The neurofibromatosis-Noonan syndrome

Growth Hormone Deficiency in a Child with Neurofibromatosis-Noonan Syndrome

Neurofibromatosis-Noonan syndrome (NFNS) is a distinct entity which shows the features of both NF1 (neurofibromatosis 1) and Noonan syndrome (NS). While growth hormone deficiency (GHD) has been relatively frequently identified in NF1 and NS patients, there is limited experience in NFNS cases. The literature includes only one case report of a NFNS patient having GHD and that report primarily focuses on the dermatological lesions that accompany the syndrome and not on growth hormone (GH) treatment. Here, we present a 13-year-old girl who had clinical features of NFNS with a mutation in the NF1 gene. The case is the first NFNS patient reported in the literature who was diagnosed to have GHD and who received GH treatment until reaching final height. The findings in this patient show that short stature is a feature of NFNS and can be caused by GHD. Patients with NFNS who show poor growth should be evaluated for GHD.

Independent NF1 and PTPN11 mutations in a family with neurofibromatosis-Noonan syndrome

Neurofibromatosis-Noonan syndrome (NFNS), an entity which combines both features of Noonan syndrome (NS) and neurofibromatosis type 1 (NF1), was etiologically unresolved until recent reports demonstrated NF1 mutations in the majority of patients with NFNS. The phenotypic overlap was explained by the involvement of the Ras pathway in both disorders, and, accordingly, clustering of the NF1 mutations in the GTPase-activating protein (GAP) domain of neurofibromin was observed in individuals with NFNS. We report on an 18-month-old girl with typical findings suggestive of NS in combination with multiple café-au-lait spots and bilateral optic gliomas suggestive of NF1. The patient was found to carry a de novo PTPN11 mutation p.T2I as well as the maternally inherited NF1 mutation c.4661+1G>C. Her otherwise healthy mother and brother, who also had the NF1 mutation, showed few café-au-lait spots as the only sign of neurofibromatosis. Since our patient's unique NF1 mutation results in skipping of exon 27a and thus involves the same region, Gap-related domain, that had been shown to be associated with NFNS, her phenotype could have been misleadingly attributed to the NF1 mutation only. Contrarily, absence of both cutaneous neurofibromas and NS features in her relatives with the same NF1 mutation, suggests that the index patient's typical NFNS phenotype is caused by an additive effect of mutations in both NF1 and PTPN11. In contrast to previous findings, we speculate that absence of cutaneous neurofibromas is not solely associated with the recurrent 3-bp in-frame deletion in exon 17.

A variable combination of features of Noonan syndrome and neurofibromatosis type I are caused by mutations in theNF1 gene

Signs of neurofibromatosis type 1 (NF1) and Noonan syndrome (NS), two distinct autosomal dominant disorders, occur together in patients reported as Watson syndrome (WS), neurofibromatosis-Noonan syndrome (NFNS), partial LEOPARD syndrome, NS with features of NF1, and NF1 with Noonan-like features. The molecular basis of these combined phenotypes was poorly understood and controversially discussed over several decades. Only recently, there is increasing evidence for WS and NFNS being allelic to NF1 in the majority of patients. In this study we describe seven novel patients from five unrelated families with variable phenotypes of the NF1-NS spectrum which were systematically analyzed for mutations in the disease-causing genes NF1 for NF1 and PTPN11 for NS. Heterozygous mutations or deletions of NF1 were identified in all patients, while no PTPN11 mutation was found. The NF1 mutation segregated with the phenotype in both familial cases. These results support the hypothesis that variable phenotypes of the NF1-NS spectrum represent variants of NF1 in the majority of cases. Constitutive deregulation of the Ras pathway either through activating mutations of PTPN11 or through haploinsufficiency of neurofibromin, which acts as a Ras-inactivating GTP-ase, is probably the common pathogenetic mechanism explaining the phenotypic overlap of NS and NF1.

NF1 gene mutations represent the major molecular event underlying neurofibromatosis-Noonan syndrome

Neurofibromatosis type 1 (NF1) demonstrates phenotypic overlap with Noonan syndrome (NS) in some patients, which results in the so-called neurofibromatosis-Noonan syndrome (NFNS). From a genetic point of view, NFNS is a poorly understood condition, and controversy remains as to whether it represents a variable manifestation of either NF1 or NS or is a distinct clinical entity. To answer this question, we screened a cohort with clinically well-characterized NFNS for mutations in the entire coding sequence of the NF1 and PTPN11 genes. Heterozygous NF1 defects were identified in 16 of the 17 unrelated subjects included in the study, which provides evidence that mutations in NF1 represent the major molecular event underlying this condition. Lesions included nonsense mutations, out-of-frame deletions, missense changes, small inframe deletions, and one large multiexon deletion. Remarkably, a high prevalence of inframe defects affecting exons 24 and 25, which encode a portion of the GAP-related domain of the protein, was observed. On the other hand, no defect in PTPN11 was observed, and no lesion affecting exons 11-27 of the NF1 gene was identified in 100 PTPN11 mutation-negative subjects with NS, which provides further evidence that NFNS and NS are genetically distinct disorders. These results support the view that NFNS represents a variant of NF1 and is caused by mutations of the NF1 gene, some of which have been demonstrated to cause classic NF1 in other individuals.

Neurofibromatosis-Noonan syndrome: Molecular evidence of the concurrence of both disorders in a patient

Noonan syndrome (NS) is an autosomal dominant disorder characterized by short stature, facial anomalies, webbed neck, sternal deformity, heart defects, and, in males, cryptorchidism. PTPN11 encodes SHP2, an important component of several signal transduction pathways that acts as a positive regulator of RAS-mitogen activated protein kinase signaling. Neurofibromatosis type 1 (NF1) is another autosomal dominant disorder characterized by hamartomas in multiple organs. The NF1 gene encodes a GAP-related protein, which acts as a negative regulator of the Ras-mediated signal transduction pathway. Clinical overlap between both syndromes, neurofibromatosis-Noonan syndrome (NFNS) is well known. We studied a female patient with typical findings of NFNS and found two mutations: a novel PTPN11 transversion, 1909A --> G, resulting in Gln510Arg, and an NF1 transversion, 2531A --> G, resulting in Leu844Arg. She inherited the PTPN11 mutation from her father and had a de novo NF1 mutation. This is the first report of molecular concurrence of both disorders in the same patient.

Neurofibromatosis--Noonan's syndrome with associated rhabdomyosarcoma of the urinary bladder in an infant: case report

Neurofibromatosis 1 is an autosomal dominant disorder. Noonan's syndrome is known to be associated with neurofibromatoses. Patients with neurofibromatosis are predisposed to developing malignant tumors. The relationship between the genetic changes in the neurofibromin gene and mechanisms associated with tumor development in neurofibromatosis has been investigated. A non-sense mutation C2446T --> R816X of the neurofibromin gene has been detected in some patients with the neurofibromatosis 1-Noonan's syndrome phenotype. We describe a case of an infant with the overlapping features of neurofibromatosis 1 and Noonan's syndrome who presented with rhabdomyosarcoma of the urinary bladder. The genetic analysis of our patient revealed neither mutation in the neurofibromatosis 1-guanosine triphosphatase-activating protein-related domain nor the R816X nonsense mutation. The phenotypic and genotypic features of neurofibromatosis, Noonan's syndrome, and cases with the overlapping features of both syndromes have been reviewed. The presentation of our case underlines the importance of careful examination for the clinical features of neurofibromatosis and phenotypic traits of associated diseases, especially in patients with malignant tumors.

Neurofibromatosis: a common neurocutaneous disorder

Neurofibromatosis (NF) type 1 (NF-1) is one of the most common of the neurocutaneous conditions, whereas NF type 2 (NF-2) accounts for an extremely small percentage of the total cases of NF. Indeed, most physicians will probably encounter at least one or two patients with NF-1 during the course of their practice. The manifestations can be varied and subtle; thus, the condition can sometimes be difficult to recognize. Nonetheless, the diagnosis of NF-1 is often clinically possible by the time the person is 10 years old. In this article, the diagnostic criteria for the most common types of NF are discussed, the common and some of the serious manifestations of both NF-1 and NF-2 are described, and suggestions for follow-up care are offered. Of importance, physicians must recognize that, although NF-1 and NF-2 share a common name, they are due to mutations in two different genes. Cure is not yet possible; thus, treatment is primarily symptomatic. A multi-disciplinary treatment team is often helpful, particularly for patients with complicated problems.

Familial neurofibromatosis type 1 associated with an overgrowth syndrome resembling Weaver syndrome

The simultaneous occurrence of familial neurofibromatosis type 1 (NF1) and an overgrowth syndrome resembling Weaver syndrome was observed in two related cases (a mother and her son). NF1 was confirmed by molecular genetic analysis showing a large deletion at 17q11.2, encompassing the entire NF1 gene. The other symptoms in the two cases were similar to the features reported in Weaver syndrome. Although the combination of NF1 and an overgrowth syndrome resembling Weaver syndrome in this family may be fortuitous, we favour the hypothesis that the deletion of the entire gene has caused this combined phenotype. Possible pathogenetic mechanisms are discussed. The observation suggests a relation between NF1 with an extraordinarily large gene deletion and a Weaver(-like) syndrome. This warrants investigation for deletions in the 17q11.2 region in Weaver(-like) syndrome patients.

Cardio-facio-cutaneous (CFC) syndrome--a distinct entity? Report of three patients demonstrating the diagnostic difficulties in delineation of CFC syndrome

We report on three patients with probable cardio-facio-cutaneous (CFC) syndrome. They present clinical findings of this condition such as: growth failure, heart defects, typical craniofacial appearance, ectodermal abnormalities, and developmental delay. We also give a detailed review of the previously published articles on CFC syndrome and discuss the differences between CFC, Noonan, and Costello syndromes. Other differential diagnoses are considered.

Ullrich-Turner syndrome and neurofibromatosis-1

There is a well-known association between neurofibromatosis-1 (NF1) and Noonan syndrome-like manifestations, including short stature, short broad neck, and hypertelorism. These anomalies are thought to be due to variable expression of the NF1 gene. We report on two girls with NF1 who were found to have the Ullrich-Turner syndrome. Case 1, a 12-year-old white girl, was followed in a Neurofibromatosis Clinic because of multiple café-au-lait spots and a family history of NF1 in her mother and sister. On examination, she had short stature, hypertelorism, and short neck with low posterior hairline. Karyotype was 86% 46,XY/14% 45,X. Case 2, the first child of a woman with NF1, presented at birth with lymphedema of hands and feet and a short broad neck. Karyotype was 45,X. At age 23 months she was short, had epicanthic folds, hypertelorism, narrow palate, right simian crease, 19 café-au-lait spots, and axillary freckling. We conclude that chromosome studies should be performed in girls with NF1 who have short stature and Noonan- or Ullrich-Turner-like findings. Dilemmas raised by the dual diagnoses of NF1 and Ullrich-Turner syndrome include potential risks of growth hormone therapy and estrogen replacement therapy.

Exclusion of allelism of Noonan syndrome and neurofibromatosis-type 1 in a large family with Noonan syndrome-neurofibromatosis association

A large four-generation family with Noonan syndrome (NS) and neurofibromatosis-type 1 (NF1) was studied for clinical association between the two diseases and for linkage analysis with polymorphic DNA markers of the NF1 region in 17q11.2. Nonrandom segregation between NS and NF1 phenotypes was observed. Neurofibromatosis was tightly linked to NF1 markers, whereas Noonan syndrome was found not be allelic to NF1. These results suggest that two mutations at two independent but closely linked loci are the cause of neurofibromatosis-Noonan syndrome (NF-NS) association in this family.

Neurofibroma in the articular disc of the temporomandibular joint: a case report

In classical Von Recklinghausen neurofibromatosis (Type I), skeletal defects occur as a result of abnormalities of derivatives of the neuroectoderm and mesoderm. Temporomandibular joint (TMJ) disorders caused by neurofibroma in the joint capsule or disc have not been reported previously in the English language literature. A case of neurofibroma in the TMJ articular disc in a 29-year-old woman with neurofibromatosis Type I is presented.

Neurofibromatosis-Noonan syndrome

Type I neurofibromatosis (NF-1) and Noonan syndrome (NS) are two fairly common genetic disorders. Patients with features of both disorders have been described, but considerable variability of phenotypic expression occurs. As a result, the correct nosology of this syndrome is uncertain. We present a patient with full expression of both NF-1 and NS phenotypes, and discuss the debate regarding the genetics of the combined syndrome.

Noonan syndrome with café-au-lait spots and multiple lentigines syndrome are not linked to the neurofibromatosis type 1 locus

Noonan syndrome, multiple lentigines syndrome (LEOPARD syndrome), Watson syndrome and neurofibromatosis type 1 share certain clinical manifestations. We present a linkage analysis using microsatellite markers located in the neurofibromatosis type 1 region at 17q11 in a family with Noonan syndrome and café-au-lait spots and in another family with multiple lentigines syndrome. No linkage of the disease to the neurofibromatosis type 1 locus was found in the families investigated. On the basis of our results, we suggest that neither familial multiple lentigines syndrome nor Noonan syndrome is caused by a defect in the neurofibromatosis type 1 gene.

Reproductive failure in a patient with neurofibromatosis-Noonan syndrome

We report on a 39-year-old man with neurofibromatosis-Noonan syndrome and long-standing infertility. Comprehensive testing did not uncover any significant endocrine abnormalities, but the testicular seminiferous epithelium was found to be severely compromised. While the occasional association of neurofibromatosis with signs of Noonan syndrome has been reported, reproductive failure has not been previously described in this condition.

Absence of linkage of Noonan syndrome to the neurofibromatosis type 1 locus

Eleven families with Noonan syndrome in either two or three generations have been identified. Following the reports of subjects with features of both Noonan syndrome and neurofibromatosis type 1, these pedigrees have been studied using a number of probes at the neurofibromatosis type 1 locus (17q11). A significantly negative lod score was obtained with the intragenic probe NF1-C2, suggesting that the genes for Noonan syndrome and neurofibromatosis type 1 are not contiguous.

Clinical variability of type 1 neurofibromatosis: is there a neurofibromatosis-Noonan syndrome?

Detailed clinical, ophthalmological, and molecular studies were performed on a multigeneration family in which there were many subjects with type 1 neurofibromatosis, a common autosomal dominant disorder. Affected family members displayed a wide range of clinical findings including, in two subjects, features seen in Noonan syndrome (triangular facies, downward slanting palpebral fissures, micrognathia, short stature, and learning disability). Subjects have been described previously whose features have overlapped with neurofibromatosis and Noonan syndrome, and it has been suggested that these persons might represent a separate condition. DNA haplotype analysis showed linkage of the neurofibromatosis phenotype seen in this family to the proximal long arm of chromosome 17 in the region where the type 1 neurofibromatosis gene has been mapped. These results imply that the Noonan phenotype seen in some patients with type 1 neurofibromatosis might be the result of variable or variant expression of the neurofibromatosis gene on chromosome 17. The possible role of non-specific factors, such as fetal hypotonia, in producing the neurofibromatosis-Noonan phenotype needs further investigation. The availability of closely linked and intragenic molecular markers for neurofibromatosis could potentially be useful in the diagnosis and characterisation of patients and families with atypical forms of neurofibromatosis.

Noonan-like/multiple giant cell lesion syndrome

A patient with the Noonan-like/multiple giant cell lesion syndrome is reported and the findings in 14 cases are reviewed. Impressive manifestations include short stature, low normal intelligence or developmental delay, ocular hypertelorism, prominent posteriorly angulated ears, giant cell lesions of bones, joints, and/or soft tissues, pectus excavatum, and pulmonic stenosis. It has been difficult to delineate the syndrome because problems in identifying the condition have resulted from incomplete or truncate ascertainment by various medical specialists.

The Noonan-CFC controversy

The Noonan syndrome and the cardio-faciocutaneous (CFC) syndrome have been described as phenotypically and genetically distinct entities. However, the resemblance between them led some authors to question the validity of this separation. We review available clinical evidence to support the opposite view, namely, that the Noonan and CFC syndromes are indeed distinct and separate conditions, both falling within the broad and causally heterogeneous spectrum of the Noonan/congenital lymphedema phenotype.

The Noonan syndrome/cherubism association

Noonan syndrome is characterized by short stature, unusual facies, congenital heart disease, chest deformity, mild mental retardation, and cryptorchidism in males. It may be sporadic or inherited as an autosomal dominant trait and occurs between 1 in 1000 and 1 in 2500 live births. Cherubism is a giant cell lesion of the jaws thought to be transmitted as an autosomal dominant trait. It is usually recognized by age 7 years, follows a variable course, and is not known to be related to other genetic disorders. We herein report on four patients with Noonan syndrome, all of whom had cherubism. Two other probable cases are cited in the literature for a total of six known cases.

Neurofibromatosis with fully expressed Noonan syndrome

We present an 18-year-old man with neurofibromatosis (NF) and classic manifestations of the Noonan syndrome (NS), including the cardiac findings. His father also has neurofibromatosis but only some of the characteristics of Noonan syndrome. This case lends further support to the notion that the neurofibromatosis-Noonan syndrome (NF-NS) is a discrete entity and demonstrates that the NF-NS can be inherited, with variable expression of the Noonan phenotype within a family.

Vertical transmission of the neurofibromatosis/Noonan syndrome

We are reporting on a boy and his mother with neurofibromatosis and manifestations of Noonan syndrome, including short stature, ptosis, midface hypoplasia, and short neck. Developmental delay was noted in the son, and the mother was noted to have a heart murmur. There was a family history of café-au-lait spots, and photographs of several of these relatives showed a facial appearance suggesting Noonan syndrome. The presence of neurofibromatosis associated with Noonan syndrome manifestations in our related patients suggests presence of a unique disorder sharing characteristics of both conditions.

Noonan's syndrome and neurofibromatosis

A child with Noonan syndrome and multiple cafe au lait spots, compatible in size and number with von Recklinghausen's neurofibromatosis, is presented. These features may represent a distinct genetic entity rather than the coincidence of two diseases.

Noonan syndrome

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