Novel FGFR2 deletion in a patient with Beare-Stevenson-like syndrome

Oncogenic activation revealed by FGFR2 genetic alterations in intrahepatic cholangiocarcinomas

BACKGROUND

Except for gene fusions, FGFR2 genetic alterations in intrahepatic cholangiocarcinomas (ICCs) have received limited attention, leaving patients harboring activating FGFR2 gene mutations with inadequate access to targeted therapies.

EXPERIMENTAL DESIGN

We sought to survey FGFR2 genetic alterations in ICC and pan-cancers using fluorescence in situ hybridization and next-generation sequencing. We conducted an analysis of the clinical and pathological features of ICCs with different FGFR2 alterations, compared FGFR2 lesion spectrum through public databases and multicenter data, and performed cellular experiments to investigate the oncogenic potential of different FGFR2 mutants.

RESULTS

FGFR2 gene fusions were identified in 30 out of 474 ICC samples, while five FGFR2 genetic alterations aside from fusion were present in 290 ICCs. The tumors containing FGFR2 translocations exhibited unique features, which we designated as the "FGFR2 fusion subtypes of ICC". Molecular analysis revealed that FGFR2 fusions were not mutually exclusive with other oncogenic driver genes/mutations, whereas FGFR2 in-frame deletions and site mutations often co-occurred with TP53 mutations. Multicenter and pan-cancer studies demonstrated that FGFR2 in-frame deletions were more prevalent in ICCs (0.62%) than in other cancers, and were not limited to the extracellular domain. We selected representative FGFR2 genetic alterations, including in-frame deletions, point mutations, and frameshift mutations, to analyze their oncogenic activity and responsiveness to targeted drugs. Cellular experiments revealed that different FGFR2 genetic alterations promoted ICC tumor growth, invasion, and metastasis but responded differently to FGFR-selective small molecule kinase inhibitors (SMKIs).

CONCLUSIONS

FGFR2 oncogenic alterations have different clinicopathological features and respond differently to SMKIs.

Candidate genes for obstructive sleep apnea in non-syndromic children with craniofacial dysmorphisms - a narrative review

Pediatric obstructive sleep apnea (POSA) is a complex disease with multifactorial etiopathogenesis. The presence of craniofacial dysmorphisms influencing the patency of the upper airway is considered a risk factor for POSA development. The craniofacial features associated with sleep-related breathing disorders (SRBD) - craniosynostosis, retrognathia and micrognathia, midface and maxillary hypoplasia - have high heritability and, in a less severe form, could be also found in non-syndromic children suffering from POSA. As genetic factors play a role in both POSA and craniofacial dysmorphisms, we hypothesize that some genes associated with specific craniofacial features that are involved in the development of the orofacial area may be also considered candidate genes for POSA. The genetic background of POSA in children is less explored than in adults; so far, only one genome-wide association study for POSA has been conducted; however, children with craniofacial disorders were excluded from that study. In this narrative review, we discuss syndromes that are commonly associated with severe craniofacial dysmorphisms and a high prevalence of sleep-related breathing disorders (SRBD), including POSA. We also summarized information about their genetic background and based on this, proposed 30 candidate genes for POSA affecting craniofacial development that may play a role in children with syndromes, and identified seven of these genes that were previously associated with craniofacial features risky for POSA development in non-syndromic children. The evidence-based approach supports the proposition that variants of these candidate genes could lead to POSA phenotype even in these children, and, thus, should be considered in future research in the general pediatric population.

Multidisciplinary Rehabilitation Approach to the Maxillo-Facial Complications of Crouson’s Disease: Case Report and Review

Background:

Craniofacial anomalies present a challenge to all health care practitioners since they necessitate long-term team follow-up, which is difficult to achieve outside of a major center where craniofacial anomalies teams normally collaborate.

Objectives:

The current review with an illustrative case focuses on the representation and review of Crouzon syndrome and its maxillofacial implications. Review of different varieties of gene mutations that produce craniosynostosis syndromes were discussed and focused on seven clinically distinct craniosynostosis syndromes that are precipitated by the mutation in one or more of the fibroblast growth factor receptors genes which affected the maxillofacial region.

Case presentation:

A complete clinical and radiographic case scenario of a patient suffering from Crouzon syndrome was presented, and discussion of the various disciplines and techniques used along the way to achieve the best results, as well as how team collaboration and patient compliance led to the best results were represented. The presented case was treated with orthodontic treatment, Le Fort-I osteotomy, and Le Fort-III osteotomy with extraoral distraction osteogenesis.

Conclusion:

The combination of different orthognathic surgery alternatives (Le Fort-III and Le Fort-I) with distraction osteogenesis and orthodontic treatment produced excellent outcomes with few complications, and the patient was extremely satisfied and cooperative. Early and thorough team-based care for Crouzon syndrome patients should be accessible at specialized craniofacial centers.

FGFR2 Extracellular Domain In-Frame Deletions are Therapeutically Targetable Genomic Alterations that Function as Oncogenic Drivers in Cholangiocarcinoma

We conducted next generation DNA sequencing on 335 biliary tract cancers and characterized the genomic landscape by anatomic site within the biliary tree. In addition to frequent FGFR2 fusions among patients with intrahepatic cholangiocarcinoma (IHCC), we identified FGFR2 extracellular domain in-frame deletions (EIDs) in 5 of 178 (2.8%) patients with IHCC, including two patients with FGFR2 p.H167_N173del. Expression of this FGFR2 EID in NIH3T3 cells resulted in constitutive FGFR2 activation, oncogenic transformation, and sensitivity to FGFR inhibitors. Three patients with FGFR2 EIDs were treated with Debio 1347, an oral FGFR-1/2/3 inhibitor, and all showed partial responses. One patient developed an acquired L618F FGFR2 kinase domain mutation at disease progression and experienced a further partial response for 17 months to an irreversible FGFR2 inhibitor, futibatinib. Together, these findings reveal FGFR2 EIDs as an alternative mechanism of FGFR2 activation in IHCC that predict sensitivity to FGFR inhibitors in the clinic.

Beare-Stevenson Syndrome With Blepharoptosis as a Complication of Front-Orbital Advancement and Remodeling

Beare-Stevenson syndrome (BSS) is an extremely rare genetic disorder characterized by a broad range of congenital malformations including craniosynostosis, cutis gyrata, facial deformities, and abnormal genitalia. The authors report a case of a 7 month old female who developed a mechanical ptosis secondary to dermatochalasis as a complication of fronto-orbital advancement and remodeling (FOAR) surgery which subsequently required multiple lid surgeries to reverse ptosis. This is the first report of blepharoptosis correction in a child with BSS as a complication of FOAR.

Translating genomics to the clinical diagnosis of disorders/differences of sex development

The medical and psychosocial challenges faced by patients living with Disorders/Differences of Sex Development (DSD) and their families can be alleviated by a rapid and accurate diagnostic process. Clinical diagnosis of DSD is limited by a lack of standardization of anatomical and endocrine phenotyping and genetic testing, as well as poor genotype/phenotype correlation. Historically, DSD genes have been identified through positional cloning of disease-associated variants segregating in families and validation of candidates in animal and in vitro modeling of variant pathogenicity. Owing to the complexity of conditions grouped under DSD, genome-wide scanning methods are better suited for identifying disease causing gene variant(s) and providing a clinical diagnosis. Here, we review a number of established genomic tools (karyotyping, chromosomal microarrays and exome sequencing) used in clinic for DSD diagnosis, as well as emerging genomic technologies such as whole-genome (short-read) sequencing, long-read sequencing, and optical mapping used for novel DSD gene discovery. These, together with gene expression and epigenetic studies can potentiate the clinical diagnosis of DSD diagnostic rates and enhance the outcomes for patients and families.

Atypical Skin Manifestations in FGFR2-Related Craniosynostosis Syndromes Broaden the Phenotypic Spectrum

Crouzon syndrome (CS) and Beare-Stevenson syndrome (BSS) are craniosynostosis syndromes caused by mutations in the fibroblast growth factor 2 (FGFR2) gene. CS is more common (1 in 60,000 live births) than BSS, where fewer than 20 individuals have been reported. The cardinal features of BSS are craniosynostosis, cutis gyrata, acanthosis nigricans, skin furrows, skin tags, anogenital anomalies, and a prominent umbilical stump. Previously described individuals with BSS have typically had mutations in exon 11 of FGFR2. Here, we present 2 patients with CS who have significant skin manifestations and some phenotypic overlap with BSS. De novo mutations in exon 8 of FGFR2 were identified in both; one is a mutation (c.799T>C; p.Ser267Pro) previously identified in individuals with CS and the other a novel in-frame deletion (c.820_824delinsTT; p.Val274_Glu275delinsLeu). No mutations in exon 11 of FGFR2, where previously reported BSS mutations have been located, were identified. This case expands the phenotypic spectrum of CS and highlights the overlap between conditions caused by mutations in FGFR2.

Fibroblast Growth Factor Receptor 2 (FGFR2) Mutation Related Syndromic Craniosynostosis

Craniosynostosis results from the premature fusion of cranial sutures, with an incidence of 1 in 2,100-2,500 live births. The majority of cases are non-syndromic and involve single suture fusion, whereas syndromic cases often involve complex multiple suture fusion. The fibroblast growth factor receptor 2 (FGFR2) gene is perhaps the most extensively studied gene that is mutated in various craniosynostotic syndromes including Crouzon, Apert, Pfeiffer, Antley-Bixler, Beare-Stevenson cutis gyrata, Jackson-Weiss, Bent Bone Dysplasia, and Seathre-Chotzen-like syndromes. The majority of these mutations are missense mutations that result in constitutive activation of the receptor and downstream molecular pathways. Treatment involves a multidisciplinary approach with ultimate surgical fixation of the cranial deformity to prevent further sequelae. Understanding the molecular mechanisms has allowed for the investigation of different therapeutic agents that can potentially be used to prevent the disorders. Further research efforts are need to better understand screening and effective methods of early intervention and prevention. Herein, the authors provide a comprehensive update on FGFR2-related syndromic craniosynostosis.

Fibroblast Growth Factor Receptor 2 Signaling in Breast Cancer

Fibroblast growth factor receptor 2 (FGFR2) is a membrane-spanning tyrosine kinase that mediates signaling for FGFs. Recent studies detected various point mutations of FGFR2 in multiple types of cancers, including breast cancer, lung cancer, gastric cancer, uterine cancer and ovarian cancer, yet the casual relationship between these mutations and tumorigenesis is unclear. Here we will discuss possible interactions between FGFR2 signaling and several major pathways through which the aberrantly activated FGFR2 signaling may result in breast cancer development. We will also discuss some recent developments in the discovery and application of therapies and strategies for breast cancers by inhibiting FGFR2 activities.

A Case of Beare-Stevenson Syndrome with Unusual Manifestations

Case series

Patient: —

Final Diagnosis: Beare-Stevenson syndrome

Symptoms: —

Medication: —

Clinical Procedure: Genetic analysis

Specialty: Pediatrics and Neonatology

Craniosynostosis: molecular pathways and future pharmacologic therapy

Craniosynostosis describes the premature fusion of one or more cranial sutures and can lead to dramatic manifestations in terms of appearance and functional impairment. Contemporary approaches for this condition are primarily surgical and are associated with considerable morbidity and mortality. The additional post-operative problems of suture refusion and bony relapse may also necessitate repeated surgeries with their own attendant risks. Therefore, a need exists to not only optimize current strategies but also to develop novel biological therapies which could obviate the need for surgery and potentially treat or even prevent premature suture fusion. Clinical studies of patients with syndromic craniosynostosis have provided some useful insights into the important signaling pathways and molecular events guiding suture fate. Furthermore, the highly conserved nature of craniofacial development between humans and other species have permitted more focused and step-wise elucidation of the molecular underpinnings of craniosynostosis. This review will describe the clinical manifestations of craniosynostosis, reflect on our understanding of syndromic and non-syndromic craniosynostoses and outline the different approaches that have been adopted in our laboratory and elsewhere to better understand the pathogenesis of premature suture fusion. Finally, we will assess to what extent our improved understanding of the pathogenesis of craniosynostosis, achieved through laboratory-based and clinical studies, have made the possibility of a non-surgical pharmacological approach both realistic and tangible.

Syndromic craniosynostosis, fibroblast growth factor receptor 2 (FGFR2) mutations, and sacrococcygeal eversion presenting as human tails

INTRODUCTION

There have been 23 previously published cases of patients with syndromic craniosynostosis and human tails. In many of these, the tail was composed of prominent coccygeal and sacral vertebrae, curved in a retroverted instead of in the normal anterograde fashion. This has been termed sacrococcygeal eversion. In those cases in which genetic testing results are reported, there were fibroblast growth factor receptor 2 (FGFR2) mutations.

METHODS

We present three patients with Pfeiffer syndrome and sacrococcygeal eversion. Two had genetic testing and both had FGFR2 mutations, one of them a novel mutation in patients with syndromic craniosynostosis and sacrococcygeal eversion. We also briefly review the literature on craniosynostosis and human tails.

RESULTS

All but one reported patient has had either Pfeiffer, Crouzon, or Beare-Stevenson syndrome. Most patients, including ours, have had severe manifestations of their syndrome. Although the pathogenesis of sacrococcygeal eversion is unknown, a similarly posteriorly curved tail bud develops in normal human embryos during the second month of gestation.

CONCLUSIONS

Perhaps increased FGFR2 activation during this embryonic period leads to abnormal differentiation or regression of the tail bud and, in turn, sacrococcygeal eversion, in certain patients with severe syndromic craniosynostosis.

Beare-Stevenson syndrome: two Dutch patients with cerebral abnormalities

Beare-Stevenson syndrome (BSS) is a rare autosomal-dominant condition characterized by cutis gyrata, craniosynostosis, acanthosis nigricans, anogenital anomalies, and a prominent umbilical stump. In 1996, two mutations in the fibroblast growth factor receptor 2 gene were found to cause this syndrome, thereby including BSS in the fibroblast growth factor receptor gene-related craniosynostosis spectrum. Until now, 12 patients with fibroblast growth factor receptor 2 gene-related BSS have been described. We report what is to our knowledge the first 2 Dutch patients with this syndrome, both caused by the mutation Tyr375Cys in the fibroblast growth factor receptor 2 gene. The patients exhibited a simplified gyral pattern, an abnormal posterior fossa, and an abnormal hippocampus on cranial magnetic resonance imaging. We discuss the clinical and radiologic findings in fibroblast growth factor receptor 2 gene-related BSS.

Fibroblast growth factor receptor 2 and its role in caudal appendage and craniosynostosis

Caudal appendage is a rare but reported finding seen in association with craniosynostosis. We report a newborn with caudal appendage secondary to sacrococcygeal eversion, a cloverleaf skull, choanal atresia, and a heterozygous mutation of Y375C in the juxtamembrane domain (exon 11) of fibroblast growth factor receptor 2 (FGFR2). Further support of this association are 22 other cases of craniosynostosis with caudal appendage or sacrococcygeal eversion in the literature. Of these, 19 had detectable mutations in FGFR2; 5, the same mutation; and 5, a similar substitution of cysteine for serine. We hypothesize that the association of craniosynostosis and caudal appendage is due to abnormal expression of FGFR2 in the tail bud of a developing embryo based on animal models. Our case and those reported in the literature suggest that in patients with caudal appendage and craniosynostosis, FGRF2 analysis should include regions outside the commonly tested exons 8 and 10, particularly the juxtamembrane domain.