2011 Symposium Abstracts

Use of a genetically engineered murine model to identify novel experimental therapeutics for plexiform neurofibromas

Wade Clapp, Department of Pediatrics, Indiana University School of Medicine and Riley Hospital for Children, Indianapolis, IN.
Interactions between tumorigenic cells and their surrounding microenvironment are critical for tumor progression. Germline mutations in the NF1 tumor suppressorgene cause neurofibromatosis type 1 (NF1), a common genetic disorder characterized by complex tumors called neurofibromas.
<Read More>

 The PI3K Catalytic Subunits, p110a and p110d, Serve Redundant Functions in Activating PTPN11-Induced Hematopoietic Progenitor Hypersensitivity to GM-CSF

Charles B Goodwin1, Rebecca J. Chan1,2 Departments of Medical and Molecular Genetics1 and of Pediatrics2, Indiana University School of Medicine, Indianapolis, Indiana

Noonan syndrome (NS) is a common (1 in 1500 to 2500 live births) autosomal-dominant disorder caused by somatic gain-of-function mutations in PTPN11 in approximately 40 – 50% of patients.  PTPN11 encodes Shp2, a non-receptor protein tyrosine phosphatase, that has been demonstrated repeatedly to play a positive role in growth factor signaling to Ras in a phosphatase-dependent manner.

<Read More>

 Sinking our teeth into Costello syndrome: Ras signaling regulates enamel deposition in humans and mice.

Goodwin A1, Oberoi S1, Charles C1, Groth JC1, Fairley CF1, Chen X2, Fagin JA2,3, Rauen KA4,5, and Klein OD1,4 1Department of Orofacial Sciences, UCSF, San Francisco, CA 2 Human Oncology and Phogenesis Program, Memorial Sloan Kettering Cancer Center NY, NY 3 Department of Medicine, Memorial Sloan Kettering Cancer Center NY, NY 4Department of Pediatrics, Division of Medical Genetics, UCSF, San Francisco, CA 5 UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, CA
Ras/MAPK signaling is critical in animal development, and receptor-tyrosine kinase signaling, which activates Ras signaling, is known to play an important role in tooth development. Our previous work has shown that increasing Ras/MAPK signaling by inactivating Sprouty genes adversely affects tooth morphogenesis. Here, we directly examined the effects of activating Ras/MAPK signaling in both humans and mice. Costello Syndrome (CS) is caused by a heterozygous de novo germline mutation in HRAS that results in a constitutively active Ras protein.
S.P. Shankar1, D. Orel-Bixler2, T.L. Young3,  K.A. Rauen4 1). Department of Human Genetics and Ophthalmology, Emory University, Atlanta, GA  2). Berkeley Optometry, University of California, Berkeley, CA  3). Center for Human Genetics and Ophthalmology, Duke University, Durham, NC  4). Medical Genetics, University of California San Francisco, San Francisco, CA

The role of the Ras/MAPK signaling in eye and vision development is being increasingly studied and shown to be important in, in-vitro studies, animal models including zebra fish and mouse models and in individuals having rasopathies. We studied 58 individuals including 28 with Cardiofaciocutaneous (CFC), 16 with Costello syndrome and 14 with Noonan syndrome during Berkeley Ras/MAPK symposium. Additionally we had collected visual exam reports from individuals not in this study. Both similarities and differences in the ocular presentation were noted in all three syndromes.  The most serious visually disabling problem not amenable to treatment currently was optic nerve hypoplasia. However, not all individuals had optic nerve involvement. About 30% of CFC, 10-20% of Costello children and 10-20% of Noonan individuals have optic nerve involvement.

<Read More> 

 Role of Neurofibromatosis/Ras in circadian rhythms and sleep

Amita Sehgal, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104

Sleep is controlled by a homeostatic system that drives the need to sleep and a circadian system that imposes a ~24hour rhythm on sleep and wake.  Ras-MAPK signaling has been implicated in both these systems in multiple species.  Using a Drosophila model, we found several years ago that loss of the Neurofibromatosis 1 gene results in loss of circadian rhythms of sleep:wake.  We showed also that the mutant phenotype results from increases in Ras-MAPK signaling, which was the first demonstration that Drosophila NF1 signals through Ras-MAPK.  Because the central clock was unaffected in NF1 mutants we attributed the arrhythmic phenotype to an effect on output from the clock.

<Read More>

 Ras/MAPK Disorders: Genotype Phenotype Correlations

Amy E. Roberts, M.D. Department of Cardiology and Division of Genetics, Children’s Hospital Boston, Boston, MA, USA

Noonan syndrome (NS) is a genetic multisystem disorder characterized by recognizable facial features, developmental delay, learning issues, short stature, congenital heart disease, renal anomalies, lymphatic malformations, and/or bleeding problems.  NS-causing mutations alter genes encoding proteins with roles in the Ras/mitogen-activated protein kinase (Ras/MAPK) pathway, leading to pathway dysregulation.  Thus far, eight genes have been shown to cause NS or closely related conditions (PTPN11, SOS1, KRAS, NRAS, RAF1, BRAF, SHOC2, and CBL).  There are multiple clinically relevant genotype-phenotype correlations that aid in risk assessment and patient management.  Genotype phenotype correlation with regard to cardiovascular, growth, development, cutaneous, and hematological features will be discussed.

<Read More>

 Ras Pathway Biology: Hematopoiesis and Cancer

Rebecca J. Chan

Germline gain-of-function mutations within genes contributing to the Ras-MAPK pathway have been identified in individuals with the phenotypically overlapping congenital disorders, Noonan syndrome, Costello syndrome, Cardio-facio-cutaneous syndrome, and LEOPARD syndrome, collectively known as neuro-cardio-facial-cutaneous syndromes.  The high prevalence of somatic mutations within the human RAS genes (KRAS, NRAS, and HRAS) and within human BRAF in adult solid tumor epithelial cancers and melanoma, respectively, suggests that children bearing germline mutations in these genes would be pre-disposed to premature malignancy of epithelial origin or melanoma.

<Read More>

Rapamycin reverses hypertrophic cardiomyopathy in a mouse model of LEOPARD syndrome-associated PTPN11 mutation

Talita M. Marin*, Kimberly Keith*, Benjamin Davies, David Connor, Prajna Guha, Xue Wu, Clare Mahone, Michael Bauer, Sotirios Banakos, Roderick Bronson, Kleber Franchini, Benjamin G. Neel  and Maria I. Kontaridis

LEOPARD syndrome (LS) is an autosomal dominant “RASopathy” disorder that manifests with congenital heart disease. Nearly all cases of LS are caused by catalytically inactivating mutations in the protein tyrosine phosphatase (PTP), non-receptor type 11 (PTPN11) gene that encodes the SH2 domain-containing PTP-2 (SHP2). RASopathies typically affect components of the RAS/MAPK pathway, yet it remains unclear how PTPN11 mutations alter cellular signaling to produce LS phenotypes. We therefore generated knockin mice harboring the Ptpn11 mutation Y279C, one of the most common LS alleles.

<Read More>

Progeria, aging and translational medicine: from obscurity to treatment trials and beyond

Leslie B. Gordon, MD, PHD

Hutchinson-Gilford progeria syndrome (Progeria) is a rare segmental premature aging syndrome that affects 200-250 children worldwide at any one time. It is caused by a mutation in the LMNA gene, whose normal lamin A protein product is central to nuclear structure and function in differentiated cells. The global expression of lamin A, and hence the aberrant protein produced in Progeria called progerin, results in a multisystem disease. Children with Progeria die of global, accelerated atherosclerosis at an average age of 13 years.

<Read More>

 Pro-hypertrophic signaling induced by the Shp2 mutation Q510E in mice

Christine Schramm,1 Deborah M. Fine,2 Michelle A. Edwards,1 Maike Krenz1 1Department of Medical Pharmacology & Physiology / Dalton Cardiovascular Research Center and 2Department of Veterinary Medicine and Surgery, University of Missouri-Columbia

Rationale: The identification of mutations in PTPN11 (encoding the protein tyrosine phosphatase Shp2) in families with congenital heart disease has facilitated mechanistic studies of various cardiovascular defects. However, the roles of normal and mutant Shp2 in the developing heart are still poorly understood. We focused our studies on the Q510E mutation in Shp2, which is associated with a particularly severe form of hypertrophic cardiomyopathy in patients. It is still under debate whether patients with this particular mutation rather fall into the Noonan Syndrome or into the LEOPARD Syndrome category since clinical differentiation between these syndromes can be very challenging, in particular in infants. To unravel the underlying disease mechanism of this aggressive mutation, we tested the biochemical characteristics of the Q510E-Shp2 protein and investigated the downstream signaling events triggered by this mutation in a mouse model.

 <Read More>

Piebaldism with Multiple Café-au-lait Macules and Intertriginous Freckling: Evidence for a Common Pathway between KIT and SPRED1

Yvonne E. Chiu, MD,1 Stefanie Dugan, MS,2 Donald G. Basel, MD, 2Dawn H. Siegel, MD1 Department of Dermatology-Division of Pediatric Dermatology, Medical College of Wisconsin and Children’s Hospital of Wisconsin Department of Pediatrics-Section of Genetics, Medical College of Wisconsin and Children’s Hospital of Wisconsin

A 5 year old boy presented with a congenital depigmented patch of the forehead, as well as acquired white forelock, depigmentation of the medial eyebrows, and depigmented patches of the body.  Additionally, he had started to develop multiple café-au-lait macules (CALMs) and freckling of the axillae and inguinal folds.  His past history was significant for mild asthma, chronic sinusitis, surgical excision of a thyroglossal duct cyst, and umbilical hernia repair.  There was no developmental delay or hearing loss.  Given concerns by other providers for tuberous sclerosis, neurofibromatosis type 1 (NF1), and Waardenburg syndrome, the patient had a prior work-up consisting of a normal brain MRI, echocardiogram, audiogram, and ophthalmology exam.  His family history was significant for similar skin findings in his father, paternal half-brother, paternal grandmother, and paternal great-grandfather.

<Read More>

 Perinatal or Adult Nf1 Inactivation using Tamoxifen-inducible PlpCre Each Cause Neurofibroma Formation

1Mayes DA, 1Rizvi TA, 1,3Cancelas JA, 1Kolasinski N, 2Ciraolo CM, 4Stemmer-Rachamimov AO, and 1Ratner N Divisions of 1Experimental Hematology and Cancer Biology, and 2Pathology, Cincinnati Children’s Hospital Medical Center, 3Hoxworth Blood Center, University of Cincinnati, Department of Pathology4, Massachusetts General Hospital and Harvard Medical School.
OBJECTIVES Neurofibromas are tumors initiated by biallelic mutation of the NF1 tumor suppressor gene in the Schwann cell lineage. One idea within the field suggests that Nf1 loss must occur within progenitor cells present within a critical window during Schwann cell development in order for neurofibromas to form. To test this hypothesis and to examine whethermyelinating Schwann cells can serve as aneurofibroma cell of origin, Nf1 loss was induced at perinatal or adult timepoints using a tamoxifen-inducible Plp-CreERT driver.

<Read More>

 NSEuroNet – a progress report about the European database

Martin Zenker, Hélène Cavé, Reza Ahmadian, Ype Elgersma, Patrick Raynal, Marco Tartaglia Institute of Human Genetics, University Hospital Magdeburg, Germany

The European network on Noonan syndrome and related disorders (NSEuroNet) is a EU-funded collaborative project that started its activities in 2010. The project is coordinated by Marco Tartaglia and aims at improving the knowledge about RASopathies at the levels of basic research as well as of practical clinical care. We provide a progress report on the RASopathy mutation and phenotype database that is a core part of the NSEuroNet project.

<Read More>

 NRAS mutations – a rare cause of Noonan syndrome

Martin Zenker Institute of Human Genetics, University Hospital Magdeburg, Germany

Noonan syndrome (MIM163950) is a clinically recognizable and genetically heterogeneous disorder. The common denominator of the various genetic alterations found in patients with Noonan syndrome and related disorders is that they cause dysregulation of RAS-MAPK signaling. Even if strict clinical criteria are applied, the molecular genetic lesion currently remains unidentified in about 10-20% of cases, thus suggesting additional genes for Noonan syndrome.

<Read More>

 Noonan syndrome-associated Raf1 mutants with increased or decreased kinase activity differentially activate Erk and cause distinct syndromic  phenotypes

Noonan syndrome (NS) is one of several  “RASopathies” caused by mutations in different components of the RAS-RAF-MEK-ERK MAPK pathway. Germ line mutations in RAF1 (encoding the serine-threonine kinase RAF1) account for ~3-5% of NS. Unlike other NS alleles, RAF1 mutations that confer increased kinase activity are highly associated with HCM.  Surprisingly, other NS-associated RAF1 mutations show normal or decreased kinase activity. To explore the pathogenesis of NS-associated RAF1 mutations, we generated  “knock-in” mice that express kinase-activating (L613V) and impaired (D486N) RAF1 mutants, respectively.

<Read More>

Neurofibromatosis Networking – Building the Tools to Advance Research Discoveries to the Clinic

Objective   Neurofibromatosis (NF) encompasses a group of rare disorders affecting 100,000 Americans. The clinical course of NF is unpredictable: it can lead to deafness, blindness, amputation or disfigurement.  The genes for the two major forms, NF1 and NF2, were identified in the early 1990’s, and the molecular signaling pathways are well understood.  The primary funders of US NF research are the Congressionally Directed Medical Research Program for Neurofibromatosis Research ($10M-$25M/year) and NIH ($11-$15M/year). Major tools developed in the last 10 years include transgenic mouse models representing individual NF manifestations, and a Phase II Clinical Trials Consortium.  In 2006, the Children’s Tumor Foundation (CTF) examined the NF research landscape looking for ‘funding gaps’ that if filled could rapidly advance NF discoveries to the clinic. The goal was to implement recommendations within 5 years.

 <Read More>

 Neurodevelopmental Profiles for RASopathies

The last few decades have seen rapid progress toward establishing neuropsychological profiles associated with Ras/MAPK pathway syndromes. Among affected individuals, cognitive functioning can vary from significant global intellectual disability to mild delays in specific domains. In a subset of individuals, no significant learning or behavior problems are seen. Research using animal models has begun to reveal neurobiological sources of differences in learning and memory processes in the RASopathies, as well as suggest potential methods to circumvent these differences. However, additional research is needed to identify the most useful neurocognitive targets of intervention in humans.

<Read More>

 N-myristoylation of SHOC2 and Mazzanti syndrome

Cordeddu and co-workers (Nat. Genet. 2009, 41:1022-1026) reported that the invariant c.4A>G missense (p.Ser2Gly) change in the SHOC2 gene, which encodes a widely expressed non-membranous protein that positively modulates RAS-MAPK signal flow, underlies a distinctive RASopathy previously recognized as Noonan-like syndrome with loose anagen hair [OMIM 607721] by Mazzanti and colleagues (Am. J. Med. Genet. 2003, 118A:279-286). This mutation was demonstrated to promote N-myristoylation of the protein and its aberrant targeting to the plasma membrane. N-myristoylation is an irreversible cotranslational lipid modification, and is observed to occur in many signal transducers that require to be anchored to the cytoplasmic leaflet of cell membranes to carry out their function.

 <Read More>


Costello Syndrome (CS) is a rare, complex, developmental disorder characterized by a number of features including— failure to thrive, characteristic facies, delay in intellectual development, hypertrophic cardiomyopathy, arrhythmia, and predisposition to both benign and malignant tumors. Past studies identifying gain-of-function mutations in the HRAS gene as the basis of human CS, and strong conservation with the mouse ortholog Hras1, have led to the development of a Gly12Val (G12V) mouse model of CS.

 <Read More>

 Molecular genetic analysis of the protein tyrosine phosphatase Shp2 (PTPN11) in the mouse telencephalon

Lisa Ehrman1, Diana Nardini1, Tilat Rizvi1, Nancy Ratner1, Masato Nakafuku2, Jeffrey Robbins3, and Ronald R. Waclaw1 1Division of Experimental Hematology and Cancer Biology, 2Division of Developmental Biology, 3Division of Molecular Cardiovascular Biology, Cincinnati Children’s Hospital Medical Center Cincinnati, OH

Shp2 (PTPN11) is an intracellular protein tyrosine phosphatase that is critical for mediating cell signaling in response to growth factors.  Germline mutations in PTPN11 have been identified Noonan and LEOPARD syndrome patients.  Patients with either syndrome exhibit several congenital malformations including a variety of cardiovascular and skeletal defects.  In addition to these defects, there is also an increased incidence of learning disabilities and cognitive impairment observed in both syndromes. The specific brain abnormalities that lead to these neurocognitive defects remain unknown. The goal of our study is to utilize mouse genetics to understand the role of Shp2 (PTPN11) in the telencephalon, which is the region of the brain most associated with higher neural functions like cognition and emotion.

 <Read More>

 Mechanisms underlying the cognitive deficits in animal models of rasopathies

Alcino J. Silva Departments of Neurobiology, Psychiatry and Biobehavioral Sciences, Psychology and Brain Research Institute, UCLA Los Angeles, California 90095 Our laboratory has been studying the molecular and cellular mechanisms responsible for learning deficits in Rasopathies, a class of genetic disorders that alter Ras signaling mechanisms, and that result in a broad range of somatic, neurologic and psychiatric phenotypes. Although our work started with studies of neurofibromatosis type I (NF1), we have also studied several other rasophaties. For example, recently we uncovered molecular and cellular mechanisms responsible for the learning deficits associated with Noonan syndrome (NS), a genetic disorder with an incidence of 1 in ~2,500. As with NF1 patients, a significant percentage of NS patients show cognitive deficits, such as learning disabilities and mental retardation. Mutations in the PTPN11 gene, which encodes the non-receptor protein tyrosine phosphatase SHP-2, account for ~50% of NS cases. Just as NF1, NS-associated SHP-2 mutants result in increases in Ras-ERK signaling, which is critically involved in learning and memory.

 <Read More>

Lovastatin, a cholesterol-lowering medication, improves cognitive deficits in children with Neurofibromatosis type 1: Phase 1 study results

Maria T. Acosta, M.D. Children’s National Medical Center, Washington, DC, USA Background: Cognitive deficits are the most important long term co-morbidity in NF1 patients. In a mouse model of neurofibromatosis type 1(NF1), lovastatin improved cognitive deficits and executive functioning. Methods:  Using a standard phase 1 study design, we examined the safety and biological impact of lovastatin as a treatment for the neurocognitive deficits in a group of 24 children 10-17 years old with diagnosis of NF1. A subset of patients underwent a 12-hour pharmacokinetics analyses.

 <Read More>

 Induced pluripotent stem cell-derived cardiomyocytes as a model to study cardiac defects in Noonan syndrome and related disorders

Rebecca Josowitz1, Sonia Mulero-Navarro1, Ilan Riess1, Sherly Pardo3 Sunita D’Souza2, Xonia Carvajal-Vergara2, Marco Tartaglia4, Ihor Lemischka2, Bruce D. Gelb1
1Child Health and Development and 2Black Family Stem Cell Institutes, Mount Sinai School of Medicine, New York, NY, USA, 10029, 3Recinto de Ciencias Medicas, Universidad de Puerto Rico, San Juan, Puerto Rico, 00936-5067, 4Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Rome, Italy, 00161.

Mutations in PTPN11 and BRAF, genes involved in the RAS/MAPK pathway, are implicated in a variety of clinical disorders, such as Noonan syndrome (NS), LEOPARD syndrome (LS), and cardio-facial-cutaneous syndrome (CFCS), members of a family of disorders termed the “RASopathies”.  These disorders are characterized by skeletal and neurological defects, as well as a high prevalence of cardiovascular abnormalities. Hypertrophic cardiomyopathy (HCM) is observed in 90% of patients with PTPN11 mutations causing LS and 40% of patients with CFCS, yet PTPN11 mutations causing NS are negatively associated with HCM. In order to further elucidate the molecular mechanisms of RASopathy-associated HCM, we have generated human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes as representative models of these syndromes. We have previously demonstrated that hiPSCs derived from patients with LS exhibit altered RAS/MAPK signaling and their derived cardiomyocytes display a molecular phenotype consistent with the cardiac hypertrophy observed clinically.

<Read More>

 Identification of novel genes critical to survival of malignant peripheral nerve sheath tumor cells via medium throughput screening using lenti-viral shRNA

Ami .V. Patel, Ph.D.,Nancy Ratner, Ph.D., Cincinnati Childrens Hospital Medical Center, Dept. of Experimental Hematology and Cancer Biology, Cincinnati, OH.

Malignant peripheral nerve sheath tumor (MPNST) is a soft tissue sarcoma that is highly invasive and eventually lethal. About 50% of MPNSTs have mutation and/or loss of the NF1 gene, while the rest are spontaneous. Many MPNSTs also show mutations in p53 and/or homozygous deletion of CDKN2. In an effort to identify novel genes that play key roles in MPNST tumorigenesis, we performed a genome wide micro-array analysis using human neurofibroma and MPNST (Miller et al., 2009). This analysis identified 130 genes that are up-regulated >3 fold in MPNSTs as compared to normal human Schwann cells. Over expression of these genes in tumors as compared to normal cells suggested that some might be critical for survival of MPNST cells. This hypothesis was directly tested by studying effects on survival of MPNST cells invitro post down regulation of the 130 genes using lenti-viral short hairpin (sh) RNA. For each shRNA experiment a shnon-targeting lenti-virus was used as a negative control and shSOX9, a construct previously shown to kill MPNST cells in vitro, was used as a positive control for an effect on cell survival. Screening was performed sequentially allowing for selection of genes with significant effects on survival.  In screen I, T265 MPNST cells were exposed to each shRNA virus.  In screen II, shRNAs were tested for effects on adenocarcinoma cells (A549) vs T265 cells. These two rounds of screens identified 8/130 genes specific for survival of T265 cells. Screen III wasperformed on four different MPNST cell lines, including T265 (NF1-/-), 8814 (NF1-/-), S462TY (NF1-/-) and SSTS26T (sporadic MPNST wild-type for NF1), to identify shRNA’s with similar or different effects on cell survival in the presence or absence of wild-type NF1gene.  No significant difference in survival was observed for NF null MPNST cells vs sporadic MPNST cell line for any gene. This approach facilitates a streamlined pathway from genome wide gene expression analysis to identification of 8 novel genes critical to survival of cancer cells in vitro and potential therapeutic targets toward a cure for MPNSTs. Supported by NIH28840 (to NR).  A.P. is the recipient of a DOD NF Postdoctoral Fellow Award.

<Read More>

HRAS mutants identified in Costello syndrome patients can induce cellular senescence: possible implications for the pathogenesis of Costello syndrome

Tetsuya Niihori, Yoko Aoki, Yoichi Matsubara Department of Medical Genetics, Tohoku University School of Medicine, Sendai, Japan;

Costello syndrome (CS) is a congenital disease that is characterized by a distinctive facial appearance, failure to thrive, mental retardation and cardiomyopathy. In 2005, we identified that heterozygous germline mutations in HRAS caused CS. Several studies have shown that CS-associated HRAS mutations are clustered in codons 12 and 13, and mutations in other codons have also been identified. However, a comprehensive comparison of the substitutions identified in patients with CS has not been conducted. In the current study, we identified four mutations (p.G12S, p.G12A, p.G12C and p.G12D) in 21 patients and analyzed the associated clinical manifestations of CS in these individuals. <Read More>

 How Loss of Neurofibromin in Oligodendrocytes Affects the Brain

Mayes D.A.,Rizvi T.A., Kolasinski N., Miller S.,& Ratner N. Department of Experimental Hematology & Cancer Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati OH

Neurofibromatosis type 1 patients are predisposed to central nervous system (CNS) phenotypes including enlarged brains, delayed acquisition of motor skills, brain tumors, and cognitive deficits.  Imaging and pathologic analysis suggest that changes in white matter myelination may underlie both the enlargement of white matter tracts that contributes to megancephaly, and/or hyper-intense signals visualized on MRI. To study the role(s) of Nf1 and HRasin oligodendrocytes, we examined the optic nerve and corpus callosum,myelinated fiber tracts.

<Read More>

High-throughput drug screening to identify novel small molecules to rescue Noonan syndrome phenotypes in Drosophila

Perundurai S Dhandapany1, Susumu Hirabayashi2, Elizabeth Horvath1, Kimihiko Oishi1, Ross L Cagan2 and Bruce D. Gelb1
1Departments of Pediatrics and Genetics & Genomic Sciences and the Child Health and Development Institute, 2Department of Developmental and Regenerative Biology, Mount Sinai Medical School, One Gustave L. Levy Place, Box 1020, NY 10029, USA

BACKGROUND: Noonan syndrome (NS) is a pleiomorphic developmental disorder, for which increased RAS pathway signaling is the primary cause. Gain-of-function mutations in PTPN11, encoding SHP-2, are the major cause. While powerful Ras signaling inhibitors are in development for cancer, such drugs may not be useful for long-term use in children with NS. To find drugs that restore normal Ras signaling in NS, we are using a transgenic Drosophila model with the D61G mutation in corkscrew mutation (cswD61G)the fly orthologue of PTPN11.

<Read More>

 Hematopoietic differentiation abnormalities in Noonan syndrome and Noonan/JMML iPS cells

Sonia Mulero-Navarro1, Ilan Riess1, Sherly Pardo3, Ana Sevilla2, Dung-Fang Lee2, Sunita D’Souza2, Helene Cave4, Marco Tartaglia5, Ihor Lemischka2, Bruce D. Gelb1

1Child Health and Development and 2Black Family Stem Cell Institutes, Mount Sinai School of Medicine, New York, NY, USA, 10029, 3Recinto de Ciencias Medicas, Universidad Puerto Rico, San Juan, Puerto Rico, 00936-5067, 4Departement Genetique Hopital Robert Debre AP-HP, Paris, France,5Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Rome, Italy, 00161

BACKGROUND: Noonan syndrome (NS) is a genetic developmental disorder caused by deregulation of the RAS/MAPK pathway. Germ-line mutations in PTPN11, which encodes SHP-2, a key component of the RAS/MAPK pathway, cause 50% of NS, while somatic mutations in this gene account for 35% of juvenile myelomonocytic leukemia (JMML). Children with NS and specific PTPN11 mutations are at increased risk for developing JMML, inferring that certain SHP-2 mutants result in abnormal differentiation and cell maturation in hematopoietic lineages. The molecular mechanisms resulting from SHP-2 dysregulation that lead to these abnormalities remain largely unexplored.

<Read More>

 Hematologic abnormalities associated with patients with cardio-facio-cutaneous syndrome

Yuka Saito1, Yoko Aoki1, Tetsuya Niihori1, Akira Ohtake2, Atsushi Shibuya2, Kazuhito Sekiguchi,3, So-ichi Suenobu3, Taturo Izumi3, Hideki Muramatsu4, Seiji Kojima4, Shigeo Kure1,5, Shigeru Tsuchiya5, Yoichi Matsubara1
1) Dept Med Genet, Tohoku Univ Sch Med, Sendai, Japan; 2) Dept Pediatr, Saitama Med Univ, Moroyama, Saitama, Japan. 3) Dept Pediatr and Child Neurol, Oita Univ Facul Med, Oita, Japan 4) Dept. Pediatr, Nagoya Univ Graduate Sch Med, Nagoya, Japan 5) Dept. Pediatr. Tohoku Univ Sch Med

Cardio-facio-cutaneous (CFC) syndrome is a multiple congenital anomaly/mental retardation syndrome characterized by a distinctive facial appearance, ectodermal abnormalities and heart defects. Clinically, it overlaps with both Noonan syndrome and Costello syndrome. Mutations in KRASBRAF and MAP2K1/2 (MEK1/2) have been identified in patients with CFC syndrome. By age 20, the cumulative incidence of cancer was approximately 4% for Noonan syndrome and 15% for Costello syndrome (Christian P. Kratz. AJMD, 2011). For Costello syndrome, tumor-screening protocols have been proposed. In contrast, little attention has been paid to the development of tumors in patients with CFC syndrome.

<Read More>

Growth Hormone Signaling

Jessica Schwartz, Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI.

Growth Hormone (GH) is a major regulator of statural growth and metabolism. Changes in gene expression and in their regulatory transcription factors often underlie the physiological responses to GH. Recent insights in understanding GH signaling indicate that the interaction of GH with GH receptors on target cells initiates multiple signaling cascades that culminate in changes in transcription factors in the nucleus. Through analysis of profiles of GH-regulated genes, we find that in addition to well-recognized Stat5-mediated signaling, GH utilizes Ras/MAPK-mediated signaling to regulate the phosphorylation and function of C/EBP-CREB family transcription factors, which in turn modulate multiple genes in response to GH.

<Read More>

Growth Hormone Signaling

Jessica Schwartz, Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI.

Growth Hormone (GH) is a major regulator of statural growth and metabolism. Changes in gene expression and in their regulatory transcription factors often underlie the physiological responses to GH. Recent insights in understanding GH signaling indicate that the interaction of GH with GH receptors on target cells initiates multiple signaling cascades that culminate in changes in transcription factors in the nucleus. Through analysis of profiles of GH-regulated genes, we find that in addition to well-recognized Stat5-mediated signaling, GH utilizes Ras/MAPK-mediated signaling to regulate the phosphorylation and function of C/EBP-CREB family transcription factors, which in turn modulate multiple genes in response to GH.

<Read More>

 Germline mutations of the CBL gene : a new RASopathie with predisposition to juvenile myelomonocytic leukemia (JMML)

Hélène Cavé, PharmD, PhD
Genetics department, CHU Robert Debré and INSERM U940, Universitary institute of Haematology, Paris, France

CBL, an E3 ubiquitin ligase and multi adaptor protein, controls proliferative networks by downregulating the growth factor receptor signaling cascades in various cell types. CBL missense mutations have recently been found in 10-15% patients having juvenile myelomonocytic leukemia (JMML), an aggressive myelodysplastic and myeloproliferative neoplasm of early childhood. The majority of these patients displays germline heterozygous CBL mutations. The process of tumorigenesis is in line with the classical Knudson hypothesis for tumor suppressor genes. The germline mutation, inherited from the parents in about half of cases, represents the first hit. Somatic loss of heterozygosity of 11q23.3, due to acquired somatic uniparental isodisomy is the second hit, positively selected for in JMML cells. Noteworthy, a mutation targeting Y371, is found in about half of the patients with germline CBL mutation who develop JMML.

<Read More>

Germline K-RasV14I mutation causes Noonan Syndrome and fatal myeloproliferative disorder

Isabel Hernández-Porras1, Alberto J. Schuhmacher1,§, Salvatore Fabbiano2, Marta Cañamero1, Francisca Mulero1, Xosé R. Bustelo2, Carmen Guerra1 and Mariano Barbacid1

1Centro Nacional de Investigaciones Oncológicas (CNIO), E-28029 Madrid, Spain.2Centro de Investigación del Cáncer, CSIC/University of Salamanca, Campus Unamuno, E37007, Salmanca, Spain. §Present address: Cancer Biology and Genetics Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA

Noonan syndrome (NS) is an autosomal dominant disorder characterized by short stature, distinctive facial dysmorphism, cardiac defects and increased risk of leukemia. Approximately 50% of NS cases are associated with germline mutations in PTPN11. Other known NS genes include SOS1, RAF1, BRAF, K-RAS, N-RAS and SHOC2. Although K-RAS mutations are found in a low percentage of clinically diagnosed patients (<3%), they usually correlate with the appearance of more severe symptoms. These mutations result in milder activation of the K-RAS protein and are different from the somatic mutations found in human tumors.

<Read More>

Epidemiological features of Costello Syndrome and Cardio-facio-cutaneous Syndrome: findings from the first nationwide survey

Y. Abe1, Y. Aoki1, S. Kuriyama2, H. Kawame3, N. Okamoto4, K. Kurosawa5, H. Ohashi6, S. Mizuno7, T. Ogata8, S. Kure9, T. Niihori1, Y. Matsubara1.
1) Dept Med Genet, Tohoku Univ Sch Med, Sendai, Japan; 2) Dept Mol Epidemiolo, Tohoku Univ Sch Med, Sendai, Japan; 3) Dept Genet Counseling, Ochanomizu Univ, Tokyo, Japan; 4) Dept Med Genet, Osaka Med Ctr & Res Inst for Maternal & Child Health, Izumi, Osaka, Japan; 5) Dev Med Genet, Kanagawa Children’s Med Ctr, Yokohama, Japan; 6) Dev Med Genet, Saitama Children’s Med Ctr, Saitama, Japan; 7) Dept Pediatr, Central Hosp, Aichi Human Service Ctr, Kasugai, Aichi, Japan; 8) Dept Pediatr, Hamamatsu Univ Sch Med, Hamamatsu, Shizuoka, Japan; 9) Dept Pediatr, Tohoku Univ Sch Med, Sendai, Japan.

Costello syndrome and cardio-facio-cutaneous (CFC) syndrome are a group of genetic disorders which result from dysregulation of the RAS/MAPK cascade. Germline mutations in HRAS are causative for Costello syndrome and those in KRAS, BRAF and MAP2K1/2 (MEK1/2) cause CFC syndrome. Since our discovery of HRAS mutations in Costello syndrome (2005) and KRAS/BRAF mutations in CFC syndrome (2006), approximately 200 patients of each syndrome have been reported. However, clinico-epidemiological features of these disorders remain to be elucidated.

<Read More>

 Epidemiological Features of Costello and CFC Syndromes

Yoko Aoki and Yoichi Matsubara
Department of Medical Genetics, Tohoku University School of Medicine, Sendai, Japan

Only a few Japanese patients with Costello and CFC syndromes had been reported by 2005. The number of patients is growing after the identification of causative genes for these disorders. However, clinico-epidemiological features of these disorders remain to be elucidated. In order to assess the prevalence, natural history, prognosis and tumor incidence, we conducted a nationwide prevalence study of patients with Costello and CFC syndromes in Japan. The protocol we followed has been established by study groups on intractable diseases granted by the Ministry of Health and Welfare of Japan. The prevalence of intractable diseases, including moyamoya disease, pancreatitis and sudden deafness has been reported using the same protocol.

<Read More>

Clinical pathways: the DYSCERNE experience

Bronwyn Kerr,M.B.B.
University of Manchester, Manchester, UK

Establishing best practice guidelines for rare disorders is difficult. Literature series are often small, and may be biased towards the most severely affected. Information on the natural history of rare disorders over a lifetime is usually incomplete. Reports of treatments and interventions will usually involve only small numbers of patients and short-term follow-up.

For affected people and their families, a related issue is the provision of available information in formats that are useful to both affected individuals and their non-expert care givers.

<Read More>

Characterisation of Costello syndrome mutations in sperm and implications for genetic counselling

Goriely A1*, McGowan SJ1, McVean GAT2& Wilkie AOM1

1Weatherall Institute of Molecular Medicine and 2Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.

Costello and Noonan syndromes are part of a small class of congenital syndromes called ‘paternal age-effect’ (PAE) disorders. Other members of this class include Apert and Crouzon syndromes (associated with FGFR2 mutations), achondroplasia, thanatophoric dysplasia (FGFR3 mutations) and MEN2a/b (RET mutations). In the vast majority of cases, these PAE disorders are caused by spontaneous point mutations and exhibit the collective properties of (1) very high apparent rates of germline base substitution (~500-1000-fold over background), (2) exclusive paternal origin, and (3) an increased average age of the unaffected father from whom the mutation originates (PAE). As somatic events, the same gain-of-function mutations have been associated with various human cancers.

 <Read More>

 Assessing Genotype-Phenotype Correlation in Costello Syndrome with the Use of a Severity Score

Elizabeth McCormick

Costello syndrome, a rare but variable genetic disorder characterized by a failure to thrive in infancy, skeletal, muscular, cardiac, and neurological abnormalities, tumor predisposition, and intellectual disability, is caused by an alteration of the HRAS gene.  Several different mutations in the HRAS gene result in the constellation of features that characterize Costello syndrome. It is possible that different mutations in this gene may lead to differing degrees of effect.  In order to assess a possible genotype-phenotype correlation, a severity scoring system was developed and each individual with Costello syndrome was scored based on certain manifestations of Costello syndrome present in early childhood, childhood, and young adulthood.

 <Read More>

 A role for synaptic plasticity in the cognitive deficits of Costello syndrome mice

Thijs van der Vaart 1,2,3, Iris Overwater 1,3, Melika Mozaffari 1,3, Mehrnoush Aghadavoud 1,3, Jaga Schreiber 1,3, Ype Elgersma 1,3
1 Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands , 2 Department of Pediatrics, Erasmus MC, Rotterdam, The Netherlands3 ENCORE Expertise Center for Neurodevelopmental disorders

Costello syndrome is a rare RASopathy caused by activating mutations in the HRAS gene. Cognitive impairments and behavioral problems are common amongst children with Costello syndrome. To understand the underlying mechanisms of these deficits, mouse models have been developed in which the endogenous HRAS gene has been mutated to express constitutively active HrasG12V, similar to patients. HrasG12V-mice showed spatial learning deficits in the Morris Water Maze, in the absence of motor performance problems or gross brain pathology.

 <Read More>

 A novel HRAS substitution (c.266C>G; p.S89C) resulting in decreased downstream signaling reveals a new dimension of RAS pathway dysregulation in human development

Gripp, KW1, Bifeld, E2, Hopkins, E1, Vinette, K3, Kirwin, S3, Stabley, D3, Sol-Church, K3, Rosenberger, G2
1 Division of Medical Genetics – A. I. duPont Hospital for Children, Wilmington, DE, USA
2 Institute of Human Genetics – University Medical Center Hamburg Eppendorf, Hamburg, Germany
Biomedical Research – A. I. duPont Hospital for Children, Wilmington, DE, USA

Costello syndrome was delineated based on its distinctive phenotype including coarse facial features, severe failure to thrive, intellectual disability, cardiac abnormalities and a high malignancy risk. Costello syndrome is caused by germline mutations in HRAS encoding a small GTPase which cycles between an inactive, GDP-bound and an active, GTP-bound state. Mutations in >90% affect Gly12 or Gly13 and are associated with a relatively homogeneous Costello syndrome phenotype. The same amino acid substitutions occur as somatic changes in malignant tumors and result in constitutive HRAS activation and increased RAF-MEK-ERK and PI3K-AKT signal flow. A few less common germline missense mutations affecting other HRAS codons were reported in patients with a distinctive, usually attenuated or mild, Costello syndrome (p.T58I, p.K117R and p.A146T/V), or in individuals with a predominant muscular phenotype (p.Q22K and p.E63K) [1]. These changes were also suspected or proven to enhance HRAS-dependent signaling.

 <Read More>

A Drosophila Approach to Ras Pathway Disease

Susumu Hirabayashi, Erdem Bangi, Tirtha Das, Benjamin Levine, Justin Graves, Alex Teague, Dhandapany Perundurai, Bruce Gelb, and Ross Cagan
Mount Sinai School of Medicine

The Ras pathway is involved in a broad palate of diseases. Typically, it acts in conjunction with other pathways; this cross-talk occurs at multiple levels: signaling, cell, tissue, and organism. Failure to account for these complexities has led to limited success in therapeutics that target Ras pathway activity. We have utilizedDrosophila to develop whole animal models designed to account for aspects of this complexity. I will discuss how our efforts highlight emergent properties as Ras signaling combines with other pathways in disease states such as cancers of the thyroid, breast, lung, and colon.

<Read More>