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Background: Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive sarcomas that typically develop in the setting of neurofibromatosis type 1 (NF1) and cause significant morbidity. Conventional therapies are often ineffective for MPNSTs. Ribonucleotide reductase subunit M2 (RRM2) is involved in DNA synthesis and repair, and is overexpressed in multiple cancers. However, its role in NF1-associated MPNSTs remains unknown. Our objective was to determine the therapeutic and prognostic potential of RRM2 in NF1-associated MPNSTs. Methods: Identification of hub genes was performed by using NF1-associated MPNST microarray datasets. We detected RRM2 expression by immunochemical staining in an MPNST tissue microarray, and assessed the clinical and prognostic significance of RRM2 in an MPNST cohort. RRM2 knockdown and the RRM2 inhibitor Triapine were used to assess cell proliferation and apoptosis in NF1-associated MPNST cells in vitro and in vivo. The underlying mechanism of RRM2 in NF1-associated MPNST was revealed by transcriptome analysis. Results: RRM2 is a key hub gene and its expression is significantly elevated in NF1-associated MPNST. We revealed that high RRM2 expression accounted for a larger proportion of NF1-associated MPNSTs and confirmed the correlation of high RRM2 expression with poor overall survival. Knockdown of RRM2 inhibited NF1-associated MPNST cell proliferation and promoted apoptosis and S-phase arrest. The RRM2 inhibitor Triapine displayed dose-dependent inhibitory effects in vitro and induced significant tumor growth reduction in vivo in NF1-associated MPNST. Analysis of transcriptomic changes induced by RRM2 knockdown revealed suppression of the AKT-mTOR signaling pathway. Overexpression of RRM2 activates the AKT pathway to promote NF1-associated MPNST cell proliferation. Conclusions: RRM2 expression is significantly elevated in NF1-associated MPNST and that high RRM2 expression correlates with poorer outcomes. RRM2 acts as an integral part in the promotion of NF1-associated MPNST cell proliferation via the AKT-mTOR signaling pathway. Inhibition of RRM2 may be a promising therapeutic strategy for NF1-associated MPNST. [ABSTRACT FROM AUTHOR]

Background: Neurofibromatosis type 1 (NF1) is a genetic neurodevelopmental disorder commonly associated with impaired cognitive function. Despite the well-explored functional roles of neural oscillations in neurotypical populations, only a limited number of studies have investigated oscillatory activity in the NF1 population. Methods: We compared oscillatory spectral power and theta phase coherence in a paediatric sample with NF1 (N = 16; mean age: 13.03 years; female: n = 7) to an age/sex-matched typically developing control group (N = 16; mean age: 13.34 years; female: n = 7) using electroencephalography measured during rest and during working memory task performance. Results: Relative to typically developing children, the NF1 group displayed higher resting state slow wave power and a lower peak alpha frequency. Moreover, higher theta power and frontoparietal theta phase coherence were observed in the NF1 group during working memory task performance, but these differences disappeared when controlling for baseline (resting state) activity. Conclusions: Overall, results suggest that NF1 is characterised by aberrant resting state oscillatory activity that may contribute towards the cognitive impairments experienced in this population. Trial registration: ClinicalTrials.gov, NCT03310996 (first posted: October 16, 2017). [ABSTRACT FROM AUTHOR]

Background: Neurofibromatosis type 1 (NF1) is an autosomal dominant with haploinsufficient, and multisystemic disorder including patches of skin Café-au-lait spots, Lisch nodules in the iris, and tumors in the peripheral nervous systems or fibromatous skin. Methods: Blood samples were collected and DNA was extracted from a large Chinese pedigree suffering from NF1 disease with three spontaneous abortions or death for proband. Analysis for whole exome sequencing (WES), Sanger sequencing, and co-segregation was carried out. Prenatal gene diagnosis was also carried out in amniotic fluid DNA. The expression of NF1 was conducted by bioinformatics. Results: A large Chinese pedigree with NF1 was recruited and a novel, heterozygous, variant (c.4272delA: p.I1426Ffs*2) for the NF1 gene in the proband was identified. This variant of NF1 produced a truncated protein that losses half of NF1 protein at the C-terminus including the CRAL-TRIO lipid-binding domain, NLS, and a small portion of Ras-GAP domain, thus leading to pathogenicity (ACMG criteria: PVS1 + PM2). NF1 expressions in different human tissues showed low tissue specificity, which may affect multiple organs presenting different phenotypes. Moreover, prenatal gene diagnosis for NF1 showed both alleles as wild types in the fetus of the proband. Conclusion: We thus successfully identified a novel, pathogenic, heterozygous variant (c.4272delA:p.I1426Ffs*2) in the NF1 gene of NF1 disorder, expanding the NF1 mutation spectrum, that will help elucidate the molecular pathogenesis of NF1 disease and to contribute to the NF1 diagnosis, genetic counseling, clinical management in this large Chinese family. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis (SWN) are three clinically distinct tumor predisposition syndromes with a shared tendency to develop peripheral and central nervous system neoplasms. Disease expression and complications of NF1, NF2, and SWN are highly variable, necessitating a multidisciplinary approach to care in order to optimize outcomes. This review will discuss the imaging appearance of NF1, NF2, and SWN and highlight the important role that imaging plays in informing management decisions in people with tumors associated with these syndromes. Recent technological advances, including the role of both whole-body and localized imaging strategies, routine anatomic and advanced magnetic resonance (MR) imaging sequences such as diffusion-weighted imaging (DWI) with quantitative apparent diffusion coefficient (ADC) mapping, and metabolic imaging techniques (MR spectroscopy and positron emission testing) are discussed in the context of the diagnosis and management of people with NF1, NF2, and SWN based on the most up-to-date clinical imaging studies. [ABSTRACT FROM AUTHOR]

Type 1 Neurofibromatosis (NF1) is a common autosomal dominant condition, with a major impact on the nervous system, eye, bone, and skin, and a predisposition to malignancy. At present it is not possible to predict clinically or on imaging, whether a brain tumour will remain indolent or undergo high-grade change. There are no consensus guidelines on the follow-up of non-optic pathway glioma (non-OPG) tumours in NF1. One hundred patients from the National NF1 Service with generalised NF1 and a diagnosis of non-OPG glioma were followed up for a median time of 63 months after glioma detection. Forty-two patients underwent surgical intervention. Ninety-one percent (38) of those requiring surgery did so within 5 years of diagnosis of glioma. Serial neuroimaging was undertaken in 88 patients. In 66 (75%), the lesion on the scan was stable or had improved at follow-up. High-grade lesions were present in five patients and were strongly associated with tumours in the thalamus (p = 0.001). Five patients died during follow-up. The diagnosis of high-grade glioma had a HR of 99.7 (95% CI 11.1-898.9, p < 000.1) on multivariate Cox regression to evaluate predictive factors related to death. In our cohort of 100 patients with NF1, we have shown that tumours in the thalamus are more likely to be associated with radiological progression, high-grade tumours, and surgical intervention. As a result of this finding, heightened surveillance with more frequent imaging should be considered in thalamic involvement. We have also demonstrated that over 40% of patients underwent surgery, and did so within 5 years of tumour diagnosis. Serial imaging should be undertaken for at the very least, 5 years from tumour detection. [ABSTRACT FROM AUTHOR]

Introduction: The object of this study is to understand abnormal dynamic of cerebrospinal fluid (CSF) in patients with neurofibromatosis type 1 (NF1), which may cause temporal lobe herniation and bulging of temporal fossa. Methods: Four patients, three females and one male, with NF1 were studied retrospectively. They presented with a similar craniofacial deformity, which consisted of pulsatile exophthalmos, an enlarged bony orbit, dysplasia of the sphenoid wing with the presence of a herniation of the temporal lobe into the orbit, and a bulging temporal fossa. Results and discussion: Surgical exploration demonstrated abnormally thickened arachnoid membrane in one case. Protruding temporal lobe, which was one of the main symptoms in NF1 patients, could be stopped by control of intracranial pressure (ICP) via programmable ventriculoperitoneal shunt (VPS) or extra ventricle drainage implantation. The dense fibrosis of the arachnoid membrane and consequent altered hemispheric CSF dynamics may cause symptoms including pulsatile exophthalmos and consequent worsening of vision, prolapse of the temporal lobe, and enlargement of the temporal fossa. This finding may not present with general features of hydrocephalus, so that delays in diagnosis often result. Conclusion: For the NF1 patients with cranio-orbito-temporal deformities, prior to any surgical reconstruction, control of increased ICP (IICP) should be primarily considered. [ABSTRACT FROM AUTHOR]

One of the potential etiologies for non-familial Neurofibromatosis Type 1 (NF1) is increasing parental age. We sought to evaluate recent evidence for parental age effects in NF1 in a large study. Individuals with NF1 and a comparison group from the U.S. general population born between 1994 and 2012 were ascertained from the NF1 Patient Registry Initiative (NPRI) and the National Center for Vital Statistics, respectively. Multiple linear regression analysis was employed to identify differences between familial NF1, non-familial NF1, and U.S. population subjects in the mean parental ages at the time of the birth of offspring in each group. In addition, we also evaluated the effect of parental age on NF1 offspring with and without a pediatric brain tumor history. A total of 313 subjects from the NPRI (including 99 brain tumor cases) matched by birth year at a 1:3 ratio to U.S. general population births (n = 939) were included. Compared to the U.S. general population and familial NF1 cases, the mean paternal age for non-familial NF1 cases was 4.34 years (95 % CI 3.23-5.46, p ≤ 0.0001) and 3.39 years (95 % CI 1.57-5.20, p ≤ 0.0001) older, respectively, after adjusting for birth year. A similar pattern was observed for maternal age. There were no statistically significant differences in the mean maternal or paternal ages between NF1 offspring with and without a pediatric brain tumor. In conclusion, these data support a parental age effect for non-familial NF1 cases, but not for pediatric brain tumors in NF1. [ABSTRACT FROM AUTHOR]

Background Neurofibromatosis type 1 (NF1) affects several areas of cognitive function including visual processing and attention. We investigated the neural mechanisms underlying the visual deficits of children and adolescents with NF1 by studying visual evoked potentials (VEPs) and brain oscillations during visual stimulation and rest periods. Methods Electroencephalogram/event-related potential (EEG/ERP) responses were measured during visual processing (NF1 n = 17; controls n = 19) and idle periods with eyes closed and eyes open (NF1 n = 12; controls n = 14). Visual stimulation was chosen to bias activation of the three detection mechanisms: achromatic, red-green and blue-yellow. Results We found significant differences between the groups for late chromatic VEPs and a specific enhancement in the amplitude of the parieto-occipital alpha amplitude both during visual stimulation and idle periods. Alpha modulation and the negative influence of alpha oscillations in visual performance were found in both groups. Conclusions Our findings suggest abnormal later stages of visual processing and enhanced amplitude of alpha oscillations supporting the existence of deficits in basic sensory processing in NF1. Given the link between alpha oscillations, visual perception and attention, these results indicate a neural mechanism that might underlie the visual sensitivity deficits and increased lapses of attention observed in individuals with NF1. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 (NF1) patients are at increased risk of developing both benign (neurofibromas) and malignant (malignant peripheral nerve sheath tumors, MPNST) tumors. Molecular data on tumor progression are scarce, and few studies have compared the NF1 locus copy number in these two tumor types. To further explore the role of such NF1 locus rearrangements in NF1 tumorigenesis, and the likely disruption to the associated genes, the NF1 gene region was analyzed in NF1-associated tumors. DNA from three MPNSTs and one neurofibroma, excised from three unrelated NF1 patients, were analyzed using an NF1 region customized array-based comparative genomic hybridization. The somatic NF1 inactivation mutational mechanisms associated with MPNSTs appear to be different from those in benign neurofibromas. Interestingly, the MPNST-associated deletion breakpoints did not involve the paralogous repetitive sequences that are involved in most germline NF1 deletions. The somatic smallest common region of deletion overlap, however, was restricted to approximately the same ~2.2-Mb interval that encompassed most of the genes deleted in NF1 recurrent constitutional deletions. A number of genes in addition to NF1 on 17q (centromere to 17q24.2) may be involved in MPNST development. A larger study is warranted to confirm these findings. As NF1 patients with such germline NF1 deletions do exhibit increased risk of developing MPNST, these present findings emphasize the likely role of at least some of these NF1 flanking genes in MPNST pathobiology. [ABSTRACT FROM AUTHOR]

Objective: Neurofibromatosis type 1 (NF1) patients have a 13% risk of developing a malignant peripheral nerve sheath tumor (MPNST). Many MPNSTs are histopathologically complex, with regions exhibiting features of the original benign plexiform neurofibroma (PNF), of an atypical PNF, or of MPNST showing varying degrees of de-differentiation. This study analyzed the genetic alterations associated with this pathological heterogeneity in order to identify the genetic processes involved in transformation from a benign to an aggressive malignant tumor. Methods: A histological and molecular analysis of a single MPNST tumor that was subdivided into three histopathologically distinct regions, a benign PNF (region 1), an atypical PNF (region 2), and a high-grade MPNST (region 3), was carried out. Tumor DNA from each region was analyzed in conjunction with the patient's lymphocyte DNA. Somatic mutation analyses included loss-of heterozygosity (LOH), MLPA analysis, NF1 gene sequencing, and a microarray comparative genomic hybridisation (array CGH) analysis. Results: The patient had a germline NF1 splice-site mutation. The NF1-associated LOH analysis found that LOH increased in the three tumor areas, with 9, 42, and 97% LOH evident in regions 1, 2, and 3, respectively. Additional genetic changes, including losses of TP53, RB1, CDKN2A, and of several oncogenes and cell-cycle genes, were found only in the malignant MPNST (region 3). Array CGH also identified genomic gains and losses in DNA from region 3. Discussion: This is the first study that correlates the histological and molecular changes associated with MPNST development, confirming the significant cellular and genetic heterogeneity that poses both diagnostic and therapeutic challenges. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 (NF1) is characterized by clinical features that primarily affect tissues derived from the neural crest (neurofibromas, café-au-lait macules). Because aberrant regulation of alternative splicing in the NF1 gene transcript may be of functional significance, cultured melanocytes from café-au-lait 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. [ABSTRACT FROM AUTHOR]