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PubMedDate not supplied

Morphology and distribution of eosinophilic granulocytes in damselfish neurofibromatosis, a model of mast cell distribution in neurofibromatosis type 1.

Mast cells (MC) are a conspicous component of neurofibromas in humans. The present study is based on damselfish neurofibromatosis (DNF) a naturally occurring animal model of neurofibromatosis type 1. Investigations of leukocytes of fishes have generally concluded that these animals lack metachromatic, basophilic mast cells and that the apparent analog in fishes is an eosinophilic granule containing cell (EGC). EGC were found at high densities in both naturally occurring neurofibromas in DNF and in those produced in laboratory transmission experiments. Tumors induced by injection of cells from cultured DNF tumor cell lines exhibited significantly higher densities of EGC than did spontaneously occurring tumors or those induced by injection of homogenized tumor tissue. EGC were significantly more common in the outer 200 microns edge of the tumors. We believe that these EGC are the piscine equivalent of the mammalian MC and that their presence in tumors in DNF will provide the first opportunity to experimentally manipulate this type of cell in neurofibromas.

Animals↗
PubMed2000

Segmental neurofibromatosis is caused by somatic mutation of the neurofibromatosis type 1 (NF1) gene.

Segmental neurofibromatosis (NF) is generally thought to result from a postzygotic NF1 (neurofibromatosis type 1) gene mutation. However, this has not yet been demonstrated at the molecular level. Using fluorescence in situ hybridisation (FISH) we identified an NF1 microdeletion in a patient with segmental NF in whom café-au-lait spots and freckles are limited to a single body region. The mutant allele was present in a mosaic pattern in cultured fibroblasts from a café-au-lait spot lesion, but was absent in fibroblasts from normal skin as well as in peripheral blood leukocytes. These findings prove the hypothesis that the molecular basis of segmental cutaneous NF is a mutation in the NF1 gene and that the regional distribution of manifestations reflects different cell clones, commensurate with the concept of somatic mosaicism.

Adolescent↗
PubMed1998

Neurofibromatosis type 2 and central neurofibromatosis.

Neurofibromatosis type 2 (NF2) is a rare disease, affecting only approximately 1000 patients in the entire United States. The diagnosis requires the presence of bilateral acoustic neuromas, but many other tumors of the nervous system are also present. It is a very different disease from von Recklinghausen's neurofibromatosis, NF1. The remarkable genetic research in recent years has defined the origin of NF2 to be the lack of a specific suppressor protein, known as Merlin. While we await a method to replace this protein, the neurosurgical care of these patients is a formidable problem. The author reviews his personal series of 41 patients with NF2 treated during the past 30 years and presents 10 cases in detail to demonstrate their considerable range of differences and the treatment problems they have posed.

Journal Article↗
PubMed1996

The early history of the neurofibromatosis. Evolution of the concept of neurofibromatosis type 2.

Although neurofibromatosis (NF) became widely recognized as a pathologic entity in the late 19th century, only relatively recently has a clear distinction been made between its generalized form and the central variety. The latter form is typified by bilateral acoustic neuromas (ANs), which may be accompanied by other intracranial tumors, in particular, meningiomas. Up until almost the current era, confusion regarding the protean manifestations of the 2 types of NF existed in the minds of clinicians and in the literature. In 1987, a consensus panel of the National Institutes of Health differentiated the clinical manifestations associated with classic von Recklinghausen syndrome from those of the predominantly intracranial subtype and they were subsequently deemed NF type 1 (NF-1) and NF type 2 (NF-2), respectively. During the last few years, the genetic flaws that underlie these 2 syndromes have been elucidated, revealing that their origins lie in defects on separate chromosomes. The early literature on the subject included repeated descriptions of patients with manifestations typical of NF-2. The investigators, however, considered the intracranial lesions to be merely 1 facet of the generalized form of the disease. A few prescient individuals, however, demonstrated an appreciation for the distinguishing characteristics between these superficially similar, yet quite different, syndromes. The goals of this article are to trace the evolution of the concept of NF-2 as a distinct clinical entity from NF-1 and to assess the early awareness of and attitudes toward bilateral ANs, familial ANs, and ANs associated with other intracranial tumors.

Europe↗
PubMed1995

17q inversion involving the neurofibromatosis type one locus in a family with neurofibromatosis type one.

We report a family with a paracentric inversion of the long arm of chromosome 17 [inv(17)(q11.2q25.1)] and neurofibromatosis type one (NF1). The family was ascertained because of NF1 and multiple miscarriages. Fluorescence in situ hybridization using cosmid probes from opposite ends of the NF1 gene confirmed that the inversion disrupts the gene. Using field inversion gel electrophoresis we have found that the inversion separates cDNA probes FB5D and AE25, which are normally adjacent to one another in the NF1 gene. This is the third published report of a gross chromosomal rearrangement responsible for NF1. The features in this family are typical for NF1, and are not unusually severe.

Adolescent↗
PubMed2004

Characterization of the somatic mutational spectrum of the neurofibromatosis type 1 (NF1) gene in neurofibromatosis patients with benign and malignant tumors.

One of the main features of neurofibromatosis type 1 (NF1) is benign neurofibromas, 10-20% of which become transformed into malignant peripheral nerve sheath tumors (MPNSTs). The molecular basis of NF1 tumorigenesis is, however, still unclear. Ninety-one tumors from 31 NF1 patients were screened for gross changes in the NF1 gene using microsatellite/restriction fragment length polymorphism (RFLP) markers; loss of heterozygosity (LOH) was found in 17 out of 91 (19%) tumors (including two out of seven MPNSTs). Denaturing high performance liquid chromatography (DHPLC) was then used to screen 43 LOH-negative and 10 LOH-positive tumors for NF1 microlesions at both RNA and DNA levels. Thirteen germline and 12 somatic mutations were identified, of which three germline (IVS7-2A>G, 3731delT, 6117delG) and eight somatic (1888delG, 4374-4375delCC, R2129S, 2088delG, 2341del18, IVS27b-5C>T, 4083insT, Q519P) were novel. A mosaic mutation (R2429X) was also identified in a neurofibroma by DHPLC analysis and cloning/sequencing. The observed somatic and germline mutational spectra were similar in terms of mutation type, relative frequency of occurrence, and putative underlying mechanisms of mutagenesis. Tumors lacking mutations were screened for NF1 gene promoter hypermethylation but none were found. Microsatellite instability (MSI) analysis revealed MSI in five out of 11 MPNSTs as compared to none out of 70 neurofibromas (p=1.8 x 10(-5)). The screening of seven MPNSTs for subtle mutations in the CDKN2A and TP53 genes proved negative, although the screening of 11 MPNSTs detected LOH involving either the TP53 or the CDKN2A gene in a total of four tumors. These findings are consistent with the view that NF1 tumorigenesis is a complex multistep process involving a variety of different types of genetic defect at multiple loci.

Alleles↗
PubMed1995

Analysis of an alternatively spliced exon of the neurofibromatosis type 1 gene in cultured melanocytes from patients with neurofibromatosis 1.

Neurofibromatosis type 1 (NF1) is characterized by clinical features that primarily affect tissues derived from the neural crest (neurofibromas, café-aulait macules). Because aberrant regulation of alternative splicing in the NF1 gene transcript may be of functional significance, cultured melanocytes from café-aulait macules (CALM), as an example of benign NF1 lesions, were examined for the expression of the different alternative splice products of this gene. Both kinds of NF1 messengers (type 1 and 2) were found not only in CALM melanocytes but also in keratinocytes, fibroblasts and blood cells. Except in blood cells, there was a predominance of the type 2 transcript. Melanocytes from NF1 patients and healthy donors showed similar expression patterns under several culture conditions. Our results suggest that the development of CALM does not correlate with a switch in the ratio of type 1 to type 2 NF1 messenger RNA.

Alternative Splicing↗
PubMed1999

Severe phenotype of neurofibromatosis type 2 in a patient with a 7.4-MB constitutional deletion on chromosome 22: possible localization of a neurofibromatosis type 2 modifier gene?

Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder predisposing to multiple neoplastic lesions with the hallmark of schwannoma arising at the eighth cranial nerve. NF2 shows a distinct clinical variability, with a mild and a severe form of the disease. The NF2 gene is mutated in constitutional DNA of affected patients from NF2 families and in sporadic cases. Comprehensive mutation analyses in patients with severe and mild phenotypes revealed mutations in only 34%-66%. In the remaining fraction, the genetic mechanism behind the development of NF2 is unknown. Analyses of germline mutations do not provide a conclusive explanation for the observed clinical heterogeneity of NF2. It can therefore be hypothesized that other factors, e.g., modifier gene(s), contribute to the development of a more severe NF2 phenotype. We report a mentally retarded patient with the severe form of NF2 who displays a 7.4 million base pair deletion on chromosome 22. We performed a full genetic characterization of this case using heterozygozity analysis of 41 markers from chromosome 22, detailed FISH mapping of deletion breakpoints, allelotyping of all other chromosomes, and sequencing of the NF2 gene in tumor DNA. Two genomically large deletions similar in size (700-800 kb), which encompass the entire NF2 gene, have been reported previously in mildly affected NF2 patients. The centromeric breakpoints of these deletions were similar to the centromeric breakpoint in the present case. However, the deletion in our patient extends over a much larger distance toward the telomere of 22q. Our results support the existence of NF2 modifier gene(s) and suggest that such a putative locus maps to a 6.5-MB interval on 22q, between D22S32 and the MB gene.

Adult↗
PubMed1997

Deletions spanning the neurofibromatosis type 1 gene: implications for genotype-phenotype correlations in neurofibromatosis type 1?

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder characterized by abnormalities of tissues predominantly derived from the neural crest. Symptoms are highly variable and severity cannot be predicted, even within families. DNA of 84 unrelated patients with NF1, unselected for clinical features or severity, were screened with intragenic polymorphic repeat markers and by Southern analysis with cDNA probes. Deletions of the entire gene were detected in five patients from four unrelated families. Their phenotype resembled that of five previously reported patients with deletions, including intellectual impairment and dysmorphic features, but without an excessive number of dermal neurofibromas. This report supports the hypothesis that large deletions spanning the entire NF1 gene may lead to a specific phenotype.

Adolescent↗
PubMed1998

Minor disease features in neurofibromatosis type 1 (NF1) and their possible value in diagnosis of NF1 in children < or = 6 years and clinically suspected of having NF1. Neurofibromatosis team of Sophia Children's Hospital.

OBJECTIVE: To establish the frequency of minor disease features in children with neurofibromatosis type 1 (NF1) and to evaluate the value of minor disease features in children < or = 6 years with a suspected diagnosis of NF1, considering that the disease is virtually 100% penetrant at 6 years of age. DESIGN: During this 10 year, prospective, multidisciplinary, follow up study, 209 children suspected of having NF1 were examined; 150 were diagnosed with NF1 and 59 were not. The present analysis included children in whom NF1 was considered to be present at 6 years of age (n=85) and children without NF1 at 6 years of age (n=42). RESULTS: The minor disease features macrocephaly (52.9%), short stature (24.7%), hypertelorism (63.5%), and thorax abnormalities (37.6%) were highly prevalent in children with NF1 and significantly associated with a diagnosis of NF1 at 6 years of age. In addition, the mean number of minor disease features was significantly higher in children with NF1 at 6 years of age compared to the group without a diagnosis at 6 years of age (mean 1.8 v 0.8, p<0.001). Moreover, children with three or more minor disease features were all diagnosed with NF1 under the age of 6 years. Multivariate analysis using a logistic regression model showed that macrocephaly, short stature, hypertelorism, and thorax abnormalities were all independently associated with the presence of NF1 at 6 years of age. CONCLUSION: In children with insufficient diagnostic criteria aged < or = 6 years, documentation of minor disease features may be a helpful aid in predicting the diagnosis of NF1 in years to come.

Adolescent↗
PubMedDate not supplied

[Neurofibromatosis type 2 (central neurofibromatosis or bilateral acoustic neuromas, vestibular schwannomas): from phenotype to gene].

Neurofibromatosis type 2 (NF2) is an autosomal dominant disease that predisposes to bilateral vestibular schwannomas (neurinomas), other central and peripheral nervous system tumours (multiple meningeomas and neurofibromas) and ocular abnormalities (cataract). The NF2 tumour suppresor gene is localised on chromosome 22q12 and encodes protein called schwannomin or merlin which is related to a family of cytoskeleton-to-membrane proteins linkers ERM (ezrin-radixin-moesin proteins). About 50% of all cases are new germline mutations, although about 20% of apparently sporadic cases represent somatic mosaicism. The majority of observed germline NF2 mutations are point mutations which result in schwannomin with an altered or absent C-terminal domain. NF2 has a variable clinical presentation, with two basic types: severe type having early onset and progressive growth of tumors and the milder type having later onset and less aggressive course. The genotype-phenotype correlations indicate a greater variability of clinical disease expression. In this paper we discuss the epidemiology, genetic and clinical characteristics, diagnostic criteria, investigations, screening for risk persons and recommendations for care and therapy of patients with NF2.

Humans↗
PubMed1989

[Neurofibromatosis 2 (bilateral acoustic neurofibromatosis)].

We report a personal series of 28 patients with neurofibromatosis 2 (NF-2), emphasizing the differences from classical NF-1. The hallmark of NF-2 is bilateral acoustic neuromas with initial symptoms usually occurring in the second or third decade. The natural history may lead to bilateral deafness, but hearing loss may also be a complication of surgery. NF-2 is frequently accompanied by additional intracranial tumors (particularly multiple meningiomas). Half of our patients had a spinal space-occupying lesion. NF-2 is inherited as an autosomal dominant trait, and many patients appear to represent new mutations.

Adolescent↗
PubMed1988

Cell culture studies on neurofibromatosis (von Recklinghausen). VI. No increased stimulation of cell proliferation by sera from neurofibromatosis patients.

The growth-stimulating activity of sera from 10 patients with von Recklinghausen neurofibromatosis (NF-1) was compared with that of sera from 10 age- and sex-matched healthy donors. Cell cultures derived from peripheral neurofibromas and from skin biopsies of healthy persons were used as indicator cells. Stimulation of 3H-thymidine incorporation increased with the clotting time of the blood samples, reaching a plateau at about 35 h with no decline of activity during the following 48 h. There was no difference between the stimulating activity of sera from the NF-1 patients and that of sera from the healthy donors with either type of indicator cells. This held true when the indicator cells were stimulated during the exponential growth phase or when serum-starved confluent cells were exposed to the various sera. Three NF-1 strains used as indicator cells during this investigation showed a significantly less vigorous response to both types of human sera and to fetal calf serum than the respective control strains. All human sera collected after 42 h clotting time were superior to fetal calf serum with both types of indicator cells.

Blood Proteins↗
PubMed2026

Double Aortic Arch in a Patient with Neurofibromatosis Type 1: Expanding the Spectrum of Neurofibromatosis-Associated Vascular Anomalies.

Neurofibromatosis type 1 (NF1) is a common genetic disorder with well-documented multisystem manifestations, including vasculopathies. A double aortic arch is a rare congenital vascular ring anomaly. We present a 59-year-old man with asymptomatic double aortic arch in the setting of a heterozygous pathogenic variant in the NF1 gene (c.6820-1G>A) that was detected on genome sequencing. Considering the burgeoning evidence for NF1's link with vasculopathy, our findings invite consideration of whether NF1's role in vascular development could influence aortic arch patterning.

Case Reports↗