Are Noonan syndrome and Noonan-like/multiple giant cell lesion syndrome distinct entities?

A Rare Case of Diffuse-type Tenosynovial Giant Cell Tumor in a Teenager With Noonan Syndrome

Noonan syndrome is a common autosomal dominant disorder associated with an increased risk of malignancy. We report a 16-year-old female with Noonan syndrome (KRAS gene variant, Q22R) and diffuse-type tenosynovial giant cell tumor, a proliferative disorder that has been rarely reported in this population. These tumors may represent a complication of the dysregulated RAS/MAPK signaling pathway that underlies Noonan syndrome. They lack typical clinical features, causing misdiagnosis and delays in management, which could lead to osseous invasion requiring more complicated surgical procedures. Increased awareness of this association will improve the clinical outcomes of patients with Noonan syndrome who develop diffuse-type tenosynovial giant cell tumors.

Multiple versus solitary giant cell lesions of the jaw: Similar or distinct entities?

The majority of giant cell lesions of the jaw present as a solitary focus of disease in bones of the maxillofacial skeleton. Less frequently they occur as multifocal lesions. This raises the clinical dilemma if these should be considered distinct entities and therefore each need a specific therapeutic approach. Solitary giant cell lesions of the jaw present with a great diversity of symptoms. Recent molecular analysis revealed that these are associated with somatic gain-of-function mutations in KRAS, FGFR1 or TRPV4 in a large component of the mononuclear stromal cells which all act on the RAS/MAPK pathway. For multifocal lesions, a small group of neoplastic multifocal giant cell lesions of the jaw remain after ruling out hyperparathyroidism. Strikingly, most of these patients are diagnosed with jaw lesions before the age of 20 years, thus before the completion of dental and jaw development. These multifocal lesions are often accompanied by a diagnosis or strong clinical suspicion of a syndrome. Many of the frequently reported syndromes belong to the so-called RASopathies, with germline or mosaic mutations leading to downstream upregulation of the RAS/MAPK pathway. The other frequently reported syndrome is cherubism, with gain-of-function mutations in the SH3BP2 gene leading through assumed and unknown signaling to an autoinflammatory bone disorder with hyperactive osteoclasts and defective osteoblastogenesis. Based on this extensive literature review, a RAS/MAPK pathway activation is hypothesized in all giant cell lesions of the jaw. The different interaction between and contribution of deregulated signaling in individual cell lineages and crosstalk with other pathways among the different germline- and non-germline-based alterations causing giant cell lesions of the jaw can be explanatory for the characteristic clinical features. As such, this might also aid in the understanding of the age-dependent symptomatology of syndrome associated giant cell lesions of the jaw; hopefully guiding ideal timing when installing treatment strategies in the future.

Multifocal Pigmented Villonodular Synovitis in the Noonan Syndrome

Noonan-like/multiple giant cell lesion (NS/MGCL) is a rare condition overlapping with Noonan syndrome. Once thought to be a specific and separate entity, it is now suggested to be a variant of the Noonan syndrome spectrum. We report the case of an 8-year-old boy with a typical clinical picture of Noonan syndrome with a de novo germline mutation of PTPN11 (c.854 T>C). During his follow-up, the patient developed multifocal pigmented villonodular synovitis which first affected the left knee and shortly after both elbows.

Giant cell lesion of the jaw as a presenting feature of Noonan syndrome

This is a case of a 20-year-old woman who presented with a left jaw mass which was resected and found to be a giant cell granuloma of the mandible. Her history and physical examination were suggestive for Noonan syndrome which was confirmed with genetic testing and the finding of a PTPN11 gene mutation which has rarely been associated with giant cell lesions of the jaw. Given her particular genetic mutation and the presence of a giant cell lesion, we present a case of Noonan-like/multiple giant cell lesion syndrome.

Psychopathological features in Noonan syndrome

INTRODUCTION

Noonan syndrome (NS) is an autosomal dominant disorder characterized by short stature, skeletal and haematological/lymphatic defects, distinctive facies, cryptorchidism, and a wide spectrum of congenital heart defects. Recurrent features also include variable cognitive deficits and behavioural problems. Recent research has been focused on the assessment of prevalence, age of onset and characterization of psychiatric features in this disorder. Herein, we evaluated the prevalence of attention deficit and hyperactivity disorder (ADHD), anxiety and depressive symptoms and syndromes in a cohort of individuals with clinical and molecular diagnosis of NS.

METHODS

The Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Children Present and Lifetime version (K-SADS PL) has been used for the assessment of psychiatric disorders according to Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). Multidimensional Anxiety Scale for Children (MASC) and the Children's Depression Inventory (CDI) have been assessed for the evaluation of anxiety and depressive symptoms and syndromes, whereas Conners Teacher and Parent Rating Scales-long version (CRS-R) have been used to evaluate ADHD.

RESULTS

The study included 27 individuals (67% males) with an average age of 10.4 years (range 6-18 years) receiving molecular diagnosis of NS or a clinically related condition, evaluated and treated at the Neuropsychiatric Unit of Children's Hospital Bambino Gesù and at the Center for Rare Diseases of Fondazione Policlinico Universitario Agostino Gemelli, in Rome. Twenty individuals showed mutations in PTPN11, five in SOS1 and two in SHOC2. The mean IQ was 94 (Standard Deviation = 17, min = 56, max = 130). Seventy percent of the individuals (n = 19; 95% Confidence Interval = 52-85%) showed ADHD features, with six individuals reaching DSM-IV-TR criteria for ADHD disorder, and thirteen showing subsyndromal traits. Symptoms or syndrome of anxiety were present in 37% of the cohort (n = 10; 95% Confidence Interval = 19-56%), with two individuals showing anxiety disorder and eight cases exhibiting subsyndromal traits.

CONCLUSION

Our results show individuals with NS do present a very high risk to develop psychiatric disorders or symptoms during paediatric age. Based on these findings, preschool assessment of inattentive, hyperactivity/impulsivity and anxiety/depressive symptoms is recommended in order to plan a personalized treatment for psychological/psychiatric issues in affected individuals. Dedicated prospective studies are required to confirm the present data and better characterize the psychopathological profile in NS.

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.

Noonan syndrome

Noonan syndrome is a genetic multisystem disorder characterised by distinctive facial features, developmental delay, learning difficulties, short stature, congenital heart disease, renal anomalies, lymphatic malformations, and bleeding difficulties. Mutations that cause Noonan syndrome alter genes encoding proteins with roles in the RAS-MAPK pathway, leading to pathway dysregulation. Management guidelines have been developed. Several clinically relevant genotype-phenotype correlations aid risk assessment and patient management. Increased understanding of the pathophysiology of the disease could help development of pharmacogenetic treatments.

Noonan syndrome: clinical features, diagnosis, and management guidelines

Noonan syndrome (NS) is a common, clinically and genetically heterogeneous condition characterized by distinctive facial features, short stature, chest deformity, congenital heart disease, and other comorbidities. Gene mutations identified in individuals with the NS phenotype are involved in the Ras/MAPK (mitogen-activated protein kinase) signal transduction pathway and currently explain ∼61% of NS cases. Thus, NS frequently remains a clinical diagnosis. Because of the variability in presentation and the need for multidisciplinary care, it is essential that the condition be identified and managed comprehensively. The Noonan Syndrome Support Group (NSSG) is a nonprofit organization committed to providing support, current information, and understanding to those affected by NS. The NSSG convened a conference of health care providers, all involved in various aspects of NS, to develop these guidelines for use by pediatricians in the diagnosis and management of individuals with NS and to provide updated genetic findings.

Tumor spectrum in children with Noonan syndrome and SOS1 or RAF1 mutations

Noonan syndrome (NS) is an autosomal dominant disorder caused by mutations in PTPN11, KRAS, SOS1, and RAF1. We performed SOS1, RAF1, BRAF, MEK1, and MEK2 mutation analysis in a cohort of 102 PTPN11- and KRAS-negative NS patients and found pathogenic SOS1 mutations in 10, RAF1 mutations in 4, and BRAF mutations in 2 patients. Three novel SOS1 mutations were found. One was classified as a rare benign variant and the other remains unclassified. We confirm a high prevalence of pulmonic stenosis and ectodermal abnormalities in SOS1-positive patients. Three patients with SOS1 mutations presented with tumors (embryonal rhabdomyosarcoma, Sertoli cell testis tumor, and granular cell tumors of the skin). One patient with a RAF1 mutation had a lesion suggestive for a giant cell tumor. This is the first report describing different tumor types in NS patients with germ line SOS1 mutations.

SOS1 and PTPN11 mutations in five cases of Noonan syndrome with multiple giant cell lesions

We report five cases of multiple giant cell lesions in patients with typical Noonan syndrome. Such association has frequently been referred to as Noonan-like/multiple giant cell (NL/MGCL) syndrome before the molecular definition of Noonan syndrome. Two patients show mutations in PTPN11 (p.Tyr62Asp and p.Asn308Asp) and three in SOS1 (p.Arg552Ser and p.Arg552Thr). The latter are the first SOS1 mutations reported outside PTPN11 in NL/MGCL syndrome. MGCL lesions were observed in jaws ('cherubism') and joints ('pigmented villonodular synovitis'). We show through those patients that both types of MGCL are not PTPN11-specific, but rather represent a low penetrant (or perhaps overlooked) complication of the dysregulated RAS/MAPK signaling pathway. We recommend discarding NL/MGCL syndrome from the nosology, as this presentation is neither gene-nor allele-specific of Noonan syndrome; these patients should be described as Noonan syndrome with MGCL (of the mandible, the long bone...). The term cherubism should be used only when multiple giant cell lesions occur without any other clinical and molecular evidence of Noonan syndrome, with or without mutations of the SH3BP2 gene.

Multiple giant cell lesions in patients with Noonan syndrome and cardio-facio-cutaneous syndrome

Noonan syndrome (NS) and cardio-facio-cutaneous syndrome (CFCS) are related developmental disorders caused by mutations in genes encoding various components of the RAS-MAPK signaling cascade. NS is associated with mutations in the genes PTPN11, SOS1, RAF1, or KRAS, whereas CFCS can be caused by mutations in BRAF, MEK1, MEK2, or KRAS. The NS phenotype is rarely accompanied by multiple giant cell lesions (MGCL) of the jaw (Noonan-like/MGCL syndrome (NL/MGCLS)). PTPN11 mutations are the only genetic abnormalities reported so far in some patients with NL/MGCLS and in one individual with LEOPARD syndrome and MGCL. In a cohort of 75 NS patients previously tested negative for mutations in PTPN11 and KRAS, we detected SOS1 mutations in 11 individuals, four of whom had MGCL. To explore further the relevance of aberrant RAS-MAPK signaling in syndromic MGCL, we analyzed the established genes causing CFCS in three subjects with MGCL associated with a phenotype fitting CFCS. Mutations in BRAF or MEK1 were identified in these patients. All mutations detected in these seven patients with syndromic MGCL had previously been described in NS or CFCS without apparent MGCL. This study demonstrates that MGCL may occur in NS and CFCS with various underlying genetic alterations and no obvious genotype-phenotype correlation. This suggests that dysregulation of the RAS-MAPK pathway represents the common and basic molecular event predisposing to giant cell lesion formation in patients with NS and CFCS rather than specific mutation effects.

Mutation analysis of the genes involved in the Ras-mitogen-activated protein kinase (MAPK) pathway in Korean patients with Noonan syndrome

Noonan syndrome (NS) is a congenital abnormality that affects multiple parts of the body. Approximately 50% of cases are caused by mutations in the PTPN11 gene. NS shares many clinical features with a group of developmental disorders including Costello syndrome and cardio-facio-cutaneous (CFC) syndrome. Recently, KRAS and SOS1 were identified as causative genes for NS. Moreover, mutations in several genes associated with the Ras-mitogen-activated protein kinase (MAPK) pathway, including HRAS, BRAF, MEK1, and MEK2 were identified in patients with Costello syndrome and CFC syndrome. Accordingly, this study carried out mutation analysis of nine genes including PTPN11, SOS1, GRB2, KRAS, HRAS, NRAS, BRAF, MEK1, and MEK2 associated with the Ras-MAPK pathway in 14 Korean patients with NS. Seven patients were found to have mutations in the PTPN11 gene. Mutation analyses of the other genes did not reveal any disease causing mutations except for one unclassified variation in the 3'-untranslated region of the HRAS gene (c.*1C>T). The patient's father also had the same substitution with the normal phenotype. Therefore, this variation is believed to be either a rare polymorphism or a disease-related variation with variable penetrance. The Ras-MAPK pathway has now emerged as a key cascade in a group of similar developmental disorders as well as in many types of cancers. This study found that, with the exception of PTPN11, mutations in genes related to the Ras-MAPK pathway appear to be uncommon, at least in Korean patients with NS.

Further evidence of genetic heterogeneity in Costello syndrome: involvement of the KRAS gene

Costello syndrome is an autosomal dominant disorder comprising growth deficiency, mental retardation, curly hair, coarse facial features, nasal papillomata, low-set ears with large lobes, cardiac anomalies, redundant skin in palms and soles with prominent creases, dark skin, and propensity to certain solid tumors. HRAS mutations have been implicated in approximately 85% of the affected cases. The clinical overlap among Costello, Noonan, and cardiofaciocutaneous syndromes is now better understood given their common molecular background, such that all these syndromes constitute a class of disorders caused by deregulated RAS-MAPK signaling. We report on a novel KRAS gene mutation in a patient presenting the clinical features typical of Costello syndrome and the additional findings seen in Noonan syndrome. This description emphasizes that a subset of patients with Costello syndrome could harbor mutations in other genes involved in the RAS-MAPK signaling.

Noonan syndrome and related disorders: genetics and pathogenesis

Noonan syndrome is a pleiomorphic autosomal dominant disorder with short stature, facial dysmorphia, webbed neck, and heart defects. In the past decade, progress has been made in elucidating the pathogenesis of this disorder using a positional cloning approach. Noonan syndrome is now known to be a genetically heterogeneous disorder with nearly one half of cases caused by gain-of-function mutations in PTPN11, the gene encoding the protein tyrosine phosphatase SHP-2. Similar germ line mutations cause two related genetic disorders, Noonan-like disorder with multiple giant cell lesion syndrome and LEOPARD syndrome, and somatic PTPN11 mutations can underlie certain pediatric hematopoietic malignancies, including juvenile myelomonocytic, acute lymphoblastic, and acute myelogenous leukemias. A mouse model of PTPN11-related Noonan syndrome was recently generated, providing a reagent for studying disease pathogenesis in greater depth as well as experimenting with novel therapeutic strategies.

Bilateral central giant cell granulomas of the mandible in an 8-year-old girl with Noonan syndrome (Noonan-like/multiple giant cell lesion syndrome)

We report a case of an 8-year-old girl who presented with bilateral central giant cell granulomas of the posterior mandible. Characteristic facial features and a history of pulmonary stenosis led us to suspect a diagnosis of Noonan syndrome. A medical geneticist confirmed this. This case report will discuss the salient features of this diagnosis.

Germ-line and somatic PTPN11 mutations in human disease

Reversible protein tyrosyl phosphorylation of cell surface receptors and downstream intracellular transducers is a major regulatory mechanism used to modulate cellular responses to extracellular stimuli, and its deregulation frequently drives aberrant cell proliferation, survival and/or differentiation. SHP-2 is a cytoplasmic Src-homology 2 domain-containing protein tyrosine phosphatase that plays an important role in intracellular signaling and is required during development and hematopoiesis. Germ-line missense mutations in PTPN11, the gene coding SHP-2, have been discovered as a major molecular event underlying Noonan syndrome, an autosomal dominant trait characterized by short stature, dysmorphic facies, and congenital heart defects, as well as in other closely related developmental disorders. More recently, a distinct class of missense mutations in the same gene has been identified to occur as a somatic event contributing to myeloid and lymphoid malignancies. This review focuses on the role of SHP-2 in signal transduction, development and hematopoiesis, as well as on the consequences of SHP-2 gain-of-function.

A novel PTPN11 gene mutation bridges Noonan syndrome, multiple lentigines/LEOPARD syndrome and Noonan-like/multiple giant cell lesion syndrome

Noonan (NS) and multiple lentigines/LEOPARD syndromes (LS) have proved to be associated with distinct PTPN11 mutations. Noonan-like/multiple giant cell lesion syndrome (NLS) is a rare disease, characterised by short stature, facial dysmorphisms, congenital heart defect (CHD) and central giant cell lesions. PTPN11 gene mutations have been reported in a single NLS family and two sporadic patients. Here we report a patient with a complex phenotype progressing throughout the years from NS at birth towards LS and NLS. PTPN11 gene analysis disclosed a novel missense mutation (Ala461Thr) in exon 12, affecting the consensus sequence of the SHP2-active site. This observation joins together NS and LS to NLS into a unique genetic defect, broadening the clinical and molecular spectrum of PTPN11-related disorders.

Orbital rhabdomyosarcoma in Noonan syndrome

The incidence of various benign and malignant tumors is increased in patients with Noonan syndrome compared with the general population. We present a 9-year-old boy with the typical features of Noonan syndrome and an acute nonaxial proptosis of the right eye. An ultrasound scan, a computed tomography scan, and magnetic resonance imaging raised suspicion of rhabdomyosarcoma. Biopsy confirmed the diagnosis. The tumor was consequently treated with combined chemotherapy and radiotherapy. Rhabdomyosarcoma is a rare but important differential diagnosis of tumor formation in children with Noonan syndrome and may arise in the orbit.

King-Denborough Syndrome: report of two Brazilian cases

We report on two boys aged 2 and 6 years-old respectively with dysmorphic face, ptosis, down-slanting palpebral fissures, hypertelorism, epicanthic folds, low-set ears, malar hypoplasia, micrognathia, high-arched palate, clinodactyly, palmar simian line, pectus excavatum, winging of the scapulae, lumbar lordosis and mild thoracic scoliosis who present congenital hypotonia, slightly delayed motor development, diffuse joint hyperextensibility and mild proximal weakness. The muscle biopsy revealed minimal but identifiable changes represented by size fiber variability, type I fiber predominance and atrophy, perimysial fibrous infiltration and some disarray of the intermyofibrillary network. These cases correspond to the first Brazilian reports of the King-Denborough syndrome and our objective is increasing the awareness of this disorder as these patients are predisposed to developing malignant hyperthermia.

PTPN11 mutations in Noonan syndrome: molecular spectrum, genotype-phenotype correlation, and phenotypic heterogeneity

Noonan syndrome (NS) is a developmental disorder characterized by facial dysmorphia, short stature, cardiac defects, and skeletal malformations. We recently demonstrated that mutations in PTPN11, the gene encoding the non-receptor-type protein tyrosine phosphatase SHP-2 (src homology region 2-domain phosphatase-2), cause NS, accounting for approximately 50% of cases of this genetically heterogeneous disorder in a small cohort. All mutations were missense changes and clustered at the interacting portions of the amino-terminal src-homology 2 (N-SH2) and protein tyrosine phosphatase (PTP) domains. A gain of function was postulated as a mechanism for the disease. Here, we report the spectrum and distribution of PTPN11 mutations in a large, well-characterized cohort with NS. Mutations were found in 54 of 119 (45%) unrelated individuals with sporadic or familial NS. There was a significantly higher prevalence of mutations among familial cases than among sporadic ones. All defects were missense, and several were recurrent. The vast majority of mutations altered amino acid residues located in or around the interacting surfaces of the N-SH2 and PTP domains, but defects also affected residues in the C-SH2 domain, as well as in the peptide linking the N-SH2 and C-SH2 domains. Genotype-phenotype analysis revealed that pulmonic stenosis was more prevalent among the group of subjects with NS who had PTPN11 mutations than it was in the group without them (70.6% vs. 46.2%; P<.01), whereas hypertrophic cardiomyopathy was less prevalent among those with PTPN11 mutations (5.9% vs. 26.2%; P<.005). The prevalence of other congenital heart malformations, short stature, pectus deformity, cryptorchidism, and developmental delay did not differ between the two groups. A PTPN11 mutation was identified in a family inheriting Noonan-like/multiple giant-cell lesion syndrome, extending the phenotypic range of disease associated with this gene.