Germ-line NF2 mutations and disease severity in neurofibromatosis type 2 patients with retinal abnormalities.
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Adolescent↗
Biomedical subjects
V F Mautner
Publications and source records attributed to V F Mautner.
Phenotypic variability associated with 14 splice-site mutations in the NF2 gene.
Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder caused by mutations in the NF2 gene. Patients carrying NF2 mutations are predisposed to cerebral and spinal tumors with bilateral vestibular schwannomas as the hallmark. Using single strand conformation polymorphism and temperature gradient gel electrophoresis analysis, we have screened 87 unrelated NF2 patients for mutations in the NF2 gene. In this study, we report phenotypes associated with 14 splice-site mutations carried by 14 propositi and 11 relatives. The mutations were distributed in exons 2, 3, 5, 7, 8, 14, and 15. These splice-site mutations were associated with various phenotypes, from severe to asymptomatic. Phenotypic variation was also observed within families. Mutations downstream from exon 8 resulted more often in mild phenotypes. No meningiomas were found in any of 13 affected or mutation bearing individuals from three families with splice-site mutations of exons 14 and 15. These data suggest that splice-site alteration is a relatively common cause of NF2, and that unlike other mutations the clinical outcomes of splice-site mutations in the NF2 gene are variable. These results add to the growing body of information on genotype-phenotype correlation in NF2.
Adolescent↗
Isolation and characterization of Schwann cells from neurofibromatosis type 2 patients.
Neurofibromatosis type 2 (NF2) is an autosomal dominant disease of the nervous system characterized by multiple schwannomas. The NF2 gene product, termed schwannomin or merlin, was hypothesized to function as a cytoskeleton-membrane linking protein due to homology to members of the protein 4.1 superfamily and to function as a tumor suppressor. We isolated and characterized pure Schwann cell cultures from schwannomas derived from neurofibromatosis 2 patients with identified germline mutations and loss of heterozygosity. We describe striking differences between NF2 and control Schwann cells in morphology, cell-cell contacts, and growth. NF2 Schwann cells form multiple long processes with filopodial and lamellopodial extensions. NF2 Schwann cells lack contact inhibition, grow in multiple layers, and show a higher proliferation rate than control cells. For the first time Schwann cells derived from patients with the NF2 genotype were cultured and characterized in vitro. These cultures are highly valuable for investigating the effects of NF2 mutations and the development of therapies.
Cell Division↗
[Tumor reduction of plexiform neurofibroma in the craniofacial and neck area].
Neurofibromatosis type 1 (NF1) is an autosomal dominant hereditary disease of high penetrance and variable expression. Epidemiologic data on craniofacial manifestations are still lacking. Up until now 74 patients with NF1 have been treated at the Department of Oral and Maxillofacial Surgery of the University of Hamburg. Forty-two patients presented periorbital and orbital neurofibromas varying in extension and in the severity of findings of the affected site. Surgical therapy is mainly based on tumour reduction, frequently combined with face-lifting. In our experience neurofibromas of the neck tend to be pseudo-encapsulated, facilitating the preparation of the tumour. On the other hand, identification and preparation of diffuse infiltrating neurofibromas in the trigeminal nerve region are difficult and local recurrence must be expected.
Adult↗
[Fluorescein angiography of retinal changes in patients with neurofibromatosis 2].
BACKGROUND: Neurofibromatosis 2 (NF2) is a rare autosomal dominant disorder (prevalence 1:37.000) associated with changes in tumor suppressor genes. Intraocular manifestations have been reported as subcapsular cataract, retinal hamartomas, epiretinal membranes, keratopathy in facial palsy, and tumors of the nerves I-V are typical ocular manifestations of NF2. PATIENTS AND MATERIALS: We prospectively examined 7 patients who met the diagnostic criteria of NF2 with regard to retinal changes using fluorescence angiography and red-free fundus photography. RESULTS: In four patients, we found window defects of the pigment epithelium in the macular or paramacular areas. In one patient we observed a combined pigment epithelial and astrocytic hamartoma. A choked papilla was found in two patients. CONCLUSIONS: Presumably, retinal changes in NF2 occur more frequently than has been assumed previously. Our results confirm that in NF2 patients more attention should be paid to abnormalities of the optic disk, the retina and the choroid.
Fluorescein Angiography↗
The diagnosis and management of neurofibromatosis 2 in childhood.
Neurofibromatosis 2 (NF2) is an autosomal-dominant condition that causes multiple benign nervous system tumors, especially vestibular schwannoma. Although frequently confused with the more common neurofibromatosis 1, NF2 presents a distinct set of diagnostic, genetic, and management issues. The presentation and natural history of NF2 differs in children and adults, with eighth nerve dysfunction often overshadowed by the effects of other tumors on the nervous system. Molecular diagnostics is an important tool for early recognition of NF2, and when performed in the context of appropriate counseling and follow-up, may lead to a better final outcome of the disease. Further research into the molecular genetic etiology of NF2 promises to broaden the possibilities of therapy for this devastating disorder.
Adolescent↗
[Neurofibromatosis versus schwannomatosis].
Neurofibromatosis Type 1 and 2 (NF1 und NF2) are different forms of neurofibromatosis, well defined both clinically and genetically. In absence of typical clinical features of NF1 (café-au-lait-spots, cutaneous neurofibromas, Lisch-nodules) or NF2 (vestibular schwanoma) clinical classification is often not possible. Neurofibromas are more common in NF1 and schwannomas are typical for NF2, but pathological histology does not provide sufficient evidence for diagnosis. We describe 14 patients who presented with the clinical picture of multiple spinal tumours. Detailed family history, exact clinical examination including an ophthalmological examination led to the diagnosis of NF2 in four cases. Mutation analysis confirmed the diagnosis of NF2 in one case by identification of a 163 base pair deletion in the NF2 transcript. To investigate the expression of schwannomin and neurofibromin we stained tumour paraffin sections of six patients with antibodies against peptides of the NF1 and the NF2 protein. Based on preserved immunoreactivities we were able to exclude diagnosis of NF1 in three and NF2 in two cases. In four patients the clinical symptoms could confirm the diagnosis of schwannomatosis. Combining the results of clinical, neurogenetical and immunohistochemical examinations we could diagnose NF1 or NF2 in ten patients in total. Immunoreactivity led to the suggestion of NF2 in two patients; the other two patients whose tumours were not stained so far, could as yet not be classified for NF.
Adult↗
Mosaicism in sporadic neurofibromatosis 2 patients.
More than half of neurofibromatosis 2 (NF2) patients represent de novo mutations which could have occurred at either pre-zygotic or post-zygotic stages. A post-zygotic mutation can result in mosaicism. In four sporadic NF2 patients, we found NF2 mutations in only a portion of corresponding leukocytes. In two other sporadic patients, no mutations were found in leukocytes but constitutional NF2 mutations were suggested by identical mutations in different tumors from each patient. We screened leukocyte DNA from a total of 16 inherited and 91 sporadic NF2 patients, and found NF2 mutations in 13 (81%) of the former and in 46 (51%) of the latter cases. The 30% difference in the rate of detection of mutations ( P = 0.051) might be partially explained by mosaicism in a portion of sporadic NF2 patients who carry the mutations in such a fashion that their leukocytes are unaffected. Among sporadic cases, we found mutations more frequently in patients with severe phenotypes (59%) than in patients with mild phenotypes (23%) (difference of 36%, P = 0.007). Mosaicism might be more common in the latter patient group since small populations of mutation-bearing cells can in some cases result in mild phenotypes and can also lead to difficulties in identifying mutations. No mutations were found in eight patients suspected of having NF2. Mosaicism with an extremely small population of affected cells may explain the incomplete phenotypes in some of these patients and the lack of mutations in their leukocytes. These findings suggest that mosaicism is relatively common in NF2 and may have important implications for diagnosis, prognosis and genetic counseling.
Adolescent↗
Voltage-dependent membrane currents of cultured human neurofibromatosis type 2 Schwann cells.
Previous experimental observations indicate that inhibition of voltage-dependent K+ currents suppresses proliferation of normal Schwann cells. In the present study we tested the opposite relationship, i.e., whether Schwann cells from tumors with abnormally high rates of proliferation would have an increase in membrane K+ currents. Whole-cell membrane currents were studied in cultured cells from schwannomas of two neurofibromatosis type 2 (NF2) patients (n = 53), one patient with a sporadic schwannoma (n = 22), and two control subjects (n = 41). Five different types of voltage-dependent membrane currents were found in all of the Schwann cells tested. Membrane depolarization activated outward K+ and Cl- currents; quinidine was found to block the K+ current (IC50 approximately 1 microM), and NPPB reduced the Cl- current. Ba2+-sensitive inward rectifier K+ currents, fast Na+ currents, and a transient, inactivating K+ current were less frequently observed. On average, NF2 cells were found to have statistically significant higher membrane potential and larger non-inactivating K+ outward current as compared to controls. Electrophysiological parameters of Schwann cells from a sporadic schwannoma showed a tendency for larger outward currents; however, the difference did not reach statistical significance. Together the data support the suggestion of a possible link between K+ outward current and proliferation of Schwann cells.
Chloride Channels↗
[The Eppendorf Pruritus Questionnaire].
In dermatological practice, itch is the leading symptom of many skin diseases with a variety of psychophysiological aspects. However, a complete inventory for the qualitative evaluation of these central nervous factors is missing, whereas in pain research, the McGill Pain Questionnaire is well established for this purpose. Thus, therapeutic effects of antipruritic agents are only incompletely described by visual analog scales or parameters of skin physiology. Here, a questionnaire modified in analogy to the McGill pain questionnaire is presented, developed in cooperation between dermatologists and neurophysiologists.
Diagnosis, Differential↗
Skin abnormalities in neurofibromatosis 2.
OBJECTIVE: To determine the prevalence, distribution, and histopathological conditions of skin abnormalities in neurofibromatosis 2 (NF2). DESIGN: Case series. SETTING: Hospital neurology department. PATIENTS: Consecutive sample of 88 patients with NF2 referred through workshops and publications, genetic counseling, and referral from neurosurgical departments; 81 patients met the National Institutes of Health, Bethesda, Md, NF2 diagnostic criteria and the diagnosis was established by mutation or segregation analyses in 7 patients. MAIN OUTCOME MEASURES: Prevalence, distribution, and type of skin abnormalities; histopathological features of 29 skin tumors selected primarily for medical indications. RESULTS: Fifty-two patients (59.1%) had 458 skin tumors, which were the first presenting sign in 27.3% of patients and usually appeared as flat dysplastic tumors or subcutaneous spherical nodular tumors of the peripheral nerves, on the limbs and trunk. Although 29 patients (33.0%) had café au lait spots, only 2 patients had as many as 6 spots. compared with patients with milder disease, patients with more severe disease had a significantly greater prevalence of skin tumors (24.0% and 71.0%, P < .001), more than 10 skin tumors (0.0% and 27.4%, P = .004), flat dysplastic skin tumors (8.0% and 54.8%, P < .001), and subcutaneous spherical nodular tumors (24.0% and 58.1%, P = .004). The histologically analyzed tumors were predominantly schwannomas, but 5 were neurofibromas and 2 were mixed tumors. CONCLUSIONS: The prevalence of some skin tumor types in NF2 is high and varies with disease severity, and schwannomas predominate in sampled tumors. The occurrence of neurofibromas is surprising, but could be explained by an interaction between neurofibromin and the NF2 gene product in regulating the ras proto-oncogene.
Adolescent↗
A missense mutation in the NF2 gene results in moderate and mild clinical phenotypes of neurofibromatosis type 2.
Since the identification of the NF2 tumor suppressor gene in 1993, various mutations have been found in NF2-related tumors and in lymphocytes from NF2 patients. Most of the reported mutations result in truncated gene products. Missense mutations affecting the tumor suppressor are rare. These missense mutations would provide valuable information for the understanding of the function of the tumor suppressor, since they should affect critical parts of the protein. In this study we describe a novel point mutation in exon 15 of the NF2 gene, which is found in lymphocyte DNA of two NF2 patients from one family. This mutation is expected to result in a substitution of Pro for Gln at codon 538. Though both of the two patients developed bilateral vestibular schwannomas, the first patient showed onset of the disease at the age of 31 years and presented with various central, peripheral and abdominal tumors, while the second patient showed later onset of clinical symptoms (at age 52 years) and presented with only two additional small spinal tumors.
Adult↗
Phenotypic variability in two families with novel splice-site and frameshift NF2 mutations.
Neurofibromatosis 2 (NF2) is a clinically variable autosomal dominant disorder, caused by mutations in the NF2 tumor suppressor gene on chromosome 22q12, that predisposes to nervous system tumors and ocular abnormalities. To assess intrafamilial phenotypic variability, we performed mutation analysis and clinical assessment on two multigeneration NF2 families with five patients and seven asymptomatic first-degree relatives of patients. One family had a point mutation of agCC --> ggCC at position 1447-2 at the exon 13/14 boundary predicted to lead to an altered splice acceptor sequence and exon deletion. The other family had an insertion of 2 base pairs (TC) at position 761 in exon 8, leading to a frameshift. Both mild and severe phenotypes occurred in each family, indicating that phenotypic variability in NF2 can be caused by factors other than NF2 mutations. Genetic counseling of NF2 families should include the possibility that presymptomatic NF2 mutation carriers can develop a different phenotype than previously diagnosed patients.
Adolescent↗
Identification of NF2 germ-line mutations and comparison with neurofibromatosis 2 phenotypes.
Neurofibromatosis 2 (NF2) is an autosomal inherited disorder that predisposes carriers to nervous system tumors. To examine genotype-phenotype correlations in NF2, we performed mutation analyses and gadolinium-enhanced magnetic resonance imaging of the head and full spine in 59 unrelated NF2 patients. In patients with vestibular schwannomas (VSs) or identified NF2 mutations, the mild phenotype was defined as < 2 other intracranial tumors and < or = 4 spinal tumors, and the severe phenotype as either > or = 2 other intracranial tumors of > 4 spinal tumors. Nineteen mutations were found in 20 (34%) of the patients and were distributed in 12 of the 17 exons of the NF2 gene, including intron-exon boundaries. Seven mutations were frameshift, six were nonsense, four were splice site, two were missense, and one was a 3-bp in frame deletion. The nonsense mutations included one codon 57 and two codon 262 C-->T transition in CpG dinucleotides. The frameshift and nonsense NF2 mutations occurred primarily in patients with severe phenotypes. The two missense mutations occurred in patients with mild phenotypes, and three of the four splice site mutations occurred in families with both mild and severe phenotypes. Truncating NF2 mutations are usually associated with severe phenotypes, but the association of some mutations with mild and severe phenotypes indicates that NF2 expression is influenced by stochastic, epigenetic, or environmental factors.
DNA Mutational Analysis↗
[Ophthalmologic spectrum of neurofibromatosis type 2 in childhood].
BACKGROUND: Neurofibromatosis type 2 (NF2) is a disorder with autosomal dominant inheritance which leads to tumor growth in the central and peripheral nervous system. In affected adult patients there is a typical association with ocular abnormalities like juvenile cataract. METHODS: Ophthalmologic investigation was carried out in ten children aged one to fourteen years with suspected NF2. The diagnosis was confirmed by further clinical examination and-in one patient-by segregation analysis. RESULTS: Nine of these ten children showed ocular abnormalities such as juvenile subcapsular cataracts, retinal hamartomas, optic nerve sheath tumors, fibrotic maculopathies as well as one case of a perineural calcification of the optic nerve and one case of a cerebral hamartoma on the ground of the third ventricle. DISCUSSION: In six children ophthalmological symptoms were the presenting symptom of the disease. The knowledge of these symptoms allows for the diagnosis of NF2 in children who present with isolated ocular deficits or with other typical criteria of the disease. The early diagnosis of the disease may lead to an improved prognosis with regard to preservation of hearing by surgery of bilateral vestibular schwannoma which occur in more than 90% of the NF2-patients.
Adolescent↗
The neuroimaging and clinical spectrum of neurofibromatosis 2.
Neurofibromatosis 2 (NF2) is an autosomal dominant disease predisposing to multiple tumors of the central and peripheral nervous system. Bilateral vestibular schwannomas are the hallmark of the disease. To define the clinical spectrum of the disease, we performed gadolinium-enhanced magnetic resonance imaging of the brain and spine as well as neurological, dermatological, and ocular examinations in 48 patients with NF2 diagnosed with the National Institutes of Health diagnostic criteria. Patients were ascertained from patient workshops and publications and from referral as a result of vestibular schwannoma surgery. Vestibular schwannomas were found in 46 patients (96%, 43 bilateral and 3 unilateral), spinal tumors were found in 43 (90%), posterior subcapsular cataracts were found in 30 (63%), meningiomas were found in 28 (58%), and trigeminal schwannomas were found in 14 (29%). The presenting symptoms included hearing loss or tinnitus in 15 patients (31%), multiple or nonspecific symptoms in 15 (31%), skin tumors in 12 (25%), and ocular symptoms in 6 (13%). When the complete spine was imaged, spinal tumors were more common in patients with NF2 than has previously been reported. This is a noteworthy finding, because spinal tumors are a major cause of NF2 morbidity and mortality.
Adolescent↗
Presymptomatic diagnosis of neurofibromatosis 2 using linked genetic markers, neuroimaging, and ocular examinations.
Neurofibromatosis 2 (NF2) is an autosomal dominant disorder that causes nervous system tumors and ocular abnormalities such as early-onset lenticular opacities. We assessed the clinical spectrum of NF2 at the time of presymptomatic DNA diagnosis in at-risk first-degree relatives. We studied five multigeneration NF2 families with short tandem repeat markers near the NF2 gene (NF2); gadolinium-enhanced high-resolution magnetic resonance imaging (GE-MRI); and ocular, dermatologic, and neurologic examinations. Eleven of 31 asymptomatic at-risk first-degree relatives were predicted by segregation analysis to be NF2 mutation carriers. Nine of the 11 NF2 mutation carriers were clinically evaluated. Four mutation carriers, including a 7-year-old, had vestibular schwannomas, early-onset cataracts, or both. However, five mutation carriers did not have clinical abnormalities, including a 38-year-old with normal cranial and spinal GE-MRIs and a normal ocular examination. These results indicate that clinical abnormalities can be present in young, but absent in middle-aged, presymptomatic NF2 mutation carriers. By identifying presymptomatic NF2 mutation carriers, DNA diagnosis of NF2 can improve genetic counseling and clinical management, and possibly reduce psychosocial difficulties in at-risk individuals.
Adult↗
Spinal tumors in patients with neurofibromatosis type 2: MR imaging study of frequency, multiplicity and variety.
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Humans↗