessment of the extremities and stature was performed using clinical examination and standard photographic images. A total of 13 patients with clinical and molecular diagnosis consistent with dominant Robinow syndrome or recessive Robinow syndrome were evaluated. All patients had limb shortening, the most common of which was mesomelia; however, rhizomelia and micromelia were also seen. These findings are relevant to clinical characterization, particularly as Robinow syndrome has classically been defined as a "mesomelic disorder." A total of eight distinct hand anomalies were identified in 12 patients with both autosomal recessive and dominant forms of Robinow syndrome. One patient did not present with any hand differences. The most common hand findings included brachydactyly, broad thumbs, and clinodactyly. A thorough understanding of the breadth of Robinow syndrome-associated extremity and hand anomalies can aid in early patient identification, improving rates of timely diagnosis and allowing for proactive management of sequelae.

Craniofacial malformations and their association with brain development: the importance of a multidisciplinary approach for treatment

The craniofacial complex develops mainly in the first trimester of pregnancy, but its final shaping and the development of the teeth extend into the second and third trimesters. It is intimately connected with the development of the brain because of the crucial role the cranial neural crest cells play and the fact that many signals which control craniofacial development originate in the brain and vice versa. As a result, malformations of one organ may affect the development of the other. Similarly, there are developmental connections between the craniofacial complex and the teeth. Craniofacial anomalies are either isolated, resulting from abnormal development of the first two embryonic pharyngeal arches, or part of multiple malformation syndromes affecting many other organs. They may stem from gene mutations, chromosomal aberrations or from environmental causes induced by teratogens. The craniofacial morphologic changes are generally cosmetic, but they often interfere with important functions such as chewing, swallowing and respiration. In addition, they may cause hearing or visual impairment. In this review we discussed only a small number of craniofacial malformations and barely touched upon related anomalies of dentition. Following a brief description of the craniofacial development, we discussed oral clefts, craniofacial microsomia, teratogens that may interfere with craniofacial development resulting in different malformations, the genetically determined craniosynostoses syndromes and few other relatively common syndromes that, in addition to the craniofacial complex, also affect other organs. The understanding of these malformations is important in dentistry as dentists play an integral role in their diagnosis and multidisciplinary treatment.