Noonan Syndrome Patients Research Articles

Long-term efficacy of recombinant human growth hormone therapy in short-statured patients with Noonan syndrome.

PurposeNoonan syndrome (NS) is characterized by short stature, heart anomalies, developmental delays, dysmorphic features, cryptorchidism, and coagulation defects. Several studies reported the short-term effects of recombinant human growth hormone (rhGH) treatment on the improvement of height. This study was performed to evaluate the long-term efficacy of rhGH in children with NS in Korea.MethodsThis study included 15 prepubertal NS children who received rhGH subcutaneously at a dose of 50–75 µg/kg/day for 6 days a week for at least >3 years. Preand posttreatment data, such as height, weight, bone age, insulin-like growth factor 1 (IGF-1), and IGF binding protein 3 (IGFBP-3) levels, were collected every 6 months.ResultsChronologic age and bone age at the start of treatment were 7.97±1.81 and 5.09±2.12 years, respectively. Height standard deviation score (SDS) was increased from –2.64±0.64 to –1.54±1.24 years after 3 years (P<0.001). Serum IGF-1 SDS levels were elevated from –1.28±1.03 to –0.10±0.94 (P<0.001). Height SDS was more increased in subjects without PTPN11 mutations compared to those with mutations after 3 years (P=0.012). However, the other parameters, including bone age, IGF-1 SDS, and IGFBP-3 SDS, were not significantly different between patients with and without PTPN11 mutations.ConclusionAlthough this study included a relatively small number of patients, long-term rhGH therapy in NS patients was safe and effective at improving height, growth velocity, and serum IGF-1 levels, in accordance with previous studies. However, the meticulous monitoring of potential adverse events is still needed because of high dose of rhGH and preexisting hyperactivity of RAS-MAPK pathway. Patients with PTPN11 mutations demonstrated a decreased response to rhGH therapy compared to those without mutations.

Left Ventricular Noncompaction in Noonan Syndrome

Noonan Syndrome (NS) is a relatively common genetic disorder with complete penetrance and variable expressivity. More than 80% of NS patients have cardiovascular abnormalities, including malformations and cardiomyopathy. However, the occurrence of left ventricular non compaction (LVNC) in a series of NS patients has not been studied. We present a case series of 6 patients from five families with NS and LVNC. Causative NS mutations were identified in 40% of unrelated patients. LVNC was present as an isolated finding, associated with cardiovascular malformation (CVM), and/ or associated with hypertrophic cardiomyopathy (HCM). This is the first series of LVNC in NS reported. Awareness of NS in LVNC is important for management and family based cardiac screening recommendations.

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.

SOS1 ASSOCIATED NOONAN SYNDROME PRESENTING WITH SUPERNUMARY TEETH; A CASE REPORT

Noonan syndrome (NS) is a common autosomal dominant disorder which is characterized by chest deformation, congenital heart disease, short stature and distinctive facial features. Supernumerary teeth are rarely seen in connection with NS, however severe gingivitis could be seen in NS patients more frequently. In this report, a 12-year-old boy with Noonan syndrome whose oral examination revealed an anterior open bite, supernumerary teeth, severe anterior gingival enlargement, dental crowding associated with diestema, tapered incisors, narrow high-arched palate and prominent rugae was presented. Mutation analysis of the BRAF, PTPN11 and SOS1 genes from peripheral blood cells showed that our patient has p.R552K mutation in exon 11 of the SOS1 gene. Dental problems like supernumary teeth might be seen in NS patients. It is necessary to collaborate with pediatric dentist during the follow-up and treatments of these cases

Five-year response to growth hormone in children with Noonan syndrome and growth hormone deficiency.

BackgroundNoonan syndrome (NS) is an autosomal dominant disorder characterized by specific features including short stature, distinctive facial dysmorphic features, congenital heart defects, hypertrophic cardiomyopathy, skeletal anomalies and webbing of the neck. Molecular screening has shown that the majority of individuals with NS have a mutation in the PTPN11 gene. Noonan syndrome children may show an impaired growth hormone (GH)/insulin-like growth factor axis. Moreover, recombinant human GH (rhGH) has been shown to improve growth rate in patients with NS, although data are still limited.MethodsIn the present study, we assessed growth response following GH therapy (0.25 mg/Kg/week) in 5 (2 M and 3 F) GH-deficient NS patients (NSGHD, mean age 8.5 years) and in 5 (2 M and 3 F) idiopathic GH deficient (IGHD, mean age 8.6 years) patients. We also evaluated the safety of rhGH therapy in NS patients with GHD.ResultsAt the beginning of GH treatment, height and growth rate were statistically lower in NSGHD children than in IGHD ones. During the first three years of rhGH therapy, NSGHD patients showed a slight improvement in height (from −2.71 SDS to −2.44 SDS) and growth rate (from −2.42 SDS to −0.23 SDS), although the values were always significantly lower than in IGHD children. After five years of rhGH treatment, height gain was higher in IGHD children (mean 28.3 cm) than in NSGHD patients (mean 23.6 cm).During the first five years of rhGH therapy, regular cardiological and haematological check-ups were performed, leading to the conclusion that rhGH therapy was safe.ConclusionsIn conclusion, pre-pubertal NS children with GHD slightly increased their height and growth rate during the first years of GH therapy, although the response to rhGH treatment was significantly lower than IGHD children. Furthermore, the therapy appeared to be safe since no severe adverse effects were reported, at least during the first five years. However, a close follow-up of these patients is mandatory, especially to monitor cardiac function.

Noonan syndrome and Turner syndrome patients respond similarly to 4 years' growth-hormone therapy: longitudinal analysis of growth-hormone-naïve patients enrolled in the NordiNet® International Outcome Study and the ANSWER Program.

BackgroundTurner syndrome (TS) and Noonan syndrome (NS) are distinct syndromes associated with short stature and other similar phenotypic features. We compared the responses to growth hormone (GH) therapy of TS and NS patients enrolled in the NordiNet® International Outcome Study (IOS) or the American Norditropin Studies: Web-Enabled Research (ANSWER) Program, which collect information on GH therapy in clinical practice.MethodsRepeated-measures regression analysis was performed on change in height standard deviation score (HSDS) and target-height-corrected HSDS, based on national normal references and treatment-naïve disease-specific references. Models were adjusted for baseline age and HSDS, and average GH dose. The study population was paediatric patients with TS and NS in the NordiNet® IOS and ANSWER Program. Longitudinal growth responses over 4 years were evaluated.ResultsIn 30 NS patients (24 males; baseline age 8.39 ± 3.45 years) and 294 TS patients (7.81 ± 3.22 years), 4-year adjusted ΔHSDS were +1.14 ± 0.13 and +1.03 ± 0.04, respectively (national references). Based on untreated, disease-specific references, 4-year adjusted ΔHSDS for NS and TS were +1.48 ± 0.10 and +1.79 ± 0.04. The analyses showed a significant increase in HSDS over time for both NS and TS (P < 0.0001). ΔHSDS in NS was higher with younger baseline age; ΔHSDS in TS was higher for patients with younger baseline age and higher GH dose.ConclusionsNS and TS patients responded well and similarly over 4 years of GH treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s13633-015-0015-1) contains supplementary material, which is available to authorized users.

Abstract 397: Generation of Raf1 Mutant and Crispr-cas9 Corrected Isogenic iPSC-derived Cardiomyocytes to Model Hypertrophic Cardiomyopathy in Noonan Syndrome

Background: Hypertrophic cardiomyopathy (HCM) is a major cause of death in infants and children. Noonan Syndrome (NS), an autosomal dominant RASopathy disorder, is characterized by multiple defects, including short stature, facial dysmorphia, and congenital heart defects that include HCM. RASopathies are caused by germ-line mutations that affect the canonical RAS-MAPK pathway. Indeed, 95% of NS patients with a mutation in Raf1 , a gene that plays an integral role in this signaling cascade, exhibit HCM. However, the molecular mechanisms that elicit HCM in these patients remain poorly understood. Objective: To generate human NS Raf1 induced-pluripotent stem cells (iPSCs), correct the mutation by genome editing and subsequently differentiate isogenic iPSC lines into cardiomyocytes to characterize the molecular and genetic basis of HCM in NS patients. Results: We generated iPSCs from skin fibroblasts obtained from a NS pediatric patient with a single point mutation in the Raf1 gene. Using electroporation of four episomal vectors containing the Yamanaka factors, we obtained several iPSC clones with normal karyotypes and strong expression of pluripotent markers (Nanog, Oct4, Lin28, Sox2) as detected by RT-qPCR and immunofluorescence. We next corrected the mutation in the NS Raf1 iPSCs using genome editing CRISPR-Cas9 nickase technology. Correction of the Raf1 mutation was determined at the clonal level by PCR followed by Restriction Fragment Length Polymorphism and confirmed by Sanger sequencing. In addition, by inducing a Cas9 nickase-dependent frame shift mutation we also generated an isogenic iPSC line where Raf1 gene was knockout (KO), as demonstrated at the RNA level by RT-qPCR and at the protein level by Western Blot. We next differentiated these multiple iPSC lines (mutant, corrected and KO) into isogenic beating cardiomyocytes, with more &gt;98% of the cells positive for specific cardiomyocyte markers (α-actinin and cardiac TroponinT). Conclusion: We have successfully generated human NS Raf1 isogenic iPSC lines and corresponding cardiomyocytes. Currently, we are in progress of characterizing these cardiac cells to determine the molecular basis of NS-dependent HCM. Ultimately, our work should reveal new targets to treat HCM in NS patients.

External ear anomalies and hearing impairment in Noonan Syndrome

ObjectiveThis is the first cohort in which hearing impairment and external ear anomalies in Noonan Syndrome are described extensively. MethodsRetrospective analysis of the otorhinolaryngological and clinical genetic data from 97 Noonan Syndrome (NS) patients. Forty-four NS patients were seen by an otorhinolaryngologist for the analysis of hearing impairment. In our cohort 80 of the 97 patients were genetically tested. In 71 of these mutations were found: in 48 patients a mutation in PTPN11, in 10 patients in SOS1, in 5 patients in SHOC2, in 5 patients in RAF1, in 1 patient in MAP2K2, in 1 patient in KRAS and in 1 patient in A2ML1. ResultsExternal ear anomalies were reported in 75 NS patients (77%). In 69 patients the ears were low-set, 28 patients had posteriorly rotated ears, 14 patients showed protruding ears and 18 had thickened helices. Hearing impairment was detected in 34 NS patients. Nine patients had sensorineural hearing impairment, two a permanent conductive hearing impairment, two other patients had mixed hearing impairment and 20 patients had conductive hearing impairment in the past, caused by otitis media with effusion. Their temporary conductive hearing impairment resolved between the ages of 2 and 18 years. Sensorineural hearing impairment varied between mild high-frequency hearing impairment and profound (uni- and bilateral) hearing impairment and was progressive in three patients. Four NS patients received cochlear implants for their severe sensorineural hearing impairment. The cohort is small for genotype–phenotype correlations, but sensorineural hearing impairment, especially the bilateral severe hearing impairment, was only seen in patients with a PTPN11 mutation. ConclusionNS is characterized by dysmorphic external ear anomalies and both sensorineural and conductive hearing impairment. Audiological examinations are recommended in all patients with Noonan Syndrome.

Cancer spectrum and frequency among children with Noonan, Costello, and cardio-facio-cutaneous syndromes.

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.

K-RasV14I recapitulates Noonan syndrome in mice.

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.

Abstract LB-10: Rational design of small molecules targeting the Ras GEF, SOS1

Abstract Ras GTPases regulate multiple intracellular signaling processes involved in gene expression, cell proliferation, and cell survival. Driver mutations of Ras signaling components including K,N,H-Ras, EGFR, PDGFR, Raf, PI3K, and Akt have been found in many types of human cancers. The activation of Ras is catalyzed by guanine-nucleotide exchange factors (GEFs), which stimulate the exchange of GDP for GTP. SOS1 is a major RasGEF that transduces receptor tyrosine kinase signals to Ras and associated ERK/Akt pathways. SOS1 gain-of-function mutations have been found in Noonan syndrome patients. In addition, SOS1 has been shown to be differentially expressed in prostate and breast cancer cells, and is involved in malignancies dependent upon aberrant Ras signaling. In the current studies, we undertake a structure-based virtual screening approach, coupled with biochemical and cell biological validations, to identify lead chemical inhibitors targeting the Ras catalytic domain of SOS1. From a 118,500 compound subset of the NCI/DTP Open Chemical Repository, 135 showed optimal docking energy to a grid of the SOS1 catalytic site from which 36 were selected for experimental screening by a guanine nucleotide exchange assay, i.e. FL-GDP dissociation of Ras under the catalysis of SOS1. Two compounds were confirmed as true hits (NSC-674954 and NSC-658497), of which NSC-658497 displayed micromolar IC50s in both inhibiting FL-GDP dissociation (IC50 - 22.2 µM) from Ras and TR-GTP loading (IC50 - 40.8 µM) of Ras catalyzed by Sos1. In addition, NSC-658497 displayed a target binding Kd of ∼7.0 µM as assayed by microscale thermophoresis, along with dose-dependently disrupting the SOS1 interaction with Ras as assayed by a GST-Ras pull-down analysis. Mutagenesis studies mapped NSC-658497 action site to the catalytic site in SOS1, involving specifically residues I825, T828, T829, and Y912. SAR analysis revealed that NSC-658497 elicits its inhibitory effect on SOS1 through a benzopyran and nitrophenyl moiety. In fibroblast cells, NSC-658497 showed dose-dependent efficacy in inhibiting EGF-stimulated Ras and ERK/AKT activities. Furthermore, NSC-658497 dose-dependently inhibited NIH/3T3, MEF, and MIA-PaCa-2 pancreatic cancer cell proliferation in conjunction with their respective downstream Ras-dependent ERK/AKT activities. Thus, we have identified a class of lead chemical inhibitors targeting SOS1 that can serve as useful tools for studying SOS1 mediated oncogenesis and as hits for further development of future cancer therapeutics. Citation Format: Chris Evelyn, Xin Duan, Jacek Biesiada, William Seibel, Jaroslaw Meller, Yi Zheng. Rational design of small molecules targeting the Ras GEF, SOS1. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-10. doi:10.1158/1538-7445.AM2014-LB-10

Next-generation sequencing identifies rare variants associated with Noonan syndrome.

Noonan syndrome (NS) is a relatively common genetic disorder, characterized by typical facies, short stature, developmental delay, and cardiac abnormalities. Known causative genes account for 70-80% of clinically diagnosed NS patients, but the genetic basis for the remaining 20-30% of cases is unknown. We performed next-generation sequencing on germ-line DNA from 27 NS patients lacking a mutation in the known NS genes. We identified gain-of-function alleles in Ras-like without CAAX 1 (RIT1) and mitogen-activated protein kinase kinase 1 (MAP2K1) and previously unseen loss-of-function variants in RAS p21 protein activator 2 (RASA2) that are likely to cause NS in these patients. Expression of the mutant RASA2, MAP2K1, or RIT1 alleles in heterologous cells increased RAS-ERK pathway activation, supporting a causative role in NS pathogenesis. Two patients had more than one disease-associated variant. Moreover, the diagnosis of an individual initially thought to have NS was revised to neurofibromatosis type 1 based on an NF1 nonsense mutation detected in this patient. Another patient harbored a missense mutation in NF1 that resulted in decreased protein stability and impaired ability to suppress RAS-ERK activation; however, this patient continues to exhibit a NS-like phenotype. In addition, a nonsense mutation in RPS6KA3 was found in one patient initially diagnosed with NS whose diagnosis was later revised to Coffin-Lowry syndrome. Finally, we identified other potential candidates for new NS genes, as well as potential carrier alleles for unrelated syndromes. Taken together, our data suggest that next-generation sequencing can provide a useful adjunct to RASopathy diagnosis and emphasize that the standard clinical categories for RASopathies might not be adequate to describe all patients.

Contribution of RIT1 mutations to the pathogenesis of Noonan syndrome: four new cases and further evidence of heterogeneity.

Noonan syndrome (NS) is a common developmental disorder presenting with dysmorphic craniofacial features, heart defects, and short stature. It belongs to the group of RASopathies caused by germline mutations in genes encoding proteins involved in the RAS/MAPK signaling pathway. Although mutations in nine genes are known to cause NS, approximately 30% of the cases still have unexplained etiology. To identify the new causative genes, 42 patients with a clinical diagnosis of NS, who had negative results on Sanger sequencing of PTPN11, SOS1, and RAF1 (the most common NS genes), were selected for whole exome sequencing. In two patients, mutations in recently described new NS gene—RIT1 were found (c.244T&gt;G [p.Phe82Val] and c.270G&gt;C [p.Met90Ile]). Further analysis of a larger cohort (n = 64) of NS patients with classic Sanger sequencing revealed the presence of RIT1 mutation c.284G&gt;C (p.Gly95Ala) in two additional patients. All the detected mutations were localized in switch II domain responsible for GTPase activity. The modeling of RIT1 protein structure revealed that the mutated amino acids and their interacting residues are evolutionary conserved and any residue replacement might change the structural stability and/or protein internal dynamics influencing catalytic activity of the protein. It seems that the identified mutations might alter protein function and therefore, the activity of ERK and P38 MAPK pathways, thus underlying the specific phenotype observed in NS patients. Our study independently confirms the role of RIT1 in the pathogenesis of Noonan syndrome. © 2014 Wiley Periodicals, Inc.

Clinical and Molecular Findings of Tunisian Patients with RASopathies

Noonan syndrome (NS) and related disorders, which are now summarized under the term RASopathies, are caused by germline mutations in genes encoding protein components of the Ras/mitogen-activated protein kinase pathway. In this study, we evaluated the clinical and molecular spectrum of 21 Tunisian patients, recruited by a cardiology unit, for whom RASopathy diagnosis was suspected by clinical geneticists. Overall, 19 patients had a clinical diagnosis of NS and 2 were classified as having Cardiofaciocutaneous (CFC) syndrome. In 52% (n = 11) of patients, a RASopathy has been molecularly confirmed. Mutations in PTPN11 and SOS1 genes were found in patients with diagnosis of NS and BRAF gene mutations in patients with CFC syndrome. As reported from other cohorts, mutations in exons 3 and 8 of the PTPN11 gene predominated in Tunisian NS patients. A very uncommon PTPN11 mutation c.5C>T (p.T2I), the functional consequences of which have so far remained unclear, was identified in one patient. As biased by the mode of recruitment, all patients included in this study had a congenital heart defect, with pulmonary valve stenosis being the most frequent one. Short stature and developmental abnormalities were present in mutation-positive cases. This is the first molecular study in patients from southern Tunisia with RASopathy diagnosis.

Acute Lymphoblastic Leukemia Developing in a Patient With Noonan Syndrome Harboring a PTPN11 Germline Mutation

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.

Dentofacial Changes of Noonan Syndrome: Report of Two Clinical Cases

Noonan syndrome (NS) is a dominant autosomal genetic syndrome that affects both genders with an estimated incidence ranging from 1:1000 to 1:2500. It is an important differential diagnosis in patients with short stature, facial dismorphism, delayed puberty, and cryptorchidism. Among the facial changes typical of NS patients are ocular hypertelorism, eyelid ptosis, external palpebral fissure diverted downward, low implantation and incomplete rotation of the auricle, mandibular micrognathia, short and webbed neck, and a triangular-shaped face.

Abstract PR02: Recurrent oncogenic mutations in the small GTPase RIT1 activate PI3K and MEK.

Abstract Recently, we identified somatic mutations in the RAS-family small GTPase gene RIT1 in 2.4% (10/413) of lung adenocarcinoma tumors. Mutation of RIT1 is mutually exclusive with other oncogenic mutations in the receptor tyrosine kinase/RAS pathway, suggesting that RIT1 mutations are rare driver mutations in lung adenocarcinoma. Oncogenic RIT1 mutations cluster in the switch II domain of the protein and are observed not only in lung adenocarcinoma but also in myeloid malignancies, breast carcinoma, cervical carcinoma, and in the germline of Noonan syndrome patients. Here we functionally characterize 26 RIT1 point mutations and in-frame insertions/deletions in murine fibroblasts and human immortalized lung epithelial cells and find that the majority of somatic RIT1 mutations are able to transform cells. Furthermore, we identified a human lung cancer cell line, NCI-H2110, with an endogenous RIT1 p.M90I mutation. Knockdown of RIT1 in NCI-H2110 cells revealed the role of RIT1 in regulation of PI3K and MEK signaling. Consistently, combination PI3K/MEK inhibition could inhibit cellular transformation induced by ectopic expression of mutated RIT1. Furthermore, PI3K inhibition suppressed in vivo growth of NCI-H2110 cells. These data identify RIT1 as an oncogene and nominate combined PI3K and MEK inhibition as a therapeutic strategy in RIT1-mutated cancers. This abstract is also presented as Poster A04. Citation Format: Alice H. Berger, Fujiko Duke, Marcin Imielinski, Nathan Kaplan, Jeremiah Wala, Geng-Xian Shi, Douglas A. Andres, Matthew Meyerson. Recurrent oncogenic mutations in the small GTPase RIT1 activate PI3K and MEK. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr PR02.

Height Outcome of the Recombinant Human Growth Hormone Treatment in Subjects with Noonan Syndrome: A Meta-Analysis

Children with Noonan Syndrome (NS) present variable growth impairment associated to facial dysmorphology and cardiovascular anomalies. Mutations in several genes of RAS/MAPK signaling pathway have been identified, likely impairing Growth Hormone (GH) sensitivity. If untreated, these patients often remain short in adulthood. Although Recombinant Human GH (rhGH) treatment improves short-term linear growth, poor data on the Final Height (FHt) of rhGH-treated subjects with NS are available. After thorough search of the published literature for pertinent studies, a meta-analysis evaluation of the efficacy and safety of rhGH treatment in NS patients were performed. In total sample (n=885; 70.0% males), administration of rhGH progressively improved height pattern, but relevant catch-up growth was not shown. The rhGH-induced growth improvement appeared until FHt [n=168; –2.151 SDS (95%CI –2.792 to –1.511)]. During 1st year of rhGH treatment, height velocity gain meta-correlated with serum insulin-like growth factor 1 (IGF1) increment [n=31; r=0.685 (95%CI 0.419 to 0.843); P<0.0001] while negative meta-correlation was detected between age at rhGH start and height velocity [n=48; r=–0.608 (95%CI –0.765 to –0.383); P<0.0001]. Height gain after 1-yr rhGH treatment (dosage range 0.35-0.46 mg/kg/wk) was higher in NS patients without protein tyrosine phosphatase non-receptor type 11 (PTPN11) gene mutation [n=33; 0.903 SDS (95%CI 0.552 to 1.254)] than that observed in subjects positive for PTPN11 mutations [n=62; 0.606 SDS (95% CI 0.274 to 0.938); P<0.0001]. While few serious adverse events were reported during rhGH treatment, causal relationship to rhGH therapy was unlikely. In conclusion, this meta-analysis indicates that rhGH treatment progressively improved height outcome of short children with NS. Future studies using carefully titrated rhGH protocols are need to optimize treatment protocols and establish possible risks, if any, leading to clear indications for practice and regulatory agencies.

Growth hormone and noonan syndrome: update in dysfunctional signaling aspects and in therapy for short stature

Short stature is a frequent feature of Noonan syndrome (NS), a disease caused by mutations of genes encoding components of the Ras/mitogen-activated protein kinases (MAPK) signalling pathway. To date numerous patients have been treated with growth hormone (GH) in various countries. However this treatment is still controversial, as its efficacy is a matter of debate. The final height gain of GH therapy represents 5 to 10 cm, at best, which is disappointing considering the length and burden of the treatment. The reasons explaining this lack of efficiency are poorly understood and they seemed to involve a waning effect after the first year of GH treatment or acceleration of bone maturation in patients on GH. Moreover, GH therapy raises questions about its safety, especially in subjects with NS who are at risk for cardiac defects and malignancies. Cases of severe adverse effects were described, yet too sporadically to conclude that they were certainly caused by GH therapy. Novels insights in understanding the dysfunction of GH-dependent processes in NS were recently reported and this manuscript aims at reviewing the latest advances. Clinical data suggested that growth retardation could be caused by a partial postreceptor resistance to GH, an impaired sensitivity to GH which could also explain the modest efficiency of GH therapy in NS patients. Similar observations were also obtained in a NS mouse model harboring a mutation in the gene encoding the tyrosine phosphatase Shp2. In the mouse, the mechanism of GH resistance is thought to involve upregulation by mutated Shp2 of GH-induced Ras/MAPK, a signaling pathway which seemed to play a negative regulatory role in the production of GH mediators involved in bone growth. Despite these recent finding, the underlying mechanisms of growth retardation and GH therapy in NS remain to be further explored in order to improve treatment for short stature.

M to T Rearrangement: An Approach to Correct Webbed Neck Deformity

For the Noonan syndrome patient, the most concerning physical defect is often congenital webbing of the neck or pterygium colli. We present a patient with pterygium colli and a low and laterally displaced nuchal hairline. Since its description, various surgical approaches have been implemented to correct the deformity. Previously reported posterior and lateral approaches have notable disadvantages with regard to hairline displacement and recurrence. In order to address these disadvantages, a new surgical technique was used on this patient. We have termed this technique an M to T rearrangement. Using a lateral approach, the M and T incisions are made and the trapezial fascial web is directly visualized and able to be completely excised. This prevents the recurrence seen with the use of posterior techniques. Inferolateral displacement of hair-bearing skin can be removed with resection of the superior intervening triangle and improves the appearance of the low nuchal hairline. The excision of excess skin along with the zig-zag closure also prevents postoperative scar contraction and recurrence. An important effect of this technique is the prevention of anterior displacement of hair bearing skin. M to T rearrangement is an effective technique for the correction of webbed neck deformities seen in Noonan and Turner syndromes.