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

Central xanthoma of the jaw in association with Noonan syndrome

Xanthomas are histiocytic lesions of the skin, soft tissue, and bone and are generally considered to be reactive in nature. When they arise in the bones of the jaw, they are referred to as central xanthomas. New evidence supports the hypothesis that central xanthomas are a separate and distinct entity from their extragnathic counterparts. Noonan syndrome (NS) is an autosomal dominant disorder that has been associated with giant cell lesions, which also commonly occur in the jaw. We present a case of a 15-year-old boy with NS who presented with a radiolucent lesion of the mandible that on excision was found to be a central xanthoma. Although giant cell lesions have been well described in NS, xanthomas of the jaw have not been reported. We will also discuss the entities that must be excluded before making a diagnosis of central xanthoma, as this can affect both treatment and follow-up.

Noonan syndrome: Severe phenotype and PTPN11 mutations

INTRODUCTION AND OBJECTIVE

Noonan syndrome (NS) is a genetic disorder characterized by a wide range of distinctive features and health problems. It caused in 50% of cases by missense mutations in PTPN11 gene. It has been postulated that it is possible to predict the disease course based into the impact of mutations on the protein.

PATIENTS AND METHODS

We report two cases of severe NS phenotype including hydrops fetalis. PTPN11 gene was studied in germinal cells of both patients by sequencing.

RESULTS

Two different mutations (p.Gly503Arg and p.Met504Val) was detected in PTPN11 gene.

DISCUSSION

These mutations have been reported previously, and when they were germinal variants, patients presented classic NS, NS with other malignancies and recently, p.Gly503Arg has been also observed in a patient with severe NS and hydrops fetalis, as our cases. Therefore, these observations shade light on that it is not always possibly to determine the genotype-phenotype relation based into the impact of mutations on the protein in NS patients with PTPN11 mutations.

Regulation of Brain-Derived Neurotrophic Factor and Growth Factor Signaling Pathways by Tyrosine Phosphatase Shp2 in the Retina: A Brief Review

SH2 domain-containing tyrosine phosphatase-2 (PTPN11 or Shp2) is a ubiquitously expressed protein that plays a key regulatory role in cell proliferation, differentiation and growth factor (GF) signaling. This enzyme is well expressed in various retinal neurons and has emerged as an important player in regulating survival signaling networks in the neuronal tissues. The non-receptor phosphatase can translocate to lipid rafts in the membrane and has been implicated to regulate several signaling modules including PI3K/Akt, JAK-STAT and Mitogen Activated Protein Kinase (MAPK) pathways in a wide range of biochemical processes in healthy and diseased states. This review focuses on the roles of Shp2 phosphatase in regulating brain-derived neurotrophic factor (BDNF) neurotrophin signaling pathways and discusses its cross-talk with various GF and downstream signaling pathways in the retina.

Novel mutations and their genotype-phenotype correlations in patients with Noonan syndrome, using next-generation sequencing

PURPOSE

Noonan Syndrome (NS) is an autosomal dominant disorder with many variable and heterogeneous conditions. The genetic basis for 20-30% of cases is still unknown. This study evaluates Iranian Noonan patients both clinically and genetically for the first time.

MATERIALS/METHODS

Mutational analysis of PTPN11 gene was performed in 15 Iranian patients, using PCR and Sanger sequencing at phase one. Then, as phase two, Next Generation Sequencing (NGS) in the form of targeted resequencing was utilized for analysis of exons from other related genes. Homology modelling for the novel founded mutations was performed as well. The genotype, phenotype correlation was done according to the molecular findings and clinical features.

RESULTS

Previously reported mutation (p.N308D) in some patients and a novel mutation (p.D155N) in one of the patients were identified in phase one. After applying NGS methods, known and new variants were found in four patients in other genes, including: CBL (p. V904I), KRAS (p. L53W), SOS1 (p. I1302V), and SOS1 (p. R552G). Structural studies of two deduced novel mutations in related genes revealed deficiencies in the mutated proteins. Following genotype, phenotype correlation, a new pattern of the presence of intellectual disability in two patients was registered.

CONCLUSIONS

NS shows strong variable expressivity along the high genetic heterogeneity especially in distinct populations and ethnic groups. Also possibly unknown other causative genes may be exist. Obviously, more comprehensive and new technologies like NGS methods are the best choice for detection of molecular defects in patients for genotype, phenotype correlation and disease management.

Genetic tests in lymphatic vascular malformations and lymphedema

Syndromes with lymphatic malformations show phenotypic variability within the same entity, clinical features that overlap between different conditions and allelic as well as locus heterogeneity. The aim of this review is to provide a comprehensive clinical genetic description of lymphatic malformations and the techniques used for their diagnosis, and to propose a flowchart for genetic testing. Literature and database searches were performed to find conditions characterised by lymphatic malformations or the predisposition to lymphedema after surgery, to identify the associated genes and to find the guidelines and genetic tests currently used for the molecular diagnosis of these disorders. This search allowed us to identify several syndromes with lymphatic malformations that are characterised by a great heterogeneity of phenotypes, alleles and loci, and a high frequency of sporadic cases, which may be associated with somatic mutations. For these disorders, we found many diagnostic tests, an absence of harmonic guidelines for molecular diagnosis and well-established clinical guidelines. Targeted sequencing is the preferred method for the molecular diagnosis of lymphatic malformations. These techniques are easy to implement and have a good diagnostic success rates. In addition, they are relatively inexpensive and permit parallel analysis of all known disease-associated genes. The targeted sequencing approach has improved the diagnostic process, giving patients access to better treatment and, potentially, to therapy personalised to their genetic profiles. These new techniques will also facilitate the prenatal and early postnatal diagnosis of congenital lymphatic conditions and the possibility of early intervention.

Molecular approaches identify a cryptic MECOM rearrangement in a child with a rapidly progressive myeloid neoplasm

Myeloid neoplasms are a heterogeneous group of hematologic disorders with divergent patterns of cell differentiation and proliferation, as well as divergent clinical courses. Rare recurrent genetic abnormalities related to this group of cancers are associated with poor outcomes. One such abnormality is the MECOM gene rearrangement that typically occurs in cases with chromosome 7 abnormalities. MECOM encodes a transcription factor that plays an essential role in cell proliferation and maintenance and also in epigenetic regulation. Aberrant expression of this gene is associated with reduced survival. Hence, its detailed characterization provides biological and clinical information relevant to the management of pediatric myeloid neoplasms. In this work, we describe a rare karyotype harboring three copies of MECOM with overexpression of the gene in a child with a very aggressive myeloid neoplasm. Cytogenetic studies defined the karyotype as 46,XX,der(7)t(3;7)(q26.2;q21.2). Array comparative genomic hybridization (aCGH) revealed a gain of 26.04 Mb in the 3q26.2-3qter region and a loss of 66.6 Mb in the 7q21.2-7qter region. RT-qPCR analysis detected elevated expression of the MECOM and CDK6 genes (458.5-fold and 35.2-fold, respectively). Overall, we show the importance of performing detailed molecular cytogenetic analysis of MECOM to enable appropriate management of high-risk pediatric myeloid neoplasms.

Mutational status of NRAS, KRAS, and PTPN11 genes is associated with genetic/cytogenetic features in children with B-precursor acute lymphoblastic leukemia

BACKGROUND

We aimed to investigate the frequencies and the association with genetic/cytogenetic abnormalities as well as prognostic relevance of RAS pathway mutations in Taiwanese children with B-precursor acute lymphoblastic leukemia (ALL), the largest cohort in Asians.

PROCEDURE

Between 1995 and 2012, marrow samples at diagnosis from 535 children were studied for NRAS, KRAS, and PTPN11 mutations. The mutational status of each gene was correlated with the clinico-hematological features, recurrent genetic abnormalities, and outcomes for those treated with TPOG-ALL-2002 protocol (n = 346).

RESULTS

The frequencies of NRAS, KRAS, and PTPN11 mutations were 10.8% (57/530), 10.2% (54/530), and 3.0% (16/526), respectively. NRAS mutations were associated with a higher frequency of hyperdiploidy (P = 0.01) and lower frequency of ETV6-RUNX1 (P < 0.01), whereas KRAS mutations were associated with younger age (P < 0.01), a higher frequency of KMT2A rearranged (P < 0.01) but no significant difference if infants with ALL were excluded, and inferior event-free survival (66.6% vs. 80.5%, P = 0.04). None of patients with TCF3-PBX1 had KRAS mutation (P = 0.02).

CONCLUSIONS

Our study showed that the frequency of KRAS mutations in Taiwan was significantly higher than that reported in Caucasians. The occurrence of RAS pathway mutations was associated with recurrent genetic/cytogenetic abnormalities in pediatric B-precursor ALL.

Ocular findings in Noonan syndrome: a retrospective cohort study of 105 patients

The aim of this retrospective study is to describe ocular findings in a large Noonan syndrome cohort and to detect associations between ocular features and genetic mutations that were not found in earlier studies. We collected ophthalmological and genetic data of 105 patients (median age, 12 years; range, 0-60 years) clinically diagnosed as Noonan syndrome. The ocular findings were linked to the genotypes. All patients with Noonan syndrome showed multiple abnormalities in the categories of vision and refraction, external ocular features, ocular alignment and motility, anterior ocular segment, and posterior ocular segment. In total, 50 patients have NS due to a mutation in PTPN11. Permanent visual impairment (bilateral best-corrected visual acuity < 0.3) was found in 7 patients, including patients with a mutation in RAF1, SHOC2, and KRAS. Keratoconus was found in 2 PTPN11 positive patients, and prominent corneal nerves were observed in a patient with a SOS1 mutation.

CONCLUSIONS

This study shows an overview of ocular abnormalities in Noonan syndrome, including permanent visual impairment caused by binocular optic nerve abnormalities and nystagmus. Delay in ophthalmological diagnosis is still present, also in patients with visual impairment. All Noonan syndrome patients should have a complete ophthalmological examination at the time of diagnosis. What is Known: • Although we discover more pathogenic mutations in patients with Noonan syndrome, Noonan syndrome still is a clinical diagnosis • Ocular features of Noonan syndrome are characterized by developmental anomalies of the eyelids and associated with other ocular abnormalities in childhood (including refractive errors, strabismus and amblyopia). What is New: • There seems to be a delay in the ophthalmological diagnosis and awareness of the broad variety ofophthalmological features including refractive errors and visual impairment in Noonan syndrome is needed. All children should have a full ophthalmological examination at the time of diagnosis. • Permanent visual impairment (best-corrected visual acuity < 0.3) is found in patients with mutations in RAF1, SHOC2, and KRAS and the cause is probably a developmental disorder of the optic nerves.

Whole-exome sequencing gives additional benefits compared to candidate gene sequencing in the molecular diagnosis of children with growth hormone or IGF-1 insensitivity

BACKGROUND

GH insensitivity (GHI) is characterised by short stature, IGF-1 deficiency and normal/elevated serum GH. IGF-1 insensitivity results in pre- and post-natal growth failure with normal/high IGF-1 levels. The prevalence of genetic defects is unknown.

OBJECTIVE

To identify the underlying genetic diagnoses in a paediatric cohort with GH or IGF-1 insensitivity using candidate gene (CGS) and whole-exome sequencing (WES) and assess factors associated with the discovery of a genetic defect.

METHODS

We undertook a prospective study of 132 patients with short stature and suspected GH or IGF-1 insensitivity referred to our centre for genetic analysis. 107 (96 GHI, 88 probands; 11 IGF-1 insensitivity, 9 probands) underwent CGS. WES was performed in those with no defined genetic aetiology following CGS.

RESULTS

A genetic diagnosis was discovered 38/107 (36%) patients (32% probands) by CGS. WES revealed 11 patients with genetic variants in genes known to cause short stature. A further 2 patients had hypomethylation in the H19/IGF2 region or mUPD7 consistent with Silver-Russell Syndrome (total with genetic diagnosis 51/107, 48% or 41/97, 42% probands). WES also identified homozygous putative variants in FANCA and PHKB in 2 patients. Low height SDS and consanguinity were highly predictive for identifying a genetic defect.

CONCLUSIONS

Comprehensive genetic testing confirms the genetic heterogeneity of GH/IGF-1 insensitivity and successfully identified the genetic aetiology in a significant proportion of cases. WES is rapid and may isolate genetic variants that have been missed by traditional clinically driven genetic testing. This emphasises the benefits of specialist diagnostic centres.

Redox Regulation of a Gain-of-Function Mutation (N308D) in SHP2 Noonan Syndrome

SHP2 (Src homology 2 domain-containing protein tyrosine phosphatase 2; PTPN11) is a ubiquitous multidomain, nonreceptor protein tyrosine phosphatase (PTP) that plays an important role in diseases such as cancer, diabetes, and Noonan syndrome (NS). NS is one of the most common genetic disorders associated with congenital heart disease, and approximately half of the patients with Noonan syndrome have gain-of-function mutations in SHP2. One of the most common NS mutations is N308D. The activity of SHP2, like that of most PTPs, is reversibly inactivated by reactive oxygen species (ROS). However, the molecular basis of this inactivation and the consequences of NS-related mutations in PTPN11 on ROS-mediated inhibition are poorly understood. Here, we investigated the mechanistic and structural details of the reversible oxidation of the NS variant SHP2_N308D. We show that SHP2_N308D is more sensitive to oxidation when compared with wild-type SHP2. We also show that although the SHP2_N308D catalytic domain can be reactivated by dithiothreitol as effectively as the wild-type, full-length SHP2_N308D is only poorly reactivated by comparison. To understand the mechanism of oxidation at a molecular level, we determined the crystal structure of oxidized SHP2_N308D. The structure shows that the catalytic Cys459 residue forms a disulfide bond with Cys367, which confirms that Cys367 functions as the "backdoor" cysteine in SHP2. Together, our data suggest that the reversible oxidation of SHP2 contributes negligibly, if at all, to the symptoms associated with NS.

Exploring the effect of D61G mutation on SHP2 cause gain of function activity by a molecular dynamics study

Noonan syndrome (NS) is a common autosomal dominant congenital disorder which could cause the congenital cardiopathy and cancer predisposition. Previous studies reported that the knock-in mouse models of the mutant D61G of SHP2 exhibited the major features of NS, which demonstrated that the mutation D61G of SHP2 could cause NS. To explore the effect of D61G mutation on SHP2 and explain the high activity of the mutant, molecular dynamic simulations were performed on wild type (WT) of SHP2 and the mutated SHP2-D61G, respectively. The principal component analysis and dynamic cross-correlation mapping, associated with secondary structure, showed that the D61G mutation affected the motions of two regions (residues Asn 58-Thr 59 and Val 460-His 462) in SHP2 from β to turn. Moreover, the residue interaction networks analysis, the hydrogen bond occupancy analysis and the binding free energies were calculated to gain detailed insight into the influence of the mutant D61G on the two regions, revealing that the major differences between SHP2-WT and SHP2-D61G were the different interactions between Gly 61 and Gly 462, Gly 61 and Ala 461, Gln 506 and Ile 463, Gly 61 and Asn 58, Ile 463 and Thr 466, Gly 462 and Cys 459. Consequently, our findings here may provide knowledge to understand the increased activity of SHP2 caused by the mutant D61G.

Critical Role for GAB2 in Neuroblastoma Pathogenesis through the Promotion of SHP2/MYCN Cooperation

Growing evidence suggests a major role for Src-homology-2-domain-containing phosphatase 2 (SHP2/PTPN11) in MYCN-driven high-risk neuroblastoma, although biologic confirmation and a plausible mechanism for this contribution are lacking. Using a zebrafish model of MYCN-overexpressing neuroblastoma, we demonstrate that mutant ptpn11 expression in the adrenal gland analog of MYCN transgenic fish promotes the proliferation of hyperplastic neuroblasts, accelerates neuroblastomagenesis, and increases tumor penetrance. We identify a similar mechanism in tumors with wild-type ptpn11 and dysregulated Gab2, which encodes a Shp2 activator that is overexpressed in human neuroblastomas. In MYCN transgenic fish, Gab2 overexpression activated the Shp2-Ras-Erk pathway, enhanced neuroblastoma induction, and increased tumor penetrance. We conclude that MYCN cooperates with either GAB2-activated or mutant SHP2 in human neuroblastomagenesis. Our findings further suggest that combined inhibition of MYCN and the SHP2-RAS-ERK pathway could provide effective targeted therapy for high-risk neuroblastoma patients with MYCN amplification and aberrant SHP2 activation.

Targeted/exome sequencing identified mutations in ten Chinese patients diagnosed with Noonan syndrome and related disorders

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.

Case report: Left ventricular noncompaction cardiomyopathy and RASopathies

The following is a case report of 6 patients with Noonan syndrome (NS) and/or a related RASsopathy that also have evidence of left ventricular noncompaction cardiomyopathy (LVNC). Noonan syndrome,a type of RASopathy, is an autosomal dominant disorder that is typically associated with congenital heart defects and hypertrophic cardiomyopathy. There have been minimal reports of Noonan syndrome or other RASopathy and the association of LVNC. This report promulgates 6 nonrelated cases of Noonan syndrome or unspecified RASopathy and LVNC.

Variable phenotypic expression in a large Noonan syndrome family segregating a novel SOS1 mutation

Noonan syndrome (NS) is an autosomal dominant multisystem condition with a variable phenotype. The most characteristic features are short stature, congenital heart defects, and recognizable facial features. Mutations in SOS1 are found in 10-20% of patients with NS. Different genotype-phenotype studies mention correlations between SOS1 mutations and some features, such as ectodermal abnormalities and specific facial features. We present a large NS family with a novel pathogenic mutation; SOS1 c.3134C>G, p.Pro1045Arg. Ten family members with NS are included with genetically confirmed mutation and clinical evaluation. The phenotype shows a broad spectrum from only few suggestive features for NS in the older generation to typical features in the youngest generation. We report on a novel pathogenic mutation in the SOS1 gene and a large clinical spectrum in a NS family with ten genetically confirmed affected individuals.

Tumor Syndromes That Include Bone Tumors: An Update

Tumor syndromes, including bone neoplasias, are genetic predisposing conditions characterized by the development of a pattern of malignancies within a family at an early age of onset. Occurrence of bilateral, multifocal, or metachronous neoplasias and specific histopathologic findings suggest a genetic predisposition syndrome. Additional clinical features not related to the neoplasia can be a hallmark of specific genetic syndromes. Mostly, those diseases have an autosomal dominant pattern of inheritance with variable percentage of penetrance. Some syndromic disorders with an increased tumor risk may show an autosomal recessive transmission or are related to somatic mosaicism. Many genetic tumor syndromes are known. This update is specifically focused on syndromes predisposing to osteosarcoma and chondrosarcoma.

Noonan syndrome: lessons learned from genetically modified mouse models

Noonan syndrome is a RASopathy that results from activating mutations in different members of the RAS/MAPK signaling pathway. At least eleven members of this pathway have been found mutated, PTPN11 being the most frequently mutated gene affecting about 50% of the patients, followed by SOS1 (10%), RAF1 (10%) and KRAS (5%). Recently, even more infrequent mutations have been newly identified by next generation sequencing. This spectrum of mutations leads to a broad variety of clinical symptoms such as cardiopathies, short stature, facial dysmorphia and neurocognitive impairment. The genetic variability of this syndrome makes it difficult to establish a genotype-phenotype correlation, which will greatly help in the clinical management of the patients. Areas covered: Studies performed with different genetically engineered mouse models (GEMMs) developed up to date. Expert commentary: GEMMs have helped us understand the role of some genes and the effect of the different mutations in the development of the syndrome. However, few models have been developed and more characterization of the existing ones should be performed to learn about the impact of the different modifiers in the phenotypes, the potential cancer risk in patients, as well as preventative and therapeutic strategies.

Congenital heart disease and genetic syndromes: new insights into molecular mechanisms

INTRODUCTION

Advances in genetics allowed a better definition of the role of specific genetic background in the etiology of syndromic congenital heart defects (CHDs). The identification of a number of disease genes responsible for different syndromes have led to the identification of several transcriptional regulators and signaling transducers and modulators that are critical for heart morphogenesis. Understanding the genetic background of syndromic CHDs allowed a better characterization of the genetic basis of non-syndromic CHDs. In this sense, the well-known association of typical CHDs in Down syndrome, 22q11.2 microdeletion and Noonan syndrome represent paradigms as chromosomal aneuploidy, chromosomal microdeletion and intragenic mutation, respectively. Area covered: For each syndrome the anatomical features, distinctive cardiac phenotype and molecular mechanisms are discussed. Moreover, the authors include recent genetic findings that may shed light on some aspects of still unclear molecular mechanisms of these syndromes. Expert commentary: Further investigations are needed to enhance the translational approach in the field of genetics of CHDs. When there is a well-established definition of genotype-phenotype (reverse medicine) and genotype-prognosis (predictive and personalized medicine) correlations, hopefully preventive medicine will make its way in this field. Subsequently a reduction will be achieved in the morbidity and mortality of children with CHDs.

Noonan syndrome in diverse populations

Noonan syndrome (NS) is a common genetic syndrome associated with gain of function variants in genes in the Ras/MAPK pathway. The phenotype of NS has been well characterized in populations of European descent with less attention given to other groups. In this study, individuals from diverse populations with NS were evaluated clinically and by facial analysis technology. Clinical data and images from 125 individuals with NS were obtained from 20 countries with an average age of 8 years and female composition of 46%. Individuals were grouped into categories of African descent (African), Asian, Latin American, and additional/other. Across these different population groups, NS was phenotypically similar with only 2 of 21 clinical elements showing a statistically significant difference. The most common clinical characteristics found in all population groups included widely spaced eyes and low-set ears in 80% or greater of participants, short stature in more than 70%, and pulmonary stenosis in roughly half of study individuals. Using facial analysis technology, we compared 161 Caucasian, African, Asian, and Latin American individuals with NS with 161 gender and age matched controls and found that sensitivity was equal to or greater than 94% for all groups, and specificity was equal to or greater than 90%. In summary, we present consistent clinical findings from global populations with NS and additionally demonstrate how facial analysis technology can support clinicians in making accurate NS diagnoses. This work will assist in earlier detection and in increasing recognition of NS throughout the world.

Cardiac defects, morbidity and mortality in patients affected by RASopathies. CARNET study results

BACKGROUND

RASopathies are developmental disease caused by mutations in genes encoding for signal transducers of the RAS-MAPK cascade. The aim of the present study was to provide a comprehensive description of morbidity and mortality in patients with molecularly confirmed RASopathy.

METHODS

A multicentric, observational, retrospective study was conducted in seven European cardiac centres participating to the CArdiac Rasopathy NETwork (CARNET). Clinical records of 371 patients with confirmed molecular diagnosis of RASopathy were reviewed. Mortality was described as crude mortality, cumulative survival and restricted estimated mean survival. Multivariable regression analysis was used to assess the impact of mutated genes on number of interventions and overall prognosis.

RESULTS

Cardiac defects occurred in 80.3% of cases, almost half of them underwent at least one intervention. Overall, crude mortality was 0.29/100 patients-year. Cumulative survival was 98.8%, 98.2%, 97.7%, 94.3%, at 1, 5, 10, and 20years, respectively. Restricted estimated mean survival at 20years follow-up was 19.6years. Ten patients died (2.7% of the entire cohort; 3.4% of patients with cardiac defect). Patients with hypertrophic cardiomyopathy (HCM) and age <2years or young adults, as well as subjects with biventricular obstruction and PTPN11 mutations had a higher risk of cardiac death.

CONCLUSIONS

The risk of intervention was higher in individuals with Noonan syndrome and pulmonary stenosis carrying PTPN11 mutations. Overall, mortality was relatively low, even though the specific association between HCM, biventricular outflow tract obstructions and PTPN11 mutations appeared to be associated with early mortality, including immediate post-operative events and sudden death.

Hotspots in PTPN11 Gene Among Indian Children With Noonan Syndrome

OBJECTIVE

To test for PTPN11 mutations in clinically diagnosed cases of Noonan syndrome.

METHODS

17 individuals with clinical diagnosis of Noonan syndrome were included in the study. Sanger sequencing of all the 15 exons of PTPN11 was done. A genotype-phenotype correlation was attempted.

RESULTS

Mutation in PTPN11 was detected in 11 out of 17 (64.7%) patients with Noonan syndrome; 72% had mutation in exon 3 and 27 % had mutation in exon 13.

CONCLUSION

PTPN11 mutation accounts for 64.7% of cases with clinical features of Noonan syndrome in India. Majority of the mutations are in exon 3 and exon 13 of PTPN11, making them the hotspots in Indian population.

Cochlear implantation and clinical features in patients with Noonan syndrome and Noonan syndrome with multiple lentigines caused by a mutation in PTPN11

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.

Structural, Functional, and Clinical Characterization of a Novel PTPN11 Mutation Cluster Underlying Noonan Syndrome

Germline mutations in PTPN11, the gene encoding the Src-homology 2 (SH2) domain-containing protein tyrosine phosphatase (SHP2), cause Noonan syndrome (NS), a relatively common, clinically variable, multisystem disorder. Here, we report on the identification of five different PTPN11 missense changes affecting residues Leu²⁶¹ , Leu²⁶² , and Arg²⁶⁵ in 16 unrelated individuals with clinical diagnosis of NS or with features suggestive for this disorder, specifying a novel disease-causing mutation cluster. Expression of the mutant proteins in HEK293T cells documented their activating role on MAPK signaling. Structural data predicted a gain-of-function role of substitutions at residues Leu²⁶² and Arg²⁶⁵ exerted by disruption of the N-SH2/PTP autoinhibitory interaction. Molecular dynamics simulations suggested a more complex behavior for changes affecting Leu²⁶¹ , with possible impact on SHP2's catalytic activity/selectivity and proper interaction of the PTP domain with the regulatory SH2 domains. Consistent with that, biochemical data indicated that substitutions at codons 262 and 265 increased the catalytic activity of the phosphatase, while those affecting codon 261 were only moderately activating but impacted substrate specificity. Remarkably, these mutations underlie a relatively mild form of NS characterized by low prevalence of cardiac defects, short stature, and cognitive and behavioral issues, as well as less evident typical facial features.

Noonan syndrome - a new survey

Noonan syndrome (NS) is an autosomal dominant disorder with vast heterogeneity in clinical and genetic features. Various symptoms have been reported for this abnormality such as short stature, unusual facial characteristics, congenital heart abnormalities, developmental complications, and an elevated tumor incidence rate. Noonan syndrome shares clinical features with other rare conditions, including LEOPARD syndrome, cardio-facio-cutaneous syndrome, Noonan-like syndrome with loose anagen hair, and Costello syndrome. Germline mutations in the RAS-MAPK (mitogen-activated protein kinase) signal transduction pathway are responsible for NS and other related disorders. Noonan syndrome diagnosis is primarily based on clinical features, but molecular testing should be performed to confirm it in patients. Due to the high number of genes associated with NS and other RASopathy disorders, next-generation sequencing is the best choice for diagnostic testing. Patients with NS also have higher risk for leukemia and specific solid tumors. Age-specific guidelines for the management of NS are available.

Severe Intellectual Disability and Enhanced Gamma-Aminobutyric Acidergic Synaptogenesis in a Novel Model of Rare RASopathies

BACKGROUND

Dysregulation of Ras-extracellular signal-related kinase (ERK) signaling gives rise to RASopathies, a class of neurodevelopmental syndromes associated with intellectual disability. Recently, much attention has been directed at models bearing mild forms of RASopathies whose behavioral impairments can be attenuated by inhibiting the Ras-ERK cascade in the adult. Little is known about the brain mechanisms in severe forms of these disorders.

METHODS

We performed an extensive characterization of a new brain-specific model of severe forms of RASopathies, the KRAS^12V mutant mouse.

RESULTS

The KRAS^12V mutation results in a severe form of intellectual disability, which parallels mental deficits found in patients bearing mutations in this gene. KRAS^12V mice show a severe impairment of both short- and long-term memory in a number of behavioral tasks. At the cellular level, an upregulation of ERK signaling during early phases of postnatal development, but not in the adult state, results in a selective enhancement of synaptogenesis in gamma-aminobutyric acidergic interneurons. The enhancement of ERK activity in interneurons at this critical postnatal time leads to a permanent increase in the inhibitory tone throughout the brain, manifesting in reduced synaptic transmission and long-term plasticity in the hippocampus. In the adult, the behavioral and electrophysiological phenotypes in KRAS^12V mice can be temporarily reverted by inhibiting gamma-aminobutyric acid signaling but not by a Ras-ERK blockade. Importantly, the synaptogenesis phenotype can be rescued by a treatment at the developmental stage with Ras-ERK inhibitors.

CONCLUSIONS

These data demonstrate a novel mechanism underlying inhibitory synaptogenesis and provide new insights in understanding mental dysfunctions associated to RASopathies.

Low-dose dasatinib rescues cardiac function in Noonan syndrome

Noonan syndrome (NS) is a common autosomal dominant disorder that presents with short stature, craniofacial dysmorphism, and cardiac abnormalities. Activating mutations in the PTPN11 gene encoding for the Src homology 2 (SH2) domain-containing protein tyrosine phosphatase-2 (SHP2) causes approximately 50% of NS cases. In contrast, NS with multiple lentigines (NSML) is caused by mutations that inactivate SHP2, but it exhibits some overlapping abnormalities with NS. Protein zero-related (PZR) is a SHP2-binding protein that is hyper-tyrosyl phosphorylated in the hearts of mice from NS and NSML, suggesting that PZR and the tyrosine kinase that catalyzes its phosphorylation represent common targets for these diseases. We show that the tyrosine kinase inhibitor, dasatinib, at doses orders of magnitude lower than that used for its anticancer activities inhibited PZR tyrosyl phosphorylation in the hearts of NS mice. Low-dose dasatinib treatment of NS mice markedly improved cardiomyocyte contractility and functionality. Remarkably, a low dose of dasatinib reversed the expression levels of molecular markers of cardiomyopathy and reduced cardiac fibrosis in NS and NSML mice. These results suggest that PZR/SHP2 signaling is a common target of both NS and NSML and that low-dose dasatinib may represent a unifying therapy for the treatment of PTPN11-related cardiomyopathies.

Mutations in the CCND1 and CCND2 genes are frequent events in adult patients with t(8;21)(q22;q22) acute myeloid leukemia

Core-binding factor acute myeloid leukemia (CBF-AML) is defined by the presence of either t(8;21)(q22;q22)/RUNX1-RUNX1T1 or inv(16)(p13.1q22)/t(16;16)(p13.1;q22)/CBFB-MYH11. The resulting fusion genes require a 'second hit' to initiate leukemogenesis. Mutation assessment of 177 adults with CBF-AML, including 68 with t(8;21) and 109 with inv(16)/t(16;16), identified not only mutations well known in CBF-AML but also mutations in the CCND1 and CCND2 genes, which represent novel frequent molecular alterations in AML with t(8;21). Altogether, CCND1 (n=2) and CCND2 (n=8) mutations were detected in 10 (15%) patients with t(8;21) in our cohort. A single CCND2 mutation was also found in 1 (0.9%) patient with inv(16). In contrast, CCND1 and CCND2 mutations were detected in only 11 (0.77%) of 1426 non-CBF-AML patients. All CCND2 mutations cluster around the highly conserved amino-acid residue threonine 280 (Thr280). We show that Thr280Ala-mutated CCND2 leads to increased phosphorylation of the retinoblastoma protein, thereby causing significant cell cycle changes and increased proliferation of AML cell lines. The identification of CCND1 and CCND2 mutations as frequent mutational events in t(8;21) AML may provide further justification for cell cycle-directed therapy in this disease.

Integrated tumor and germline whole-exome sequencing identifies mutations in MAPK and PI3K pathway genes in an adolescent with rosette-forming glioneuronal tumor of the fourth ventricle

The integration of genome-scale studies such as whole-exome sequencing (WES) into the clinical care of children with cancer has the potential to provide insight into the genetic basis of an individual's cancer with implications for clinical management. This report describes the results of clinical tumor and germline WES for a patient with a rare tumor diagnosis, rosette-forming glioneuronal tumor of the fourth ventricle (RGNT). Three pathogenic gene alterations with implications for clinical care were identified: somatic activating hotspot mutations in FGFR1 (p.N546K) and PIK3CA (p.H1047R) and a germline pathogenic variant in PTPN11 (p.N308S) diagnostic for Noonan syndrome. The molecular landscape of RGNT is not well-described, but these data are consistent with prior observations regarding the importance of the interconnected MAPK and PI3K/AKT/mTOR signaling pathways in this rare tumor. The co-occurrence of FGFR1, PIK3CA, and PTPN11 alterations provides further evidence for consideration of RGNT as a distinct molecular entity from pediatric low-grade gliomas and suggests potential therapeutic strategies for this patient in the event of tumor recurrence as novel agents targeting these pathways enter pediatric clinical trials. Although RGNT has not been definitively linked with cancer predisposition syndromes, two prior cases have been reported in patients with RASopathies (Noonan syndrome and neurofibromatosis type 1 [NF1]), providing an additional link between these tumors and the mitogen-activated protein kinase (MAPK) signaling pathway. In summary, this case provides an example of the potential for genome-scale sequencing technologies to provide insight into the biology of rare tumors and yield both tumor and germline results of potential relevance to patient care.

Noonan syndrome-causing genes: Molecular update and an assessment of the mutation rate

Noonan syndrome is a common autosomal dominant disorder characterized by short stature, congenital heart disease and facial dysmorphia with an incidence of 1/1000 to 2500 live births. Up to now, several genes have been proven to be involved in the disturbance of the transduction signal through the RAS-MAP Kinase pathway and the manifestation of Noonan syndrome. The first gene described was PTPN11, followed by SOS1, RAF1, KRAS, BRAF, NRAS, MAP2K1, and RIT1, and recently SOS2, LZTR1, and A2ML1, among others. Progressively, the physiopathology and molecular etiology of most signs of Noonan syndrome have been demonstrated, and inheritance patterns as well as genetic counseling have been established. In this review, we summarize the data concerning clinical features frequently observed in Noonan syndrome, and then, we describe the molecular etiology as well as the physiopathology of most Noonan syndrome-causing genes. In the second part of this review, we assess the mutational rate of Noonan syndrome-causing genes reported up to now in most screening studies. This review should give clinicians as well as geneticists a full view of the molecular aspects of Noonan syndrome and the authentic prevalence of the mutational events of its causing-genes. It will also facilitate laying the groundwork for future molecular diagnosis research, and the development of novel treatment strategies.

Prevalence of Migraine in Noonan Syndrome

A randomized double-controlled trial involving 22 patients with Noonan syndrome (NS) and 22 normal individuals (control group) was carried out to determine the prevalence of migraine in patients with NS. The NS group consisted of 11 males aged 19.55 ± 6.11 years and 11 females aged 18.81 ± 5.47 years. The control group consisted of 11 males aged 19.55 ± 6.6 years and 11 females aged 18.81 ± 5.47 years. Seven NS-group patients reported migraine without aura (MO), and three reported probable MO (PMO). Taken together, these represent a prevalence of migraine in the NS group of 45.5%. Two control-group patients reported MO, a prevalence of 9.09%. The prevalence of migraine was significantly higher in the NS-group patients than in the controls ( P < 0.005), suggesting a positive association between NS and migraine. Nevertheless, further studies are needed to confirm our findings.

How necessary is to analyze PTPN11 gene in fetuses with first trimester cystic hygroma and normal karyotype?

Cystic hygroma (CH) is a vascular-lymphatic malformation and can occur either as an isolated finding or as a part of a syndrome. The incidence of CH is about 1:1000-1:6000 births. Ultrasonographic diagnosis of CH is usually obtained in the first trimester, and the lesion can appear in septated or non-septated forms. Increased nuchal translucency and CH have been associated with a wide range of structural and genetic abnormalities. Most of CHs are associated with a number of chromosomal abnormalities especially Trisomy 21, 13, 18 and Turner syndrome. Besides, the associations between CH and non-chromosomal syndromes were also reported and Noonan Syndrome (NS) is one of the leading causes. Approximately 50% of NS cases are caused by mutations in the PTPN11 gene. A novel PTPN11 mutation defined in two separate fetuses with CH and associated with NS phenotype is being reported here.

Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes as a Model for Heart Development and Congenital Heart Disease

Congenital heart disease (CHD) remains a significant health problem, with a growing population of survivors with chronic disease. Despite intense efforts to understand the genetic basis of CHD in humans, the etiology of most CHD is unknown. Furthermore, new models of CHD are required to better understand the development of CHD and to explore novel therapies for this patient population. In this review, we highlight the role that human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes can serve to enhance our understanding of the development, pathophysiology and potential therapeutic targets for CHD. We highlight the use of hiPSC-derived cardiomyocytes to model gene regulatory interactions, cell-cell interactions and tissue interactions contributing to CHD. We further emphasize the importance of using hiPSC-derived cardiomyocytes as personalized research models. The use of hiPSCs presents an unprecedented opportunity to generate disease-specific cellular models, investigate the underlying molecular mechanisms of disease and uncover new therapeutic targets for CHD.

Mutation Spectrum and Phenotypic Features in Noonan Syndrome with PTPN11 Mutations: Definition of Two Novel Mutations

OBJECTIVES

To evaluate the spectrum of PTPN11 gene mutations in Noonan syndrome patients and to study the genotype-phenotype associations.

METHODS

In this study, twenty Noonan syndrome patients with PTPN11 mutations were included. The patients underwent a detailed clinical and physical evaluation. To identify inherited cases, parents of all mutation positive patients were analyzed.

RESULTS

Thirteen different PTPN11 mutations, two of them being novel, were detected in the study group. These mutations included eleven missense mutations: p.G60A, p.D61N, p.Y62D, p.Y63C, p.E69Q, p.Q79R, p.Y279C,p.N308D, p.N308S, p.M504V, p.Q510R and two novel missense mutations: p.I56V and p.I282M. The frequency of cardiac abnormalities and short stature were found to be 80 % and 80 %, respectively. Mental retardation was not observed in patients having exon 8 mutations. No significant correlations were detected between other phenotypic features and genotypes.

CONCLUSIONS

By identifying genotype-phenotype correlations, this study provides information on phenotypes observed in NS patients with different PTPN11 mutations.

First applications of a targeted exome sequencing approach in fetuses with ultrasound abnormalities reveals an important fraction of cases with associated gene defects

Background. Fetal malformations and other structural abnormalities are relatively frequent findings in the course of routine prenatal ultrasonographic examination. Due to their considerable genetic and clinical heterogeneity, the underlying genetic cause is often elusive and the resulting inability to provide a precise diagnosis precludes proper reproductive and fetal risk assessment. We report the development and first applications of an expanded exome sequencing-based test, coupled to a bioinformatics-driven prioritization algorithm, targeting gene disorders presenting with abnormal prenatal ultrasound findings.

Methods. We applied the testing strategy to14 euploid fetuses, from 11 on-going pregnancies and three products of abortion, all with various abnormalities or malformations detected through prenatal ultrasound examination. Whole exome sequencing (WES) was followed by variant prioritization, utilizing a custom analysis pipeline (Fetalis algorithm), targeting 758 genes associated with genetic disorders which may present with abnormal fetal ultrasound findings.

Results. A definitive or highly-likely diagnosis was made in 6 of 14 cases (43%), of which 3 were abortuses (Ellis-van Creveld syndrome, Ehlers-Danlos syndrome and Nemaline myopathy 2) and 3 involved on-going pregnancies (Citrullinemia, Noonan syndrome, PROKR2-related Kallmann syndrome). In the remaining eight on-going pregnancy cases (57%), a ZIC1 variant of unknown clinical significance was detected in one case, while in seven cases testing did not reveal any pathogenic variant(s). Pregnancies were followed-up to birth, resulting in one neonate harboring the PROKR2 mutation, presenting with isolated minor structural cardiac abnormalities, and in seven apparently healthy neonates.

Discussion. The expanded targeted exome sequencing-based approach described herein (Fetalis), provides strong evidence suggesting a definite and beneficial increase in our diagnostic capabilities in prenatal diagnosis of otherwise chromosomally balanced fetuses with troubling ultrasound abnormalities. Furthermore, the proposed targeted exome sequencing strategy, designed primarily as a diagnostic rather than a research discovery tool, overcomes many of the problems and limitations associated with clinical wide-scale WES testing in a prenatal setting.

Sequential Ligand-Dependent Notch Signaling Activation Regulates Valve Primordium Formation and Morphogenesis

RATIONALE

The Notch signaling pathway is crucial for primitive cardiac valve formation by epithelial-mesenchymal transition, and NOTCH1 mutations cause bicuspid aortic valve; however, the temporal requirement for the various Notch ligands and receptors during valve ontogeny is poorly understood.

OBJECTIVE

The aim of this study is to determine the functional specificity of Notch in valve development.

METHODS AND RESULTS

Using cardiac-specific conditional targeted mutant mice, we find that endothelial/endocardial deletion of Mib1-Dll4-Notch1 signaling, possibly favored by Manic-Fringe, is specifically required for cardiac epithelial-mesenchymal transition. Mice lacking endocardial Jag1, Notch1, or RBPJ displayed enlarged valve cusps, bicuspid aortic valve, and septal defects, indicating that endocardial Jag1 to Notch1 signaling is required for post-epithelial-mesenchymal transition valvulogenesis. Valve dysmorphology was associated with increased mesenchyme proliferation, indicating that Jag1-Notch1 signaling restricts mesenchyme cell proliferation non-cell autonomously. Gene profiling revealed upregulated Bmp signaling in Jag1-mutant valves, providing a molecular basis for the hyperproliferative phenotype. Significantly, the negative regulator of mesenchyme proliferation, Hbegf, was markedly reduced in Jag1-mutant valves. Hbegf expression in embryonic endocardial cells could be readily activated through a RBPJ-binding site, identifying Hbegf as an endocardial Notch target. Accordingly, addition of soluble heparin-binding EGF-like growth factor to Jag1-mutant outflow tract explant cultures rescued the hyperproliferative phenotype.

CONCLUSIONS

During cardiac valve formation, Dll4-Notch1 signaling leads to epithelial-mesenchymal transition and cushion formation. Jag1-Notch1 signaling subsequently restrains Bmp-mediated valve mesenchyme proliferation by sustaining Hbegf-EGF receptor signaling. Our studies identify a mechanism of signaling cross talk during valve morphogenesis involved in the origin of congenital heart defects associated with reduced NOTCH function.

Growth references for Japanese individuals with Noonan syndrome

BACKGROUND

Noonan syndrome (NS) is a clinically and genetically heterogeneous syndrome characterized by distinctive facial features, short stature, congenital heart diseases, and other comorbidities. NS-specific growth charts are essential for NS care, but currently no such charts are available for Asian populations.

METHODS

We conducted a nationwide survey by collaborating with three academic societies in Japan. We obtained the data of 356 clinically diagnosed NS subjects from 20 hospitals. The Lambda-Mu-Sigma method was used for establishing growth charts.

RESULTS

A total of 308 subjects (males: 159 and females: 149) were analyzed after excluding 48 subjects because of missing auxological data (26 subjects), presence of complications affecting growth (5 subjects), and extreme longitudinal growth aberrations which lay more than three standard deviation scores from the mean in this population (17 subjects). Genetic analyses were performed in 150 patients (48.7%); 103 (68.7%) were reported to have some abnormalities in the known causative genes. Cardiovascular diseases were found in 256 patients (83.1%). The NS-specific height, weight, and BMI charts were constructed with 3,249 mixed longitudinal and cross-sectional measurements.

CONCLUSION

Growth standards for Japanese individuals with NS were established. These charts are expected to be used in various clinical settings.

The impact of growth hormone therapy on adult height in noonan syndrome: a systematic review

BACKGROUND

Recombinant human growth hormone (rhGH) is being used to promote linear growth in short children with Noonan syndrome. However, its efficacy is still controversial.

AIMS

To systematically determine the impact of rhGH therapy on adult height in children with Noonan syndrome.

METHODS

We searched the Cochrane Central Register of Controlled Trials, ISI Web of Science, MEDLINE, and the bibliographic references from all retrieved articles published until April 2014. Studies reporting adult/near-adult height in children with Noonan syndrome treated with rhGH or reporting at least a 3-year follow-up were analysed. Quality and strength of recommendation were assessed according to the Endocrine Society criteria.

RESULTS

No controlled trials reporting adult height were available. Five studies were identified reporting adult height or near adult height. Data comparison showed inter-individual variability in the response to rhGH, mean height gain standard deviation score ranging between 0.6 and 1.4 according to national standards, and between 0.6 and 2 according to Noonan standards. Significant biases affected all the studies.

CONCLUSIONS

High-quality controlled trials on the impact of rhGH therapy on adult height are lacking, and the robustness of available data is not sufficient to recommend such therapy in children with Noonan syndrome.

Spectrum of mutations and genotype-phenotype analysis in Noonan syndrome patients with RIT1 mutations

RASopathies are autosomal dominant disorders caused by mutations in more than 10 known genes that regulate the RAS/MAPK pathway. Noonan syndrome (NS) is a RASopathy characterized by a distinctive facial appearance, musculoskeletal abnormalities, and congenital heart defects. We have recently identified mutations in RIT1 in patients with NS. To delineate the clinical manifestations in RIT1 mutation-positive patients, we further performed a RIT1 analysis in RASopathy patients and identified 7 RIT1 mutations, including two novel mutations, p.A77S and p.A77T, in 14 of 186 patients. Perinatal abnormalities, including nuchal translucency, fetal hydrops, pleural effusion, or chylothorax and congenital heart defects, are observed in all RIT1 mutation-positive patients. Luciferase assays in NIH 3T3 cells demonstrated that the newly identified RIT1 mutants, including p.A77S and p.A77T, and the previously identified p.F82V, p.T83P, p.Y89H, and p.M90I, enhanced Elk1 transactivation. Genotype-phenotype correlation analyses of previously reported NS patients harboring RIT1, PTPN11, SOS1, RAF1, and KRAS revealed that hypertrophic cardiomyopathy (56 %) was more frequent in patients harboring a RIT1 mutation than in patients harboring PTPN11 (9 %) and SOS1 mutations (10 %). The rates of hypertrophic cardiomyopathy were similar between patients harboring RIT1 mutations and patients harboring RAF1 mutations (75 %). Short stature (52 %) was less prevalent in patients harboring RIT1 mutations than in patients harboring PTPN11 (71 %) and RAF1 (83 %) mutations. These results delineate the clinical manifestations of RIT1 mutation-positive NS patients: high frequencies of hypertrophic cardiomyopathy, atrial septal defects, and pulmonary stenosis; and lower frequencies of ptosis and short stature.

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.

Nonsynonymous Single-Nucleotide Variations on Some Posttranslational Modifications of Human Proteins and the Association with Diseases

Protein posttranslational modifications (PTMs) play key roles in a variety of protein activities and cellular processes. Different PTMs show distinct impacts on protein functions, and normal protein activities are consequences of all kinds of PTMs working together. With the development of high throughput technologies such as tandem mass spectrometry (MS/MS) and next generation sequencing, more and more nonsynonymous single-nucleotide variations (nsSNVs) that cause variation of amino acids have been identified, some of which result in the damage of PTMs. The damaged PTMs could be the reason of the development of some human diseases. In this study, we elucidated the proteome wide relationship of eight damaged PTMs to human inherited diseases and cancers. Some human inherited diseases or cancers may be the consequences of the interactions of damaged PTMs, rather than the result of single damaged PTM site.

RAS diseases in children

RAS genes encode a family of 21 kDa proteins that are an essential hub for a number of survival, proliferation, differentiation and senescence pathways. Signaling of the RAS-GTPases through the RAF-MEK-ERK pathway, the first identified mitogen-associated protein kinase (MAPK) cascade is essential in development. A group of genetic syndromes, named "RASopathies", had been identified which are caused by heterozygosity for germline mutations in genes that encode protein components of the RAS/MAPK pathway. Several of these clinically overlapping disorders, including Noonan syndrome, Noonan-like CBL syndrome, Costello syndrome, cardio-facio-cutaneous (CFC) syndrome, neurofibromatosis type I, and Legius syndrome, predispose to cancer and abnormal myelopoiesis in infancy. This review focuses on juvenile myelomonocytic leukemia (JMML), a malignancy of early childhood characterized by initiating germline and/or somatic mutations in five genes of the RAS/MAPK pathway: PTPN11, CBL, NF-1, KRAS and NRAS. Natural courses of these five subtypes differ, although hematopoietic stem cell transplantation remains the only curative therapy option for most children with JMML. With whole-exome sequencing studies revealing few secondary lesions it will be crucial to better understand the RAS/MAPK signaling network with its crosstalks and feed-back loops to carefully design early clinical trials with novel pharmacological agents in this still puzzling leukemia.

Cardiomyopathies in Noonan syndrome and the other RASopathies

Noonan syndrome and related disorders (Noonan syndrome with multiple lentigines, Costello syndrome, cardiofaciocutaneous syndrome, Noonan syndrome with loose anagen hair, and other related traits) are autosomal dominant traits. Mutations causing these disorders alter proteins relevant for signaling through RAS. Thus, these traits are now collectively called the RASopathies. While the RASopathies have pleiomorphic features, this review will focus on the hypertrophic cardiomyopathy observed in varying percentages of all of these traits. In addition, inherited abnormalities in one pathway gene, RAF1, cause pediatric-onset dilated cardiomyopathy. The pathogeneses for the RASopathy-associated cardiomyopathies are being elucidated, principally using animal models, leading to genotype-specific insights into how signal transduction is perturbed. Based on those findings, small molecule therapies seem possible for RASopathy-associated cardiomyopathies.

Correlation of mutation profile and response in patients with myelofibrosis treated with ruxolitinib

Although most patients with myelofibrosis (MF) derive benefit from ruxolitinib, some are refractory, have a suboptimal response, or quickly lose their response. To identify genes that may predict response to ruxolitinib, we performed targeted next-generation sequencing (NGS) of a panel of 28 genes recurrently mutated in hematologic malignancies in a cohort of patients with MF who were treated with ruxolitinib in a phase 1/2 study. We also tested for CALR deletions by standard polymerase chain reaction methods. Ninety-eight percent of patients had a mutation in ≥1 gene. Seventy-nine (82.1%) patients had the JAK2(V617F) mutation, 9 (9.5%) had CALR mutations (7 type 1, 2 type 2), 3 (3.1%) had MPL mutations, and 4 (4.2%) were negative for all 3. ASXL1/JAK2 and TET2/JAK2 were the most frequently comutated genes. Mutations in NRAS, KRAS, PTPN11, GATA2, TP53, and RUNX1 were found in <5% of patients. Spleen response (≥50% reduction in palpable spleen size) was inversely correlated with the number of mutations; patients with ≤2 mutations had ninefold higher odds of a spleen response than those with ≥3 mutations (odds ratio = 9.37; 95% confidence interval, 1.86-47.2). Patients with ≥3 mutations also had a shorter time to treatment discontinuation and shorter overall survival than those with fewer mutations. In multivariable analysis, only number of mutations and spleen response remained associated with time to treatment discontinuation. Patients with ≥3 mutations had the worst outcomes, suggesting that multigene profiling may be useful for therapeutic planning for MF.