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The RASopathies are a family of clinically related disorders caused by mutations affecting genes participating in the RAS-MAPK signaling cascade. Among them, Noonan syndrome (NS) and Noonan syndrome with multiple lentigines (NSML) are allelic conditions principally associated with dominant mutations in PTPN11, which encodes the nonreceptor SH2 domain-containing protein tyrosine phosphatase SHP2. Individual PTPN11 mutations are specific to each syndrome and have opposite consequences on catalysis, but all favor SHP2's interaction with signaling partners. Here, we report on a subject with NS harboring biallelic variants in PTPN11. While the former (p.Leu261Phe) had previously been reported in NS, the latter (p.Thr357Met) is a novel change impairing catalysis. Members of the family carrying p.Thr357Met, however, did not show any obvious feature fitting NSML or within the RASopathy phenotypic spectrum. A major impact of this change on transcript processing and protein stability was excluded. These findings further support the view that NSML cannot be ascribed merely to impaired SHP2's catalytic activity and suggest that PTPN11 mutations causing this condition act through an alternative dominant mechanism.

Noonan syndrome with multiple lentigines (NSML), previously known as LEOPARD syndrome, is a rare autosomal dominant disorder with an unknown prevalence. Characteristics of this disease include cutaneous, neurologic, and cardiologic abnormalities. In this case report, we present a 12-year-old girl who was admitted to the emergency department for acute-onset left weakness, unsteady gait, nausea, and vomiting. Her physical exam notably showed left side upper motor neuron signs and dysmetria. CT scan revealed an acute hemorrhage of the right thalamus. Physical exam exhibited several craniofacial dysmorphisms and lentigines. The genetic test revealed a heterozygous missense mutation in the protein tyrosine phosphatase non-receptor type 11 (PTPN11) gene and a variant of unknown significance of the MYH11 gene. To the best of our knowledge, this is the first case of a patient with NSML presenting an intracerebral hemorrhage.

BackgroundGermline variants inPTPN11are the primary cause of Noonan syndrome with multiple lentigines (NSML) and Noonan syndrome (NS), which share common skin and facial symptoms, cardiac anomalies and retardation of growth. Hearing loss is considered an infrequent feature in patients with NSML/NS. However, in our cohort, we identified a group of patients withPTPN11pathogenic variants that were primarily manifested in congenital sensorineural hearing loss (SNHL). This study evaluated the incidence ofPTPN11-related NSML or NS in patients with congenital SNHL and explored the expression ofPTPN11and the underlying mechanisms in the auditory system.MethodsA total of 1502 patients with congenital SNHL were enrolled. Detailed phenotype-genotype correlations were analysed in patients withPTPN11variants. Immunolabelling of Ptpn11 was performed in P35 mice. Zebrafish withPtpn11knockdown/mutant overexpression were constructed to further explore mechanism underlying the phenotypes.ResultsTen NSML/NS probands were diagnosed via the identification of pathogenic variants ofPTPN11, which accounted for ~0.67% of the congenital SNHL cases. In mice cochlea, Shp2, which is encoded byPtpn11, is distributed in the spiral ganglion neurons, hair cells and supporting cells of the inner ear. In zebrafish, knockdown ofptpn11aand overexpression of mutantPTPN11were associated with a significant decrease in hair cells and supporting cells. We concluded that congenital SNHL could be a major symptom inPTPN11-associated NSML or NS. Other features may be mild, especially in children.ConclusionScreening forPTPN11in patients with congenital hearing loss and variant-based diagnoses are recommended.

Cafe au lait macules (CALMs) are a common, isolated dermatologic finding in the general population. But when do these irregularly shaped, jagged-edged, flat, hyperpigmented birthmarks suggest something that may warrant referral? Most pediatric providers are familiar with the association of CALMs and neurofibromatosis type 1. There are, however, other genetic conditions associated with these seemingly benign skin spots. This article provides an overview of CALMs, followed by a summary of several conditions associated with CALMs ranging from the most common (neurofibromatosis type 1) to rare, ring chromosome syndromes. It reviews the associated gene(s), pattern of inheritance, incidence, presenting symptoms, diagnosis, and management for these genetic conditions.

Neurofibromatosis type 1 (NF1) is the most common disorder characterized by multiple café-au-lait macules. Most individuals with this autosomal dominant disorder also have other features, such as skinfold freckling, iris Lisch nodules and benign or malignant peripheral nerve sheath tumours. Legius syndrome is a less frequent autosomal dominant disorder with similar multiple café-au-lait macules and skinfold freckling. Legius syndrome is not characterized by an increased risk of tumours, and a correct diagnosis is important. In young children with a sporadic form of multiple café-au-lait macules with or without freckling and no other manifestations of NF1 these 2 conditions cannot be differentiated based on clinical examination. Molecular analysis of the NF1 and SPRED1 genes is usually needed to differentiate the 2 conditions. Other less frequent conditions with café-au-lait macules are Noonan syndrome with multiple lentigines, constitutional mismatch repair deficiency and McCune-Albright syndrome. ispartof: ACTA DERMATO-VENEREOLOGICA vol:100 issue:7 pages:161-167 ispartof: location:Sweden status: published

Purpose To report a case of Noonan syndrome with multiple lentigines with unusual ocular features. Methods The authors describe a case of a Seven-year-old girl with Noonan syndrome with multiple lentigines and anomalous optic discs. Results A Seven-year-old girl with genetically proven Noonan syndrome with multiple lentigines (PTPN11 gene mutation) and anomalous optic discs was referred for treatment of persistent macular detachment after 1 year of conservative follow up. The right eye demonstrated an optic disc coloboma with best-corrected visual acuity of 20/32, the left eye demonstrated an optic disc pit with serous macular detachment (best-corrected visual acuity 20/50 - 20/80). Optical coherence tomography demonstrated a neurosensory detachment. 25 gauge pars plana vitrectomy was performed with posterior hyaloid detachment, drainage over disc pit area and SF6 20% gas tamponade. Surgery resulted in subretinal fluid reduction and improvement of visual acuity to 20/32. Conclusion A case of Noonan syndrome with multiple lentigines with optic disc coloboma in the right eye and optic disc pit with related maculopathy in the left eye. To the authors' knowledge, this is the first reported case describing the association of Noonan syndrome with multiple lentigines and congenital optic disc anomalies. Optic disc pit maculopathy was managed surgically due to its longstanding nature with deteriorating visual acuity.

Purpose Noonan syndrome with multiple lentigines (NSML) is an autosomal dominant disorder presenting with hypertrophic cardiomyopathy (HCM). Up to 85% of NSML cases are caused by mutations in the PTPN11 gene that encodes for the Src homology 2 (SH2) domain-containing protein tyrosine phosphatase 2 (SHP2). We previously showed that low-dose dasatinib protects from the development of cardiac fibrosis in a mouse model of NSML harboring a Ptpn11Y279C mutation. This study is performed to determine the pharmacokinetic (PK) and pharmacodynamic (PD) properties of a low-dose of dasatinib in NSML mice and to determine its effectiveness in ameliorating the development of HCM. Methods Dasatinib was administered intraperitoneally into NSML mice with doses ranging from 0.05 to 0.5 mg/kg. PK parameters of dasatinib in NSML mice were determined. PD parameters were obtained for biochemical analyses from heart tissue. Dasatinib-treated NSML mice (0.1 mg/kg) were subjected to echocardiography and assessment of markers of HCM by qRT-PCR. Transcriptome analysis was performed from the heart tissue of low-dose dasatinib-treated mice. Results Low-dose dasatinib exhibited PK properties that were linear across doses in NSML mice. Dasatinib treatment of between 0.05 and 0.5 mg/kg in NSML mice yielded an exposure-dependent inhibition of c-Src and PZR tyrosyl phosphorylation and inhibited AKT phosphorylation. We found that doses as low as 0.1 mg/kg of dasatinib prevented HCM in NSML mice. Transcriptome analysis identified differentially expressed HCM-associated genes in the heart of NSML mice that were reverted to wild type levels by low-dose dasatinib administration. Conclusion These data demonstrate that low-dose dasatinib exhibits desirable therapeutic PK properties that is sufficient for effective target engagement to ameliorate HCM progression in NSML mice. These data demonstrate that low-dose dasatinib treatment may be an effective therapy against HCM in NSML patients.

Noonan syndrome with multiple lentigines (NSML) is a rare autosomal dominant disorder that presents with cardio-cutaneous-craniofacial defects. Hypertrophic cardiomyopathy (HCM) represents the major life-threatening presentation in NSML. Mutations in the PTPN11 gene that encodes for the protein tyrosine phosphatase (PTP), SHP2, represents the predominant cause of HCM in NSML. NSML-associated PTPN11 mutations render SHP2 catalytically inactive with an “open” conformation. NSML-associated PTPN11 mutations cause hypertyrosyl phosphorylation of the transmembrane glycoprotein, protein zero-related (PZR), resulting in increased SHP2 binding. Here we show that NSML mice harboring a tyrosyl phosphorylation–defective mutant of PZR (NSML/PZR(Y242F)) that is defective for SHP2 binding fail to develop HCM. Enhanced AKT/S6 kinase signaling in heart lysates of NSML mice was reversed in NSML/PZR(Y242F) mice, demonstrating that PZR/SHP2 interactions promote aberrant AKT/S6 kinase activity in NSML. Enhanced PZR tyrosyl phosphorylation in the hearts of NSML mice was found to drive myocardial fibrosis by engaging an Src/NF-κB pathway, resulting in increased activation of IL-6. Increased expression of IL-6 in the hearts of NSML mice was reversed in NSML/PZR(Y242F) mice, and PZR(Y242F) mutant fibroblasts were defective for IL-6 secretion and STAT3-mediated fibrogenesis. These results demonstrate that NSML-associated PTPN11 mutations that induce PZR hypertyrosyl phosphorylation trigger pathophysiological signaling that promotes HCM and cardiac fibrosis.

Somatic mutations in RAS and related pathway genes such as NF1 have been strongly implicated in the development of cancer while also being implicated in a diverse group of developmental disorders named the ‘RASopathies’, including neurofibromatosis type 1 (NF1), Noonan syndrome (NS), Noonan syndrome with multiple lentigines (NSML), Costello syndrome (CS), cardiofaciocutaneous syndrome (CFC), and capillary malformation–arteriovenous syndrome (CM-AVM). It remains unclear why (i) there is little overlap in mutational subtype between Ras-driven malignancies associated with sporadic disease and those associated with the RASopathy syndromes, and (ii) RASopathy-associated cancers are usually of different histological origin to those seen with sporadic mutations of the same genes. For instance, germline variants in KRAS and NRAS are rarely found at codons 12, 13 or 61, the most common sites for somatic mutations in sporadic cancers. An exception is CS, where germline variants in codons 12 and 13 of HRAS occur relatively frequently. Given recent renewed drug interest following early clinical success of RAS G12C and farnesyl transferase inhibitors, an improved understanding of this relationship could help guide targeted therapies for both sporadic and germline cancers associated with the Ras pathway., Highlights • RAS mutations have been associated with a range of malignancies and with developmental disorders called RASopathies. • Cancers associated with sporadic and germline RAS mutations are dissimilar in histological origins and mutational subtypes. • This disparity highlights our incomplete understanding of the relationship between the RAS–MAPK pathway and cancer. • Recent advances in targeting Ras G12C, HRAS and MEK have led to renewed interest in targeted therapies in this pathway.

Legius syndrome is characterized by the presence of multiple cafe-au-lait macules (CALMs), axillary freckling, macrocephaly and clinically overlaps with neurofibromatosis type 1 (NF1). However, Legius syndrome patients show a milder phenotype with tumoral complications systematically absent. Inactivating SPRED1 mutations were identified in Legius syndrome. SPRED1 interacts with neurofibromin and both proteins are negative regulators of the RAS-MAPK pathway. Constitutive Mismatch Repair Deficiency (CMMRD) is a differential diagnosis of NF1. CMMRD patients show in addition to multiple CALMs supplementary clinical features of NF1. Similar NF1 syndromes with CALMs are piebaldism, neurofibromatosis type 2, schwannomatosis, Noonan syndrome with multiple lentigines, McCune-Albright syndrome, and isolated cafe-au-lait spots. Differential diagnoses of NF1 are infantile myofibromatosis, Proteus syndrome, orbital neurofibromas, hyaline fibromatosis syndrome, and hybrid nerve sheath tumors.

The RAS pathway is a highly conserved cascade of protein-protein interactions and phosphorylation that is at the heart of signalling networks that govern proliferation, differentiation and cell survival. Recent findings indicate that the RAS pathway plays a role in the regulation of energy metabolism via the control of mitochondrial form and function but little is known on the participation of this effect in RAS-related rare human genetic diseases. Germline mutations that hyperactivate the RAS pathway have been discovered and linked to human developmental disorders that are known as RASopathies. Individuals with RASopathies, which are estimated to affect approximately 1/1000 human birth, share many overlapping characteristics, including cardiac malformations, short stature, neurocognitive impairment, craniofacial dysmorphy, cutaneous, musculoskeletal, and ocular abnormalities, hypotonia and a predisposition to developing cancer. Since the identification of the first RASopathy, type 1 neurofibromatosis (NF1), which is caused by the inactivation of neurofibromin 1, several other syndromes have been associated with mutations in the core components of the RAS-MAPK pathway. These syndromes include Noonan syndrome (NS), Noonan syndrome with multiple lentigines (NSML), which was formerly called LEOPARD syndrome, Costello syndrome (CS), cardio-facio-cutaneous syndrome (CFC), Legius syndrome (LS) and capillary malformation-arteriovenous malformation syndrome (CM-AVM). Here, we review current knowledge about the bioenergetics of the RASopathies and discuss the molecular control of energy homeostasis and mitochondrial physiology by the RAS pathway.

LEOPARD syndrome, also known as Gorlin syndrome II, cardiocutaneous syndrome, lentiginosis profusa syndrome, Moynahan syndrome, was more recently coined as Noonan syndrome with multiple lentigines (NSML), inside the RASopathies. Historically, the acronym LEOPARD refers to the presence of distinctive clinical features such as: lentigines (L), electrocardiographic/conduction abnormalities (E), ocular hypertelorism (O), pulmonary stenosis (P), genital abnormalities (A), retardation of growth (R), and sensorineural deafness (D). This condition is identified in 85% of patients with phenotype hallmarks caused by presence a germline point mutation in PTPN11 gene. Association of melanoma to NSML seems to be rare: to our knowledge, two patients so far were reported in the literature. We herein present a patient diagnosed with LEOPARD syndrome, in whom molecular investigation confirmed the presence of the c.1403C>T mutation in exon 12 of the PTPN11 gene, who developed four superficial spreading melanomas and three atypical lentiginous hyperplasias. Three of the melanomas were achromic or hypochromic, three were in situ, and one had a Breslow index under 0.5 mm. Dermoscopic examination showed some characteristic white structures in most of the lesions, which were a signature pattern and a key for the diagnosis. ispartof: Dermatology practical & conceptual vol:8 issue:1 pages:59-62 ispartof: location:Austria status: published

Noonan Syndrome with Multiple Lentigines (NSML) is associated with congenital heart disease in form of pulmonary valve stenosis and hypertrophic cardiomyopathy (HCM). Genetically, NSML is primarily caused by mutations in the non-receptor protein tyrosine phosphatase SHP2. Importantly, certain SHP2 mutations such as Q510E can cause a particularly severe form of HCM with heart failure in infancy. Due to lack of insight into the underlying pathomechanisms, an effective custom-tailored therapy to prevent heart failure in these patients has not yet been found. SHP2 regulates numerous signaling cascades governing cell growth, differentiation, and survival. Experimental models have shown that NSML mutations in SHP2 cause dysregulation of downstream signaling, in particular involving the protein kinase AKT. AKT, and especially the isoform AKT1, has been shown to be a major regulator of cardiac hypertrophy. We therefore hypothesized that hyperactivation of AKT1 is required for the development of Q510E-SHP2-induced HCM. We previously generated a transgenic mouse model of NSML-associated HCM induced by Q510E-SHP2 expression in cardiomyocytes starting before birth. Mice display neonatal-onset HCM with initially preserved contractile function followed by functional decline around 2months of age. As a proof-of-principle study, our current goal was to establish to which extent a genetic reduction in AKT1 rescues the Q510E-SHP2-induced cardiac phenotype in vivo. AKT1 deletion mice were crossed with Q510E-SHP2 transgenic mice and the resulting compound mutant offspring analyzed. Homozygous deletion of AKT1 greatly reduced viability in our NSML mouse model, whereas heterozygous deletion of AKT1 in combination with Q510E-SHP2 expression was well tolerated. Despite normalization of pro-hypertrophic signaling downstream of AKT, heterozygous deletion of AKT1 did not ameliorate cardiac hypertrophy induced by Q510E-SHP2. However, the functional decline caused by Q510E-SHP2 expression was effectively prevented by reducing AKT1 protein. This demonstrates that AKT1 plays an important role in the underlying pathomechanism. Furthermore, the functional rescue was associated with an increase in the capillary-to-cardiomyocyte ratio and normalization of capillary density per tissue area in the compound mutant offspring. We therefore speculate that limited oxygen supply to the hypertrophied cardiomyocytes may contribute to the functional decline observed in our mouse model of NSML-associated HCM.

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.

The best known cafe-au-lait syndrome is neurofibromatosis type 1 (NF1). Legius syndrome (LS) is another, rarer syndrome with cafe-au-lait macules (CALMs). In young patients their clinical picture is often indistinguishable. We investigated the presence of choroidal abnormalities in syndromes with CALMs as a candidate tool for a more efficient diagnosis. Thirty-four patients with NF1 (14 with a truncating mutation, 14 with a non-truncating mutation and 6 with unknown mutation) and 11 patients with LS. All patients underwent an ophthalmological examination. Infrared images were performed. Choroidal nodules were diagnosed in 65% of the NF1 group. About 71% of NF1 patients with a truncating mutation and 50% of patients with a non-truncating mutation were found to have nodules. Choroidal nodules were seen in 18% of the LS patients, never more than one nodule/eye was detected in this group. Choroidal nodules are more abundantly present in NF1 genotypes with truncating mutations. In contrast, the number of choroidal nodules in LS is comparable with their presence in healthy individuals. Especially at an early age, when the clinical picture is incomplete, the detection of choroidal nodules is of diagnostic value, and helps in an appropriate genetic counselling and follow-up. These results support the suggestion to include choroidal nodules to the diagnostic criteria for NF1.

Noonan syndrome with multiple lentigines (NSML), formerly known as LEOPARD syndrome (LS), is an autosomal dominant inherited multisystemic disorder. Most patients involve mutation in SHP2 encoded by tyrosine-protein phosphatase non-receptor type 11 (PTPN11) gene. Studies have shown that NSML-associated Y279C mutation exhibited the reduced phosphatase activity, leading to loss-of-function (LOF) of SHP2. However, the effect of the Y279C mutation on the SHP2 at the molecular level is unclear. In this study, molecular dynamics simulations of SHP2 wild-type (SHP2WT) and Y279C mutant (SHP2Y279C) were performed to investigate the structural differences in proteins after Y279C mutation and to find out the reason for loss-of-function of SHP2. Through a series of post-dynamic analyses, it was found that the protein occupied a smaller phase space after Y279C mutation, showing reduced flexibility. Specifically, due to the mutation of Y279C, the secondary structures of these two regions (residues Lys70-Ala72 and Gly462-Arg465) were significantly transformed from Turn to α-helix and β-strand. Furthermore, by calculating the residue interaction network, hydrogen bond occupancy and binding free energy, it was further revealed that the conformational differences between SHP2WT and SHP2Y279C systems were mainly caused by the differences in the interaction between Arg465–Phe469, Ile463–Gly467, Cys279–Lys70, Cys459–Ala72, Gly464–Phe71, Phe71–Ile463, Ile463–Ala505 and Arg465–Glu361. Consequently, this finding is expected to provide a new insight into the reason for loss-of-function of SHP2 caused by Y279C mutation. Communicated by Ramaswamy H. Sarma

Background A 9-year-old Arabic boy attending middle school presented with an out-of-hospital cardiac arrest due to ventricular fibrillation recorded by Holter electrocardiographic monitoring. He had a background history of Noonan syndrome with multiple lentigines (also known as LEOPARD syndrome), a rare condition of autosomal dominant inheritance with approximately 200 cases reported worldwide. Case presentation Apart from characteristic features, the boy was known to have asymmetric septal hypertrophy with a maximum wall thickness of 24 mm measured by cardiovascular magnetic resonance imaging. A day prior to the event, he attended cardiology follow-up at our institution, and Holter monitoring was commenced. Following cardiopulmonary resuscitation by bystanders and paramedics, he reverted back into sinus rhythm after a total downtime of 24 min. He was initially treated in the intensive care unit and underwent implantable cardioverter defibrillator implantation. He has made a full recovery and remains at the top of his class. Conclusion This case demonstrates that sudden cardiac arrest in patients with secondary forms of hypertrophic cardiomyopathy is not necessarily protected by apparently favorable phenotypes and that events may be preceded by non-sustained ventricular tachycardia observed by Holter monitoring. Implantable cardioverter defibrillator implantation plays a critical role in both primary and secondary prevention in patients at high risk of out-of-hospital cardiac arrest.

We report the case of a 14 years and 8 months girl, who is the first child of nonconsanguineous parents, with short stature, obstructive hypertrophic cardiomyopathy, multiple facial lentigines, high and wide forehead, downslanting palpebral fissures, low-set ears, short neck, and pectus excavatum; all features suggestive of Noonan syndrome with multiple lentigines (NSML). In addition, the patient exhibited craniosynostosis. Molecular analysis of rats sarcoma (RAS)/mitogen-activated protein kinase (MAPK) pathway genes with high-resolution melting curve analysis followed by sequencing showed a RAF1 amino acid substitution of valine to glycine at position 263 (p.V263G). The present report provides clinical data regarding the first association of a RAF1 variant and craniosynostosis in a patient with clinical diagnosis of NSML.

The concomitant occurrence of hypertrophic cardiomyopathy and congenital heart defect in patients with RASopathies has previously been reported as associated to a worse clinical outcome, particularly closed to cardiac surgery. Different mechanisms of disease have been demonstrated to be associated with the two classes of PTPN11 mutations underlying Noonan syndrome and Noonan syndrome with multiple lentigines (also known as LEOPARD syndrome). Although differential diagnosis between these two syndromes could be difficult, particularly in the first age of life, we underline the relevance in discriminating these two disorders in terms of affected signaling pathway to allow an effective targeted pharmacological treatment.

The neurofibromatoses, which include neurofibromatosis type I (NF1), neurofibromatosis type II (NF2), and schwannomatosis, are a group of syndromes characterized by tumor growth in the nervous system. The RASopathies are a group of syndromes caused by germline mutations in genes that encode components of the RAS/mitogen-activated protein kinase (MAPK) pathway. The RASopathies include NF1, Noonan syndrome, Noonan syndrome with multiple lentigines, Costello syndrome, cardio-facio-cutaneous syndrome, Legius syndrome, capillary malformation arterio-venous malformation syndrome, and SYNGAP1 autism. Due to their common underlying pathogenetic etiology, all these syndromes have significant phenotypic overlap of which one common feature include a predisposition to tumors, which may be benign or malignant. Together as a group, they represent one of the most common multiple congenital anomaly syndromes estimating to affect approximately one in 1000 individuals worldwide. The subcontinent of India represents one of the largest populations in the world, yet remains underserved from an aspect of clinical genetics services. In an effort to bridge this gap, the First International Conference on RASopathies and Neurofibromatoses in Asia: Identification and Advances of New Therapeutics was held in Kochi, Kerala, India. These proceedings chronicle this timely and topical international symposium directed at discussing the best practices and therapies for individuals with neurofibromatoses and RASopathies. Children's Tumor Foundation; Fonds De La Recherche Scientifique ‐ FNRS, Grant/Award Numbers: T002614, T024719F; Manchester NIHR Biomedical Research Centre, Grant/Award Number: IS‐BRC‐1215‐20007; NIH/NIAMS, Grant/Award Number: R01AR062165; Axis Health Biomedicals and the Doctor's Academy; Schiller India; MedGenome; Wales Gene Park; University of Wales Trinity Saint David; Cardiff University; AstraZeneca

Noonan syndrome with multiple lentigines (NSML), formerly known as LEOPARD Syndrome, is a rare autosomal dominant disorder. Approximately 90% of NSML cases are caused by missense mutations in the PTPN11 gene which encodes the protein tyrosine phosphatase SHP2. A human induced pluripotent stem cell (iPSC) line was generated using peripheral blood mononuclear cells (PBMCs) from a patient with NSML that carries a gene mutation of p.Q510P on the PTPN11 gene using non-integrating Sendai virus technique. This iPSC line offers a useful resource to study the disease pathophysiology and a cell-based model for drug development to treat NSML.

Multiple cafe-au-lait macules (CALM) are usually associated with neurofibromatosis type 1 (NF1), one of the most common hereditary disorders. However, a group of genetic disorders presenting with CALM have mutations that are involved in human skin pigmentation regulation signaling pathways, including KIT ligand/KIT proto-oncogene receptor tyrosine kinase and Ras/mitogen-activated protein kinase. These disorders, which include Legius syndrome, Noonan syndrome with multiple lentigines or LEOPARD syndrome, and familial progressive hyperpigmentation) are difficult to distinguish from NF1 at early stages, using skin appearance alone. Furthermore, certain syndromes are clinically overlapping and molecular testing is a vital diagnostic method. The present review aims to provide an overview of these ‘NF1-like’ inherited diseases and recommend a cost-effective strategy for making a clear diagnosis among these diseases with an ambiguous borderline.

RASopathies are a group of syndromes caused by germline mutations of the RAS/MAPK pathway. They include Noonan syndrome, cardio-facio-cutaneous syndrome, Costello syndrome, and Noonan syndrome with multiple lentigines, which share many characteristic features including cardiac abnormalities. Here, we retrospectively reviewed the clinical manifestations and evaluated the genotype-phenotype associations with special focus on cardiac lesions of the patients with RASopathies. Cardiac symptoms were the most common initial presentation (27 %), except for admission to neonatal intensive care. Although there was a significant gap between the first visit to the hospital and the diagnosis of the genetic syndrome (19.9 ± 39.1 months), the age at the clinical diagnosis of the genetic syndrome was significantly lower in patients with CHD than in patients without CHD (47.26 ± 67.42 vs. 86.17 ± 85.66 months, p = 0.005). A wide spectrum of cardiac lesions was detected in 76.1 % (118/155) of included patients. The most common lesion was pulmonary stenosis, followed by atrial septal defect and hypertrophic cardiomyopathy (HCMP). About half of the pulmonary stenosis and HCMP patients progressed during the median follow-up period of 109.9 (range 9.7-315.4) months. Early rapid aggravation of cardiac lesions was linked to poor prognosis. MEK1, KRAS, and SOS1 mutations tend to be highly associated with pulmonary stenosis. Cardiologists may play important roles in early detection and diagnosis of RASopathies as well as associated CHDs. Due to the variety of clinical presentations and their progression of severity, proper management with regular long-term follow-up of these patients is essential.

The RASopathies are a group of disorders due to variations of genes associated with the Ras/MAPK pathway. Some of the RASopathies include neurofibromatosis type 1 (NF1), Noonan syndrome, Noonan syndrome with multiple lentigines, cardiofaciocutaneous (CFC) syndrome, Costello syndrome, Legius syndrome, and capillary malformation-arteriovenous malformation (CM-AVM) syndrome. In combination, the RASopathies are a frequent group of genetic disorders. This report summarizes the proceedings of the 4th International Symposium on Genetic Disorders of the Ras/MAPK pathway and highlights gaps in the field. (c) 2016 Wiley Periodicals, Inc.

Clinical symptoms often reflect molecular correlations between mutated proteins. Alignment between interactome and phenome levels reveals new disease genes and connections between previously unrelated diseases. Despite a great potential for novel discoveries, this approach is still rarely used in genomics. In the present study, we analyzed the data of 6 syndromes belonging to the RASopathy class of disorders (RASopathies) and presented them as a model to study associations between genome, interactome, and phenome levels. Causative genes and clinical symptoms were collected from OMIM and NCBI GeneReviews databases for 6 syndromes: Noonan, Noonan syndrome with multiple lentigines, neurofibromatosis type 1, cardiofaciocutaneous, and Legius and Costello syndrome. The STRING tool was used for the identification of protein interactions. Six RASopathy syndromes were found to be associated with 12 causative genes. We constructed an interactome of RASopathy proteins and their neighbors and developed a database of 328 clinical symptoms. The collected data was presented at genome, interactome, and phenome levels and as an integrated network of all 3 data types. The present study provides a baseline for future studies of associations between interactome and phenome in RASopathies and could serve as a novel approach to analyze phenotypically and genetically related diseases.

Introducción. Las RASopatías son un conjunto de síndromes fenotípicamente superpuestos causados por mutaciones en genes implicados en la vía RAS/MAPK. La herencia es autosómica dominante, presentan características clínicas comunes, como baja talla, dismorfias craneofaciales, cardiopatia congénita, manifestaciones ectodérmicas y mayor riesgo de cáncer. El diagnóstico molecular es clave. Objetivo. Identificar mutaciones en los genes PTPN11, SOS1,RAF1, BRAFy HRAS,y comparar las principales características clínicas en pacientes con confirmación molecular. Población y métodos. Se estudiaron niños con diagnóstico clínico de RASopatía evaluados entre agosto de 2013 y febrero de 2017. Resultados. Se identificaron mutaciones en el 71 % (87/122) de los pacientes. El estudio molecular confirmó el diagnóstico en el 73 % de los pacientes con síndrome de Noonan. La mutación más prevalente fue c.922A>G (p.Asn308Asp) en el gen PTPN11. Se detectó una variante no descrita en RAF1, c.1467G>C (p.Leu489Phe). Se confirmó el sindrome cardiofaciocutáneo en el 67 % de los casos con mutaciones en el gen BRAF. El síndrome de Costello y el síndrome de Noonan con múltiples lentigos se confirmaron en todos los casos. Conclusión. La confirmación del diagnóstico clínico permitió un diagnóstico diferencial más preciso. Se determinó la prevalencia de las mutaciones en PTPN11 (el 58 %), SOS1 (el 10 %) y RAF1 (el 5 %) en niños con síndrome de Noonan, en PTPN11 (el 100 %) en el sindrome de Noonan con múltiples lentigos, en BRAF (el 67 %) en el síndrome cardiofaciocutáneo y en HRAS (el 100 %) en el sindrome de Costello. Introduction. RASopathies are a set of syndromes with phenotypic overlapping features caused by gene mutations involved in the RAS/MAPK pathway. They are autosomal dominantly inherited and share common clinical characteristics, including short stature, craniofacial dysmorphisms, congenital heart disease, ectodermal manifestations, and a higher risk for cancer. A molecular diagnosis is a key factor. Objective. To identify PTPN11, SOS1, RAF1, BRAF, and HRAS mutations and compare the main clinical characteristics of patients with molecular confirmation. Population and methods. Children with a clinical diagnosis of RASopathy assessed between August 2013 and February 2017. Results. Mutations were identified in 71 % (87/122) of patients. The molecular test confirmed diagnosis in 73 % of patients with Noonan syndrome. The most prevalent mutation was c.922A>G (p.Asn308Asp) in the PTPN11 gene. A previously undescribed variant in RAF1 was detected: c.1467G>C (p.Leu489Phe). Cardiofaciocutaneous syndrome was confirmed in 67 % of cases with BRAF mutations. Costello syndrome and Noonan syndrome with multiple lentigines were confirmed in all cases. Conclusion. The confirmation of clinical diagnosis allowed for a more accurate differential diagnosis. The prevalence of PTPN11 (58 %), SOS1 (10 % ), and RAF1 mutations (5 %) in children with Noonan syndrome, of PTPN11 mutations (100 %) in those with Noonan syndrome with multiple lentigines, of BRAF mutations (67 %) in those with cardiofaciocutaneous syndrome, and of HRAS mutations (100 %) in those with Costello syndrome was determined.

The RASopathies are a complex group of diseases regarding phenotype and genetic etiology. The ClinGen RASopathy Expert Panel assessed published and other publicly available evidence supporting the association of 19 genes with RASopathy conditions. Using the semi-quantitative literature curation method developed by the ClinGen Gene Curation Working Group, evidence for each gene was curated and scored for Noonan syndrome, Costello syndrome, cardiofaciocutaneous (CFC) syndrome, Noonan syndrome with multiple lentigines (NSML), and Noonan-like syndrome with loose anagen hair (NS/LAH).The curated evidence supporting each gene-disease relationship was then discussed and approved by the ClinGen RASopathy Expert Panel. Each association’s strength was classified as Definitive, Strong, Moderate, Limited, Disputed, or No Evidence. Eleven genes were classified as definitively associated with at least one RASopathy condition. Two genes classified as strong for association with at least one RASopathy condition while one gene was moderate and three were limited. The RAS EP also refuted the association of two genes for a RASopathy condition. Overall, our results provide a greater understanding of the different gene-disease relationships within the RASopathies and can help guide and direct clinicians, patients and researchers who are identifying variants in individuals with a suspected RASopathyGRANT NUMBERS:Research reported in this publication was supported by the National Human Genome Research Institute (NHGRI) under award number U41HG006834. MZ received support from German Federal Ministry of Education and Research (BMBF): NSEuroNet (FKZ 01GM1602A), GeNeRARe (FKZ 01GM1519A).

Catalytically activating mutations in Ptpn11, which encodes the protein tyrosine phosphatase SHP2, cause 50% of Noonan Syndrome (NS) cases, whereas inactivating mutations in Ptpn11 are responsible for nearly all cases of the similar, but distinct, developmental disorder Noonan Syndrome with Multiple Lentigines (NSML, formerly called LEOPARD Syndrome). Both types of disease mutations are gain-of-function mutations because they induce SHP2 to constitutively adopt an open conformation, yet they have opposing effects on SHP2 catalytic activity. Here, we report that the catalytic activity of SHP2 is required for the pathogenic effects of Ptpn11 gain-of-function disease-associated mutations on the development of hydrocephalus in the mouse. Targeted pan-neuronal knock-in of the Ptpn11 activating mutation E76K resulted in hydrocephalus due to aberrant development of ependymal cells and their cilia. These pathogenic effects of the E76K mutation were completely suppressed by the additional mutation C459S, which abolishes catalytic activity of SHP2. Moreover, ependymal cells in NSML mice bearing the Ptpn11 inactivating mutation Y279C were also unaffected. Mechanistically, the Ptpn11E76K mutation induced developmental defects in ependymal cells by enhancing dephosphorylation and inhibition of the transcriptional activator STAT3. Whereas STAT3 activity was reduced in Ptpn11E76K/+ cells, the activities of the kinases ERK and AKT were enhanced, and neural cell–specific Stat3 knockout mice also manifested developmental defects in ependymal cells and cilia. These genetic and biochemical data demonstrate a catalytic–dependent role of Ptpn11 gain-of-function disease mutations in the pathogenesis of hydrocephalus.

Neurofibromatosis type 1 (NF1) has long been considered a well-defined, recognizable monogenic disorder, with neurofibromas constituting a pathognomonic sign. This dogma has been challenged by recent descriptions of patients with enlarged nerves or paraspinal tumors, suggesting that neurogenic tumors and hypertrophic neuropathy may be a complication of Noonan syndrome with multiple lentigines (NSML) or RASopathy phenotype. We describe a 15-year-old boy, whose mother previously received clinical diagnosis of NF1 due to presence of bilateral cervical and lumbar spinal lesions resembling plexiform neurofibromas and features suggestive of NS. NF1 molecular analysis was negative in the mother. The boy presented with Noonan features, multiple lentigines and pectus excavatum. Next-generation sequencing analysis of all RASopathy genes identified p.Ser548Arg missense mutation in SOS1 in the boy, confirmed in his mother. Brain and spinal magnetic resonance imaging scans were negative in the boy. No heart involvement or deafness was observed in proband or mother. This is the first report of a SOS1 mutation associated with hypertrophic neuropathy resembling plexiform neurofibromas, a rare complication in Noonan phenotypes with mutations in RASopathy genes. Our results highlight the overlap between RASopathies, suggesting that NF1 diagnostic criteria need rethinking. Genetic analysis of RASopathy genes should be considered when diagnosis is uncertain.

Background Noonan syndrome (NS) and Noonan syndrome with multiple lentigines (NSML) are autosomal dominant developmental disorders. NS and NSML are caused by abnormalities in genes that encode proteins related to the RAS-MAPK pathway, including PTPN11, RAF1, BRAF, and MAP2K. In this study, we diagnosed ten NS or NSML patients via targeted sequencing or whole exome sequencing (TS/WES). Methods TS/WES was performed to identify mutations in ten Chinese patients who exhibited the following manifestations: potential facial dysmorphisms, short stature, congenital heart defects, and developmental delay. Sanger sequencing was used to confirm the suspected pathological variants in the patients and their family members. Results TS/WES revealed three mutations in the PTPN11 gene, three mutations in RAF1 gene, and four mutations in BRAF gene in the NS and NSML patients who were previously diagnosed based on the abovementioned clinical features. All the identified mutations were determined to be de novo mutations. However, two patients who carried the same mutation in the RAF1 gene presented different clinical features. One patient with multiple lentigines was diagnosed with NSML, while the other patient without lentigines was diagnosed with NS. In addition, a patient who carried a hotspot mutation in the BRAF gene was diagnosed with NS instead of cardiofaciocutaneous syndrome (CFCS). Conclusions TS/WES has emerged as a useful tool for definitive diagnosis and accurate genetic counseling of atypical cases. In this study, we analyzed ten Chinese patients diagnosed with NS and related disorders and identified their correspondingPTPN11, RAF1, and BRAF mutations. Among the target genes, BRAF showed the same degree of correlation with NS incidence as that of PTPN11 or RAF1.

Noonan syndrome [NS; Mendelian Inheritance in Men (MIM) #163950] and related syndromes [Noonan syndrome with multiple lentigines (formerly called LEOPARD syndrome; MIM #151100), Noonan-like syndrome with loose anagen hair (MIM #607721), Costello syndrome (MIM #218040), cardio-facio-cutaneous syndrome (MIM #115150), type I neurofibromatosis (MIM #162200), and Legius syndrome (MIM #611431)] are a group of related genetic disorders associated with distinctive facial features, cardiopathies, growth and skeletal abnormalities, developmental delay/mental retardation, and tumor predisposition. NS was clinically described more than 50 years ago, and disease genes have been identified throughout the last 3 decades, providing a molecular basis to better understand their physiopathology and identify targets for therapeutic strategies. Most of these genes encode proteins belonging to or regulating the so-called RAS/MAPK signaling pathway, so these syndromes have been gathered under the name RASopathies. In this review, we provide a clinical overview of RASopathies and an update on their genetics. We then focus on the functional and pathophysiological effects of RASopathy-causing mutations and discuss therapeutic perspectives and future directions.

Noonan syndrome (NS) is an autosomal dominant developmental disorder caused by mutations in the RAS-MAPK signaling pathway that is well known for its relationship with oncogenesis. An 8.1-fold increased risk of cancer in Noonan syndrome has been reported, including childhood leukemia and solid tumors. The same study found a patient with a dysembryoplastic neuroepithelial tumor (DNET) and suggested that DNET tumors are associated with NS. Herein we report an 8-year-old boy with genetically confirmed NS and a DNET. Literature review identified eight other reports, supporting the association between NS and DNETs. The review also ascertained 13 non-DNET brain tumors in individuals with NS, bringing to 22 the total number of NS patients with brain tumors. Tumor growth while receiving growth hormone (GH) occurred in our patient and one other patient. It is unknown whether the development or progression of tumors is augmented by GH therapy, however there is concern based on epidemiological, animal and in vitro studies. This issue was addressed in a 2015 Pediatric Endocrine Society report noting there is not enough data available to assess the safety of GH therapy in children with neoplasia-predisposition syndromes. The authors recommend that GH use in children with such disorders, including NS, be undertaken with appropriate surveillance for malignancies. Our case report and literature review underscore the association of NS with CNS tumors, particularly DNET, and call attention to the recommendation that clinicians treating NS patients with GH do so with awareness of the possibility of increased neoplasia risk.

Background Noonan syndrome with multiple lentigines (NSML), formerly known as LEOPARD syndrome, is an autosomal-dominant disorder characterised by lentigines, EKG abnormalities, ocular hypertelorism, pulmonic stenosis, abnormal genitalia, growth retardation and deafness. There is significant clinical overlap between NSML and other disorders that result from dysregulated rat sarcoma/mitogen-activated protein kinase pathway (RASopathies). Except for neurofibromatosis type 1, other RASopathies are not known to be typically associated with neurogenic tumours. Methods and results We evaluated patients from three families with pigmentary skin lesions, progressive neuropathy, enlarged nerves, massive burden of paraspinal tumours (neurofibroma was confirmed in one patient) and a clinical diagnosis of NSML. All patients had a mutation in the protein tyrosine phosphatase catalytic domain of the PTPN11 gene; two unrelated patients had the p.Thr468Met mutation, while the family consisting of two affected individuals harboured the p.Thr279Cys mutation. Molecular analysis performed on hypertrophic nerve tissue did not disclose a second somatic hit in NF1, PTPN11, NF2 or SMARCB1 genes. Conclusions Neurogenic tumours and hypertrophic neuropathy are unusual complications of NSML and may be an under-recognised manifestation that would warrant surveillance. Our observation may also have implications for other disorders caused by RAS-pathway dysregulation.

Noonan syndrome (NS) and related disorders, such as NS with multiple lentigines (formerly called LEOPARD syndrome), cardiofaciocutaneous syndrome, and Costello syndrome, constitute an important group of developmental malformation syndromes with variable clinical and molecular features. Their underlying pathophysiologic mechanism involves dysregulation of the Ras/mitogen-activated protein kinase signaling pathway, an essential mediator of developmental and growth processes in the prenatal and postnatal setting. Malignant tumor development is an important complication encountered in other RASopathies, such as neurofibromatosis type 1, but the neoplastic risks and incidence of malignant tumors are less clearly defined in NS and related disorders of the Noonan spectrum. Malignant tumor development remains an important complication variably seen in the RASopathies and, thus, a clear understanding of the underlying risks is essential for appropriate clinical care in this patient population. This review discusses previously published reports of malignancies in individuals with RASopathies of the Noonan spectrum.

Noonan syndrome with multiple lentigines (NSML) frequently manifests with hypertrophic cardiomyopathy (HCM). Recently, it was demonstrated that mTOR inhibition reverses HCM in NSML mice. We report for the first time on the effects of treatment with a rapamycin analog in an infant with LS and a malignant form of HCM. In the boy, progressive HCM was diagnosed during the first week of life and diagnosis of NSML was established at age 20 weeks by showing a heterozygous Q510E mutation in the PTPN11 gene. Immunoblotting with antibodies against pERK, pAkt, and pS6RP in fibroblasts demonstrated reduced RAS/MAPK and enhanced Akt/mTOR pathway activities. Because of the patient’s critical condition, everolimus therapy was started at age 24 weeks and continued until heart transplantation at age 36 weeks. Prior to surgery, heart failure improved from NYHA stage IV to II and brain natriuretic peptide values decreased from 9600 to

Noonan syndrome with multiple lentigines (NSML), formerly referred to as LEOPARD syndrome, is a rare autosomal-dominant condition, characterized by multiple lentigines, electrocardiographic conduction abnormalities, ocular hypertelorism, pulmonary stenosis, abnormal genitalia, growth retardation, and sensorineural deafness. To date, PTPN11, RAF1, and BRAF have been reported to be causal for NSML. We report on a 13-year-old Japanese boy, who was diagnosed with NSML. He was found to have a novel heterozygous missense variant (c.305A > G; p.E102G) in MAP2K1, a gene mostly causal for cardio-facio-cutaneous syndrome (CFCS). He manifested fetal macrosomia, and showed hypotonia and poor sucking in the neonatal period. He had mild developmental delay, and multiple lentigines appearing at approximately age 3 years, as well as flexion deformity of knees bilaterally, subtle facial characteristics including ocular hypertelorism, sensorineural hearing loss, and precocious puberty. He lacked congenital heart defects or hypertrophic cardiomyopathy, frequently observed in patients with NSML, mostly caused by PTPN11 mutations. He also lacked congenital heart defects, characteristic facial features, or intellectual disability, frequently observed in those with CFCS caused by MAP2K1 or MAP2K2 mutations. This may be the first patient clinically diagnosed with NSML, caused by a mutation in MAP2K1. © 2014 Wiley Periodicals, Inc.

Item does not contain fulltext Existing literature only reports a few patients with Noonan syndrome (NS) and Noonan syndrome with multiple lentigines (NSML) who underwent cochlear implantation (CI). The present study describes four NS patients and one NSML patient with a PTPN11 mutation. They all had severe to profound hearing loss, and they received a CI. The age at which the CI surgery occurred ranged from 1 to 13 years old, and the audiological results in all five patients improved after the CI. Otological and audiological examinations in NS and NSML are important, and for those with severe hearing loss, the CI surgery improved the audiological outcome regardless of age.

Noonan Syndrome with Multiple Lentigines (NSML, formerly LEOPARD syndrome) is an autosomal dominant "RASopathy" disorder manifesting in congenital heart disease. Most cases of NSML are caused by catalytically inactivating mutations in the protein tyrosine phosphatase (PTP), non-receptor type 11 (PTPN11), encoding the SH2 domain-containing PTP-2 (SHP2) protein. We previously generated knock-in mice harboring the PTPN11 mutation Y279C, one of the most common NSML alleles; these now-termed SHP2Y279C/+ mice recapitulate the human disorder and develop hypertrophic cardiomyopathy (HCM) by 12 weeks of age. Functionally, heart and/or cardiomyocyte lysates from SHP2Y279C/+ mice exhibit increased basal and agonist-induced AKT and mTOR activities. Here, we sought to determine whether we could reverse the hypertrophy in SHP2Y279C/+ mice using ARQ 092, an oral and selective allosteric AKT inhibitor currently in clinical trials for patients with PI3K/AKT-driven tumors or Proteus syndrome. We obtained echocardiographs of SHP2Y279C/+ and wildtype (SHP2+/+) littermates, either in the presence or absence of ARQ 092 at 12, 14, and 16 weeks of age. While SHP2Y279C/+ mice developed significant left ventricular hypertrophy by 12 weeks, as indicated by decreased chamber dimension and increased posterior wall thickness, treatment of SHP2Y279C/+ mice with ARQ 092 normalized the hypertrophy in as early as 2 weeks following treatment, with hearts comparable in size to those in wildtype (SHP2+/+) mice. In addition, we observed an increase in fractional shortening (FS%) in SHP2Y279C/+ mice, an effect of increased compensatory hypertrophy, which was not apparent in SHP2Y279C/+ mice treated with ARQ 092, suggesting functional improvement of HCM upon treatment with the AKT inhibitor. Finally, we found that ARQ 092 specifically inhibited AKT activity, as well as its downstream effectors, PRAS and S6RP in NSML mice. Taken together, these data suggest ARQ 092 may be a promising novel therapy for treatment of hypertrophy in NSML patients.

The RAS/MAPK signaling pathway plays key roles in development, cell survival and proliferation, as well as in cancer pathogenesis. Molecular genetic studies have identified a group of developmental syndromes, the RASopathies, caused by germ line mutations in this pathway. The syndromes included within this classification are neurofibromatosis type 1 (NF1), Noonan syndrome (NS), Noonan syndrome with multiple lentigines (NS-ML, formerly known as LEOPARD syndrome), Costello syndrome (CS), cardio-facio-cutaneous syndrome (CFC), Legius syndrome (LS, NF1-like syndrome), capillary malformation-arteriovenous malformation syndrome (CM-AVM), and hereditary gingival fibromatosis (HGF) type 1. Although these syndromes present specific molecular alterations, they are characterized by a large spectrum of functional and morphological abnormalities, which include heart defects, short stature, neurocognitive impairment, craniofacial malformations, and, in some cases, cancer predisposition. The development of genetically modified animals, such as mice (Mus musculus), flies (Drosophila melanogaster), and zebrafish (Danio rerio), has been instrumental in elucidating the molecular and cellular bases of these syndromes. Moreover, these models can also be used to determine tumor predisposition, the impact of different genetic backgrounds on the variable phenotypes found among the patients and to evaluate preventative and therapeutic strategies. Here, we review a wide range of genetically modified mouse models used in the study of RASopathies and the potential application of novel technologies, which hopefully will help us resolve open questions in the field.

RASopathies are phenotypically overlapping genetic disorders caused by dysregulation of the RAS/mitogen-activated protein kinase (MAPK) signaling pathway. RASopathies include Noonan syndrome, cardio-facio-cutaneous (CFC) syndrome, Costello syndrome, Neurofibromatosis type 1, Legius syndrome, Noonan syndrome with multiple lentigines, Noonan-like syndrome, hereditary gingival fibromatosis, and capillary malformation/arteriovenous malformation syndrome. Recently, six patients with craniosynostosis and Noonan syndrome involving KRAS mutations were described in a review, and a patient with craniosynostosis and Noonan syndrome involving a SHOC2 mutation has also been reported. Here, we describe patients with craniosynostosis and Noonan syndrome due to de novo mutations in PTPN11 and patients with craniosynostosis and CFC syndrome due to de novo mutations in BRAF or KRAS. All of these patients had cranial deformities in addition to the typical phenotypes of CFC syndrome and Noonan syndrome. In RASopathy, patients with cranial deformities, further assessments may be necessary to look for craniosynostosis. Future studies should attempt to elucidate the pathogenic mechanism responsible for craniosynostosis mediated by the RAS/MAPK signaling pathway.

The RAS-mitogen-activated protein kinase (MAPK) signaling pathway plays critical roles in brain function, including learning and memory. Mutations of molecules in the RAS-MAPK pathway are associated with a group of disorders called RASopathies, which include Noonan syndrome, neurofibromatosis type 1, Costello syndrome, Noonan syndrome with multiple lentigines, Legius syndrome, and cardio-facio-cutaneous syndrome. RASopathies share certain clinical symptoms, including craniofacial abnormalities, heart defects, delayed growth, and cognitive deficits such as learning disabilities, while each individual syndrome also displays unique phenotypes. Recent studies using mouse models of RASopathies showed that each disorder may have a distinct molecular and cellular etiology depending on the cellular specificity of the mutated molecules. Here, we review the cell-type specific roles of the regulators of the RAS-MAPK pathway in cognitive function (learning and memory) and their contribution to the development of RASopathies. We also discussed recent technical advances in analyzing cell type-specific transcriptomes and proteomes in the nervous system. Understanding specific mechanisms for these similar but distinct disorders would facilitate the development of mechanism-based individualized treatment for RASopathies.

Src homology-2 domain-containing phosphatase 2 (SHP2), encoded by the PTPN11 gene, is a highly conserved, non-transmembrane protein-tyrosine phosphatase (PTP), found in all metazoans. The molecular details of SHP2 regulation by phosphotyrosyl (pTyr) peptide ligand binding are well-understood, and knowledge of these details is critical to understanding SHP2 function in health and disease. Studies using mice with gain- or loss-of-function alleles of Ptpn11 have provided much detail about the physiological functions and signaling pathways regulated by SHP2 at the cellular and whole organism levels. Germline mutations in PTPN11 cause Noonan syndrome, Noonan syndrome with multiple lentigines (previously, LEOPARD syndrome), as well as the cartilage tumor syndrome, metachondromatosis. Somatic PTPN11 mutations occur in several types of hematologic malignancy, most notably juvenile myelomonocytic leukemia and, more rarely, in neuroblastoma and other solid tumors. PTPN11 is crucial for transformation initiated by mutant receptor-tyrosine kinases (RTKs) and is an important effector of H. pylori virulence. However, the direct target(s) of SHP2 responsible for its physiological and pathological effects remain controversial and their identification remains a major goal for the future research.

A patient with Noonan syndrome with multiple lentigines (NSML) and multiple giant cell lesions (MGCL) in mandibles and maxillae is described. A mutation p.Thr468Met in the PTPN11-gene was found. This is the second reported NSML patient with MGCL. Our case adds to the assumption that, despite a different molecular pathogenesis and effect on the RAS/MEK pathway, NSML shares the development of MGCL, with other RASopathies.

RASopathies comprise several genetic syndromes with mainly cardio-facial-cutaneous manifestations. We report a patient with Noonan syndrome with multiple lentigines (NSML) due to a PTPN11 (p.Thr468Met) mutation associated with hypertrophic neuropathy of lumbar plexus in an adult woman, initially referred for neuropathic pain. Differential diagnosis of neurofibromatosis type 1 (NF1) and other RASopathies is difficult without molecular testing. © 2016 Wiley Periodicals, Inc.