Noonan Syndrome


Noonan Syndrome is an autosamal dominant multi-system disorder, characterised by facial anomalies, short stature, developmental delay, cardiac abnormalities and other symptoms. The syndrome pre-disposes to myeloproliferative disorders ( mainly chronic myeolomonocytic leukemia / juvenile myelomonocytic leukemia and acute lymphoblastic leukemia), with reports of neuroblastoma, rhabdomyosarcoma and a wide range of other tumors.

Literature Analysis

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  • LEOPARD Syndrome
  • Genetic Predisposition
  • Cohort Studies
  • DNA Mutational Analysis
  • Noonan Syndrome
  • Ultrasonography, Prenatal
  • Phenotype
  • Acute Lymphocytic Leukaemia
  • PTPN11
  • Restriction Fragment Length Polymorphism
  • KRAS
  • Telomere
  • Autologous Transplantat
  • Protein Tyrosine Phosphatases
  • Costello Syndrome
  • Facies
  • Mitogen-Activated Protein Kinases
  • Congenital Heart Defects
  • Newborns
  • SOS1 Protein
  • Leukemia, Myelomonocytic, Juvenile
  • DNA Sequence Analysis
  • Intracellular Signaling Peptides and Proteins
  • Mutation
  • Proto-Oncogene Proteins
  • NRAS
  • Protein Tyrosine Phosphatase, Non-Receptor Type 11
  • ras Proteins
  • NF1
  • Adolescents
  • Pedigree
  • Neurofibromatosis
  • Germ-Line Mutation
  • Missense Mutation
  • Genes, Dominant
  • MAP Kinase Signaling System
  • Neurofibromatosis 1
  • Exons
  • Genotype
  • Retroperitoneal Neoplasms
  • Infant
  • Childhood Cancer
Tag cloud generated 08 August, 2015 using data from PubMed, MeSH and CancerIndex

Mutated Genes and Abnormal Protein Expression (6)

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PTPN11 12q24 CFC, NS1, SHP2, BPTP3, PTP2C, PTP-1D, SH-PTP2, SH-PTP3 -PTPN11 and Noonan Syndrome
KRAS 12p12.1 NS, NS3, CFC2, KRAS1, KRAS2, RASK2, KI-RAS, C-K-RAS, K-RAS2A, K-RAS2B, K-RAS4A, K-RAS4B -KRAS mutation in Noonan Syndrome
SOS1 2p21 GF1, HGF, NS4, GGF1, GINGF -SOS1 mutation in Noonan Syndrome
RAF1 3p25 NS5, CRAF, Raf-1, c-Raf, CMD1NN -RAF1 mutation in Noonan Syndrome
NRAS 1p13.2 NS6, CMNS, NCMS, ALPS4, N-ras, NRAS1 -NRAS mutation Noonan Syndrome
CBL 11q23.3 CBL2, NSLL, C-CBL, RNF55, FRA11B -CBL mutation in Noonan Syndrome

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications

Noonan Syndrome and cancer:
Kratz CP, Franke L, Peters H, et al.
Cancer spectrum and frequency among children with Noonan, Costello, and cardio-facio-cutaneous syndromes.
Br J Cancer. 2015; 112(8):1392-7 [PubMed] Article available free on PMC after 14/04/2016 Related Publications
BACKGROUND: Somatic mutations affecting components of the Ras-MAPK pathway are a common feature of cancer, whereas germline Ras pathway mutations cause developmental disorders including Noonan, Costello, and cardio-facio-cutaneous syndromes. These 'RASopathies' also represent cancer-prone syndromes, but the quantitative cancer risks remain unknown.
METHODS: We investigated the occurrence of childhood cancer including benign and malignant tumours of the central nervous system in a group of 735 individuals with germline mutations in Ras signalling pathway genes by matching their information with the German Childhood Cancer Registry.
RESULTS: We observed 12 cases of cancer in the entire RASopathy cohort vs 1.12 expected (based on German population-based incidence rates). This corresponds to a 10.5-fold increased risk of all childhood cancers combined (standardised incidence ratio (SIR)=10.5, 95% confidence interval=5.4-18.3). The specific cancers included juvenile myelomonocytic leukaemia=4; brain tumour=3; acute lymphoblastic leukaemia=2; rhabdomyosarcoma=2; and neuroblastoma=1. The childhood cancer SIR in Noonan syndrome patients was 8.1, whereas that for Costello syndrome patients was 42.4.
CONCLUSIONS: These data comprise the first quantitative evidence documenting that the germline mutations in Ras signalling pathway genes are associated with increased risks of both childhood leukaemia and solid tumours.

Nair S, Fort JA, Yachnis AT, Williams CA
Optic nerve pilomyxoid astrocytoma in a patient with Noonan syndrome.
Pediatr Blood Cancer. 2015; 62(6):1084-6 [PubMed] Related Publications
Noonan syndrome (NS; MIM 163950) is an autosomal dominant syndrome which is clinically diagnosed by the distinct facial features, short stature, cardiac anomalies and developmental delay. About 50% of cases are associated with gain of function mutations in PTPN11 gene which leads to activation of the RAS/mitogen-activated protein kinase signaling pathway. This is known to have a role in tumorigenesis. Despite this, only limited reports of solid tumors (Fryssira H, Leventopoulos G, Psoni S, et al. Tumor development in three patients with Noonan syndrome. Eur J Pediatr 2008;167:1025-1031; Schuettpelz LG, McDonald S, Whitesell K et al. Pilocytic astrocytoma in a child with Noonan syndrome. Pediatr Blood Cancer 2009;53:1147-1149; Sherman CB, Ali-Nazir A, Gonzales-Gomez I, et al. Primary mixed glioneuronal tumor of the central nervous system in a patient with Noonan syndrome. J Pediatr Hematol Oncol 2009;31:61-64; Sanford RA, Bowman R, Tomita T, et al. A 16 year old male with Noonan's syndrome develops progressive scoliosis and deteriorating gait. Pediatr Neurosurg 1999;30:47-52) and no prior reports of optic gliomas have been described in patients with NS. We present here a patient with NS with a PTPN11 mutation and an optic pathway pilomyxoid astrocytoma.

Hernández-Porras I, Fabbiano S, Schuhmacher AJ, et al.
K-RasV14I recapitulates Noonan syndrome in mice.
Proc Natl Acad Sci U S A. 2014; 111(46):16395-400 [PubMed] Article available free on PMC after 14/04/2016 Related Publications
Noonan syndrome (NS) is an autosomal dominant genetic disorder characterized by short stature, craniofacial dysmorphism, and congenital heart defects. NS also is associated with a risk for developing myeloproliferative disorders (MPD), including juvenile myelomonocytic leukemia (JMML). Mutations responsible for NS occur in at least 11 different loci including KRAS. Here we describe a mouse model for NS induced by K-Ras(V14I), a recurrent KRAS mutation in NS patients. K-Ras(V14I)-mutant mice displayed multiple NS-associated developmental defects such as growth delay, craniofacial dysmorphia, cardiac defects, and hematologic abnormalities including a severe form of MPD that resembles human JMML. Homozygous animals had perinatal lethality whose penetrance varied with genetic background. Exposure of pregnant mothers to a MEK inhibitor rescued perinatal lethality and prevented craniofacial dysmorphia and cardiac defects. However, Mek inhibition was not sufficient to correct these defects when mice were treated after weaning. Interestingly, Mek inhibition did not correct the neoplastic MPD characteristic of these mutant mice, regardless of the timing at which the mice were treated, thus suggesting that MPD is driven by additional signaling pathways. These genetically engineered K-Ras(V14I)-mutant mice offer an experimental tool for studying the molecular mechanisms underlying the clinical manifestations of NS. Perhaps more importantly, they should be useful as a preclinical model to test new therapies aimed at preventing or ameliorating those deficits associated with this syndrome.

Hyakuna N, Muramatsu H, Higa T, et al.
Germline mutation of CBL is associated with moyamoya disease in a child with juvenile myelomonocytic leukemia and Noonan syndrome-like disorder.
Pediatr Blood Cancer. 2015; 62(3):542-4 [PubMed] Related Publications
Germline mutations in CBL have been identified in patients with Noonan syndrome-like phenotypes, while juvenile myelomonocytic leukemia (JMML) harbors duplication of a germline CBL, resulting in acquired isodisomy. The association between moyamoya disease and Noonan syndrome carrying a PTPN11 mutation has recently been reported. We present a patient with JMML who developed moyamoya disease and neovascular glaucoma. Our patient exhibited a Noonan syndrome-like phenotype. Genetic analysis revealed acquired isodisomy and a germline heterozygous mutation in CBL. This is a rare case of CBL mutation associated with moyamoya disease. Prolonged RAS pathway signaling may cause disruption of cerebrovascular development.

Bezniakow N, Gos M, Obersztyn E
The RASopathies as an example of RAS/MAPK pathway disturbances - clinical presentation and molecular pathogenesis of selected syndromes.
Dev Period Med. 2014 Jul-Sep; 18(3):285-96 [PubMed] Related Publications
The RASopathies are a class of developmental syndromes. Each of them exhibits distinctive phenotypic features, although there are numerous overlapping clinical manifestations that include: dysmorphic craniofacial features, congenital cardiac defects, skin abnormalities, varying degrees of intellectual disability and increased risk of malignancies. These disorders include: Noonan syndrome, Costello syndrome, LEOPARD syndrome, cardio-facio-cutaneous syndrome (CFC), capillary malformation-arteriovenous malformation syndrome (CM-AVM), Legius syndrome and neurofibromatosis type 1 (NF1). The RASopathies are associated with the presence of germline mutation in genes encoding specific proteins of the RAS/mitogen - activated protein kinase (MAPK) pathway that plays a crucial role in embryonic and postnatal development. In this review, we present the clinical and molecular features of selected syndromes from the RASopathies group.

Strullu M, Caye A, Lachenaud J, et al.
Juvenile myelomonocytic leukaemia and Noonan syndrome.
J Med Genet. 2014; 51(10):689-97 [PubMed] Related Publications
BACKGROUND: Infants with Noonan syndrome (NS) are predisposed to developing juvenile myelomonocytic leukaemia (JMML) or JMML-like myeloproliferative disorders (MPD). Whereas sporadic JMML is known to be aggressive, JMML occurring in patients with NS is often considered as benign and transitory. However, little information is available regarding the occurrence and characteristics of JMML in NS.
METHODS AND RESULTS: Within a large prospective cohort of 641 patients with a germline PTPN11 mutation, we identified MPD features in 36 (5.6%) patients, including 20 patients (3%) who fully met the consensus diagnostic criteria for JMML. Sixty percent of the latter (12/20) had severe neonatal manifestations, and 10/20 died in the first month of life. Almost all (11/12) patients with severe neonatal JMML were males. Two females who survived MPD/JMML subsequently developed another malignancy during childhood. Although the risk of developing MPD/JMML could not be fully predicted by the underlying PTPN11 mutation, some germline PTPN11 mutations were preferentially associated with myeloproliferation: 10/48 patients with NS (20.8%) with a mutation in codon Asp61 developed MPD/JMML in infancy. Patients with a p.Thr73Ile mutation also had more chances of developing MPD/JMML but with a milder clinical course. SNP array and whole exome sequencing in paired tumoral and constitutional samples identified no second acquired somatic mutation to explain the occurrence of myeloproliferation.
CONCLUSIONS: JMML represents the first cause of death in PTPN11-associated NS. Few patients have been reported so far, suggesting that JMML may sometimes be overlooked due to early death, comorbidities or lack of confirmatory tests.

Huang WQ, Lin Q, Zhuang X, et al.
Structure, function, and pathogenesis of SHP2 in developmental disorders and tumorigenesis.
Curr Cancer Drug Targets. 2014; 14(6):567-88 [PubMed] Related Publications
Src homology 2 (SH2)-containing protein tyrosine phosphatase 2 (SHP2), encoded by the human PTPN11 gene, is a ubiquitously expressed protein tyrosine phosphatase (PTP) that consists of two tandem Src homology (SH2) domains (N-SH2 and C-SH2), a PTP catalytic domain, and a C-terminal tail with tyrosyl phosphorylation sites. It plays critical roles in numerous cellular processes through the regulation of various signaling pathways in PTP catalytic activity-dependent and -independent manners. Dysfunction of SHP2 resulting from pathogenic mutations and aberrant expression leads to the dysregulation of multiple signaling pathways, thus contributing to different human disorders. Germline and somatic mutations in PTPN11 are involved in Noonan syndrome (NS), LEOPARD syndrome (LS), and hematological malignancies, as well as several solid tumors. In this report, we provide an overview of the current knowledge of the structure and function of SHP2, and further discuss the molecular and pathogenic mechanism of SHP2 in human diseases, with a special focus on tumorigenesis. Furthermore, we summarize that SHP2 might itself represent a potential drug target for cancer prevention and treatment. Ongoing research and development of SHP2-specific inhibitors would enhance this potential.

Pootrakul L, Nazareth MR, Cheney RT, Grassi MA
Lymphangioma circumscriptum of the vulva in a patient with Noonan syndrome.
Cutis. 2014; 93(6):297-300 [PubMed] Related Publications
Lymphangioma circumscriptum (LC) results from the development of abnormal lymphatic vasculature and is characterized by the presence of grouped vesicles filled with clear or colored fluid. Vulvar localization is uncommon. Abnormalities of the lymphatic system, such as lymphedema and cystic hygroma, are well-known features of genetic disorders such as Noonan syndrome (NS) and Turner syndrome. We report the case of a patient with NS who presented with LC of the vulva. We also discuss the expanding spectrum of clinical anomalies associated with the presentation of NS.

Santoro C, Pacileo G, Limongelli G, et al.
LEOPARD syndrome: clinical dilemmas in differential diagnosis of RASopathies.
BMC Med Genet. 2014; 15:44 [PubMed] Article available free on PMC after 14/04/2016 Related Publications
BACKGROUND: Diagnosis within RASopathies still represents a challenge. Nevertheless, many efforts have been made by clinicians to identify specific clinical features which might help in differentiating one disorder from another. Here, we describe a child initially diagnosed with Neurofibromatosis-Noonan syndrome. The follow-up of the proband, the clinical evaluation of his father together with a gene-by-gene testing approach led us to the proper diagnosis.
CASE PRESENTATION: We report a 8-year-old male with multiple café-au-lait macules, several lentigines and dysmorphic features that suggest Noonan syndrome initially diagnosed with Neurofibromatosis-Noonan syndrome. However, after a few years of clinical and ophthalmological follow-up, the absence of typical features of Neurofibromatosis type 1 and the lack of NF1 mutation led us to reconsider the original diagnosis. A new examination of the patient and his similarly affected father, who was initially referred as healthy, led us to suspect LEOPARD syndrome, The diagnosis was then confirmed by the occurrence in both patients of a heterozygous mutation c.1403 C > T, p.(Thr468Met), of PTPN11. Subsequently, the proband was also found to have type-1 Arnold-Chiari malformation in association with syringomyelia.
CONCLUSION: Our experience suggests that differential clinical diagnosis among RASopathies remains ambiguous and raises doubts on the current diagnostic clinical criteria. In some cases, genetic tests represent the only conclusive proof for a correct diagnosis and, consequently, for establishing individual prognosis and providing adequate follow-up. Thus, molecular testing represents an essential tool in differential diagnosis of RASophaties. This view is further strengthened by the increasing accessibility of new sequencing techniques.Finally, to our knowledge, the described case represents the third report of the occurrence of Arnold Chiari malformation and the second description of syringomyelia with LEOPARD syndrome.

Ahmed B, Amin M
Postpubertal cherubism with Noonan syndrome.
J Coll Physicians Surg Pak. 2014; 24 Suppl 1:S39-40 [PubMed] Related Publications
Cherubism is a self limiting, autosomal dominant, fibro-osseous lesion of the maxillo facial region affecting the young adults. The etiology is considered to be a mutation of the SH3BP2 gene from chromosome 4p16.3. Sporadic non-familial cases have also been reported. The affected subjects usually present with simultaneous, bilateral swellings of the maxillae and/or mandible, premature loss of primary teeth, malocclusion due to disturbed eruption pattern of permanent teeth and a characteristic chubby faced angelic eyed appearance. This usually presents as an isolated finding, however, it can exist in association with syndromes like Noonan's syndrome, Jaffe syndrome, Gardener syndrome and Ollier's disease. Treatment is focused on the exact genetic diagnosis and management of symptomatic conditions utilizing cosmetic surgery and orthodontics. Genetic counselling of the affected families may help to decrease its incidence. This report presents a rare case of cherubism with associated features of Noonan syndrome.

Ekvall S, Sjörs K, Jonzon A, et al.
Novel association of neurofibromatosis type 1-causing mutations in families with neurofibromatosis-Noonan syndrome.
Am J Med Genet A. 2014; 164A(3):579-87 [PubMed] Related Publications
Neurofibromatosis-Noonan syndrome (NFNS) is a rare condition with clinical features of both neurofibromatosis type 1 (NF1) and Noonan syndrome (NS). All three syndromes belong to the RASopathies, which are caused by dysregulation of the RAS-MAPK pathway. The major gene involved in NFNS is NF1, but co-occurring NF1 and PTPN11 mutations in NFNS have been reported. Knowledge about possible involvement of additional RASopathy-associated genes in NFNS is, however, very limited. We present a comprehensive clinical and molecular analysis of eight affected individuals from three unrelated families displaying features of NF1 and NFNS. The genetic etiology of the clinical phenotypes was investigated by mutation analysis, including NF1, PTPN11, SOS1, KRAS, NRAS, BRAF, RAF1, SHOC2, SPRED1, MAP2K1, MAP2K2, and CBL. All three families harbored a heterozygous NF1 variant, where the first family had a missense variant, c.5425C>T;p.R1809C, the second family a recurrent 4bp-deletion, c.6789_6792delTTAC;p.Y2264Tfs*6, and the third family a splice-site variant, c.2991-1G>A, resulting in skipping of exon 18 and an in-frame deletion of 41 amino acids. These NF1 variants have all previously been reported in NF1 patients. Surprisingly, both c.6789_6792delTTAC and c.2991-1G>A are frequently associated with NF1, but association to NFNS has, to our knowledge, not previously been reported. Our results support the notion that NFNS represents a variant of NF1, genetically distinct from NS, and is caused by mutations in NF1, some of which also cause classical NF1. Due to phenotypic overlap between NFNS and NS, we propose screening for NF1 mutations in NS patients, preferentially when café-au-lait spots are present.

Cizmarova M, Kostalova L, Pribilincova Z, et al.
Rasopathies - dysmorphic syndromes with short stature and risk of malignancy.
Endocr Regul. 2013; 47(4):217-22 [PubMed] Related Publications
OBJECTIVES: The term ´Rasopathies´ represents a group of five neurodevelopmental syndromes (Noonan, LEOPARD, Costello, Cardio-facio-cutaneous, and Neurofibromatose-Noonan syndrome) caused by germline mutation in genes encoding proteins involved in RAS/MAPK (rat sarcoma/mitogen-activated protein kinase) signaling pathway. The RAS/MAPK signaling pathway participates in regulation of cell determination, proliferation, differentiation, migration, and senescence and dysregulation of this pathway can lead to the risk of tumorigenesis. In this review, we aim to summarize the current clinical and molecular genetic knowledge on Rasopathies with special attention for the risk of cancer. We propose also clinical and therapeutic approach for patients with malignancy.
METHODS: We are reviewing the clinical and molecular basis of Rasopathies based on recent studies, clinical examination, and molecular diagnostics (mutation analysis of causal genes for Rasopathies) in Slovak pediatric patients.
RESULTS: Some clinical features, such as short stature, a specific facial dysmorphology and cardiac abnormalities are common to all of Rasopathy syndromes. However, there are unique signs by which the syndromes can differ from each other, especially multiple lentigo in LEOPARD syndrome, increased risk of malignancy in Costello syndrome, dry hyperkeratotic skin in patients with cardio-facio-cutaneous syndrome, and neurofibromas and cafe-au-lait spots in neurofibromatosis-Noonan syndrome.
CONCLUSION: Despite the overlapping clinical features, Rasopathy syndromes exhibit unique fenotypical features and the precise molecular diagnostics may lead to confirmation of each syndrome. The molecular diagnostics may allow the detection of pathogenic mutation associated with tumorigenesis.

Sakamoto K, Imamura T, Asai D, et al.
Acute lymphoblastic leukemia developing in a patient with Noonan syndrome harboring a PTPN11 germline mutation.
J Pediatr Hematol Oncol. 2014; 36(2):e136-9 [PubMed] Related Publications
Noonan syndrome (NS) is a congenital genetic disorder characterized by certain facial features, short stature, and congenital heart disease. The disorder is caused by genetic alterations in the RAS/MAPK signal pathway. NS patients show a predisposition to malignancy; however, acute lymphoblastic leukemia (ALL) is rarely reported. Here, we describe a NS patient with B-cell precursor ALL (BCP-ALL) harboring a hyperdiploid karyotype and a PTPN11 germline mutation (c.922A>G; p.N308D). We also discuss the relationship between the hyperdiploid karyotype and genetic alterations in the RAS/MAPK pathway in BCP-ALL.

Yu B, Liu W, Yu WM, et al.
Targeting protein tyrosine phosphatase SHP2 for the treatment of PTPN11-associated malignancies.
Mol Cancer Ther. 2013; 12(9):1738-48 [PubMed] Article available free on PMC after 14/04/2016 Related Publications
Activating mutations in PTPN11 (encoding SHP2), a protein tyrosine phosphatase (PTP) that plays an overall positive role in growth factor and cytokine signaling, are directly associated with the pathogenesis of Noonan syndrome and childhood leukemias. Identification of SHP2-selective inhibitors could lead to the development of new drugs that ultimately serve as treatments for PTPN11-associated diseases. As the catalytic core of SHP2 shares extremely high homology to those of SHP1 and other PTPs that play negative roles in cell signaling, to identify selective inhibitors of SHP2 using computer-aided drug design, we targeted a protein surface pocket that is adjacent to the catalytic site, is predicted to be important for binding to phosphopeptide substrates, and has structural features unique to SHP2. From computationally selected candidate compounds, #220-324 effectively inhibited SHP2 activity with an IC50 of 14 μmol/L. Fluorescence titration experiments confirmed its direct binding to SHP2. This active compound was further verified for its ability to inhibit SHP2-mediated cell signaling and cellular function with minimal off-target effects. Furthermore, mouse myeloid progenitors with the activating mutation (E76K) in PTPN11 and patient leukemic cells with the same mutation were more sensitive to this inhibitor than wild-type cells. This study provides evidence that SHP2 is a "druggable" target for the treatment of PTPN11-associated diseases. As the small-molecule SHP2 inhibitor identified has a simple chemical structure, it represents an ideal lead compound for the development of novel anti-SHP2 drugs. Mol Cancer Ther; 12(9); 1738-48. ©2013 AACR.

Timeus F, Crescenzio N, Baldassarre G, et al.
Functional evaluation of circulating hematopoietic progenitors in Noonan syndrome.
Oncol Rep. 2013; 30(2):553-9 [PubMed] Article available free on PMC after 14/04/2016 Related Publications
Noonan syndrome (NS) is an autosomal dominant disorder, characterized by short stature, multiple dysmorphisms and congenital heart defects. A myeloproliferative disorder (NS/MPD), resembling juvenile myelomonocytic leukemia (JMML), is occasionally diagnosed in infants with NS. In the present study, we performed a functional evaluation of the circulating hematopoietic progenitors in a series of NS, NS/MPD and JMML patients. The different functional patterns were compared with the aim to identify a possible NS subgroup worthy of stringent hematological follow-up for an increased risk of MPD development. We studied 27 NS and 5 JMML patients fulfilling EWOG-MDS criteria. The more frequent molecular defects observed in NS were mutations in the PTPN11 and SOS genes. The absolute count of monocytes, circulating CD34+ hematopoietic progenitors, their apoptotic rate and the number of circulating CFU-GMs cultured in the presence of decreasing concentrations or in the absence of granulocyte-macrophage colony-stimulating factor (GM-CSF) were evaluated. All JMML patients showed monocytosis>1,000/µl. Ten out of the 27 NS patients showed monocytosis>1,000/µl, which included the 3 NS/MPD patients. In JMML patients, circulating CD34+ cells were significantly increased (median, 109.8/µl; range, 44-232) with a low rate of apoptosis (median, 2.1%; range, 0.4-12.1%), and circulating CFU-GMs were hyper-responsive to GM-CSF. NS/MPD patients showed the same flow cytometric pattern as the JMML patients (median, CD34+ cells/µl, 205.7; range, 58-1374; median apoptotic rate, 1.4%; range, 0.2-2.4%) and their circulating CFU-GMs were hyper-responsive to GM-CSF. These functional alterations appeared 10 months before the typical clinical manifestations in 1 NS/MPD patient. In NS, the CD34+ absolute cell count and circulating CFU-GMs showed a normal pattern (median CD34+ cells/µl, 4.9; range, 1.3-17.5), whereas the CD34+ cell apoptotic rate was significantly decreased in comparison with the controls (median, 8.6%; range, 0-27.7% vs. median, 17.6%; range, 2.8-49.6%), suggesting an increased CD34+ cell survival. The functional evaluation of circulating hematopoietic progenitors showed specific patterns in NS and NS/MPD. These tests are a reliable integrative tool that, together with clinical data and other hematological parameters, could help detect NS patients with a high risk for a myeloproliferative evolution.

Eckmann-Scholz C, Salmassi A, Jonat W, Alkatout I
Distended jugular lymphatic sacs in fetuses with increased nuchal translucency: correlation with first-trimester findings in aberrant karyotypes.
J Matern Fetal Neonatal Med. 2014; 27(3):257-60 [PubMed] Related Publications
OBJECTIVE: We investigated the prognostic relevance of ultrasound visibility of distendend jugular lymphatic sacs (JLS) in fetuses with aberrant karyotypes in First-trimester-screening. Furthermore we tried to differentiate between increased nuchal translucency (NT) and cystic hygroma colli.
METHODS: We performed a retrospective single center study in 1874 patients presenting for First-trimester-screening between 2009 and 2013. All fetuses with an abnormal risk calculation and NT > 2.5 mm (95th percentile) were reviewed for ultrasound visibility of JLS. A group of 30 fetuses with normal risk calculation served as control. Karyotyping was performed by chorionic-villi-sampling or amniocentesis, respectively.
RESULTS: In a total of 2030 fetuses 70 (3.44%) with pathologic first-trimester-screening results showed either aberrant karyotypes or severe ultrasound pathologies. Main aberrant karyotypes were trisomy 21 (25), trisomy 18 (16), trisomy 13(six), Monosomy X (four), 47, XYY or 47, XXX (three) and Noonan' syndrome (two). Distended JLS were visible in 47% of all cases. Statistical anaylsis found a significant correlation between NT and JLS size for the fetuses with trisomies 21, 18 and 13 (r = 0.53, p < 0.002). Cystic hygroma colli was present in all Turner and Noonan syndromes.
CONCLUSIONS: Distended JLS have a strong correlation with abnormal karyotypes and increased nuchal translucency. Karyotyping should be offered in these cases.

Müller PJ, Rigbolt KT, Paterok D, et al.
Protein tyrosine phosphatase SHP2/PTPN11 mistargeting as a consequence of SH2-domain point mutations associated with Noonan Syndrome and leukemia.
J Proteomics. 2013; 84:132-47 [PubMed] Related Publications
UNLABELLED: SHP2/PTPN11 is a key regulator of cytokine, growth factor and integrin signaling. SHP2 influences cell survival, proliferation and differentiation by regulating major signaling pathways. Mutations in PTPN11 cause severe diseases like Noonan, LEOPARD syndrome or leukemia. Whereas several of these mutations result in altered enzymatic activity due to impaired auto-inhibition, not all disease patterns can be explained by this mechanism. In this study we analyzed altered binding properties of disease-related SHP2-mutants bearing point mutations within the SH2-domain (T42A, E139D, and R138Q). Mutants were chosen according to SPR assays, which revealed different binding properties of mutated SH2 towards phosphorylated receptor peptides. To analyze global changes in mutant binding properties we applied quantitative mass spectrometry (SILAC). Using an in vitro approach we identified overall more than 1000 protein candidates, which specifically bind to the SH2-domain of SHP2. We discovered that mutations in the SH2-domain selectively affected protein enrichment by altering the binding capacity of the SH2-domain. Mutation-dependent, enhanced or reduced exposure of SHP2 to its binding partners could have an impact on the dynamics of signaling networks. Thus, disease-associated mutants of SHP2 should not only be discussed in the context of deregulated auto-inhibition but also with respect to deregulated protein targeting of the SHP2 mutants.
BIOLOGICAL SIGNIFICANCE: Using quantitative mass spectrometry based proteomics we provided evidence that disease related mutations in SHP2 domains of SHP2 are able to influence SHP2 recruitment to its targets in mutation dependent manner. We discovered that mutations in the SH2-domain selectively affected protein enrichment ratios suggesting altered binding properties of the SH2-domain. We demonstrated that mutations within SHP2, which had been attributed to affect the enzymatic activity (i.e. affect the open/close status of SHP2), also differ in respect to binding properties. Our study indicates that SHP2 mutations need to be discussed not only in terms of deregulated auto-inhibition but also with respect to deregulated protein targeting properties of the SHP2 mutants. Discovery of the new binding partners for disease-related SHP2 mutants might provide a fruitful foundation for developing strategies targeting Noonan-associated leukemia.

Gaudineau A, Doray B, Schaefer E, et al.
Postnatal phenotype according to prenatal ultrasound features of Noonan syndrome: a retrospective study of 28 cases.
Prenat Diagn. 2013; 33(3):238-41 [PubMed] Related Publications
OBJECTIVE: Noonan syndrome is a frequent genetic disorder with autosomal dominant transmission. Classically, it combines postnatal growth restriction with dysmorphic and malformation syndromes that vary widely in expressivity. Lymphatic dysplasia induced during the embryonic stage might interfere with tissue migration. Our hypothesis is that the earlier the edema, the more severe postnatal phenotype.
METHOD: This retrospective study analyzed data from all 32 cases of Noonan syndrome diagnosed in the Medical Genetics Department of Hautepierre Hospital in Strasbourg, France, between 1995 and 2011. The postnatal evolution of Noonan syndrome was compared according to the presence of at least one prenatal ultrasound feature of lymphatic dysplasia.
RESULTS: The most frequent prenatal ultrasound features found were increased nuchal translucency, cystic hygroma and polyhydramnios; their global prevalence was 46.4%. The presence of these features was not significantly associated with the postnatal phenotype of Noonan syndrome.
CONCLUSION: The results of our study indicate that prenatal ultrasound features of lymphatic dysplasia do not predict an unfavorable postnatal prognosis for Noonan syndrome.

Ben-Shachar S, Constantini S, Hallevi H, et al.
Increased rate of missense/in-frame mutations in individuals with NF1-related pulmonary stenosis: a novel genotype-phenotype correlation.
Eur J Hum Genet. 2013; 21(5):535-9 [PubMed] Article available free on PMC after 14/04/2016 Related Publications
Neurofibromatosis type 1 (NF1) and its related disorders (NF1-Noonan syndrome (NFNS) and Watson syndrome (WS)) are caused by heterozygous mutations in the NF1 gene. Pulmonary stenosis (PS) occurs more commonly in NF1 and its related disorders than in the general population. This study investigated whether PS is associated with specific types of NF1 gene mutations in NF1, NFNS and WS. The frequency of different NF1 mutation types in a cohort of published and unpublished cases with NF1/NFNS/WS and PS was examined. Compared with NF1 in general, NFNS patients had higher rates of PS (9/35=26% vs 25/2322=1.1%, P value<0.001). Stratification according to mutation type showed that the increased PS rate appears to be driven by the NFNS group with non-truncating mutations. Eight of twelve (66.7%) NFNS cases with non-truncating mutations had PS compared with a 1.1% PS frequency in NF1 in general (P<0.001); there was no increase in the frequency of PS in NFNS patients with truncating mutations. Eight out of eleven (73%) individuals with NF1 and PS, were found to have non-truncating mutations, a much higher frequency than the 19% reported in NF1 cohorts (P<0.015). Only three cases of WS have been published with intragenic mutations, two of three had non-truncating mutations. Therefore, PS in NF1 and its related disorders is clearly associated with non-truncating mutations in the NF1 gene providing a new genotype-phenotype correlation. The data indicate a specific role of non-truncating mutations on the NF1 cardiac phenotype.

Yimenicioğlu S, Yakut A, Karaer K, et al.
A new nonsense mutation in the NF1 gene with neurofibromatosis-Noonan syndrome phenotype.
Childs Nerv Syst. 2012; 28(12):2181-3 [PubMed] Related Publications
PURPOSE: Neurofibromatosis-Noonan syndrome is a rare autosomal dominant disorder which combines neurofibromatosis type 1 (NF1) features with Noonan syndrome. NF1 gene mutations are reported in the majority of these patients.
METHOD: Sequence analysis of the established genes for Noonan syndrome revealed no mutation; a heterozygous NF1 point mutation c.7549C>T in exon 51, creating a premature stop codon (p.R2517X), had been demonstrated.
RESULT: Neurofibromatosis-Noonan syndrome recently has been considered a subtype of NF1 and caused by different NF1 mutations.
CONCLUSION: We report the case of a 14-year-old boy with neurofibromatosis type 1 with Noonan-like features, who complained of headache with triventricular hydrocephaly and a heterozygous NF1 point mutation c.7549C>T in exon 51.

Stevenson DA, Allen S, Tidyman WE, et al.
Peripheral muscle weakness in RASopathies.
Muscle Nerve. 2012; 46(3):394-9 [PubMed] Related Publications
INTRODUCTION: RASopathies are a group of genetic conditions due to alterations of the Ras/MAPK pathway. Neurocutaneous findings are hallmark features of the RASopathies, but musculoskeletal abnormalities are also frequent. The objective was to evaluate handgrip strength in the RASopathies.
METHODS: Individuals with RASopathies (e.g., Noonan syndrome, Costello syndrome, cardio-facio-cutaneous [CFC] syndrome, and neurofibromatosis type 1 [NF1]) and healthy controls were evaluated. Two methods of handgrip strength were tested: GRIP-D Takei Hand Grip Dynamometer and the Martin vigorimeter. A general linear model was fitted to compare average strength among the groups, controlling for confounders such as age, gender, height, and weight.
RESULTS: Takei dynamometer: handgrip strength was decreased in each of the syndromes compared with controls. Decreased handgrip strength compared with sibling controls was also seen with the Martin vigorimeter (P < 0.0001).
CONCLUSIONS: Handgrip strength is decreased in the RASopathies. The etiology of the reduced muscle force is unknown, but likely multifactorial.

Kraoua L, Journel H, Bonnet P, et al.
Constitutional NRAS mutations are rare among patients with Noonan syndrome or juvenile myelomonocytic leukemia.
Am J Med Genet A. 2012; 158A(10):2407-11 [PubMed] Related Publications
Recently, germline mutations of NRAS have been shown to be associated with Noonan syndrome (NS), a relatively common developmental disorder characterized by short stature, congenital heart disease, and distinctive facial features. We report on the mutational analysis of NRAS in a cohort of 125 French patients with NS and no known mutation for PTPN11, KRAS, SOS1, MEK1, MEK2, RAF1, BRAF, and SHOC2. The c.179G>A (p.G60E) mutation was identified in two patients with typical NS, confirming that NRAS germline mutations are a rare cause of this syndrome. We also screened our cohort of 95 patients with juvenile myelomonocytic leukemia (JMML). Among 17 patients with NRAS-mutated JMML, none had clinical features suggestive of NS. None of the 11 JMML patients for which germline DNA was available had a constitutional NRAS mutation.

Pasmant E, Amiel J, Rodriguez D, et al.
Two independent de novo mutations as a cause for neurofibromatosis type 1 and Noonan syndrome in a single family.
Am J Med Genet A. 2012; 158A(9):2290-1 [PubMed] Related Publications
Here we report on a family with two siblings born to unrelated healthy parents, one with neurofibromatosis type 1 (NF1) and the other with Noonan syndrome (NS). Molecular investigations performed on the NF1 and PTPN11 genes showed two independent de novo mutations as a cause for NF1 in the NF1 proband and NS in her affected brother. Both de novo mutations were potentially of paternal origin, given the advanced paternal age at the time of conception.

Moskovszky L, Idowu B, Taylor R, et al.
Analysis of giant cell tumour of bone cells for Noonan syndrome/cherubism-related mutations.
J Oral Pathol Med. 2013; 42(1):95-8 [PubMed] Related Publications
BACKGROUND: Giant cell tumour of bone (GCTB) is an osteolytic tumour which contains numerous osteoclast-like giant cells and a proliferation of mononuclear stromal cells (MSC). Giant cell-rich osteolytic lesions can also develop in the jaw bones in Noonan syndrome, a cherubism-like developmental abnormality that is transmitted in an autosomal dominant fashion, often because of mutation in the PTPN11 or BRAF genes.
METHODS: We screened GCTBs for mutations in PTPN11 and BRAF to determine whether GCTBs develop through alterations of genes involved in Noonan syndrome. MSC were isolated from 10 GCTBs.
RESULTS: Chromosome banding analysis of these cells revealed telomeric associations (tas) in 7 of the 10 cases. Thus, the cultured cells expressed a cytogenetic abnormality typically found in short-term cultures from GCTBs. Sequencing of DNA extracted from the seven GCTB-derived MSC cultures displaying tas did not identify any mutation in PTPN11 or in exons 9-15 of BRAF.
CONCLUSION: Our findings indicate that the molecular pathways involved in GCTB development are different from those causing Noonan syndrome. The method for isolating and culturing GCTB stromal cells described in this study generated a population of MSC that contained tas, indicating that it is useful for obtaining stromal cells from GCTB and other giant cell-rich lesions, such as giant cell reparative granuloma, for genetic and other studies.

Ortiz MV, Skoda-Smith S, Rauen KA, et al.
Juvenile myelomonocytic leukemia in a 16-year-old with Noonan syndrome: case report.
J Pediatr Hematol Oncol. 2012; 34(7):569-72 [PubMed] Related Publications
A 16-year-old man with splenomegaly presented with ascites and bilateral leg eschars. Although he had intermittently elevated absolute monocyte counts, a diagnosis of juvenile myelomonocytic leukemia (JMML) was discounted because of his age and lack of persistent leukocytosis. Detailed examination demonstrated features consistent with Noonan syndrome (NS), including typical facies, growth retardation, a cardiac defect, and a history of a coagulopathy. He underwent a splenectomy where the surgeons encountered a rind of tissue composed of monocytes encasing the abdominal organs. After splenectomy, his leukocytes rose to over 100×10(9)/L with a monocytosis, suggesting JMML. On the basis of the clinical suspicion of NS, mutation analysis revealed a KRAS mutation, which is known to be common to both NS and JMML. Clinicians should have high index of suspicion for JMML in patients with Noonan features, regardless of a patient's age.

Moos D, Droitcourt C, Rancherevince D, et al.
Atypical granular cell tumor occurring in an individual with Noonan syndrome treated with growth hormone.
Pediatr Dermatol. 2012 Sep-Oct; 29(5):665-6 [PubMed] Related Publications
We report a large infiltrating atypical granular cell tumor in a child with Noonan syndrome. Even though granular cell tumors are rare in childhood, five cases have been reported in children with Noonan syndrome. This study compares these different cases and explores the possibility of activation of the granular cell by the Ras pathway.

Pauli S, Steinemann D, Dittmann K, et al.
Occurrence of acute lymphoblastic leukemia and juvenile myelomonocytic leukemia in a patient with Noonan syndrome carrying the germline PTPN11 mutation p.E139D.
Am J Med Genet A. 2012; 158A(3):652-8 [PubMed] Related Publications
Noonan syndrome (NS) is a common autosomal dominant condition characterized by short stature, congenital heart defects, and dysmorphic facial features caused in approximately 50% of cases by missense mutations in the PTPN11 gene. NS patients are predisposed to malignancies including myeloproliferative disorders or leukemias. We report a female NS patient carrying a PTPN11 germline mutation c.417 G > C (p.E139D), who developed in her second year of life an acute lymphoblastic leukemia (ALL) and after remission, she developed at 4 years of age a juvenile myelomonocytic leukemia (JMML). Molecular genetic analysis of lymphoblastic blasts at the time of the ALL diagnosis revealed the germline mutation in a heterozygous state, while in the myelomonocytic blasts occurring with JMML diagnosis, the mutation p.E139D was found in a homozygous state due to a uniparental disomy (UPD). These findings lead to the suggestion that the pathogenesis of ALL and JMML in our patient is due to different mechanisms including somatically acquired secondary chromosomal abnormalities.

Sugumaran HK, Pappas JG, Kodsi SR
Congenital absence of the superior oblique tendon in Noonan-neurofibromatosis syndrome.
J AAPOS. 2011; 15(6):593-4 [PubMed] Related Publications
A 5-year-old girl with Noonan-neurofibromatosis syndrome was diagnosed with bilateral superior oblique palsy. At surgery, the right superior oblique tendon was absent, and further exploration revealed abnormal tissue inserting into Tenon's capsule. Orbital imaging was not performed. Congenital absence of the superior oblique tendon was diagnosed. Although Noonan syndrome is known to have many ocular manifestations, absence of the superior oblique tendon has not been previously reported.

Zenker M
Clinical manifestations of mutations in RAS and related intracellular signal transduction factors.
Curr Opin Pediatr. 2011; 23(4):443-51 [PubMed] Related Publications
PURPOSE OF REVIEW: Recent advances in molecular genetic research have led to the definition of the new group of genetic syndromes, the RAS-mitogen-activated protein kinase (MAPK) pathway disorders or 'RASopathies'. They comprise Noonan syndrome and related disorders (cardio-facio-cutaneous and Costello syndromes), as well as neurofibromatosis type 1. This review summarizes the recent literature with a special focus on genotype-phenotype correlations.
RECENT FINDINGS: Although the picture is still incomplete, and additional genes are likely to exist, the underlying genetic alteration can now be found in a large majority of patients with a RASopathy phenotype. The most recently discovered novel genes for Noonan syndrome or Noonan syndrome-like disorders, NRAS, SHOC2, and CBL, account for small fractions of the patient population. The increasing knowledge about the spectrum of gene mutations and associated clinical manifestations has led to a refinement of genotype-phenotype correlations. Recent studies have added new insights into tumor predisposition and prenatal manifestations. Model systems are being developed to investigate innovative treatment approaches.
SUMMARY: Constitutional overactivation at various levels of the RAS-MAPK pathway causes overlapping syndromes, comprising characteristic facial features, cardiac defects, cutaneous abnormalities, growth deficit, neurocognitive delay, and predisposition to malignancies. Each syndrome also exhibits unique features that probably reflect genotype-related specific biological effects.

Bakker M, Pajkrt E, Mathijssen IB, Bilardo CM
Targeted ultrasound examination and DNA testing for Noonan syndrome, in fetuses with increased nuchal translucency and normal karyotype.
Prenat Diagn. 2011; 31(9):833-40 [PubMed] Related Publications
OBJECTIVE: To define sonographic criteria that may improve the prenatal diagnosis of Noonan syndrome by targeted DNA testing.
METHODS: We searched our Fetal Medicine Unit records for all cases with a final diagnosis of Noonan syndrome. A literature review was undertaken to identify the sonographic features of Noonan syndrome fetuses. Information was pooled to define the most common features.
RESULTS: In our database, we identified three cases of Noonan syndrome. The diagnosis was suspected prenatally in two of them. Thirty-nine cases were identified in the literature. In the presented cases we show that suspicion of Noonan syndrome should arise when, after an increased nuchal translucency, ultrasound investigation in the second trimester shows a persistant nuchal fold (NF) or cystic hygroma in combination with at least one of the following features: hydrops fetalis, pleural effusion, cardiac anomalies, polyhydramnios or specific facial abnormalities.
CONCLUSION: Prenatal ultrasound findings in Noonan syndrome can be subtle and aspecific, but when specific characteristics are present additional targeted DNA analysis is indicated.

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