New multiple congenital anomalies/mental retardation syndrome with cardio-facio-cutaneous involvement--the CFC syndrome

Unique Aspects of Hypertrophic Cardiomyopathy in Children

Hypertrophic cardiomyopathy (HCM) is a primary heart muscle disease characterized by left ventricular hypertrophy that can be asymptomatic or with presentations that vary from left ventricular outflow tract obstruction, heart failure from diastolic dysfunction, arrhythmias, and/or sudden cardiac death. Children younger than 1 year of age tend to have worse outcomes and often have HCM secondary to inborn errors of metabolism or syndromes such as RASopathies. For children who survive or are diagnosed after 1 year of age, HCM outcomes are often favourable and similar to those seen in adults. This is because of sudden cardiac death risk stratification and medical and surgical innovations. Genetic testing and timely cardiac screening are paving the way for disease-modifying treatment as gene-specific therapies are being developed.

Systematic ophthalmologic evaluation in cardio-facio-cutaneous syndrome: A genotype-endophenotype correlation

Cardio-facio-cutaneous syndrome (CFCS) is a rare genetic disorder belonging to the RASopathies, a group of developmental syndromes caused by upregulated RAS/MAPK signaling. Pathogenic variants affecting four genes, KRAS, BRAF, MAP2K1 and MAP2K2, encoding core signal transducers of the pathway, underlie the condition. Major clinical features include a distinctive facies, ectodermal and cardiac anomalies, reduced postnatal growth, intellectual disability, and musculoskeletal abnormalities. Similar to other RASopathies, reports of visual impairment, high refractive error, optic nerve pallor, and other ocular abnormalities have been anecdotally reported in the literature. The aim of our study is to report the prevalence of ophthalmologic abnormalities in a large monocentric cohort of individuals affected by CFCS and explore the occurrence of genotype-endophenotype correlations in this series of patients. We observed that BRAF mutations are associated to a higher prevalence of anisometropia >3D (11.8% vs. 0%) and high astigmatism (29.4% vs. 0%; both p < 0.001) while patients with mutations in other genes had a significantly higher prevalence of myopia >6 D (60% vs. 5.9%; p = 0.012). Pale optic disc was associated with higher prevalence of inferior oblique muscle (IO) overaction (33.3% vs. 0%) and lower prevalence of ptosis (0% vs. 11.8%; both p < 0.001). Combined exotropia, IO overaction and nystagmus were frequent in patients with pale optic nerve. Our findings might suggest the need for earlier ophthalmologic referral for CFCS patients due to high risk of amblyopia, especially those expressing BRAF mutations.

The "FEEDS (FEeding Eating Deglutition Skills)" over Time Study in Cardiofaciocutaneous Syndrome

Feeding, eating and deglutition difficulties are key concerns in patients with cardiofaciocutaneous syndrome (CFCS). This study intends to quantify the development of feeding skills from birth to adulthood in patients with CFCS. Twenty-seven patients (eight males; mean age: 16.7 ± 8.3 years; median age: 15 years, age range: 1.5-38 years) with molecularly confirmed clinical diagnosis of CFCS were prospectively recruited from the Rare Disease Unit, Paediatrics Department, Fondazione Policlinico Agostino Gemelli-IRCCS, Rome, Italy, over a one-year period. Pathogenic variants along with key information regarding oro-motor features were collected. Sialorrhea was quantified using the Drooling Quotient 5. Feeding abilities were screened using the Italian version of the Montreal Children's Hospital Feeding Scale (I-MCH-FS). The oral sensory processing section of the Sensory Profile completed the assessment. Mild-to-profuse drooling was experienced by 25% of patients, and food taste selectivity was a constant during infancy (65%), with persistence even beyond adolescence. Nineteen percent of participants with long-term enteral feeding dependency had BRAF, KRAS and MAP2K1 mutations. These findings document that mealtime challenges in CFCS do not remain restricted only to the paediatric age, and that supportive care until adulthood plays a key role.

An Unusual Presentation of Cardiofaciocutaneous Syndrome Diagnosed Through Whole Genome Sequencing: A Case Report

Cardiofaciocutaneous syndrome is a rare, sporadic disease caused by germline mutations in the Ras/MAPK (mitogen-activated protein kinase) pathway. Patients usually present with craniofacial anomalies, cardiac defects, and neurocutaneous abnormalities. The features of cardiofaciocutaneous syndrome overlap with two other syndromes known as Noonan's syndrome and Costello's syndrome. Similarly, those two syndromes are caused by mutations in the Ras/MAPK pathway. The diagnosis of cardiofaciocutaneous syndrome is suspected based on the clinical presentation and confirmed by genetic analysis. We report a case of a seven-month-old boy who presented with complaints of developmental delay, poor weight gain, and seizures. Physical examination revealed several dysmorphic features, including coarse facies, long philtrum, thin upper lip, a broad forehead, and long toes. Neurological examination showed hypotonia in all four limbs, with normal power and reflexes. However, the infant did not have any remarkable cutaneous abnormalities. Whole-exome sequencing picked up a BRAF gene mutation, and the patient was diagnosed with cardiofaciocutaneous syndrome. On follow-up, the patient developed findings suggestive of autoimmune hepatitis. Cardiofaciocutaneous syndrome remains a challenging diagnosis that requires a detailed assessment of the patient, as well as qualified centers with genetic analysis for diagnosis confirmation. Management of cardiofaciocutaneous patients requires a multidisciplinary team approach in order to improve the outcomes. Further exploration is required into atypical presentations of the disease as well as autoimmune disease associated with RASopathies.

Clinical overview on RASopathies

RASopathies comprise a group of clinically overlapping developmental disorders caused by genetic variations affecting components or modulators of the RAS-MAPK signaling cascade, which lead to dysregulation of signal flow through this pathway. Noonan syndrome and the less frequent, clinically related disorders, Costello syndrome, cardiofaciocutaneous syndrome, Noonan syndrome with multiple lentigines, and Noonan syndrome-like disorder with loose anagen hair are part of the RASopathy spectrum and share a recognizable pattern of multisystem involvement. This review describes the "Noonan syndrome-like" phenotype as a common phenotypic signature of generalized developmental RAS pathway dysregulation. Distinctive features of the different entities are revisited against the background of the understanding of underlying genetic alterations and genotype correlations, which has evolved rapidly during the past 20 years, thereby leading to suggestions regarding the nosology of RASopathies.

Dermatological manifestations, management, and care in RASopathies

RASopathies are rare genetic disorders caused by germline pathogenic variants in genes belonging to the RAS/MAPK pathway, which signals cell proliferation, differentiation, survival and death. The dysfunction of such signaling pathway causes syndromes with overlapping clinical manifestations. Skin and adnexal lesions are the cardinal clinical signs of RASopathies, such as cardiofaciocutaneous syndrome, Noonan syndrome with multiple lentigines, formerly known as LEOPARD syndrome, Costello syndrome, neurofibromatosis (NF1), Legius syndrome, Noonan-like syndrome with loose anagen hair (NSLH) and Noonan syndrome. As NF1, one of the most common RASopathies, described in 1882, has its clinical features well delineated, we will focus on the dermatological diagnosis, management and care of non-NF1 RASopathies, which are less known and more recently described. Dermatological manifestations are important clinical diagnostic elements that can aid differential diagnosis among RASopathies. They can affect dermis and epidermis, causing pigmented lesions (melanocytic nevi, café-au-lait spots, and lentigines), hyperkeratosis (keratosis pilaris, ulerythema ophryogenes, and palmoplantar keratosis) or hyperplasia. To date there are rare known links to malignancy, but oftentimes skin lesions require close attention because they can highly affect quality of life.

RASopathies: The musculoskeletal consequences and their etiology and pathogenesis

The RASopathies comprise an ever-growing number of clinical syndromes resulting from germline mutations in components of the RAS/MAPK signaling pathway. While multiple organs and tissues may be affected by these mutations, this review will focus on how these mutations specifically impact the musculoskeletal system. Herein, we review the genetics and musculoskeletal phenotypes of these syndromes in humans. We discuss how mutations in the RASopathy syndromes have been studied in translational mouse models. Finally, we discuss how signaling molecules within the RAS/MAPK pathway are involved in normal and abnormal bone biology in the context of osteoblasts, osteoclasts and chondrocytes.

Phoniatric, Audiological, Orodental and Speech Problems in a Boy with Cardio-Facio-Cutaneous Syndrome Type 3 (CFC 3) Due to a Pathogenic Variant in MAP2K1 - Case Study

Cardio-facio-cutaneous syndrome 3 (CFC3) due to variants in MAP2K1 is a rare genetic disorder manifested mainly by short stature, facial dysmorphism, abnormalities of the cardiovascular system, skin changes, and intellectual disability. The aim of the study is the evaluation of the occurrence of pathological changes in the upper respiratory tract, orthodontic disorders, as well as voice, speech and hearing abnormalities in an 11-year-old boy with CFC3 syndrome. The lack of detailed diagnostics of speech, voice and hearing disorders, as well as the degree of their severity was an inspiration to undertake research in this field. Pathological changes in face, oral cavity, upper respiratory tract (nose, nasopharynx, larynx), and hearing organ, as well as voice and speech quality, were assessed in an 11-year-old boy with CFC3 syndrome. Pathologies of the upper respiratory tract (adenoid hypertrophy, narrowing of the nasal passages) and laryngeal asymmetry were found without significant changes in voice quality in the acoustic examination, except for the voice timbre change confirmed in narrowband spectrography. Complex audiological assessment confirmed the existence of bilateral sensorineural hearing loss. Speech pathology assessment revealed abnormalities in the structure of articulation organ, its decreased motor efficiency, imprecision, reduced coordination, as well as the presence of autistic features. Exome sequencing showed the heterozygous variant c.371C>T (p.Pro124Leu) in the MAP2K1 gene, previously described as pathogenic, thus supporting a causative relevance. Phoniatric, audiological, orodental and speech problems should be considered as features of cardio-facio-cutaneous syndrome type 3 (CFC 3) phenotype due to a pathogenic variant in MAP2K1.

Cardiofaciocutaneous syndrome - a longitudinal study of a case over 33 years: case report and review of the literature

Cardiofaciocutaneous (CFC) syndrome [Online Mendelian Inheritance in Man (OMIM) #115150] is characterized by craniofacial dysmorphism, heart malformation, ectodermal abnormalities, neuromotor delay and intellectual disability. It is not a frequent disease, about 300 cases have been reported in the medical literature. We describe the case of a 34-year-old patient presenting with CFC syndrome phenotype, monitored since the age of 1 1/2 years. Clinical findings included craniofacial dysmorphism, development delay, heart malformation and severe intellectual disability. The evolution was with progressive intellectual disability, hypogonadism, hypertrophic cardiomyopathy, wrinkled palms and soles. Molecular analysis showed a heterozygous variant in the B-Raf proto-oncogene, serine/threonine kinase (BRAF) gene (7q34): NM_001354609.2:c.1502A>G, with pathogenic significance. We report this case, observed along a period of 33 years, for illustration of clinical evolutive particularities, and for difficulties in establishing the positive diagnosis.

Activating mutations in BRAF disrupt the hypothalamo-pituitary axis leading to hypopituitarism in mice and humans

Germline mutations in BRAF and other components of the MAPK pathway are associated with the congenital syndromes collectively known as RASopathies. Here, we report the association of Septo-Optic Dysplasia (SOD) including hypopituitarism and Cardio-Facio-Cutaneous (CFC) syndrome in patients harbouring mutations in BRAF. Phosphoproteomic analyses demonstrate that these genetic variants are gain-of-function mutations leading to activation of the MAPK pathway. Activation of the MAPK pathway by conditional expression of the BrafV600E/+ allele, or the knock-in BrafQ241R/+ allele (corresponding to the most frequent human CFC-causing mutation, BRAF p.Q257R), leads to abnormal cell lineage determination and terminal differentiation of hormone-producing cells, causing hypopituitarism. Expression of the BrafV600E/+ allele in embryonic pituitary progenitors leads to an increased expression of cell cycle inhibitors, cell growth arrest and apoptosis, but not tumour formation. Our findings show a critical role of BRAF in hypothalamo-pituitary-axis development both in mouse and human and implicate mutations found in RASopathies as a cause of endocrine deficiencies in humans.

Familial cardio-facio-cutaneous syndrome: Vertical transmission of the BRAF p.G464R pathogenic variant and review of the literature

Cardio-facio-cutaneous syndrome (CFC) is one of the RASopathies and is caused by germline mutations that activate the Ras/mitogen-activated protein kinase (MAPK) pathway. CFC is due to heterozygous germline mutations in protein kinases BRAF, MEK1, or MEK2 and rarely in KRAS, a small GTPase. CFC is a multiple congenital anomaly disorder in which individuals may have craniofacial dysmorphia, heart issues, skin and hair anomalies, and delayed development. Pathogenic variants for CFC syndrome are usually considered de novo because vertical transmission has only been reported with MEK2 and KRAS. The index case was a 3-year-old male with features consistent with the clinical diagnosis of CFC. Sequencing revealed a previously reported heterozygous likely pathogenic variant BRAF p.G464R. Upon detailed family history, the index case's pregnant mother was noted to have similar features to her son. Targeted familial testing of the BRAF pathogenic variant was performed on the mother, confirming her diagnosis. Prenatal genetic testing for the fetus was declined, but postnatal molecular testing of the index case's sister was positive for the familial BRAF p.G464R variant. Functional analysis of the variant demonstrated increased kinase activity. We report the first identified vertically transmitted functional BRAF pathogenic variant. Our findings emphasize the importance of obtaining a comprehensive evaluation of family members and that activating pathogenic variants within the canonical MAPK cascade mediated by BRAF are compatible with human reproduction.

Anesthetic Management of a Pediatric Patient With Cardiofaciocutaneous Syndrome

Cardiofaciocutaneous (CFC) syndrome is a rare condition characterized by congenital heart disease, craniofacial dysmorphology, and dermatological abnormalities. CFC syndrome is one of the RASopathies, a family of syndromes that also includes Noonan and Costello syndromes, all with underlying gene mutations involving the Ras/mitogen-activated protein kinase pathways. Important considerations for anesthesiologists caring for these patients include the need to evaluate for possible cardiac defects, anticipating and planning for potentially difficult airway management, and the consideration of potential weakness of the respiratory muscles. Musculoskeletal abnormalities, such as muscle weakness and decreased muscle mass, are observed in all RASopathies, but are particularly prominent in CFC syndrome. In patients with CFC syndrome who experience respiratory muscle weakness, the use of desflurane and remifentanil may aid in a faster recovery and effectively help reduce the risk of respiratory complications, such as respiratory depression, following general anesthesia because of their rapid metabolism or elimination.

Cardio-facio-cutaneous syndrome-associated pathogenic MAP2K1 variants activate autophagy

MAP2K1 encodes mitogen-activated protein kinase 1 (MEK1). Mutations in MAP2K1 lead to continuous activation of MEK/ERK signaling pathway, giving rise to cardio-facio-cutaneous syndrome (CFCS). However, the molecular mechanisms of abnormal activation of MEK/ERK signaling pathway and the role of autophagy, if any, in manifesting CFCS in MAP2K mutants remain unclear. Here, we report three Chinese children with CFCS having MAP2K1 pathogenic variants, identified by exome sequencing. They presented with dysmorphic facial features, seizures, psychomotor retardation, and short stature. Additionally, the third child showed pulmonary valve stenosis, multiple skeletal deformities, and osteoporosis. Whole exome sequencing revealed two heterozygous missense mutations in exon 3 of MAP2K1 (c.383G>T; p.Gly128Val and c.389A>G; p.Tyr130Cys), as well as a novel heterozygous missense variant (c.170A>T; p.Lys57Met) in exon 2 of MAP2K1. In SH-SY5Y cells, we identified, for the first time, that MAP2K1 mutations can activate the p-ERK-dependent cell cycle progression and autophagy, and cause CFCS. Our results extended the mutational spectrum of MAP2K1, examined the role of MEK1 protein in nerve cell functions, and demonstrated, for the first time, that autophagy may mediate the altered MAP2K1 function, leading to CFCS phenotypes.

The impact of RASopathy-associated mutations on CNS development in mice and humans

The RAS signaling pathway is involved in the regulation of developmental processes, including cell growth, proliferation, and differentiation, in the central nervous system (CNS). Germline mutations in the RAS signaling pathway genes are associated with a group of neurodevelopmental disorders, collectively called RASopathy, which includes neurofibromatosis type 1, Noonan syndrome, cardio-facio-cutaneous syndrome, and Costello syndrome. Most mutations associated with RASopathies increase the activity of the RAS-ERK signaling pathway, and therefore, most individuals with RASopathies share common phenotypes, such as a short stature, heart defects, facial abnormalities, and cognitive impairments, which are often accompanied by abnormal CNS development. Recent studies using mouse models of RASopathies demonstrated that particular mutations associated with each disorder disrupt CNS development in a mutation-specific manner. Here, we reviewed the recent literatures that investigated the developmental role of RASopathy-associated mutations using mutant mice, which provided insights into the specific contribution of RAS-ERK signaling molecules to CNS development and the subsequent impact on cognitive function in adult mice.

Antenatal diagnosis of cardio-facio-cutaneous syndrome: Prenatal characteristics and contribution of fetal facial dysmorphic signs in utero. About a case and review of literature

Antenatal diagnosis of cardio-facio-cutaneous syndrome: prenatal characteristics and contribution of fetal facial dysmorphic signs in utero. This paper is a case study and review of literature. "RASopathies" is the term coined for a group of genetic diseases that share modulation inside the MAPKinase pathway. Mutations inside the coding sequence of any of these genes may be responsible for the upregulation of the RAS pathway, leading on the clinical level to Type 1 Neurofibromatosis (NF1), Noonan syndrome (NS), Costello syndrome (CS), Multiple Lentigines, Loose Anagen Hair syndrome, Cardio-Facio-Cutaneous syndrome (CFCS), and, more recently, Legius syndrome. While the postnatal presentation of this group is well-known, prenatal findings are less well recognized. The presence of a RASopathy during the prenatal period can be suspected on account of non-specific abnormalities: polyhydramnios, cystic hygroma or high nuchal translucency, macrosomia with proportionate short long bones, macrocephaly, renal, lymphatic, or cardiac defects. The current case report underlines the characteristic dysmorphic facial features on 3D-ultrasound (hypertelorism, down-slanting palpebral fissures, a long and marked philtrum, and low-set posteriorly rotated ears) that allow for a "RASopathy" to be postulated. After detecting a copy number variation (CNV) absence on a CGH array, we performed a RASopathy gene panel analysis, which identified a so-far unreported heterozygous de novo mutation in the BRAF gene (namely NM_004333.4 : c.1396 G > C ; p.Gly466Arg). Genetic counseling has, therefore, focused on the diagnosis of a RASopathy and predictable phenotype of CFCS, a distinct entity characterized by an increased risk of intellectual disability and early-onset feeding problems. We suggest that a more detailed prenatal facial evaluation should be performed in fetuses presenting high nuchal thickness, heart defects, or unusual findings, along with the absence of a CNV on a CGH array. Due to the dysmorphic facial features, targeted RASopathy genes are presumed to likely to be responsible for NS, CFCS, and CS.

Endocrine abnormalities in cardiofaciocutaneous syndrome: a case of precocious puberty, hyperprolactinemia and diabetes insipidus

A 7-year-8-month-old boy with cardiofaciocutaneous syndrome caused by the D638E mutation of the B-Raf proto-oncogene (BRAF) presented with new-onset seizures. He was incidentally found to have advanced Tanner staging on physical examination. Hormonal testing revealed pubertal levels of gonadotropins and sex steroid hormones. On brain imaging, a lack of visualisation of the posterior pituitary bright spot was observed, in addition to mild thinning of the corpus callosum and the lateral gyri of the cerebellar hemispheres. A diagnosis of idiopathic central precocious puberty was made and the patient was started on leuprolide depot treatment. Pituitary hormone testing revealed hyperprolactinemia for which the patient did not receive treatment as he was asymptomatic. During a subsequent hospital admission for seizures, the patient was diagnosed with transient central diabetes insipidus for which he required treatment with a desmopressin infusion.

C-type natriuretic peptide improves growth retardation in a mouse model of cardio-facio-cutaneous syndrome

Cardio-facio-cutaneous (CFC) syndrome, a genetic disorder caused by germline mutations in BRAF, KRAS, MAP2K1 and MAP2K2, is characterized by growth retardation, heart defects, dysmorphic facial appearance and dermatologic abnormalities. We have previously reported that knock-in mice expressing the CFC syndrome-associated mutation, Braf Q241R, showed growth retardation because of gastrointestinal dysfunction. However, other factors associated with growth retardation, including chondrogenesis and endocrinological profile, have not been examined. Here, we show that 3- and 4-week-old BrafQ241R/+ mice have decreased body weight and length, as well as reduced growth plate width in the proximal tibiae. Furthermore, proliferative and hypertrophic chondrocyte zones of the growth plate were reduced in BrafQ241R/+ mice compared with Braf+/+ mice. Immunohistological analysis revealed that extracellular signal-regulated kinase (ERK) activation was enhanced in hypertrophic chondrocytes in BrafQ241R/+ mice. In accordance with growth retardation and reduced growth plate width, decreased serum levels of insulin-like growth factor 1 (IGF-1) and IGF binding protein 3 (IGFBP-3) were observed in BrafQ241R/+ mice at 3 and 4 weeks of age. Treatment with C-type natriuretic peptide (CNP), a stimulator of endochondral bone growth and a potent inhibitor of the FGFR3-RAF1-MEK/ERK signaling, increased body and tail lengths in Braf+/+ and BrafQ241R/+ mice. In conclusion, ERK activation in chondrocytes and low serum IGF-1/IGFBP-3 levels could be associated with the growth retardation observed in BrafQ241R/+ mice. Our data also suggest that CNP is a potential therapeutic target in CFC syndrome.

Chondroblastoma-like mass of the temporal bone, secondary aneurysmal bone cyst, and intracerebral hemorrhage in a patient with cardiofaciocutaneous syndrome: case report

Cardiofaciocutaneous syndrome (CFCS) is a rare developmental disorder that is phenotypically similar to Noonan syndrome and is associated with mutations in BRAF, MEK1, MEK2, and KRAS. The relationship between malignancy risk and CFCS is unclear with few cases published in the literature. The purpose of this paper is to describe the case of a patient with CFCS presenting in extremis as a result of a large intracerebral hemorrhage arising from a temporal bone mass with histopathology most consistent with chondroblastoma and secondary aneurysmal bone cyst. This is the first case to document an association between CFCS and chondroblastoma.

Leucine-485 deletion variant of BRAF may exhibit the severe end of the clinical spectrum of CFC syndrome

The genotype-phenotype correlation in BRAF variant in cardio-facio-cutaneous (CFC) syndrome is not clearly defined. Here we report a case with a severe clinical phenotype and a novel BRAF variant, p.Leu485del. The present case showed severe intellectual disability, impaired awareness, hyperekplexia, involuntary movements, early onset refractory seizures, and delayed myelination on brain magnetic resonance imaging as well as a polycystic and dysplastic kidney, which are previously unreported anomalies in CFC or RAS/mitogen-activated protein kinase syndromes related to BRAF variant. CFC syndrome, especially caused by BRAF variant, should be included in the differential diagnosis of patients with developmental and epileptic encephalopathies and hyperekplexia. Furthermore, we need to keep in mind that missense variants or the deletion of Leucine-485 may be associated with severe symptoms.

Activated Braf induces esophageal dilation and gastric epithelial hyperplasia in mice

Germline mutations in BRAF are a major cause of cardio-facio-cutaneous (CFC) syndrome, which is characterized by heart defects, characteristic craniofacial dysmorphology and dermatologic abnormalities. Patients with CFC syndrome also commonly show gastrointestinal dysfunction, including feeding and swallowing difficulties and gastroesophageal reflux. We have previously found that knock-in mice expressing a Braf Q241R mutation exhibit CFC syndrome-related phenotypes, such as growth retardation, craniofacial dysmorphisms, congenital heart defects and learning deficits. However, it remains unclear whether BrafQ241R/+ mice exhibit gastrointestinal dysfunction. Here, we report that BrafQ241R/+ mice have neonatal feeding difficulties and esophageal dilation. The esophagus tissues from BrafQ241R/+ mice displayed incomplete replacement of smooth muscle with skeletal muscle and decreased contraction. Furthermore, the BrafQ241R/+ mice showed hyperkeratosis and a thickened muscle layer in the forestomach. Treatment with MEK inhibitors ameliorated the growth retardation, esophageal dilation, hyperkeratosis and thickened muscle layer in the forestomach in BrafQ241R/+ mice. The esophageal dilation with aberrant skeletal-smooth muscle boundary in BrafQ241R/+ mice were recovered after treatment with the histone H3K27 demethylase inhibitor GSK-J4. Our results provide clues to elucidate the pathogenesis and possible treatment of gastrointestinal dysfunction and failure to thrive in patients with CFC syndrome.

Impaired Osteogenesis of Disease-Specific Induced Pluripotent Stem Cells Derived from a CFC Syndrome Patient

Cardiofaciocutaneous (CFC) syndrome is a rare genetic disorder caused by mutations in the extracellular signal-regulated kinase (ERK) signaling. However, little is known about how aberrant ERK signaling is associated with the defective bone development manifested in most CFC syndrome patients. In this study, induced pluripotent stem cells (iPSCs) were generated from dermal fibroblasts of a CFC syndrome patient having rapidly accelerated fibrosarcoma kinase B (BRAF) gain-of-function mutation. CFC-iPSCs were differentiated into mesenchymal stem cells (CFC-MSCs) and further induced to osteoblasts in vitro. The osteogenic defects of CFC-MSCs were revealed by alkaline phosphatase activity assay, mineralization assay, quantitative real-time polymerase chain reaction (qRT-PCR), and western blotting. Osteogenesis of CFC-MSCs was attenuated compared to wild-type (WT)-MSCs. In addition to activated ERK signaling, increased p-SMAD2 and decreased p-SMAD1 were observed in CFC-MSCs during osteogenesis. The defective osteogenesis of CFC-MSCs was rescued by inhibition of ERK signaling and SMAD2 signaling or activation of SMAD1 signaling. Importantly, activation of ERK signaling and SMAD2 signaling or inhibition of SMAD1 signaling recapitulated the impaired osteogenesis in WT-MSCs. Our findings indicate that SMAD2 signaling and SMAD1 signaling as well as ERK signaling are responsible for defective early bone development in CFC syndrome, providing a novel insight on the pathological mechanism and therapeutic targets.

A review of craniofacial and dental findings of the RASopathies

OBJECTIVES

The RASopathies are a group of syndromes that have in common germline mutations in genes that encode components of the Ras/mitogen-activated protein kinase (MAPK) pathway and have been a focus of study to understand the role of this pathway in development and disease. These syndromes include Noonan syndrome (NS), Noonan syndrome with multiple lentigines (NSML or LEOPARD syndrome), neurofibromatosis type 1 (NF1), Costello syndrome (CS), cardio-facio-cutaneous (CFC) syndrome, neurofibromatosis type 1-like syndrome (NFLS or Legius syndrome) and capillary malformation-arteriovenous malformation syndrome (CM-AVM). These disorders affect multiple systems, including the craniofacial complex. Although the craniofacial features have been well described and can aid in clinical diagnosis, the dental phenotypes have not been analysed in detail for each of the RASopathies. In this review, we summarize the clinical features of the RASopathies, highlighting the reported craniofacial and dental findings.

METHODS

Review of the literature.

RESULTS

Each of the RASopathies reviewed, caused by mutations in genes that encode different proteins in the Ras pathway, have unique and overlapping craniofacial and dental characteristics.

CONCLUSIONS

Careful description of craniofacial and dental features of the RASopathies can provide information for dental clinicians treating these individuals and can also give insight into the role of Ras signalling in craniofacial development.

Cardiofaciocutaneous Syndrome: Case Report of a Rare Disorder

Cardiofaciocutaneous syndrome or CFC syndrome is a rare genetic disorder first described in 1986. It is one of the RASopathies involving multiple organs particularly the heart, skin and face affecting males and females equally. The phenotypic features overlap with 2 other conditions, the Noonan and Costello syndrome. We report on a 22-month-old boy with CFC syndrome presenting with typical craniofacial appearance, heart defects, ectodermal abnormalities, growth failure and developmental delay. Estimated population of affected individuals worldwide is a few hundreds.

Cardiofacio-cutaneous syndrome: Classical presentation of a rare genodermatoses

Cardiofacio-cutaneous syndrome is a rare genodermatoses with multiple congenital anomalies (MCA) and mental retardation. Although various mutations have been described, the diagnosis can be made clinically based on constellation of symptoms. Herein, we report a classical case with typical craniofacial features and atrial septal defect.

Mapping Breakpoints of Complex Chromosome Rearrangements Involving a Partial Trisomy 15q23.1-q26.2 Revealed by Next Generation Sequencing and Conventional Techniques

Complex chromosome rearrangements (CCRs), which are rather rare in the whole population, may be associated with aberrant phenotypes. Next-generation sequencing (NGS) and conventional techniques, could be used to reveal specific CCRs for better genetic counseling. We report the CCRs of a girl and her mother, which were identified using a combination of NGS and conventional techniques including G-banding, fluorescence in situ hybridization (FISH) and PCR. The girl demonstrated CCRs involving chromosomes 3 and 8, while the CCRs of her mother involved chromosomes 3, 5, 8, 11 and 15. HumanCytoSNP-12 Chip analysis identified a 35.4 Mb duplication on chromosome 15q21.3-q26.2 in the proband and a 1.6 Mb microdeletion at chromosome 15q21.3 in her mother. The proband inherited the rearranged chromosomes 3 and 8 from her mother, and the duplicated region on chromosome 15 of the proband was inherited from the mother. Approximately one hundred genes were identified in the 15q21.3-q26.2 duplicated region of the proband. In particular, TPM1, SMAD6, SMAD3, and HCN4 may be associated with her heart defects, and HEXA, KIF7, and IDH2 are responsible for her developmental and mental retardation. In addition, we suggest that a microdeletion on the 15q21.3 region of the mother, which involved TCF2, TCF12, ADMA10 and AQP9, might be associated with mental retardation. We delineate the precise structures of the derivative chromosomes, chromosome duplication origin and possible molecular mechanisms for aberrant phenotypes by combining NGS data with conventional techniques.

Objective studies of the face of Noonan, Cardio-facio-cutaneous, and Costello syndromes: A comparison of three disorders of the Ras/MAPK signaling pathway

Noonan, Cardio-facio-cutaneous, and Costello syndromes are disorders of the Ras/MAPK pathway that share many clinical features. This observational and anthropometric study was conducted to describe the key facial features of each syndrome in order to improve discrimination between the three conditions, particularly in young children where diagnosis is most challenging. Direct measurement of the head and face was used to enhance diagnostic accuracy, and identify the most unusual or specific dimensions. The Noonan syndrome cohort included 123 individuals, aged 6 months to 41 years. There were 20 children and adolescents with Cardio-facio-cutaneous syndrome, and 28 individuals with Costello syndrome, aged 1-32 years. The facial phenotypes of these syndromes, particularly Noonan syndrome, are well-described but objective data have not been published in peer-reviewed literature. In this study, subjective observations, in the main, were validated by anthropometry with one exception. In individuals with Costello syndrome, mouth width was normal, thus the impression of wide mouth is likely due to full lips or the mouth being viewed in relation to a narrow lower face. When the three conditions were compared objectively, syndrome-specific pattern profiles showed high concordance in early life. At older ages, Cardio-facio-cutaneous syndrome was distinguished by increased width of the mid/lower face, and reduced growth of maxillary and mandibular dimensions was noted in both Noonan and Costello syndromes. Despite substantial similarities in face shape in older individuals with these two conditions, bulbous nasal tip, full lips, and an apparently wide mouth in those with Costello Syndrome facilitate discrimination from Noonan syndrome. © 2016 Wiley Periodicals, Inc.

Clinical Report: Cognitive decline in a patient with Cardiofaciocutaneous syndrome

Cardiofaciocutaneous Syndrome (CFCS) is a rare genetic syndrome caused by mutations in one of four genes: BRAF, MAP2K1, MAP2K2, and KRAS. There is tremendous phenotypic heterogeneity in patients with CFCS and so confirmation of diagnosis requires genetic testing. Neurologic and/or cognitive symptoms are present in almost all CFCS individuals. Little is known about cognitive function in older patients with CFCS. In this report, we present the cognitive, neuropsychiatric, and imaging findings of a patient diagnosed with CFCS who after having remained stable developed progressive cognitive/behavioral and motor decline.

New Mutations Associated with Rasopathies in a Central European Population and Genotype-Phenotype Correlations

We performed the genetic analysis of Rasopathy syndromes in patients from Central European by direct sequencing followed by next generation sequencing of genes associated with Rasopathies. All 51 patients harboured the typical features of Rasopathy syndromes. Thirty-five mutations were identified in the examined patients (22 in PTPN11, two in SOS1, one in RIT1, one in SHOC2, two in HRAS, three in BRAF, two in MAP2K1 and two in the NF1 gene). Two of them (p.Gly392Glu in the BRAF gene and p.Gln164Lys in the MAP2K1 gene) were novel with a potentially pathogenic effect on the structure of these proteins. Statistically significant differences in the presence of pulmonary stenosis (63.64% vs. 23.81%, P = 0.013897) and cryptorchidism (76.47% vs. 30%, P = 0.040224) were identified as the result of comparison of the prevalence of phenotypic features in patients with the phenotype of Noonan syndrome and mutation in the PTPN11 gene, with the prevalence of the same features in patients without PTPN11 mutation. Cryptorchidism as a statistically significant feature in our patients with PTPN11 mutation was not reported as significant in other European countries (Germany, Italy and Greece). The majority of mutations were clustered in exons 3 (45.45%), 8 (22.73%), and 13 (22.73%) of the PTPN11 gene.

Adult mice expressing a Braf Q241R mutation on an ICR/CD-1 background exhibit a cardio-facio-cutaneous syndrome phenotype

Activation of the RAS pathway has been implicated in oncogenesis and developmental disorders called RASopathies. Germline mutations in BRAF have been identified in 50-75% of patients with cardio-facio-cutaneous (CFC) syndrome, which is characterized by congenital heart defects, distinctive facial features, short stature and ectodermal abnormalities. We recently demonstrated that mice expressing a Braf Q241R mutation, which corresponds to the most frequent BRAF mutation (Q257R) in CFC syndrome, on a C57BL/6J background are embryonic/neonatal lethal, with multiple congenital defects, preventing us from analyzing the phenotypic consequences after birth. Here, to further explore the pathogenesis of CFC syndrome, we backcrossed these mice onto a BALB/c or ICR/CD-1 genetic background. On a mixed (BALB/c and C57BL/6J) background, all heterozygous Braf(Q241R/+) mice died between birth and 24 weeks and exhibited growth retardation, sparse and ruffled fur, liver necrosis and atrial septal defects (ASDs). In contrast, 31% of the heterozygous Braf(Q241R/+) ICR mice survived over 74 weeks. The surviving Braf(Q241R/+) ICR mice exhibited growth retardation, sparse and ruffled fur, a hunched appearance, craniofacial dysmorphism, long and/or dystrophic nails, extra digits and ovarian cysts. The Braf(Q241R/+) ICR mice also showed learning deficits in the contextual fear-conditioning test. Echocardiography indicated the presence of pulmonary stenosis and ASDs in the Braf(Q241R/+) ICR mice, which were confirmed by histological analysis. These data suggest that the heterozygous Braf(Q241R/+) ICR mice show similar phenotypes as CFC syndrome after birth and will be useful for elucidating the pathogenesis and potential therapeutic strategies for RASopathies.

The lymphatic phenotype in Noonan and Cardiofaciocutaneous syndrome

The RASopathies, which include Noonan syndrome (NS) and Cardiofaciocutaneous syndrome (CFC), are autosomal dominant disorders with genetic heterogeneity associated with germline mutations of genes in the Ras/mitogen-activated protein kinase (MAPK; RAS-MAP kinase) pathway. The conditions overlap and are characterised by facial dysmorphism, short stature and congenital heart disease. NS and CFC, in particular, are known to be associated with lymphatic problems, but this has not been well characterised to date. We describe 11 patients with Noonan or CFC syndrome with significant, persistent and progressive lymphatic dysplasia. The lymphatic disorders in Noonan and CFC syndrome are rare, but have a characteristic pattern with bilateral lower limb lymphoedema, genital swelling with chylous reflux and frequent systemic involvement, including intestinal lymphangiectasia and chylothoraces, which may be progressive. Lymphoscintigraphy demonstrates reflux and/or rerouting of lymphatic drainage associated with incompetent veins on the venous duplex scans.

Anesthesia for a pediatric patient with cardiofaciocutaneous syndrome

Cardiofaciocutaneous syndrome is a rare syndrome that is characterized by distinct craniofacial features, cardiac abnormalities, and multiple organ involvement. Patients may present with pulmonary stenosis, hypertrophic cardiomyopathy, micrognathia, a short neck, laryngomalacia, and tracheomalacia; all of which may significantly impact the perioperative course of these patients. We describe a 6-year-old child with cardiofaciocutaneous syndrome presenting for an orthopedic procedure. He had an uneventful perioperative and postoperative course.

The Shodair Medical Genetics Department--recent past and future developments

Philip Pallister and John Opitz laid the ground work for a unique genetic service model in Montana that continues to flourish through ongoing support by the Montana Legislature, the Montana Department of Public Health and Human Services and the Shodair Foundation. At the heart of the model are clinical and laboratory genetic specialists based at Shodair Children's Hospital in Helena providing genetic care for patients through outreach clinics. Clinical services are supported by a state-of-the-art cytogenetics and molecular genetic laboratory as well a fetal genetic pathology program. Over the years, the reach of regular genetics clinics expanded to include large geographic areas including northwest (Kalispell), west central (Missoula), southwest (Bozeman, Butte), north central (Great Falls), and south central Montana (Billings). Building on the foundation of its world-renowned pioneers, the next generation of medical geneticists at Shodair carries the responsibility of integrating genomic medicine in the diagnosis and care of their patients, reducing inequality of services within Montana and partnering with colleagues across specialties to develop a more personalized practice of medicine.

BRAF gene: From human cancers to developmental syndromes

The BRAF gene encodes for a serine/threonine protein kinase that participates in the MAPK/ERK signalling pathway and plays a vital role in cancers and developmental syndromes (RASopathies). The current review discusses the clinical significance of the BRAF gene and other members of RAS/RAF cascade in human cancers and RAS/MAPK syndromes, and focuses the molecular basis and clinical genetics of BRAF to better understand its parallel involvement in both tumourigenesis and RAS/MAPK syndromes—Noonan syndrome, cardio-facio-cutaneous syndrome and LEOPARD syndrome.

Cardio-facio-cutaneous syndrome: clinical features, diagnosis, and management guidelines

Cardio-facio-cutaneous syndrome (CFC) is one of the RASopathies that bears many clinical features in common with the other syndromes in this group, most notably Noonan syndrome and Costello syndrome. CFC is genetically heterogeneous and caused by gene mutations in the Ras/mitogen-activated protein kinase pathway. The major features of CFC include characteristic craniofacial dysmorphology, congenital heart disease, dermatologic abnormalities, growth retardation, and intellectual disability. It is essential that this condition be differentiated from other RASopathies, as a correct diagnosis is important for appropriate medical management and determining recurrence risk. Children and adults with CFC require multidisciplinary care from specialists, and the need for comprehensive management has been apparent to families and health care professionals caring for affected individuals. To address this need, CFC International, a nonprofit family support organization that provides a forum for information, support, and facilitation of research in basic medical and social issues affecting individuals with CFC, organized a consensus conference. Experts in multiple medical specialties provided clinical management guidelines for pediatricians and other care providers. These guidelines will assist in an accurate diagnosis of individuals with CFC, provide best practice recommendations, and facilitate long-term medical care.

Perinatal features of the RASopathies: Noonan syndrome, cardiofaciocutaneous syndrome and Costello syndrome

The RASopathies are a family of developmental disorders caused by heritable defects of the RAS/MAPK signaling pathway. While the postnatal presentation of this group of disorders is well known, the prenatal and neonatal findings are less widely recognized. We report on the perinatal presentation of 10 patients with Noonan syndrome (NS), nine with Cardiofaciocutaneous syndrome (CFCS) and three with Costello syndrome (CS), in conjunction with the results of a comprehensive literature review. The majority of perinatal findings in NS, CS, and CFCS are shared: polyhydramnios; prematurity; lymphatic dysplasia; macrosomia; relative macrocephaly; respiratory distress; hypotonia, as well as cardiac and renal anomalies. In contrast, fetal arrhythmia and neonatal hypoglycemia are relatively specific to CS. NS, CS, and CFCS should all be considered as a possible diagnosis in pregnancies with a normal karyotype and ultrasound findings of a RASopathy. Recognition of the common perinatal findings of these disorders should facilitate both their prenatal and neonatal diagnosis.

New BRAF knockin mice provide a pathogenetic mechanism of developmental defects and a therapeutic approach in cardio-facio-cutaneous syndrome

Cardio-facio-cutaneous (CFC) syndrome is one of the 'RASopathies', a group of phenotypically overlapping syndromes caused by germline mutations that encode components of the RAS-MAPK pathway. Germline mutations in BRAF cause CFC syndrome, which is characterized by heart defects, distinctive facial features and ectodermal abnormalities. To define the pathogenesis and to develop a potential therapeutic approach in CFC syndrome, we here generated new knockin mice (here Braf(Q241R/+)) expressing the Braf Q241R mutation, which corresponds to the most frequent mutation in CFC syndrome, Q257R. Braf(Q241R/+) mice manifested embryonic/neonatal lethality, showing liver necrosis, edema and craniofacial abnormalities. Histological analysis revealed multiple heart defects, including cardiomegaly, enlarged cardiac valves, ventricular noncompaction and ventricular septal defects. Braf(Q241R/+) embryos also showed massively distended jugular lymphatic sacs and subcutaneous lymphatic vessels, demonstrating lymphatic defects in RASopathy knockin mice for the first time. Prenatal treatment with a MEK inhibitor, PD0325901, rescued the embryonic lethality with amelioration of craniofacial abnormalities and edema in Braf(Q241R/+) embryos. Unexpectedly, one surviving pup was obtained after treatment with a histone 3 demethylase inhibitor, GSK-J4, or NCDM-32b. Combination treatment with PD0325901 and GSK-J4 further increased the rescue from embryonic lethality, ameliorating enlarged cardiac valves. These results suggest that our new Braf knockin mice recapitulate major features of RASopathies and that epigenetic modulation as well as the inhibition of the ERK pathway will be a potential therapeutic strategy for the treatment of CFC syndrome.

Cardio-facio-cutaneous syndrome with precocious puberty, growth hormone deficiency and hyperprolactinemia

Cardio-facio-cutaneous (CFC) syndrome is a rare disorder characterized by craniofacial dysmorphia, ectodermal abnormalities, cardiac malformations, as well as growth and developmental delay. Although some endocrine abnormalities have been reported in this syndrome, very little is known about CFC syndrome-related endocrine disorders. A 7.5-year-old boy was admitted to our endocrinology clinic with the complaint of short stature. He had a height of 103 cm [-4 standard deviation (SD)], a weight of 16 kg (<3(th) percentile, -1.7 SD), a facial appearance typical for the CFC syndrome, optic nerve hypoplasia and pulmonary stenosis. Genetic investigation revealed a heterozygous mutation in exon 3 of the MEK1 gene, c.389A>G (p. Y130C). During his long-term follow-up, the patient developed a variety of endocrine disorders including precocious puberty, growth hormone deficiency and hyperprolactinemia.

Diagnosis of Noonan syndrome and related disorders using target next generation sequencing

Background

Noonan syndrome is an autosomal dominant developmental disorder with a high phenotypic variability, which shares clinical features with other rare conditions, including LEOPARD syndrome, cardiofaciocutaneous syndrome, Noonan-like syndrome with loose anagen hair, and Costello syndrome. This group of related disorders, so-called RASopathies, is caused by germline mutations in distinct genes encoding for components of the RAS-MAPK signalling pathway. Due to high number of genes associated with these disorders, standard diagnostic testing requires expensive and time consuming approaches using Sanger sequencing. In this study we show how targeted Next Generation Sequencing (NGS) technique can enable accurate, faster and cost-effective diagnosis of RASopathies.

Methods

In this study we used a validation set of 10 patients (6 positive controls previously characterized by Sanger-sequencing and 4 negative controls) to assess the analytical sensitivity and specificity of the targeted NGS. As second step, a training set of 80 enrolled patients with a clinical suspect of RASopathies has been tested. Targeted NGS has been successfully applied over 92% of the regions of interest, including exons for the following genes: PTPN11, SOS1, RAF1, BRAF, HRAS, KRAS, NRAS, SHOC, MAP2K1, MAP2K2, CBL.

Results

All expected variants in patients belonging to the validation set have been identified by targeted NGS providing a detection rate of 100%. Furthermore, all the newly detected mutations in patients from the training set have been confirmed by Sanger sequencing. Absence of any false negative event has been excluded by testing some of the negative patients, randomly selected, with Sanger sequencing.

Conclusion

Here we show how molecular testing of RASopathies by targeted NGS could allow an early and accurate diagnosis for all enrolled patients, enabling a prompt diagnosis especially for those patients with mild, non-specific or atypical features, in whom the detection of the causative mutation usually requires prolonged diagnostic timings when using standard routine. This approach strongly improved genetic counselling and clinical management.

Cutaneous manifestations in Costello and cardiofaciocutaneous syndrome: report of 18 cases and literature review

Costello syndrome (CS) and cardiofaciocutaneous syndrome (CFCS) are congenital disorders involving the Ras-MAPK pathway with phenotypic overlap. These two entities are thought to share common cutaneous findings, although so far they have been poorly studied. The objective of this prospective observational study was to describe the spectrum of skin findings in CS and CFCS and to highlight those specific to each of these two diseases. Patients with a confirmed diagnosis of CFCS or CS underwent a systematic skin examination during the annual workshop organized by the French CS association in 2007 and 2009 in Bordeaux, France. Eighteen patients were included in the study. Specific skin abnormalities, including cutis laxa, curly hair, pruritus, and hyperhidrosis, are shared by CFCS and CS, whereas others may help to differentiate between these two syndromes. Acanthosis nigricans, papillomas, and loose thick skin of the dorsum of the hands are characteristic of CS, whereas sparse eyebrows and dry hyperkeratotic skin are suggestive of CFCS. Our results highlight that a systematic cutaneous examination, in addition to dysmorphologic and noncutaneous anomalies, may be helpful in establishing the diagnosis of CFCS and CS. The physiopathologic link between constitutional Ras-MAPK pathway activation and the observed ectodermal findings remains to be investigated.

Small G Proteins in the Cardiovascular System: Physiological and Pathological Aspects

Small G proteins exist in eukaryotes from yeast to human and constitute the Ras superfamily comprising more than 100 members. This superfamily is structurally classified into five families: the Ras, Rho, Rab, Arf, and Ran families that control a wide variety of cell and biological functions through highly coordinated regulation processes. Increasing evidence has accumulated to identify small G proteins and their regulators as key players of the cardiovascular physiology that control a large panel of cardiac (heart rhythm, contraction, hypertrophy) and vascular functions (angiogenesis, vascular permeability, vasoconstriction). Indeed, basal Ras protein activity is required for homeostatic functions in physiological conditions, but sustained overactivation of Ras proteins or spatiotemporal dysregulation of Ras signaling pathways has pathological consequences in the cardiovascular system. The primary object of this review is to provide a comprehensive overview of the current progress in our understanding of the role of small G proteins and their regulators in cardiovascular physiology and pathologies.

Deletion of MAP2K2/MEK2: a novel mechanism for a RASopathy?

RASopathies are a class of genetic syndromes caused by germline mutations in genes encoding Ras/mitogen-activated protein kinase (Ras/MAPK) pathway components. Cardio-facio-cutaneous (CFC) syndrome is a RASopathy characterized by distinctive craniofacial features, skin and hair abnormalities, and congenital heart defects caused by activating mutations of BRAF, MEK1, MEK2, and KRAS. We define the phenotype of seven patients with de novo deletions of chromosome 19p13.3 including MEK2; they present with a distinct phenotype but have overlapping features with CFC syndrome. Phenotypic features of all seven patients include tall forehead, thick nasal tip, underdeveloped cheekbones, long midface, sinuous upper vermilion border, tall chin, angular jaw, and facial asymmetry. Patients also have developmental delay, hypotonia, heart abnormalities, failure to thrive, obstructive sleep apnea, gastroesophageal reflux and integument abnormalities. Analysis of epidermal growth factor-stimulated fibroblasts revealed that P-MEK1/2 was ∼50% less abundant in cells carrying the MEK2 deletion compared to the control. Significant differences in total MEK2 and Sprouty1 abundance were also observed. Our cohort of seven individuals with MEK2 deletions has overlapping features associated with RASopathies. This is the first report suggesting that, in addition to activating mutations, MEK2 haploinsufficiency can lead to dysregulation of the MAPK pathway.

Ablation of BRaf impairs neuronal differentiation in the postnatal hippocampus and cerebellum

This study focuses on the role of the kinase BRaf in postnatal brain development. Mice expressing truncated, non-functional BRaf in neural stem cell-derived brain tissue demonstrate alterations in the cerebellum, with decreased sizes and fuzzy borders of the glomeruli in the granule cell layer. In addition we observed reduced numbers and misplaced ectopic Purkinje cells that showed an altered structure of their dendritic arborizations in the hippocampus, while the overall cornus ammonis architecture appeared to be unchanged. In male mice lacking BRaf in the hippocampus the size of the granule cell layer was normal at postnatal day 12 (P12) but diminished at P21, as compared to control littermates. This defect was caused by a reduced ability of dentate gyrus progenitor cells to differentiate into NeuN positive granule cell neurons. In vitro cell culture of P0/P1 hippocampal cells revealed that BRaf deficient cells were impaired in their ability to form microtubule-associated protein 2 positive neurons. Together with the alterations in behaviour, such as autoaggression and loss of balance fitness, these observations indicate that in the absence of BRaf all neuronal cellular structures develop, but neuronal circuits in the cerebellum and hippocampus are partially disturbed besides impaired neuronal generation in both structures.