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Best Practice & Research. Clinical... Feb 2011Noonan syndrome is a relatively common, clinically variable developmental disorder. Cardinal features include postnatally reduced growth, distinctive facial dysmorphism,... (Review)
Review
Noonan syndrome is a relatively common, clinically variable developmental disorder. Cardinal features include postnatally reduced growth, distinctive facial dysmorphism, congenital heart defects and hypertrophic cardiomyopathy, variable cognitive deficit and skeletal, ectodermal and hematologic anomalies. Noonan syndrome is transmitted as an autosomal dominant trait, and is genetically heterogeneous. So far, heterozygous mutations in nine genes (PTPN11, SOS1, KRAS, NRAS, RAF1, BRAF, SHOC2, MEK1 and CBL) have been documented to underlie this disorder or clinically related phenotypes. Based on these recent discoveries, the diagnosis can now be confirmed molecularly in approximately 75% of affected individuals. Affected genes encode for proteins participating in the RAS-mitogen-activated protein kinases (MAPK) signal transduction pathway, which is implicated in several developmental processes controlling morphology determination, organogenesis, synaptic plasticity and growth. Here, we provide an overview of clinical aspects of this disorder and closely related conditions, the molecular mechanisms underlying pathogenesis, and major genotype-phenotype correlations.
Topics: Adolescent; Child; Costello Syndrome; Ectodermal Dysplasia; Facies; Failure to Thrive; Heart Defects, Congenital; Humans; Infant; Intracellular Signaling Peptides and Proteins; LEOPARD Syndrome; Loose Anagen Hair Syndrome; Mitogen-Activated Protein Kinases; Neurofibromatosis 1; Noonan Syndrome; Protein Tyrosine Phosphatase, Non-Receptor Type 11; Proto-Oncogene Proteins B-raf; Proto-Oncogene Proteins c-cbl; Proto-Oncogene Proteins c-raf; SOS1 Protein
PubMed: 21396583
DOI: 10.1016/j.beem.2010.09.002 -
Anales de Pediatria Jul 2020Noonan syndrome (NS) is a relatively common genetic condition characterised by short stature, congenital heart defects, and distinctive facial features. NS and other...
Noonan syndrome (NS) is a relatively common genetic condition characterised by short stature, congenital heart defects, and distinctive facial features. NS and other clinically overlapping conditions such as NS with multiple lentigines (formerly called LEOPARD syndrome), cardiofaciocutaneous syndrome, or Costello syndrome, are caused by mutations in genes encoding proteins of the RAS-MAPKinases pathway. Because of this shared mechanism, these conditions have been collectively termed «RASopathies». Despite the recent advances in molecular genetics, nearly 20% of patients still lack a genetic cause, and diagnosis is still made mainly on clinical grounds. NS is a clinically and genetically heterogeneous condition, with variable expressivity and a changing phenotype with age, and affects multiple organs and systems. Therefore, it is essential that physicians involved in the care of these patients are familiarised with their manifestations and the management recommendations, including management of growth and development. Data on growth hormone treatment efficacy are sparse, and show a modest response in height gains, similar to that observed in Turner syndrome. The role of RAS/MAPK hyper-activation in the pathophysiology of this group of disorders offers a unique opportunity for the development of targeted approaches.
Topics: Diagnosis, Differential; Genetic Markers; Genotype; Humans; Mitogen-Activated Protein Kinases; Mutation; Noonan Syndrome; Phenotype; Proto-Oncogene Proteins p21(ras)
PubMed: 32493603
DOI: 10.1016/j.anpedi.2020.04.008 -
Heart Failure Clinics Jan 2022RASopathies are multisystemic disorders caused by germline mutations in genes linked to the RAS/mitogen-activated protein kinase pathway. Diagnosis of RASopathy can be... (Review)
Review
RASopathies are multisystemic disorders caused by germline mutations in genes linked to the RAS/mitogen-activated protein kinase pathway. Diagnosis of RASopathy can be triggered by clinical clues ("red flags") which may direct the clinician toward a specific gene test. Compared with sarcomeric hypertrophic cardiomyopathy, hypertrophic cardiomyopathy in RASopathies (R-HCM) is associated with higher prevalence of congestive heart failure and shows increased prevalence and severity of left ventricular outflow tract obstruction. Biventricular involvement and the association with congenital heart disease, mainly pulmonary stenosis, have been commonly described in R-HCM. The aim of this review is to assess the prevalence and unique features of R-HCM and to define the available therapeutic options.
Topics: Cardiomyopathy, Hypertrophic; Genetic Testing; Heart Defects, Congenital; Humans; Noonan Syndrome; Prognosis
PubMed: 34776080
DOI: 10.1016/j.hfc.2021.07.004 -
Orphanet Journal of Rare Diseases May 2008LEOPARD syndrome (LS, OMIM 151100) is a rare multiple congenital anomalies condition, mainly characterized by skin, facial and cardiac anomalies. LEOPARD is an acronym... (Review)
Review
LEOPARD syndrome (LS, OMIM 151100) is a rare multiple congenital anomalies condition, mainly characterized by skin, facial and cardiac anomalies. LEOPARD is an acronym for the major features of this disorder, including multiple Lentigines, ECG conduction abnormalities, Ocular hypertelorism, Pulmonic stenosis, Abnormal genitalia, Retardation of growth, and sensorineural Deafness. About 200 patients have been reported worldwide but the real incidence of LS has not been assessed. Facial dysmorphism includes ocular hypertelorism, palpebral ptosis and low-set ears. Stature is usually below the 25th centile. Cardiac defects, in particular hypertrophic cardiomyopathy mostly involving the left ventricle, and ECG anomalies are common. The lentigines may be congenital, although more frequently manifest by the age of 4-5 years and increase throughout puberty. Additional common features are café-au-lait spots (CLS), chest anomalies, cryptorchidism, delayed puberty, hypotonia, mild developmental delay, sensorineural deafness and learning difficulties. In about 85% of the cases, a heterozygous missense mutation is detected in exons 7, 12 or 13 of the PTPN11 gene. Recently, missense mutations in the RAF1 gene have been found in two out of six PTPN11-negative LS patients. Mutation analysis can be carried out on blood, chorionic villi and amniotic fluid samples. LS is largely overlapping Noonan syndrome and, during childhood, Neurofibromatosis type 1-Noonan syndrome. Diagnostic clues of LS are multiple lentigines and CLS, hypertrophic cardiomyopathy and deafness. Mutation-based differential diagnosis in patients with borderline clinical manifestations is warranted. LS is an autosomal dominant condition, with full penetrance and variable expressivity. If one parent is affected, a 50% recurrence risk is appropriate. LS should be suspected in foetuses with severe cardiac hypertrophy and prenatal DNA test may be performed. Clinical management should address growth and motor development and congenital anomalies, in particular cardiac defects that should be monitored annually. Hypertrophic cardiomyopathy needs careful risk assessment and prophylaxis against sudden death in patients at risk. Hearing should be evaluated annually until adulthood. With the only exception of ventricular hypertrophy, adults with LS do not require special medical care and long-term prognosis is favourable.
Topics: Adult; Cardiomyopathy, Hypertrophic; Child, Preschool; Face; Female; Humans; LEOPARD Syndrome; Mutation; Protein Tyrosine Phosphatase, Non-Receptor Type 11; Skin
PubMed: 18505544
DOI: 10.1186/1750-1172-3-13 -
American Journal of Human Genetics Feb 2006Germline mutations in PTPN11, the gene encoding the protein tyrosine phosphatase SHP-2, cause Noonan syndrome (NS) and the clinically related LEOPARD syndrome (LS),...
Germline mutations in PTPN11, the gene encoding the protein tyrosine phosphatase SHP-2, cause Noonan syndrome (NS) and the clinically related LEOPARD syndrome (LS), whereas somatic mutations in the same gene contribute to leukemogenesis. On the basis of our previously gathered genetic and biochemical data, we proposed a model that splits NS- and leukemia-associated PTPN11 mutations into two major classes of activating lesions with differential perturbing effects on development and hematopoiesis. To test this model, we investigated further the diversity of germline and somatic PTPN11 mutations, delineated the association of those mutations with disease, characterized biochemically a panel of mutant SHP-2 proteins recurring in NS, LS, and leukemia, and performed molecular dynamics simulations to determine the structural effects of selected mutations. Our results document a strict correlation between the identity of the lesion and disease and demonstrate that NS-causative mutations have less potency for promoting SHP-2 gain of function than do leukemia-associated ones. Furthermore, we show that the recurrent LS-causing Y279C and T468M amino acid substitutions engender loss of SHP-2 catalytic activity, identifying a previously unrecognized behavior for this class of missense PTPN11 mutations.
Topics: Adult; Amino Acid Sequence; Cohort Studies; Female; Germ-Line Mutation; Humans; Intracellular Signaling Peptides and Proteins; LEOPARD Syndrome; Leukemia; Male; Mutation; Noonan Syndrome; Protein Conformation; Protein Tyrosine Phosphatase, Non-Receptor Type 11; Protein Tyrosine Phosphatases
PubMed: 16358218
DOI: 10.1086/499925 -
Orphanet Journal of Rare Diseases Nov 2011Xeroderma pigmentosum (XP) is defined by extreme sensitivity to sunlight, resulting in sunburn, pigment changes in the skin and a greatly elevated incidence of skin... (Review)
Review
Xeroderma pigmentosum (XP) is defined by extreme sensitivity to sunlight, resulting in sunburn, pigment changes in the skin and a greatly elevated incidence of skin cancers. It is a rare autosomal recessive disorder and has been found in all continents and racial groups. Estimated incidences vary from 1 in 20, 000 in Japan to 1 in 250, 000 in the USA, and approximately 2.3 per million live births in Western Europe.The first features are either extreme sensitivity to sunlight, triggering severe sunburn, or, in patients who do not show this sun-sensitivity, abnormal lentiginosis (freckle-like pigmentation due to increased numbers of melanocytes) on sun-exposed areas. This is followed by areas of increased or decreased pigmentation, skin aging and multiple skin cancers, if the individuals are not protected from sunlight. A minority of patients show progressive neurological abnormalities. There are eight XP complementation groups, corresponding to eight genes, which, if defective, can result in XP. The products of these genes are involved in the repair of ultraviolet (UV)-induced damage in DNA. Seven of the gene products (XPA through G) are required to remove UV damage from the DNA. The eighth (XPV or DNA polymerase η) is required to replicate DNA containing unrepaired damage. There is wide variability in clinical features both between and within XP groups. Diagnosis is made clinically by the presence, from birth, of an acute and prolonged sunburn response at all exposed sites, unusually early lentiginosis in sun-exposed areas or onset of skin cancers at a young age. The clinical diagnosis is confirmed by cellular tests for defective DNA repair. These features distinguish XP from other photodermatoses such as solar urticaria and polymorphic light eruption, Cockayne Syndrome (no pigmentation changes, different repair defect) and other lentiginoses such as Peutz-Jeghers syndrome, Leopard syndrome and Carney complex (pigmentation not sun-associated), which are inherited in an autosomal dominant fashion. Antenatal diagnosis can be performed by measuring DNA repair or by mutation analysis in CVS cells or in amniocytes. Although there is no cure for XP, the skin effects can be minimised by rigorous protection from sunlight and early removal of pre-cancerous lesions. In the absence of neurological problems and with lifetime protection against sunlight, the prognosis is good. In patients with neurological problems, these are progressive, leading to disabilities and a shortened lifespan.
Topics: DNA Repair; Europe; Humans; Japan; Neoplasms; Nervous System Diseases; United States; Xeroderma Pigmentosum
PubMed: 22044607
DOI: 10.1186/1750-1172-6-70 -
Frontiers in Cardiovascular Medicine 2023As binary switches, RAS proteins switch to an ON/OFF state during signaling and are on a leash under normal conditions. However, in RAS-related diseases such as cancer... (Review)
Review
As binary switches, RAS proteins switch to an ON/OFF state during signaling and are on a leash under normal conditions. However, in RAS-related diseases such as cancer and RASopathies, mutations in the genes that regulate RAS signaling or the RAS itself permanently activate the RAS protein. The structural basis of this switch is well understood; however, the exact mechanisms by which RAS proteins are regulated are less clear. RAS/MAPK syndromes are multisystem developmental disorders caused by germline mutations in genes associated with the RAS/mitogen-activated protein kinase pathway, impacting 1 in 1,000-2,500 children. These include a variety of disorders such as Noonan syndrome (NS) and NS-related disorders (NSRD), such as cardio facio cutaneous (CFC) syndrome, Costello syndrome (CS), and NS with multiple lentigines (NSML, also known as LEOPARD syndrome). A frequent manifestation of cardiomyopathy (CM) and hypertrophic cardiomyopathy associated with RASopathies suggest that RASopathies could be a potential causative factor for CM. However, the current supporting evidence is sporadic and unclear. RASopathy-patients also display a broad spectrum of congenital heart disease (CHD). More than 15 genes encode components of the RAS/MAPK signaling pathway that are essential for the cell cycle and play regulatory roles in proliferation, differentiation, growth, and metabolism. These genes are linked to the molecular genetic pathogenesis of these syndromes. However, genetic heterogeneity for a given syndrome on the one hand and alleles for multiple syndromes on the other make classification difficult in diagnosing RAS/MAPK-related diseases. Although there is some genetic homogeneity in most RASopathies, several RASopathies are allelic diseases. This allelism points to the role of critical signaling nodes and sheds light on the overlap between these related syndromes. Even though considerable progress has been made in understanding the pathophysiology of RASopathy with the identification of causal mutations and the functional analysis of their pathophysiological consequences, there are still unidentified causal genes for many patients diagnosed with RASopathies.
PubMed: 37529712
DOI: 10.3389/fcvm.2023.1176828 -
Orthodontics & Craniofacial Research Jun 2017The RASopathies are a group of syndromes that have in common germline mutations in genes that encode components of the Ras/mitogen-activated protein kinase (MAPK)... (Review)
Review
OBJECTIVES
The RASopathies are a group of syndromes that have in common germline mutations in genes that encode components of the Ras/mitogen-activated protein kinase (MAPK) pathway and have been a focus of study to understand the role of this pathway in development and disease. These syndromes include Noonan syndrome (NS), Noonan syndrome with multiple lentigines (NSML or LEOPARD syndrome), neurofibromatosis type 1 (NF1), Costello syndrome (CS), cardio-facio-cutaneous (CFC) syndrome, neurofibromatosis type 1-like syndrome (NFLS or Legius syndrome) and capillary malformation-arteriovenous malformation syndrome (CM-AVM). These disorders affect multiple systems, including the craniofacial complex. Although the craniofacial features have been well described and can aid in clinical diagnosis, the dental phenotypes have not been analysed in detail for each of the RASopathies. In this review, we summarize the clinical features of the RASopathies, highlighting the reported craniofacial and dental findings.
METHODS
Review of the literature.
RESULTS
Each of the RASopathies reviewed, caused by mutations in genes that encode different proteins in the Ras pathway, have unique and overlapping craniofacial and dental characteristics.
CONCLUSIONS
Careful description of craniofacial and dental features of the RASopathies can provide information for dental clinicians treating these individuals and can also give insight into the role of Ras signalling in craniofacial development.
Topics: Arteriovenous Malformations; Cafe-au-Lait Spots; Capillaries; Costello Syndrome; Craniofacial Abnormalities; Ectodermal Dysplasia; Facies; Failure to Thrive; Germ-Line Mutation; Heart Defects, Congenital; Humans; LEOPARD Syndrome; MAP Kinase Signaling System; Neurofibromatosis 1; Noonan Syndrome; Port-Wine Stain; ras Proteins
PubMed: 28643916
DOI: 10.1111/ocr.12144 -
Revista de Neurologia May 2017The term 'RASopathies' covers a series of diseases that present mutations in the genes that code for the proteins of the RAS/MAPK pathway. These diseases include... (Review)
Review
INTRODUCTION
The term 'RASopathies' covers a series of diseases that present mutations in the genes that code for the proteins of the RAS/MAPK pathway. These diseases include neurofibromatosis type 1, Noonan syndrome, Legius syndrome, LEOPARD syndrome, Costello syndrome and cardiofaciocutaneous syndrome. Involvement of the RAS/MAPK pathway not only increases predisposition to develop tumours, but also determines the presence of phenotypic anomalies and alterations in learning processes.
AIM
To review the use of therapeutic strategies with mechanisms that have a selective action on RASopathies.
DEVELOPMENT
The fact that the RAS pathway is involved in a third of all neoplasms has led to the development and study of different drugs at this level. Some of these pharmaceutical agents have been tested in RASopathies, mainly in neurofibromatosis type 1. Here we analyse the use of different antitarget treatments: drugs that act on the membrane receptors, such as tyrosine kinase inhibitors, in the mTOR pathway or MEK inhibitors. These latter have shown potential benefits in recent studies conducted on different RASopathies.
CONCLUSIONS
Today, thanks to the results from the first studies conducted with MEK inhibitor based mainly on animal models, a number of promising clinical trials are being carried out.
Topics: Abnormalities, Multiple; Animals; Clinical Trials as Topic; Drug Evaluation, Preclinical; Genes, ras; Genetic Diseases, Inborn; Humans; MAP Kinase Kinase Kinases; MAP Kinase Signaling System; Molecular Targeted Therapy; Neoplastic Syndromes, Hereditary; Neurofibromatosis 1; Noonan Syndrome; Protein Kinase Inhibitors; Syndrome; TOR Serine-Threonine Kinases; ras Proteins
PubMed: 28524213
DOI: No ID Found