Neurofibromatosis type 1

How do people with neurofibromatosis type 1 (the forgotten victims) live? A grounded theory study

Background

Neurofibromatosis type I (NF1) is a rare genetic disorder, associated with some physical symptoms including spots and tiny bumps on the skin, and internal organ involvement. People suffering from neurofibromatosis face various challenges in their daily lives. However, there is little understanding on how patients deal with neurofibromatosis. This study aimed to investigate the life challenges of patients with NF1.

Methods

This qualitative study was performed by implementing a grounded theory with the cooperation of the Society for Neurofibromatosis Patients over the course of 15 months in 2019 across 4 provinces in Iran. Twenty‐four patients with NF1 were interviewed. An analysis was performed using the constant comparative method.

Findings

The results of the analyses indicated that the major concern of the NF1 patients was feelings of failure and falling behind in life. In the face of failure in life in such a context, patients used the main strategy of “unsuccessful struggle to escape” the disease and its complications, which was represented itself in the forms of ‘hopelessness and impatience’, ‘suicidal thoughts and unsuccessful suicide attempts’, ‘isolation and seclusion’, ‘expressing complaints and grievances to God’, ‘hiding the disease’ and ‘hopelessness and refusing to receive care’. The implementation of such strategies helped patients reduce tension and achieve a temporary, though vulnerable and fragile, sense of relief and peace.

Conclusion

Given an unfavourable life condition, NF1 patients turned to a harmful passive strategy in the face of the challenges posed by the disease.

Patient or Public Contribution

Public contributors were active partners throughout, and co‐authored the paper.

Neural network classifiers for images of genetic conditions with cutaneous manifestations

Neural networks have shown strong potential in research and in healthcare. Mainly due to the need for large datasets, these applications have focused on common medical conditions, where more data are typically available. Leveraging publicly available data, we trained a neural network classifier on images of rare genetic conditions with skin findings. We used approximately 100 images per condition to classify 6 different genetic conditions. We analyzed both preprocessed images that were cropped to show only the skin lesions as well as more complex images showing features such as the entire body segment, the person, and/or the background. The classifier construction process included attribution methods to visualize which pixels were most important for computer-based classification. Our classifier was significantly more accurate than pediatricians or medical geneticists for both types of images and suggests steps for further research involving clinical scenarios and other applications.

The recurrent homozygous translation start site variant in CCDC134 in an individual with severe osteogenesis imperfecta of non-Morrocan ancestry

Osteogenesis imperfecta (OI) is a rare low-bone mass skeletal Mendelian disorder characterized by bone fragility leading to bone fractures, with deformities and stunted growth in the more severe phenotypes. Other common, nonskeletal findings include blue sclerae and dentinogenesis imperfecta. It is caused mainly by quantitative or structural defects in type I collagen, although dysregulation of different signaling pathways that play a role in bone morphogenesis has been described to be associated with a small fraction of individuals with OI. Recently, a homozygous variant in the translation start site of CCDC134, showing increased activation of the RAS/MAPK signaling pathway, has been reported in three families of Moroccan origin with a severe, deforming form of OI. We report on a 9-year-old Brazilian boy, harboring the same homozygous variant in CCDC134, also presenting severe bone involvement. This report contributes to the phenotypic delineation of this novel autosomal recessive form of OI, which presents with high prevalence of nonunion fractures considered rare events in OI in general. In addition, it expands the phenotype to include base skull anomalies, potentially leading to serious complications, as seen in severe forms of OI. A poor response to bisphosphonate therapy was observed in these individuals. As the variant in CCDC134 leads to dysregulation of the RAS/MAPK signaling pathway, drugs targeted to this pathway could be an alternative to achieve a better management of these individuals.

Predictive Modeling for Clinical Features Associated With Neurofibromatosis Type 1

Objective

To perform a longitudinal analysis of clinical features associated with neurofibromatosis type 1 (NF1) based on demographic and clinical characteristics and to apply a machine learning strategy to determine feasibility of developing exploratory predictive models of optic pathway glioma (OPG) and attention-deficit/hyperactivity disorder (ADHD) in a pediatric NF1 cohort.

Methods

Using NF1 as a model system, we perform retrospective data analyses using a manually curated NF1 clinical registry and electronic health record (EHR) information and develop machine learning models. Data for 798 individuals were available, with 578 comprising the pediatric cohort used for analysis.

Results

Males and females were evenly represented in the cohort. White children were more likely to develop OPG (odds ratio [OR]: 2.11, 95% confidence interval [CI]: 1.11–4.00, p = 0.02) relative to their non-White peers. Median age at diagnosis of OPG was 6.5 years (1.7–17.0), irrespective of sex. Males were more likely than females to have a diagnosis of ADHD (OR: 1.90, 95% CI: 1.33–2.70, p < 0.001), and earlier diagnosis in males relative to females was observed. The gradient boosting classification model predicted diagnosis of ADHD with an area under the receiver operator characteristic (AUROC) of 0.74 and predicted diagnosis of OPG with an AUROC of 0.82.

Conclusions

Using readily available clinical and EHR data, we successfully recapitulated several important and clinically relevant patterns in NF1 semiology specifically based on demographic and clinical characteristics. Naive machine learning techniques can be potentially used to develop and validate predictive phenotype complexes applicable to risk stratification and disease management in NF1.

Delineating the autistic phenotype in children with neurofibromatosis type 1

Background

Existing research has demonstrated elevated autistic behaviours in children with neurofibromatosis type 1 (NF1), but the autistic phenotype and its relationship to other neurodevelopmental manifestations of NF1 remains unclear. To address this gap, we performed detailed characterisation of autistic behaviours in children with NF1 and investigated their association with other common NF1 child characteristics.

Methods

Participants were drawn from a larger cross-sectional study examining autism in children with NF1. The population analysed in this study scored above threshold on the Social Responsiveness Scale-Second Edition (T-score ≥ 60; 51% larger cohort) and completed the Autism Diagnostic Interview-Revised (ADI-R) and/or the Autism Diagnostic Observation Schedule-Second Edition (ADOS-2). All participants underwent evaluation of their intellectual function, and behavioural data were collected via parent questionnaires.

Results

The study cohort comprised 68 children (3–15 years). Sixty-three per cent met the ADOS-2 ‘autism spectrum’ cut-off, and 34% exceeded the more stringent threshold for ‘autistic disorder’ on the ADI-R. Social communication symptoms were common and wide-ranging, while restricted and repetitive behaviours (RRBs) were most commonly characterised by ‘insistence on sameness’ (IS) behaviours such as circumscribed interests and difficulties with minor changes. Autistic behaviours were weakly correlated with hyperactive/impulsive attention deficit hyperactivity disorder (ADHD) symptoms but not with inattentive ADHD or other behavioural characteristics. Language and verbal IQ were weakly related to social communication behaviours but not to RRBs.

Limitations

Lack of genetic validation of NF1, no clinical diagnosis of autism, and a retrospective assessment of autistic behaviours in early childhood.

Conclusions

Findings provide strong support for elevated autistic behaviours in children with NF1. While these behaviours were relatively independent of other NF1 comorbidities, the importance of taking broader child characteristics into consideration when interpreting data from autism-specific measures in this population is highlighted. Social communication deficits appear similar to those observed in idiopathic autism and are coupled with a unique RRB profile comprising prominent IS behaviours. This autistic phenotype and its relationship to common NF1 comorbidities such as anxiety and executive dysfunction will be important to examine in future research. Current findings have important implications for the early identification of autism in NF1 and clinical management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13229-021-00481-3.

Neurofibromatosis in Children: Actually and Perspectives

The three types of neurofibromatosis, namely type 1, type 2, and schwannomatosis, are generally associated with various benign tumors affecting the skin and the nervous system. On rare occasions, especially in patients with neurofibromatosis type 1 (NF1), malignant neoplasms may also be present, several of them possessing a more aggressive course than in individuals without this syndrome. As such, a clear delineation between the three variants of neurofibromatosis is crucial to establish the correct diagnosis and management, as well as predict the neoplasm-related outcomes. Neurofibromin, the principal product of the NF1 gene, is a potent inhibitor of cellular proliferation, having been linked to several key signaling pathways involved in tumor growth. Therefore, it may provide a useful therapeutic target for tumor management in these patients. In this article, we want to present the association between deficiency of neurofibromin and the consequences of the lack of this protein leading to different kinds of malignant tumors. The therapy is still uncertain and most therapeutic options are in development or clinical trials.

Genotypes and clinical intervention of patients with neurofibromatosis type 1 associated dystrophic scoliosis

OBJECTIVE

To analyze the genotypic characteristics of patients with neurofibromatosis type 1 (NF1) associated dystrophic scoliosis and to summarize the outcomes of the surgical treatment of these patients.

METHODS

Exome sequencing (ES) combined with multiplex ligation-dependent probe amplification (MLPA) was used for genotypic identification. All patients underwent surgical treatments for spinal deformities, and the outcomes of the surgery was summarized by analyzing the clinical and imaging parameters before and after the surgery.

RESULTS

Fourteen patients (six males and eight females) were clinically diagnosed as NF1 associated dystrophic scoliosis with common symptoms including café-au-lait spots, paravertebral tumors, and dystrophic scoliosis. NF1 mutations were detected in 12 (85.7%) patients, including four nonsense mutations, three splicing mutations, three frameshift mutations, and two exon deletions. The first surgical procedure included growing-rod surgery in 10 patients and posterior spinal fusion in four patients. The follow-up duration was 2.3 years (1.0-10.3 years), and the Cobb angle of the main curve improved from 61.5° (30°-125°) pre-operatively to 14.5° (0°-42°) at the last follow-up, with an average correction rate of 74.0% (44-100%). Instrumentation-related complications occurred in four patients during the follow-up period.

CONCLUSIONS

In patients with dystrophic scoliosis who met the clinical diagnostic criteria for NF1, the mutation detection rate of ES combined with MLPA was 85.7%. There was no mutation hotspot in NF1 gene, molecular diagnosis could offer information about genetic counseling, prenatal diagnosis and eugenics. Surgical treatment according to patient's age and severity could effectively correct the spinal deformities.

Are Children Suffering From Congenital Pseudarthrosis of the Tibia Associated With Decreased Bone Strength?

BACKGROUND

Congenital pseudarthrosis of the tibia (CPT) is a rare and difficult-to-treat congenital disease in neonates. Our previous study found that exosomes derived from serum of children with CPT inhibit bone formation. In this study, we used ultrasound bone densitometry to detect the bone strength differences between hospitalized children with CPT and with non-metabolic diseases to determine the bone strength of children with CPT.

METHODS

A total of 37 children with CPT with a mean age of 3.14 ± 1.81 years and 40 hospitalized children with a mean age of 3.32 ± 2.66 years with supracondylar fracture of the humerus and without a bone metabolic disease (control group) were recruited in our hospital. The ultrasonic bone densitometer was used to examine the bilateral calcaneus of the subjects. We collected the broadband ultrasonic attenuation (BUA), speed of sound (SOS), quantitative ultrasound index (QUI), bone strength index (STI) and bone mineral density estimation (BMDe) values. Multivariable regression was used to examine the associations between quantitative ultrasound measurement differences and age, body mass index (BMI), neurofibromatosis type 1 (NF1) and CPT Crawford type. Intra-class correlation coefficient (ICC) was calculated to estimate intra- and inter-rater agreements.

RESULTS

74 calcaneus scans were taken from CPT patients (23 boys and 14 girls) and 80 calcaneus scans were taken from the control (24 boys and 16 girls). The CPT patients exhibited significantly lower SOS (1,368.75 ± 136.78 m/s), STI (7.2319 ± 38.6525), QUI (8.2532 ± 56.1720), and BMDe (-0.0241 ± 0.3552 g/cm³) than the control (SOS: 1,416.02 ± 66.15 m/s, STI: 7.96 ± 16.884, QUI: 28.8299 ± 25.461, BMDe: 0.0180 ± 0.1610 g/cm³). Multiple regression revealed that SOS, STI and QUI were statistically significant and negatively correlated with CPT Crawford classification.

CONCLUSIONS

We found the incidence of decreased bone strength in CPT group was higher than that in the non-bone metabolic disease group. This phenomenon was not related to NF1 but related to CPT Crawford classification, which suggested that the higher the grade of the CPT Crawford classification, the lower the bone strength and the higher the risk of fracture.

Pediatric Metastatic Pheochromocytoma and Paraganglioma: Clinical Presentation and Diagnosis, Genetics, and Therapeutic Approaches

Although pediatric pheochromocytomas and paragangliomas (PPGLs) are rare, they have important differences compared to those in adults. Unfortunately, without timely diagnosis and management, these tumors have a potentially devastating impact on pediatric patients. Pediatric PPGLs are more often extra-adrenal, multifocal/metastatic, and recurrent, likely due to these tumors being more commonly due to a genetic predisposition than in adults. This genetic risk results in disease manifestations at an earlier age giving these tumors time to advance before detection. In spite of these problematic features, advances in the molecular and biochemical characterization of PPGLs have heralded an age of increasingly personalized medicine. An understanding of the genetic basis for an individual patient's tumor provides insight into its natural history and can guide clinicians in management of this challenging disease. In pediatric PPGLs, mutations in genes related to pseudohypoxia are most commonly seen, including the von Hippel-Lindau gene (VHL) and succinate dehydrogenase subunit (SDHx) genes, with the highest risk for metastatic disease associated with variants in SDHB and SDHA. Such pathogenic variants are associated with a noradrenergic biochemical phenotype with resultant sustained catecholamine release and therefore persistent symptoms. This is in contrast to paroxysmal symptoms (e.g., episodic hypertension, palpitations, and diaphoresis/flushing) as seen in the adrenergic, or epinephrine-predominant, biochemical phenotype (due to episodic catecholamine release) that is commonly observed in adults. Additionally, PPGLs in children more often present with signs and symptoms of catecholamine excess. Therefore, children, adolescents, and young adults present differently from older adults (e.g., the prototypical presentation of palpitations, perspiration, and pounding headaches in the setting of an isolated adrenal mass). These presentations are a direct result of genetic determinants and highlight the need for pediatricians to recognize these differences in order to expedite appropriate evaluations, including genetic testing. Identification and familiarity with causative genes inform surveillance and treatment strategies to improve outcomes in pediatric patients with PPGL.

Neurofibromatosis Type 1 Gene Alterations Define Specific Features of a Subset of Glioblastomas

Neurofibromatosis type 1 (NF1) gene mutations or alterations occur within neurofibromatosis type 1 as well as in many different malignant tumours on the somatic level. In glioblastoma, NF1 loss of function plays a major role in inducing the mesenchymal (MES) subtype and, therefore defining the most aggressive glioblastoma. This is associated with an immune signature and mediated via the NF1–MAPK–FOSL1 axis. Specifically, increased invasion seems to be regulated via mutations in the leucine-rich domain (LRD) of the NF1 gene product neurofibromin. Novel targets for therapy may arise from neurofibromin deficiency-associated cellular mechanisms that are summarised in this review.

MEK inhibition exerts temporal and myeloid cell-specific effects in the pathogenesis of neurofibromatosis type 1 arteriopathy

Mutations in the NF1 tumor suppressor gene are linked to arteriopathy. Nf1 heterozygosity (Nf1+/–) results in robust neointima formation, similar to humans, and myeloid-restricted Nf1+/– recapitulates this phenotype via MEK-ERK activation. Here we define the contribution of myeloid subpopulations to NF1 arteriopathy. Neutrophils from WT and Nf1+/– mice were functionally assessed in the presence of MEK and farnesylation inhibitors in vitro and neutrophil recruitment to lipopolysaccharide was assessed in WT and Nf1+/– mice. Littermate 12–15 week-old male wildtype and Nf1+/– mice were subjected to carotid artery ligation and provided either a neutrophil depleting antibody (1A8), liposomal clodronate to deplete monocytes/macrophages, or PD0325901 and neointima size was assessed 28 days after injury. Bone marrow transplant experiments assessed monocyte/macrophage mobilization during neointima formation. Nf1+/– neutrophils exhibit enhanced proliferation, migration, and adhesion via p21^Ras activation of MEK in vitro and in vivo. Neutrophil depletion suppresses circulating Ly6C^low monocytes and enhances neointima size, while monocyte/macrophage depletion and deletion of CCR2 in bone marrow cells abolish neointima formation in Nf1+/– mice. Taken together, these findings suggest that neurofibromin-MEK-ERK activation in circulating neutrophils and monocytes during arterial remodeling is nuanced and points to important cross-talk between these populations in the pathogenesis of NF1 arteriopathy.

Epilepsy in NF1: Epidemiologic, Genetic, and Clinical Features. A Monocentric Retrospective Study in a Cohort of 784 Patients

An increased lifetime risk of epilepsy has been reported in neurofibromatosis type 1 (NF1) patients, ranging between 4% and 14%. To further analyze the correlation between NF1 and epilepsy, we retrospectively reviewed the epidemiologic, clinical, radiological, and molecular data of 784 unselected patients diagnosed with NF1 and referred to the neurofibromatosis outpatient clinics at the University Hospital of Padua. A crude prevalence of epilepsy of 4.7% was observed. In about 70% of cases, seizures arose in the context of neuroradiological findings, with the main predisposing factors being cerebral vasculopathies and hydrocephalus. In the absence of structural abnormalities, the prevalence of epilepsy was found to be 1.27%, which is approximately equal to the total prevalence in the general population. NF1 patients with seizures exhibit a higher incidence of intellectual disability and/or developmental delay, as well as of isolated learning disabilities. The comparison of causative NF1 mutations between the two groups did not reveal a specific genotype-phenotype correlation. Our data refine the current knowledge on epileptological manifestations in NF1 patients, arguing against the hypothesis that specific mechanisms, inherent to neurofibromin cellular function, might determine an increased risk of epilepsy in this condition.

Concomitant variants in NF1, LZTR1 and GNAZ genes probably contribute to the aggressiveness of plexiform neurofibroma and warrant treatment with MEK inhibitor

Neurofibromatosis 1 (NF1) is caused by germline mutations in the NF1 gene and manifests as proliferation of various tissues, including plexiform neurofibromas. The plexiform neurofibroma phenotype varies from indolent to locally aggressive, suggesting contributions of other modifiers in addition to somatic loss of NF1. In this study, we investigated a life-threatening plexiform neurofibroma in a 9-month-old female infant with NF1. Germline mutations in two RASopathy-associated genes were identified using whole-exome sequencing-a de novo pathogenic variant in the NF1 gene, and a known pathogenic variant in the LZTR1 gene. Somatic analysis of the plexiform neurofibroma revealed NF1 loss of heterozygosity and a variant in GNAZ, a gene encoding a G protein-coupled receptor. Cells expressing mutant GNAZ exhibited increased ERK 1/2 activation compared to those expressing wild-type GNAZ. Taken together, we suggest the variants in NF1, LZRT1 and GNAZ act synergistically in our patient, leading to MAPK pathway activation and contributing to the severity of the patient's plexiform neurofibromatosis. After treatment with the MEK inhibitor, trametinib, a prominent clinical improvement was observed in this patient. This case study contributes to the knowledge of germline and somatic non-NF1 variants affecting the NF1 clinical phenotype and supports use of personalized, targeted therapy.

Assessing Psychiatric Comorbidity and Pharmacologic Treatment Patterns Among Patients With Neurofibromatosis Type 1

Background and objective

Neurofibromatosis 1 (NF1) is a genetic disorder that is accompanied by psychiatric comorbidities such as depression, anxiety, and attention-deficit hyperactivity disorder (ADHD) in more than half of the patients. However, there are limited data describing optimal treatment strategies for these conditions. This study aimed to address that gap in understanding and explore the neurobiological basis of psychiatric comorbidities in NF1.

Materials and methods

A retrospective cohort study was conducted among NF1 patients with a comorbid diagnosis of depression, anxiety, and/or ADHD. These disease states were chosen based on their relatively high reported prevalence in NF1 and shared pathophysiological mechanisms via monoaminergic dysfunction. Information regarding demographics, psychotherapeutic medication use, and clinical outcomes was gathered from electronic medical records. Relationships between patient- and medication-related factors and outcome measures were assessed using statistical analysis.

Results

The study population (n = 82) consisted of NF1 patients with a comorbid diagnosis of depression (76.8%), anxiety (53.7%), and/or ADHD (23.2%). The use of second-generation antipsychotic agent augmentation therapy or hydroxyzine monotherapy was associated with significantly more behavioral health (BH)-related emergency department (ED) visits, admissions, and inpatient days in the study population. Conversely, the use of bupropion augmentation therapy, buspirone augmentation therapy, and stimulants was associated with improved clinical outcomes, though these results were not statistically significant.

Conclusions

Based on our findings in this real-world study setting, patients with NF1 and psychiatric comorbidities appear to experience significant benefits from medications that enhance dopaminergic neurotransmission (e.g., bupropion, stimulants) when compared to drugs that oppose it (e.g., second-generation antipsychotics).

Visuospatial but Not Verbal Working Memory Deficits in Adult Patients With Neurofibromatosis Type 1

Background: Cognitive dysfunction is one of the main symptoms of neurofibromatosis type 1 (NF1). As an important cognitive function, working memory (WM) has rarely been systematically analyzed in NF1 by isolating the particular domain of WM, and existing data involving WM in adult patients with NF1 are insufficient. This study aimed to investigate the characteristics of different types of WM in NF1 from the perspective of the adult population. Method: We comprehensively analyzed WM in both verbal and visuospatial WM domains by using the N-back task (including the verbal N-back task and the visuospatial N-back task) in 31 adults with NF1 and 34 healthy controls matched for age, gender, education levels, and general cognitive status. The accuracy and reaction times (RTs) in the N-back task were entered into mixed-design ANOVA. Results: Compared with healthy controls, adults with NF1 presented significantly lower mean accuracy and longer RTs in the visuospatial N-back task. However, no significant difference was found between the NF1 group and healthy controls in the verbal N-back task. Conclusions: The present study suggested that adults with NF1 might have deficits in visuospatial WM. We did not find evidence for verbal WM deficits in adult patients with NF1. Our findings supplement and refine the existing data on WM in the context of NF1.

Auditory Dysfunction Among Individuals With Neurofibromatosis Type 1

IMPORTANCE

Neurofibromatosis type 1 (NF1) affects hearing through disruption of central auditory processing. The mechanisms, functional severity, and management implications are unclear.

OBJECTIVE

To investigate auditory neural dysfunction and its perceptual consequences in individuals with NF1.

DESIGN, SETTING, AND PARTICIPANTS

This case-control study included children and adults with NF1 and control participants matched on age, sex, and hearing level. Patients were recruited through specialist neurofibromatosis and neurogenetic outpatient clinics between April and September 2019. An evaluation of auditory neural activity, monaural/binaural processing, and functional hearing was conducted. Diffusion-weighted magnetic resonance imaging (MRI) data were collected from a subset of participants (10 children with NF1 and 10 matched control participants) and evaluated using a fixel-based analysis of apparent fiber density.

MAIN OUTCOMES AND MEASURES

Type and severity of auditory dysfunction evaluated via laboratory testing and questionnaire data.

RESULTS

A total of 44 participants (18 [41%] female individuals) with NF1 with a mean (SD) age of 16.9 (10.7) years and 44 control participants (18 [41%] female individuals) with a mean (SD) age of 17.2 (10.2) years were included in the study. Overall, 11 participants (25%) with NF1 presented with evidence of auditory neural dysfunction, including absent, delayed, or low amplitude electrophysiological responses from the auditory nerve and/or brainstem, compared with 1 participant (2%) in the control group (odds ratio [OR], 13.03; 95% CI, 1.59-106.95). Furthermore, 14 participants (32%) with NF1 showed clinically abnormal speech perception in background noise compared with 1 participant (2%) in the control group (OR, 20.07; 95% CI, 2.50-160.89). Analysis of diffusion-weighted MRI data of participants with NF1 showed significantly lower apparent fiber density within the ascending auditory brainstem pathways. The regions identified corresponded to the neural dysfunction measured using electrophysiological assessment.

CONCLUSIONS AND RELEVANCE

The findings of this case-control study could represent new neurobiological and clinical features of NF1. Auditory dysfunction severe enough to impede developmental progress in children and restrict communication in older participants is a common neurobiological feature of the disorder.

RETINAL VASCULAR ABNORMALITIES IN CHILDREN WITH NEUROFIBROMATOSIS TYPE 1

PURPOSE

Retinal vascular abnormalities (RVAs) have been recently described in patients with neurofibromatosis Type 1 (NF1) as vascular tortuosity, best visible on infrared imaging. This study assessed clinical RVA's characteristics in a large series of children with NF1.

METHODS

This retrospective observational study was conducted in children (0-18 years) with an NF1 diagnosis. Using near-infrared imaging, RVAs were classified according to the nature of vessels involvement and their degree of tortuosity.

RESULTS

Retinal imaging from 140 children, with a median age of 8.8 years (1.5-18), was included; 52 patients (37.1%) (81 eyes) exhibited RVAs. These RVAs comprised 96% (50/52) of simple vascular tortuosity and 17% (9/52) of a corkscrew pattern. A corkscrew pattern involved only small veins, whereas simple vascular tortuosity could affect both arteries and veins. No statistically significant age correlation was observed, but evolution of RVAs from simple vascular tortuosity to corkscrew pattern was observed in 5 cases.

CONCLUSION

Retinal vascular abnormalities occurred in 37.1% of children with NF1. These abnormalities may result from NF1 promoting localized tortuosity in both small arteries and veins, whereas only small second-order or tertiary-order venules evolve to a highly tortuous pattern.

The cryo-EM structure of the human neurofibromin dimer reveals the molecular basis for neurofibromatosis type 1

Neurofibromin (NF1) mutations cause neurofibromatosis type 1 and drive numerous cancers, including breast and brain tumors. NF1 inhibits cellular proliferation through its guanosine triphosphatase-activating protein (GAP) activity against rat sarcoma (RAS). In the present study, cryo-electron microscope studies reveal that the human ~640-kDa NF1 homodimer features a gigantic 30 × 10 nm array of α-helices that form a core lemniscate-shaped scaffold. Three-dimensional variability analysis captured the catalytic GAP-related domain and lipid-binding SEC-PH domains positioned against the core scaffold in a closed, autoinhibited conformation. We postulate that interaction with the plasma membrane may release the closed conformation to promote RAS inactivation. Our structural data further allow us to map the location of disease-associated NF1 variants and provide a long-sought-after structural explanation for the extreme susceptibility of the molecule to loss-of-function mutations. Collectively these findings present potential new routes for therapeutic modulation of the RAS pathway.

Dissociated Deficits between Explicit and Implicit Empathetic Pain Perception in Neurofibromatosis Type 1

Cognitive impairments and social-function deficits are severe complaints in neurofibromatosis type 1 (NF1) patients. Empathetic pain perception may be disrupted in NF1 patients because of high-level cognitive deficits. This study investigated the empathy profiles of adult patients with NF1, especially concerning whether explicit and implicit empathetic pain perception are abnormal in this population. We examined empathetic pain perception through a paradigm based on perceiving another person’s pain; in this task, patients were required to make judgments about the presence of pain or the laterality of the body part, as shown in a picture. Twenty NF1 patients without obvious social or communication difficulties completed the task, and the results were compared with results from the normal controls (NCs). Regarding explicit empathetic pain processing, i.e., judging the presence of “pain” or “no pain”, there were no significant differences between patients and controls in accuracy or reaction time. However, in implicit empathetic processing, i.e., judging the laterality of “pain” or “no-pain” pictures, NF1 patients had significantly lower accuracy (p = 0.038) and significantly higher reaction times (p = 0.004) than the NCs. These results were consistent with those of a previous study showing that high-level cognitive deficits were prominent in NF1 patients when performing challenging tasks. The mechanisms and related brain network activity underlying these deficits should receive attention in the future.

A therapeutic window for preventive therapy in NF1-associated optic pathway glioma

Pediatric low-grade gliomas (pLGGs) are almost universally driven by abnormal activation of RAS-mediated MEK-ERK/MAPK signaling pathway. pLGGs predominantly occur in children, suggesting that they originate in an ERK-dependent neural stem/progenitor population(s) transiently present in the developing brain. Our recent preclinical study reveals a cell-lineage-of-origin and develops a chemopreventative therapeutic strategy.

Targeted Therapies for the Neurofibromatoses

Over the past several years, management of the tumors associated with the neurofibromatoses has been recognized to often require approaches that are distinct from their spontaneous counterparts. Focus has shifted to therapy aimed at minimizing symptoms given the risks of persistent, multiple tumors and new tumor growth. In this review, we will highlight the translation of preclinical data to therapeutic trials for patients with neurofibromatosis, particularly neurofibromatosis type 1 and neurofibromatosis type 2. Successful inhibition of MEK for patients with neurofibromatosis type 1 and progressive optic pathway gliomas or plexiform neurofibromas has been a significant advancement in patient care. Similar success for the malignant NF1 tumors, such as high-grade gliomas and malignant peripheral nerve sheath tumors, has not yet been achieved; nor has significant progress been made for patients with either neurofibromatosis type 2 or schwannomatosis, although efforts are ongoing.

What Are the Place and Modalities of Surgical Management for Pancreatic Neuroendocrine Neoplasms? A Narrative Review

Pancreatic neuroendocrine neoplasms (panNENs) are a heterogeneous group of tumors derived from cells with neuroendocrine differentiation. They are considered malignant by default. However, their outcomes are variable depending on their presentation in the onset of hereditary syndromes, hormonal secretion, grading, and extension. Therefore, although surgical treatment has long been suggested as the only treatment of pancreatic neuroendocrine neoplasms, its modalities are an evolving landscape. For selected patients (small, localized, non-functional panNENs), a "wait and see" strategy is suggested, as it is in the setting of multiple neuroendocrine neoplasia type 1, but the accurate size cut-off remains to be established. Parenchyma-sparring pancreatectomy, aiming to limit pancreatic insufficiency, are also emerging procedures, which place beyond the treatment of insulinomas and small non-functional panNENs (in association with lymph node picking) remains to be clarified. Furthermore, giving the fact that the liver is generally the only metastatic site, surgery keeps a place of choice alongside medical therapies in the treatment of metastatic disease, but its modalities and extensions are still a matter of debate. This narrative review aims to describe the current recommended surgical management for pancreatic NENs and controversies in light of the actual recommendations and recent literature.

Optic pathway glioma and the sex association in neurofibromatosis type 1: a single-center study

Background

Low-grade optic pathway glioma (OPG) develops in 15–20% of children with neurofibromatosis type 1 (NF1). OPGs are symptomatic in 30–50% and one-third of these require treatment. A few studies have suggested female sex as a risk factor for visual impairment associated with NF1-OPG. This descriptive study investigated the correlation between NF1-OPG growth, sex and visual impairment.

Method

We based our cross-sectional study on a systematic, retrospective data collection in a NF1 cohort of children and adolescents below 21 years of age followed at Center for Rare Diseases, Aarhus University Hospital, Denmark. For each patient with OPG a medical chart review was performed including demographics, ophthalmological examinations and magnetic resonance imaging (MRI) of OPG.

Results

Of 176 patients with NF1 (85 females, 91 males), we identified 21 patients with OPG (11.9%) with a preponderance of females, p = 0.184. Eight females (62%) and one male (13%) had visual impairment at the last ophthalmological evaluation. Five out of 21 children with OPG (24%) underwent diagnostic MRI because of clinical findings at the ophthalmological screening. Nine children (43%) had symptoms suggestive of OPG and seven (33%) experienced no OPG-related symptoms before the diagnostic MRI. Of eight children diagnosed with OPG ≤ two years of age, one had visual impairment. Of 13 children diagnosed > two years of age, eight had visual impairment; in each group, four of the children were treated with chemotherapy. The study suggested no correlation between NF1-OPG growth and sex.

Conclusion

Our data suggest sex as a risk factor for visual impairment, while an OPG diagnose ≤ two years of age was a protective factor for visual impairment. Females with NF1-OPG had a higher prevalence of visual impairment outcome compared to males. Interestingly, our data also suggest a better response to treatment in children with OPG diagnosed ≤ two years of age compared to older children. The findings in our study suggest sex as a potential prognostic factor for visual impairment.

Neurovascular Syndromes

Patients with cerebrovascular syndromes are at risk for additional concerns associated with their syndrome. A wide variety of syndromes are associated with cerebrovascular diseases. Multidisciplinary care is helpful to ensure comprehensive evaluation and management. Precise diagnosis and appreciation for the underlying syndrome is critical for effective cerebrovascular and broader care. This text focuses on these conditions with a focus on underlying pathophysiology and associated genetics, presentation, diagnosis, and management of each disease.

Brain Cancers in Genetic Syndromes

PURPOSE OF REVIEW

Although genetic conditions that cause primary central nervous system tumors are rare, their pathophysiology influences both treatment and surveillance. This article reviews the most frequently occurring genetic conditions associated with brain cancers and highlights the most recent therapeutic approaches in the treatment of Lynch syndrome (and other disorders of the mismatch repair system), neurofibromatosis 1, and Li-Fraumeni syndrome.

RECENT FINDINGS

Recent advances in molecular diagnostics have considerably improved the ability to diagnose genetic conditions in people with primary brain tumors. The common application of next-generation sequencing analyses of tissue increases the frequency with which clinicians are forced to address the possibility of an underlying genetic condition based on tissue molecular findings. Clinicians must be aware of the clinical presentation of genetic conditions predisposing to brain tumors in order to discern which patients are appropriate for germline genetic testing. Advances in therapeutics for specific genetic variants are increasingly available, and accurately diagnosing an underlying genetic condition may directly impact patient outcomes.

What Every Internist-Endocrinologist Should Know about Rare Genetic Syndromes in Order to Prevent Needless Diagnostics, Missed Diagnoses and Medical Complications: Five Years of 'Internal Medicine for Rare Genetic Syndromes'

Patients with complex rare genetic syndromes (CRGS) have combined medical problems affecting multiple organ systems. Pediatric multidisciplinary (MD) care has improved life expectancy, however, transfer to internal medicine is hindered by the lack of adequate MD care for adults. We have launched an MD outpatient clinic providing syndrome-specific care for adults with CRGS, which, to our knowledge, is the first one worldwide in the field of internal medicine. Between 2015 and 2020, we have treated 720 adults with over 60 syndromes. Eighty-nine percent of the syndromes were associated with endocrine problems. We describe case series of missed diagnoses and patients who had undergone extensive diagnostic testing for symptoms that could actually be explained by their syndrome. Based on our experiences and review of the literature, we provide an algorithm for the clinical approach of health problems in CRGS adults. We conclude that missed diagnoses and needless invasive tests seem common in CRGS adults. Due to the increased life expectancy, an increasing number of patients with CRGS will transfer to adult endocrinology. Internist-endocrinologists (in training) should be aware of their special needs and medical pitfalls of CRGS will help prevent the burden of unnecessary diagnostics and under- and overtreatment.

Giant mediastinal mass in a 3-year-old boy: A rare presentation of neurofibromatosis type I

Neurofibromatosis type 1 (NF1) is an autosomal dominant disease diagnosed with the presentation of café-au-lait macules, skinfold freckling, iris Lisch nodules, neurofibromas, osseous lesion, and optic gliomas. Mediastinal mass as the first presentation of NF1 is very rare, with a frequency of about 2.7%. Here, we present a rare case of NF1 in a 3-year-old boy admitted with respiratory distress and superior vena cava syndrome.

First Case of Tricuspid Valve Surgery in a Neurofibromatosis Type 1 Patient

The neurofibromatosis is a large class of different genetic disorders: Neurofibromatosis type 1, type 2, type 3 (or Schwannomatosys), which have different clinical characterization. Neurofibromatosis type 1 (NF1), also known as Von Recklinghausen disease, represents 95% of the total cases. It is a complex autosomal dominant disorder with multisystem involvement, frequently associated to cardiac malformation. We present the case of a 52-years-old male affected by NF-1 with severe tricuspid regurgitation and atrial septal defect (ASD). No previous report about tricuspid valve surgery in NF-1 are available in the literature. A complete perioperative assessment was performed, including dermatologist evaluation, angio-CT scan and transesophageal echocardiography. The patient underwent uneventfully tricuspid valve replacement and ASD closure, with no wound complication even at 6-months follow-up. Treating congenital malformation in patient with complex genetic disorders like NF-1 is safe and can be resolutive, permitting to reduce long-term risk of complications for the patients. Preoperative assessments are fundamental, as well as in-hospital care and expertise on congenital heart defects.

Treatment of cutaneous neurofibromas with carbon dioxide laser: Technique and patient experience

Cutaneous neurofibromas (cNF) are one of the hallmarks of neurofibromatosis 1 (NF1). The number of cNFs varies between individuals from a few to hundreds or even thousands and increases throughout adult life. cNFs cause a significant disease burden to adult patients and constitute an unmet need for therapy, since they may cause itch and pain and, being conspicuous and unsightly, stigmatize the patient. There is a lack of reports on how the outcome of various treatment options are perceived by the patients. Here we describe a technique for cNF removal using CO₂ laser, and report how patients experience the procedure. Questionnaires were sent to patients who had had CO₂ laser surgery in the French Referral Center for Neurofibromatoses, and in the Turku University Hospital, Finland, to retrospectively evaluate the patients' global satisfaction of the procedure, treatment indications, and reasons for withdrawal from treatment, if this was the case. The number of returned questionnaires was 233/473 in France and 23/27 in Finland. The results showed that the most important indications for cNF removal were esthetic, and pain and itch caused by the tumors. In general, the procedure was well tolerated, and the degree of satisfaction was 8-10 on a scale from 0 to 10. For those 30% who discontinued the tumor removal program, the main reasons were organizational constraints, a non-satisfactory esthetic result, too many cNFs to treat, or problems with healing. Thus, the CO₂ laser method is well tolerated but does not fully answer to the needs of the patients. Since medical treatment is not yet available, we encourage the use of laser removal of cNFs as a feasible method to decrease the tumor burden of the patients.

The importance of suicide risk assessment in patients affected by neurofibromatosis

OBJECTIVE

Neurofibromatosis 1 (NF1) is a chronic medical disease that often presents with psychiatric disorders. We investigated suicidal ideation in NF1 patients compared to healthy controls. We also evaluated whether hopelessness, depressive symptoms and perceived disability may mediate suicidal ideation in patients with NF1.

METHODS

We enrolled 60 patients with NF1 and 50 healthy controls with no history of NF1. Patients underwent a full psychiatric evaluation. Psychiatric diagnosis was made according to Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) criteria. Patients and controls underwent a series of psychometric measures, namely the Columbia Suicide Severity Rating Scale, the Beck Hopelessness Scale, the Italian Perceived Disability Scale and the Beck Depression Inventory.

RESULTS

Suicidal ideation was significantly higher in patients with NF1 (45%) than in controls (10%). Patients also presented more severe perceived disability and hopelessness and more frequent psychiatric disorders than controls. Multivariable logistic regression analysis showed that perceived disability was independently associated with the presence of suicidal ideation in patients with NF1.

CONCLUSIONS

In conclusion, our results showed that suicidal ideation was present in almost half of patients with NF1, suggesting the importance of suicide assessment in these patients.Key pointsPatients with NF1 have an increased suicide ideation when compared to healthy controlsIncreased suicidal ideation correlates with perceived disability, but not with the presence of psychiatric disordersAssessment of suicidal ideation should be performed in patients with NF1.

RASopathies: The musculoskeletal consequences and their etiology and pathogenesis

The RASopathies comprise an ever-growing number of clinical syndromes resulting from germline mutations in components of the RAS/MAPK signaling pathway. While multiple organs and tissues may be affected by these mutations, this review will focus on how these mutations specifically impact the musculoskeletal system. Herein, we review the genetics and musculoskeletal phenotypes of these syndromes in humans. We discuss how mutations in the RASopathy syndromes have been studied in translational mouse models. Finally, we discuss how signaling molecules within the RAS/MAPK pathway are involved in normal and abnormal bone biology in the context of osteoblasts, osteoclasts and chondrocytes.

The structure of neurofibromin isoform 2 reveals different functional states

The autosomal dominant monogenetic disease neurofibromatosis type 1 (NF1) affects approximately one in 3,000 individuals and is caused by mutations in the NF1 tumour suppressor gene, leading to dysfunction in the protein neurofibromin (Nf1)1,2. As a GTPase-activating protein, a key function of Nf1 is repression of the Ras oncogene signalling cascade. We determined the human Nf1 dimer structure at an overall resolution of 3.3 Å. The cryo-electron microscopy structure reveals domain organization and structural details of the Nf1 exon 23a splicing3 isoform 2 in a closed, self-inhibited, Zn-stabilized state and an open state. In the closed conformation, HEAT/ARM core domains shield the GTPase-activating protein-related domain (GRD) so that Ras binding is sterically inhibited. In a distinctly different, open conformation of one protomer, a large-scale movement of the GRD occurs, which is necessary to access Ras, whereas Sec14-PH reorients to allow interaction with the cellular membrane4. Zn incubation of Nf1 leads to reduced Ras-GAP activity with both protomers in the self-inhibited, closed conformation stabilized by a Zn binding site between the N-HEAT/ARM domain and the GRD-Sec14-PH linker. The transition between closed, self-inhibited states of Nf1 and open states provides guidance for targeted studies deciphering the complex molecular mechanism behind the widespread neurofibromatosis syndrome and Nf1 dysfunction in carcinogenesis.

Treatment during a developmental window prevents NF1-associated optic pathway gliomas by targeting Erk-dependent migrating glial progenitors

The mechanism of vulnerability to pediatric low-grade gliomas (pLGGs)-the most common brain tumor in children-during development remains largely unknown. Using mouse models of neurofibromatosis type 1 (NF1)-associated pLGGs in the optic pathway (NF1-OPG), we demonstrate that NF1-OPG arose from the vulnerability to the dependency of Mek-Erk/MAPK signaling during gliogenesis of one of the two developmentally transient precursor populations in the optic nerve, brain-derived migrating glial progenitors (GPs), but not local progenitors. Hyperactive Erk/MAPK signaling by Nf1 loss overproduced GPs by disrupting the balance between stem-cell maintenance and gliogenesis of hypothalamic ventricular zone radial glia (RG). Persistence of RG-like GPs initiated NF1-OPG, causing Bax-dependent apoptosis in retinal ganglion cells. Removal of three Mek1/Mek2 alleles or transient post-natal treatment with a low-dose MEK inhibitor normalized differentiation of Nf1^-/- RG-like GPs, preventing NF1-OPG formation and neuronal degeneration. We provide the proof-of-concept evidence for preventing pLGGs before tumor-associated neurological damage enters an irreversible phase.

Novel Variants and Clinical Characteristics of 16 Patients from Southeast Asia with Genetic Variants in Neurofibromin-1

Neurofibromatosis type 1 (NF1) is one of the most common inherited disorders. It is caused by mutations in the neurofibromin-1 gene (NF1) and affects the formation and growth of nerve tissues. More than 3,600 pathogenic variants in the NF1 gene have been identified from patients with most of the germline variants are from the Western populations. We found 16 patients (15 Chinese and 1 Asian Indian) who had heterozygous variants in NF1 through targeted next-generation sequencing. There were 15 different variants: 4 frameshift, 4 nonsense, 5 missense, and 2 splice variants. One nonsense variant and three frameshift variants had never been reported in any population or patient database. Twelve of the 16 patients met the NF1 diagnostic criteria, and each was found to have a pathogenic or likely pathogenic variant. Three different missense variants of unknown significance were discovered in the other four patients who did not meet NF1 diagnostic criteria. Our findings add four novel variants to the list of genetic mutations linked to NF1's various clinical manifestations.

Familial left cervical neurofibromatosis 1 with scoliosis: A case report

BACKGROUND

Neurofibromatosis type 1 (NF1) is an inherited autosomal dominant disorder affecting many parts of the body with café au lait spots, skeletal deformity, and scoliosis. A familial case of NF1 with scoliosis and a painless mass had not yet been reported.

CASE SUMMARY

We describe the case of a 15-year-old male patient with a painless lump on the left side of his neck for 10 years and scoliosis. His right shoulder was about 5 cm lower than the left, the left side of his face was deformed, and the left submandibular skin was relaxed. The folding and drooping were obvious and movement was poor. Computed tomography revealed the involvement of the neck, upper chest wall, and surrounding left shoulder, accompanied by bone changes and scoliosis. Histological evaluation showed subepidermal pale blue mucoid degeneration, fibrous fusiform cells in the dermis in a fascicular, woven arrangement. His mother had the same medical history. The diagnosis was neurofibromatosis of the left neck. Various parts of the tumor tissue were serially resected during several visits. Eight months after surgery, there was a slight tendency to regrow.

CONCLUSION

This case of slow-progressing NF1 highlights the importance of early diagnosis and treatment to reduce its impact on the patient’s growth and development.

Survival and NF1 Analysis in a Cohort of Orthopedics Patients with Malignant Peripheral Nerve Sheath Tumors

Neurofibromatosis type 1 (NF1) is an autosomal dominant tumor syndrome in which benign plexiform neurofibromas are at risk of transforming into malignant peripheral nerve sheath tumors (MPNSTs), a very rare soft-tissue sarcoma. The prognosis of patients with MPNSTs is poor, with most studies reporting <50% survival at five years. However, studies evaluating MPNSTs are limited and report heterogeneous results. Because no MPNST-specific evidence-based treatment guideline exists, individual institutional experiences are very informative to the field. The main objective of this study was to investigate and report MPNST prognostic clinical and genetic biomarkers from our institution's Orthopedics service experience treating 20 cases from 1992 to 2017. Most patients were treated with resection and adjuvant radiation. Extended follow-up, averaging 11.4 years (ranging 1.1 to 25.1), revealed excellent five-year survival rates: 70% for overall and 60% for metastatic disease. An S100 B immunonegative tumor phenotype was associated with a significantly worse outcome than MPNSTs with positive S100 B stain. In addition, NF1 gene mutation analysis was performed on 27 families with NF1 in which at least one affected family member developed MPNSTs. Of the 27 NF1 germline mutations, five were large deletions spanning (or nearly spanning) the gene (18.5%), substantially more than such deletions in NF1 in general, consistent with increased risk of MPNSTs in such cases.

NuMorph: Tools for cortical cellular phenotyping in tissue-cleared whole-brain images

Tissue-clearing methods allow every cell in the mouse brain to be imaged without physical sectioning. However, the computational tools currently available for cell quantification in cleared tissue images have been limited to counting sparse cell populations in stereotypical mice. Here, we introduce NuMorph, a group of analysis tools to quantify all nuclei and nuclear markers within the mouse cortex after clearing and imaging by light-sheet microscopy. We apply NuMorph to investigate two distinct mouse models: a Topoisomerase 1 (Top1) model with severe neurodegenerative deficits and a Neurofibromin 1 (Nf1) model with a more subtle brain overgrowth phenotype. In each case, we identify differential effects of gene deletion on individual cell-type counts and distribution across cortical regions that manifest as alterations of gross brain morphology. These results underline the value of whole-brain imaging approaches, and the tools are widely applicable for studying brain structure phenotypes at cellular resolution.

Assessment of Mosaicism and Detection of Cryptic Alleles in CRISPR/Cas9-Engineered Neurofibromatosis Type 1 and TP53 Mutant Porcine Models Reveals Overlooked Challenges in Precision Modeling of Human Diseases

Genome editing in pigs has been made efficient, practical, and economically viable by the CRISPR/Cas9 platform, representing a promising new era in translational modeling of human disease for research and preclinical development of therapies and devices. Porcine embryo microinjection provides a universally available, efficient option over somatic-cell nuclear transfer, but requires that critical considerations be made in genotypic validation of the models that routinely go unaddressed. Accurate validation of genotypes is especially important when modeling genetic disorders, such as neurofibromatosis type 1 (NF1) that exhibits complex genotype–phenotypic relationships. NF1, an autosomal dominant disorder, is particularly hard to model as it manifests very differently across patients, and even within families, with over 3,000 disease-associated mutations of the neurofibromin 1 (NF1) gene identified. The precise nature of the mutations plays a role in the complex phenotypic presentation of the disorder that includes benign and malignant peripheral and central nervous system tumors, a variety of motor deficits and debilitating cognitive impairments and musculoskeletal, cardiovascular, and gastrointestinal disorders. NF1 can also often involve mutations in passenger genes such as TP53. In this manuscript, we describe the creation of three novel porcine models of NF1 and a model additionally harboring a mutation in TP53 by embryo microinjection of CRISPR/Cas9. We present the challenges encountered in validation of genotypes and the methodological strategies developed to counter the hurdles. We present simple options for quantifying level of mosaicism: a quantitative method (targeted amplicon sequencing) for small edits such as SNPs and indels and a semiquantitative method (competitive PCR) for large edits. Characterization of mosaicism allowed for strategic selection of founder pigs for rapid, economical expansion of genetically defined lines. We also present commonly observed unexpected DNA repair products (i.e., structural variants or cryptic alleles) that are refractory to PCR amplification and thus evade detection. We present the use of copy number variance assays to overcome hurdles in detecting cryptic alleles. The report provides a framework for genotypic validation of porcine models created by embryo microinjection and the expansion of lines in an efficient manner.

Insights into the Pathogenesis of NF1-Associated Neoplasms

Neurofibromatosis type 1 (NF1) is one of the most common neurocutaneous genetic disorders, presenting with different cutaneous features such as café-au-lait macules, intertriginous skin freckling, and neurofibromas. Although most of the disease manifestations are benign, patients are at risk for a variety of malignancies, including malignant transformation of plexiform neurofibromas. Numerous studies have investigated the mechanisms by which these characteristic neurofibromas develop, with progress made toward unraveling the various players involved in their complex pathogenesis. In this review, we summarize the current understanding of the cells that give rise to NF1 neoplasms as well as the molecular mechanisms and cellular changes that confer tumorigenic potential. We also discuss the role of the tumor microenvironment and the key aspects of its various cell types that contribute to NF1-associated tumorigenesis. An increased understanding of these intrinsic and extrinsic components is critical for developing novel therapeutic approaches for affected patients.

Autophagy is involved in neurofibromatosis type I gene-modulated osteogenic differentiation in human bone mesenchymal stem cells

Neurofibromatosis type I (NF1) is an autosomal dominant genetic disease that is caused by mutations in the NF1 gene. Various studies have previously demonstrated that the mTOR complex 1 signaling pathway is essential for the NF1-modulated osteogenic differentiation of bone mesenchymal stem cells (BMSCs). Additionally, the mTOR signaling pathway plays a notable role in autophagy. The present study hypothesized that NF1 could modulate the osteogenic differentiation of BMSCs by regulating the autophagic activities of BMSCs. In the present study, human BMSCs were cultured in an osteogenic induction medium. The expression of the NF1 gene was either knocked down or overexpressed by transfection with a specific small interfering RNA (siRNA) targeting NF1 or the pcDNA3.0 NF1-overexpression plasmid, respectively. Autophagic activities of BMSCs (Beclin-1, P62, LC3B I, and LC3B II) were determined using western blotting, electron microscopy, acridine orange (AO) staining and autophagic flux/lysosomal detection by fluorescence microscopy. In addition, the autophagy activator rapamycin (RAPA) and inhibitor 3-methyladenine (3-MA) were used to investigate the effects of autophagy on NF1-modulated osteogenic differentiation in BMSCs. Inhibiting NF1 with siRNA significantly decreased the expression levels of autophagy markers Beclin-1 and LC3B-II, in addition to osteogenic differentiation markers osterix, runt-related transcription factor 2 and alkaline phosphatase. By contrast, overexpressing NF1 with pcDNA3.0 significantly increased their levels. Transmission electron microscopy, AO staining and autophagic flux/lysosomal detection assays revealed that the extent of autophagosome formation was significantly decreased in the NF1-siRNA group but significantly increased in the NF1-pcDNA3.0 group when compared with the NC-siRNA and pcDNA3.0 groups, respectively. In addition, the activity of the PI3K/AKT/mTOR pathway [phosphorylated (p)-PI3K, p-AKT, p-mTOR and p-p70S6 kinase] was significantly upregulated in the NF1-siRNA group compared with the NC-siRNA group, and significantly inhibited in the NF1-pcDNA3.0 group, compared with the pcDNA3.0 group. The knockdown effects of NF1-siRNA on the autophagy and osteogenic differentiation of BMSCs were reversed by the autophagy activator RAPA, while the overexpression effects of NF1-pcDNA3.0 on the autophagy and osteogenic differentiation of BMSCs were reversed by the autophagy inhibitor 3-MA. In conclusion, results from the present study suggest at the involvement of autophagy in the NF1-modulated osteogenic differentiation of BMSCs. Furthermore, NF1 may partially regulate the autophagic activity of BMSCs through the PI3K/AKT/mTOR signaling pathway.

A Review of Selumetinib in the Treatment of Neurofibromatosis Type 1-Related Plexiform Neurofibromas

OBJECTIVE

To evaluate the safety and efficacy of selumetinib, a novel MEK inhibitor, for the treatment of plexiform neurofibromas (PN) in patients with neurofibromatosis type 1 (NF1).

DATA SOURCES

An English-based literature search of PubMed, EMBASE, and ClinicalTrials.gov was conducted using the terms selumetinib AND neurofibromatosis from inception to August 1, 2021.

STUDY SELECTION AND DATA EXTRACTION

Relevant prescribing information, abstracts, and articles identified through the search were considered for inclusion in this review.

DATA SYNTHESIS

The open-label, multicenter, single-arm, phase II SPRINT trial demonstrated clinically significant improvements in PN-related complications. Of 50 symptomatic patients, 68% experienced a partial response, with a median change in tumor volume of -27.9% from baseline. Estimated progression-free survival at 3 years was 84%. Additionally, clinically meaningful improvements were seen on patient- and parent-reported assessments evaluating pain, range of motion, disfigurement, and quality of life. Overall, the adverse effect profile for selumetinib appears mild and manageable.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Selumetinib is the first FDA-approved treatment for inoperable PN in patients with NF1, demonstrating that MEK inhibition is a promising therapeutic strategy. Studies are ongoing to assess the effect of selumetinib on other NF1-associated tumor types and to determine the optimal dosing schedule and treatment duration. Cost and treatment burden must be considered when selecting selumetinib therapy.

CONCLUSION

Selumetinib exhibits impressive antitumor activity and sustained clinical benefit in patients lacking other viable treatment options. Further studies are warranted to determine the optimal age of initiation, treatment duration, and overall cost-effectiveness of selumetinib.

Circulating tumor DNA for malignant peripheral nerve sheath tumors in neurofibromatosis type 1

PURPOSE

The leading cause of early death in patients with neurofibromatosis type 1 (NF1) is malignant peripheral nerve sheath tumor (MPNST). The principles of management include early diagnosis, surgical clearance and close monitoring for tumor recurrence. Current methods for diagnosis, detection of residual disease and monitoring tumor burden are inadequate, as clinical and radiological features are non-specific for malignancy in patients with multiple tumors and lack the sensitivity to identify early evidence of malignant transformation or tumor recurrence. Circulating tumor DNA (ctDNA) is a promising tool in cancer management and has the potential to improve the care of patients with NF1. In the following article we summarise the current understanding of the genomic landscape of MPNST, report on the previous literature of ctDNA in MPNST and outline the potential clinical applications for ctDNA in NF1 associated MPNST. Finally, we describe our prospective cohort study protocol investigating the utility of using ctDNA as an early diagnostic tool for MPNSTs in NF1 patients.

Cancer evolution: Darwin and beyond

Clinical and laboratory studies over recent decades have established branched evolution as a feature of cancer. However, while grounded in somatic selection, several lines of evidence suggest a Darwinian model alone is insufficient to fully explain cancer evolution. First, the role of macroevolutionary events in tumour initiation and progression contradicts Darwin's central thesis of gradualism. Whole-genome doubling, chromosomal chromoplexy and chromothripsis represent examples of single catastrophic events which can drive tumour evolution. Second, neutral evolution can play a role in some tumours, indicating that selection is not always driving evolution. Third, increasing appreciation of the role of the ageing soma has led to recent generalised theories of age-dependent carcinogenesis. Here, we review these concepts and others, which collectively argue for a model of cancer evolution which extends beyond Darwin. We also highlight clinical opportunities which can be grasped through targeting cancer vulnerabilities arising from non-Darwinian patterns of evolution.

Characteristics, treatment patterns, healthcare resource use, and costs among pediatric patients diagnosed with neurofibromatosis type 1 and plexiform neurofibromas: a retrospective database analysis of a medicaid population

OBJECTIVES

The objectives of this study were to describe the characteristics and initial treatment patterns, healthcare resource use (HCRU), and costs of patients newly diagnosed with neurofibromatosis type 1 (NF1)-related plexiform neurofibromas (PN).

METHODS

This was a retrospective study of individuals enrolled in the IBM MarketScan Multi-State Medicaid database from 1 October 2014 to 31 December 2017. Patients aged ≤18 years at the index date (first diagnosis of NF1 or PN, whichever occurred later) with at least 1 ICD-10-CM diagnosis code for both NF1 and PN were included. All-cause HCRU and the associated direct costs during the follow-up period were calculated per patient per year (PPPY) in 2018 USD.

RESULTS

A total of 383 patients were included with a mean follow-up of 448 days. Most patients were diagnosed by a specialist (63.5%). During the follow-up period, pain medications were used by 58.5% of patients, 25.1% were treated with chemotherapy, 7.1% received surgery for PN, 1.6% received MEK inhibitors, and 0.8% received radiation. Mean PPPY inpatient, outpatient, ER, pharmacy, and other visits were 1.4, 17.3, 1.6, 13.6, and 25.8, respectively. Mean ± SD (median) total PPPY healthcare costs were $17,275 ± $61,903 ($2889), with total medical costs of $14,628 ± $56,203 ($2334) and pharmacy costs of $2646 ± $13,303 ($26).

CONCLUSIONS

This study showed that many pediatric patients newly diagnosed with NF1 and PN were initially treated with supportive care only, highlighting a substantial unmet medical need. This study also highlights the considerable economic burden among patients with NF1 and PN.

Case report of neurofibromatosis type 1 combined with primary ciliary dyskinesia

Neurofibromatosis (NF) is a genetic disease in which the lungs are rarely involved. However, in NF cases with lung involvement, chest computed tomography may show bilateral basal reticulations, apical bullae, and cysts without bronchiectasis. Herein, we report a patient diagnosed with NF on the basis of the results of genetic testing who presented with early-onset wet cough and bronchiectasis. Considering the differential diagnosis of bronchiectasis combined with his early-onset wet cough, sinusitis, and sperm quality decline, we considered the possibility of primary ciliary dyskinesia (PCD). Further electron microscopy analysis of cilia and identification of homozygous mutations in the RSPH4A gene confirmed the diagnosis of PCD. Therefore, for patients with NF, when an image change exists in the lungs that does not correspond to NF, the possibility of other diagnoses, including PCD, must be considered.