Cognitive function and academic performance in neurofibromatosis. 1: consensus statement from the NF1 Cognitive Disorders Task Force

Neurocognitive functioning in adults with neurofibromatosis type 1- a nationwide population-based study

BACKGROUND

Neurofibromatosis type 1 (NF1) is a genetic condition characterized by various somatic manifestations and cognitive impairments, but the latter are sparsely described in adults. This study aimed at characterizing potential impairments of neurocognitive functions using neuropsychological tests as well as a self-report questionnaire.

METHODS

In a nationwide, population-based study including 103 adults with NF1 and 38 age- and gender-matched NF1-free comparisons, we used a comprehensive neurocognitive test battery to assess intelligence and visual short-term memory, immediate visuospatial recall, reaction time, sustained attention, motor speed, planning, planning time, working memory as well as multitasking and a questionnaire to assess executive functions. Descriptive statistics, multivariate analysis of variance (MANOVA), and general linear models with repeated measure analysis of variance (ANOVA) were used.

RESULTS

We observed a statistically significant difference in overall performance-based cognitive functioning. Adults with NF1 showed significant, moderate-to-severe impairments in intelligence, visual short-term memory, immediate visuospatial recall, sustained attention (p < 0.0001-0.002), and some executive functions (p = 0.008 - 0.001), whereas other cognitive functions (multitasking, reaction time, motor speed, spatial working memory, planning time, and planning efficacy as well as some self-reported executive functions) were unimpaired.

CONCLUSIONS

This is the first study with a population-based sample of persons with NF1 and the results show impairments of intelligence and other cognitive functions. The pattern of both significant cognitive impairments and non-significantly different cognitive functions suggests a cognitive profile of selective rather than generalized cognitive deficits in NF1.

Visual Deficits and Diagnostic and Therapeutic Strategies for Neurofibromatosis Type 1: Bridging Science and Patient-Centered Care

Neurofibromatosis type 1 (NF1) is an inherited autosomal dominant disorder primarily affecting children and adolescents characterized by multisystemic clinical manifestations. Mutations in neurofibromin, the protein encoded by the Nf1 tumor suppressor gene, result in dysregulation of the RAS/MAPK pathway leading to uncontrolled cell growth and migration. Neurofibromin is highly expressed in several cell lineages including melanocytes, glial cells, neurons, and Schwann cells. Individuals with NF1 possess a genetic predisposition to central nervous system neoplasms, particularly gliomas affecting the visual pathway, known as optic pathway gliomas (OPGs). While OPGs are typically asymptomatic and benign, they can induce visual impairment in some patients. This review provides insight into the spectrum and visual outcomes of NF1, current diagnostic techniques and therapeutic interventions, and explores the influence of NF1-OPGS on visual abnormalities. We focus on recent advancements in preclinical animal models to elucidate the underlying mechanisms of NF1 pathology and therapies targeting NF1-OPGs. Overall, our review highlights the involvement of retinal ganglion cell dysfunction and degeneration in NF1 disease, and the need for further research to transform scientific laboratory discoveries to improved patient outcomes.

Shedding New Light: Novel Therapies for Common Disorders in Children with Neurofibromatosis Type I

Neurofibromatosis type I (NF1) is a common dominantly inherited disorder, and one of the most common of the RASopathies. Most individuals with NF1 develop plexiform neurofibromas and cutaneous neurofibromas, nerve tumors caused by NF1 loss of function in Schwann cells. Cell culture models and mouse models of NF1 are being used to test drug efficacy in preclinical trials, which led to Food and Drug Administration approval for use of MEK inhibitors to shrink most inoperable plexiform neurofibromas. This article details methods used for testing in preclinical models, and outlines newer models that may identify additional, curative, strategies.

Statins in Children with Neurofibromatosis Type 1: A Systematic Review of Randomized Controlled Trials

BACKGROUND

Statins, apart from their plasma-cholesterol-lowering ability, exert several pleiotropic effects, making them a potential treatment for other diseases. Animal studies have showed that statins, through the inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase, can affect the Ras/MAPK pathway, thus providing impetus to examine the efficacy of statins in the pediatric population with neurofibromatosis type 1 (NF1). We aimed to systematically address all relevant evidence of statin treatment in children with NF1.

METHODS

We searched PubMed and Cochrane Library resources up to 2 June 2023 for randomized controlled trials (RCTs) written in English and evaluating statins versus placebo in children with NF1 (PROSPERO registration number: CRD42023439424).

RESULTS

Seven RCTs were suitable to be included in this qualitative synthesis, with a total participation of 336 children with NF1. The duration of the studies ranged from 12 to 52 weeks. The mean age of the pediatric population was 10.9 years old. Three studies investigated the role of simvastatin, while four studies examined lovastatin. According to our analysis, neither simvastatin nor lovastatin improved cognitive function, full-scale intelligence, school performance, attention problems, or internalizing behavioral problems when compared with placebo in children with NF1. Statins were well tolerated in all included RCTs.

CONCLUSION

Although safe, current evidence demonstrates that statins exert no beneficial effect in cognitive function and behavioral problems in children with NF1.

Polysomnographic study in pediatric neurofibromatosis type 1

Background

Neurofibromatosis type 1 (NF1) is a genetic disease that alters neurodevelopment. We aimed to analyze the sleep macrostructure of a sample of children affected by NF1 without neurocognitive co-morbidities and MRI reports of unidentified bright objects (UBOs).

Methods

A 100 pre-pubertal children participated in the cross-sectional study: 50 subjects were children diagnosed with NF1 and 50 subjects were typically developing healthy children (TDC). All participants underwent polysomnographic evaluation through which conventional sleep parameters were collected: Total sleep time (TST), Sleep latency (SOL), first REM latency (FRL), number of stage shifts/h (SS/h), number of awakenings/h (AWN/h), wake after sleep onset (WASO%), sleep efficiency percentage (SE%), percentage of sleep time spent in sleep stages 1 (N1%) and 2 (N2%), slow-wave sleep (N3%), and REM sleep (REM%). Additionally, nocturnal respiratory events such as apnea/hypopnea index (AHI), oxygen desaturation index (ODI), and periodic limb movement index (PLMI) were recorded.

Results

Neurofibromatosis type 1 children showed a reduction in sleep duration parameters (TST; p < 0.001), sleep efficiency (SE%; p < 0.001), and stage N2% (p < 0.001). Moreover, the number of awakenings per hour (AWN/h), wake after sleep onset (WASO%), and respiratory events such as AHI, ODI, and PLMI resulted higher in NF1 vs. TDC children.

Conclusion

The data showed that the sleep macrostructure differs between NF1 and TDC children. These findings suggest that the evaluation of sleep may provide useful support in corroborating the diagnosis and offers additional therapeutic management perspectives in NF1 and genetic neurodevelopmental disorders in general.

Evaluating Focal Areas of Signal Intensity (FASI) in Children with Neurofibromatosis Type-1 (NF1) Treated with Selumetinib on Pediatric Brain Tumor Consortium (PBTC)-029B

Background: Understanding the effect of selumetinib on FASI may help elucidate the biology, proliferative potential, and role in neurocognitive changes for these NF1-associated lesions. Methods: Patients with NF1-associated LGG and FASI treated with selumetinib on PBTC-029B were age-matched to untreated patients with NF1-associated FASI at Cincinnati Children’s Hospital Medical Center. Paired bidirectional measurements were compared over time using nonparametric tests. Results: Sixteen age-matched pairs were assessed (age range: 2.8–16.9 years, 60% male). Initial FASI burden was not different between groups (median range 138.7 cm2 [88.4–182.0] for the treated subjects vs. 121.6 cm2 [79.6—181.9] for the untreated subjects; p = 0.98). Over a mean follow-up of 18.9 (±5.9) months, the LGG size consistently decreased with treatment while no consistent change among the treated or untreated FASI size was seen. At the paired time points, the median treated LGG decreased significantly more than the treated FASI (−41.3% (LGG) versus −10.7% (FASI), p = 0.006). However, there was no difference in the median size change in the treated versus untreated FASI (−10.7% (treated FASI) versus −17.9% (untreated FASI), p = 0.08). Among the treated subjects, there was no correlation between the change in LGG and FASI (r = −0.04, p = 0.88). Conclusions: Treatment with selumetinib did not affect the overall FASI size in children with NF1 treated for progressive low-grade glioma.

Brain and/or Spinal Cord Tumors Accompanied with Other Diseases or Syndromes

Several medical conditions that interest both the brain and the spinal cord have been described throughout the history of medicine. Formerly grouped under the term Phacomatosis because lesions of the eye were frequently encountered or genodermatosis when typical skin lesions were present, these terms have been progressively discarded. Although originally reported centuries ago, they still represent a challenge for their complexity of cure. Nowadays, with the introduction of advanced genetics and the consequent opportunity of whole-genome sequencing, new single cancer susceptibility genes have been identified or better characterized; although there is evidence that the predisposition to a few specific tumor syndromes should be accounted to a group of mutations in different genes while certain syndromes appeared to be manifestations of different mutations in the same gene adding supplementary problems in their characterization and establishing the diagnosis. Noteworthy, many syndromes have been genetically determined and well-characterized, accordingly in the near future, we expect that new targeted therapies will be available for the definitive cure of these syndromes and other gliomas (Pour-Rashidi et al. in World Neurosurgery, 2021). The most common CNS syndromes that will be discussed in this chapter include neurofibromatosis (NF) types 1 and 2, von Hippel-Lindau (VHL) disease, and tuberous sclerosis complex (TSC), as well as syndromes having mostly extra-neural manifestations such as Cowden, Li-Fraumeni, Turcot, and Gorlin syndromes.

Perspectives on adapting a mobile application for pain self-management in neurofibromatosis type 1: results of online focus group discussions with individuals living with neurofibromatosis type 1 and pain management experts

OBJECTIVE

Neurofibromatosis type 1 (NF1) is a genetic disorder in which chronic pain commonly occurs. The study sought to understand the needs of individuals with NF1 and pain management experts when adapting a pain self-management mobile health application (app) for individuals with NF1.

DESIGN

We conducted a series of online, audio-recorded focus groups that were then thematically analysed.

SETTING

Online focus groups with adults currently residing in the USA.

PARTICIPANTS

Two types of participants were included: individuals with NF1 (n=32 across six focus groups) and pain management experts (n=10 across three focus groups).

RESULTS

Six themes across two levels were identified. The individual level included lifestyle, reasons for using the mobile app and concerns regarding its use. The app level included desired content, desired features and format considerations. Findings included recommendations to grant free access to the app and include a community support feature for individuals to relate and validate one another's experience with pain from NF1. In addition, participants noted the importance of providing clear instructions on navigating the app, the use of an upbeat, hopeful tone and appropriate visuals.

CONCLUSIONS

Both participant groups endorsed the use of iCanCope (iCC) as an NF1 pain self-management mobile app. Differences between groups were noted, however. The NF1 group appeared interested in detailed and nuanced pain tracking capabilities; the expert group prioritised tracking information such as mood, nutrition and activity to identify potential associations with pain. In tailoring the existing iCC app for individuals with NF1, attention should be paid to creating a community support group feature and to tailoring content, features and format to potential users' specific needs.

Bibliometric analysis of the top 100 most-cited articles in neurofibromatosis

Background:

Neurofibromatosis (NF) is an umbrella term that refers to three distinct disease entities: NF Type 1, Type 2, and schwannomatosis. Here, we reviewed the scientific performance and the most influential publications on NF.

Methods:

A keyword-based search was performed using the Scopus database. The top 100 articles were grouped based on NF types and the studied entities. The differences between the articles, authors, and journals were quantified based on certain parameters. Other parameters were collected for the complete citational analysis.

Results:

The top 100 articles were published between 1961 and 2020. The most trending period of research was in the 1990s and articles studying the clinical aspect and the underlying genetic correlation made up 84% of all articles from the list. The United States of America (USA) had the highest number of contributions (69 articles, 69%). The top institute of contribution to the list was the Howard Hughes Medical Institute, USA (14 articles, 14%). Author-based analysis reveals that the neurologist D. H. Gutmann from St. Louis Children’s Hospital, USA, was the most active and authored 11 articles (11%) on the list.

Conclusion:

The publication trends show that articles studying medical and surgical management were of little interest. The top 100 articles did not include any randomized control trials, and the highest level of evidence was obtained from reviews of pooled knowledge as well as population-based and longitudinal studies.

Social behavior in RASopathies and idiopathic autism

Background

RASopathies are genetic syndromes that result from pathogenic variants in the RAS-MAPK cellular signaling pathway. These syndromes, which include neurofibromatosis type 1, Noonan syndrome, cardiofaciocutaneous syndrome, and Costello syndrome, are associated with a complex array of medical and behavioral health complications. Despite a heightened risk for social challenges and autism spectrum disorder (ASD), few studies have compared different aspects of social behavior across these conditions. It is also unknown whether the underlying neuropsychological characteristics that contribute to social competence and socially empathetic (“prosocial”) behaviors differ in children with RASopathies as compared to children with nonsyndromic (i.e., idiopathic) ASD.

Methods

In this cross-sectional, survey-based investigation, caregivers of preschool and school-aged children with RASopathies (n = 202) or with idiopathic ASD (n = 109) provided demographic, medical, and developmental information about their child, including psychiatric comorbidities. For children who were able to communicate verbally, caregivers also completed standardized rating scales to assess social competence and empathetic behavior as well as symptoms of hyperactivity/inattention and emotional problems.

Results

As compared to children with idiopathic ASD, children with RASopathies were rated as demonstrating more resilience in the domain of empathy relative to their overall social competence. Similarities and differences emerged in the psychological factors that predicted social behavior in these two groups. Stronger communication skills and fewer hyperactive-impulsive behaviors were associated with increased empathy and social competence for both groups. Greater emotional challenges were associated with lower social competence for children with RASopathies and stronger empathy for children with idiopathic ASD. Among children with RASopathy and a co-occurring ASD diagnosis, socially empathetic behaviors were observed more often as compared to children with idiopathic ASD.

Conclusions

Findings suggest that the development of social behavior among children with RASopathies involves a distinct pattern of strengths and weaknesses as compared to a behaviorally defined disorder (idiopathic ASD). Identification of areas of resilience as well as behavioral and social challenges will support more targeted intervention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11689-021-09414-w.

The diagnostic accuracy and prognostic value of OCT for the evaluation of the visual function in children with a brain tumour: A systematic review

Purpose

To systematically review the evidence on the diagnostic accuracy and prognostic value of retinal optical coherence tomography (OCT) to detect visual acuity (VA) or visual field (VF) loss in children with a brain tumour.

Methods

PubMed, Embase and Cochrane Library databases were searched from inception to February 2021. We included studies evaluating retinal OCT and standard visual function parameters (VA and or VF) in children with a brain tumour. Two authors independently extracted data from each included study. They also assessed the methodological quality of the studies using the QUADAS-2 or QUIPS tool. The diagnostic accuracy of OCT was evaluated with receiver operating characteristic analysis, sensitivity, specificity, positive predictive value and negative predictive value. The prognostic value of OCT was evaluated with predictive measures (odds ratio).

Results

We included five diagnostic studies, with a total of 186 patients, all diagnosed with optic pathway glioma. No prognostic studies were eligible for inclusion. Included studies evaluated either retinal nerve fiber layer (RNFL) thickness or ganglion cell layer—inner plexiform layer (GCL-IPL) thickness. There was considerable heterogeneity between OCT devices, OCT protocols, visual function parameters and threshold values. Sensitivity and specificity for RNFL thickness measurement ranged from 60.0% to 100.0% and 76.6% to 100%, respectively. For GCL-IPL thickness measurement, area under the curve ranged from 0.91 to 0.98 for different diameters.

Conclusion

The literature regarding the diagnostic accuracy and prognostic value of OCT parameters in children with a brain tumour is scarce. Due to heterogeneity and a considerable risk of bias of included studies, we cannot draw solid conclusions regarding the accuracy of retinal OCT. Future research should investigate the potential of OCT as diagnostic and prognostic tool for the evaluation of the visual function and detection of visual impairment in children with any type of brain tumour.

Reading Comprehension Impairment in Children With Neurofibromatosis Type 1 (NF1): The Need of Multimodal Assessment of Attention

Attention span, which has been shown to have an impact on reading quality in many other conditions, is one of the main cognitive disorders of neurofibromatosis type 1 (NF1). The aim of this work is to observe the impact of attention on reading comprehension, in NF1 and non-NF1 children. A multicenter, cross-sectional study was conducted on 150 children (8-12 years old) with or without NF1 (75 NF1 vs 75 non-NF1; 72 female, 78 male), matched for age, sex, handedness, and reading level, thus forming a continuum from good to poor readers in both NF1 and non-NF1 groups. Children with intellectual deficiency or neurologic or psychiatric disorder were excluded. Attentional skills were assessed by combining a parent questionnaire (Child Behavior CheckList) and a performance-based assessment (Conner's Continuous Performance Test-Second Edition). Reading comprehension was assessed through a standardized reading comprehension test (ORLEC Lobrot). The performance-based attention scores were associated with text and sentence comprehension ability (P = .0235 and P = .0164, respectively), while indirect questionnaire attention scores were only associated with sentence comprehension (P = .0263). For both groups, the correlations between questionnaire and performance-based measures were low. We have shown that reading comprehension is greatly influenced by attention in NF1 and non-NF1, even if predictors of good reading comprehension also include IQ score and reading accuracy. Indirect observer-rated questionnaires and direct performance-based measures of attention do not assess the same variables, are linked to different components of reading skills, and are not interchangeable assessments of attention difficulties. Both assessments are complementary and must be used simultaneously, leading to recommendations that support multimodal assessment of attention.

Hypertension in Children and Adolescents with Turner Syndrome (TS), Neurofibromatosis 1 (NF1), and Williams Syndrome (WS)

PURPOSE OF REVIEW

Turner syndrome (TS), neurofibromatosis type 1(NF1), and William Syndrome (WS) are 3 genetic conditions that are all associated with a substantial increase in risk of hypertension. In this review, we focus on factors leading to hypertension and on clinical manifestations and management of hypertension in children and adolescents with these genetic conditions RECENT FINDINGS: In most instances, hypertension is secondary. There is a high prevalence of masked hypertension in TS; however, the extent to which control of the BP helps reduce the risk of aortic dissection/aneurysm in TS is not yet fully elucidated. Vasculopathies are the least emphasized but most important manifestation of NF1. Of note, routine screening for pheochromocytoma in NFI is not recommended as it is not cost-effective. Cardiovascular complications are the major cause of death in patients with WBS. ABPM identifies patients without overt aortic or renovascular narrowing. Antihypertensive agents such as ARBs that have direct vascular wall effects and agents that inhibit oxidative stress (minoxidil) should be considered, even in those who do not exhibit overt hypertension. Elevated blood pressure in children and adolescence manifests early with end-organ changes and when left untreated, increases risk for premature onset of cardiovascular disease. Vigilant monitoring of the blood pressure is recommended. Accurate early diagnosis and management of hypertension will delay or prevent target organ damage and ensure a healthier transition to adulthood among children afflicted with these conditions.

An executive functioning perspective in neurofibromatosis type 1: from ADHD and autism spectrum disorder to research domains

PURPOSE

Neurofibromatosis type 1 (NF1) is a rare monogenic disorder associated with executive function (EF) deficits and heightened risk for attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). The goal of this paper is to understand how EFs provide a common foundation to understand vulnerabilities for ADHD and ASD within NF1.

METHODS

A literature review and synthesis was conducted.

RESULTS

EF difficulties in working memory, inhibitory control, cognitive flexibility, and planning are evident in NF1, ADHD, and ASD. However, relatively little is known about the heterogeneity of EFs and ADHD and ASD outcomes in NF1. Assessment of ADHD and ASD in NF1 is based on behavioral symptoms without understanding neurobiological contributions. Recent efforts are promoting the use of dimensional and multidisciplinary methods to better understand normal and abnormal behavior, including integrating information from genetics to self-report measures.

CONCLUSION

NF1 is a monogenic disease with well-developed molecular and phenotypic research as well as complementary animal models. NF1 presents an excellent opportunity to advance our understanding of the neurobiological impact of known pathogenic variation in normal and abnormal neural pathways implicated in human psychopathology. EFs are core features of NF1, ADHD, and ASD, and these neurodevelopmental outcomes are highly prevalent in NF1. We propose a multilevel approach for understanding EFs in patients with NF1.This is essential to advance targeted interventions for NF1 patients and to advance the exciting field of research in this condition.

Are morphological and structural MRI characteristics related to specific cognitive impairments in neurofibromatosis type 1 (NF1) children?

INTRODUCTION

NF1 children have cognitive disorders, especially in executive functions, visuospatial, and language domains, the pathophysiological mechanisms of which are still poorly understood.

MATERIALS AND METHODS

A correlation study was performed from neuropsychological assessments and brain MRIs of 38 NF1 patients and 42 controls, all right-handed, aged 8-12 years and matched in age and gender. The most discriminating neuropsychological tests were selected to assess their visuospatial, metaphonological and visuospatial working memory abilities. The MRI analyses focused on the presence and location of Unidentified Bright Objects (UBOs) (1), volume analysis (2) and diffusion analysis (fractional anisotropy and mean diffusivity) (3) of the regions of interest including subcortical structures and posterior fossa, as well as shape analysis of subcortical structures (4). The level of attention, intelligence quotient, age and gender of the patients were taken into account in the statistical analysis. Then, we studied how diffusion and volumes parameters were associated with neuropsychological characteristics in NF1 children.

RESULTS

NF1 children present different brain imaging characteristics compared to the control such as (1) UBOs in 68%, (2) enlarged total intracranial volume, involving all subcortical structures, especially thalamus, (3) increased MD and decreased FA in thalamus, corpus callosum and hippocampus. These alterations are diffuse, without shape involvement. In NF1 group, brain microstructure is all the more altered that volumes are enlarged. However, we fail to find a link between these brain characteristics and neurocognitive scores.

CONCLUSION

While NF1 patients have obvious pathological brain characteristics, the neuronal substrates of their cognitive deficits are still not fully understood, perhaps due to complex and multiple pathophysiological mechanisms underlying this disorder, as suggested by the heterogeneity observed in our study. However, our results are compatible with an interpretation of NF1 as a diffuse white matter disease.

Focal Areas of High Signal Intensity in Children with Neurofibromatosis Type 1: Expected Evolution on MRI

BACKGROUND AND PURPOSE

Focal areas of high signal intensity are T2WI/T2-FLAIR hyperintensities frequently found on MR imaging of children diagnosed with neurofibromatosis type 1, often thought to regress spontaneously during adolescence or puberty. Due to the risk of tumor in this population, some focal areas of high signal intensity may pose diagnostic problems. The objective of this study was to assess the characteristics and temporal evolution of focal areas of high signal intensity in children with neurofibromatosis type 1 using long-term follow-up with MR imaging.

MATERIALS AND METHODS

We retrospectively examined the MRIs of children diagnosed with neurofibromatosis type 1 using the National Institutes of Health Consensus Criteria (1987), with imaging follow-up of at least 4 years. We recorded the number, size, and surface area of focal areas of high signal intensity according to their anatomic distribution on T2WI/T2-FLAIR sequences. A generalized mixed model was used to analyze the evolution of focal areas of high signal intensity according to age, and separate analyses were performed for girls and boys.

RESULTS

Thirty-nine patients (ie, 285 MR images) with a median follow-up of 7 years were analyzed. Focal areas of high signal intensity were found in 100% of patients, preferentially in the infratentorial white matter (35% cerebellum, 30% brain stem) and in the capsular lenticular region (22%). They measured 15 mm in 95% of cases. They appeared from the age of 1 year; increased in number, size, and surface area to a peak at the age of 7; and then spontaneously regressed by 17 years of age, similarly in girls and boys.

CONCLUSIONS

Focal areas of high signal intensity are mostly small (<15 mm) abnormalities in the posterior fossa or capsular lenticular region. Our results suggest that the evolution of focal areas of high signal intensity is not related to puberty with a peak at the age of 7 years. Knowledge of the predictive evolution of focal areas of high signal intensity is essential in the follow-up of children with neurofibromatosis type 1.

Predicting pediatric optic pathway glioma progression using advanced magnetic resonance image analysis and machine learning

BACKGROUND

Optic pathway gliomas (OPGs) are low-grade tumors of the white matter of the visual system with a highly variable clinical course. The aim of the study was to generate a magnetic resonance imaging (MRI)-based predictive model of OPG tumor progression using advanced image analysis and machine learning techniques.

METHODS

We performed a retrospective case-control study of OPG patients managed between 2009 and 2015 at an academic children's hospital. Progression was defined as radiographic tumor growth or vision decline. To generate the model, optic nerves were manually highlighted and optic radiations (ORs) were segmented using diffusion tractography tools. For each patient, intensity distributions were obtained from within the segmented regions on all imaging sequences, including derivatives of diffusion tensor imaging (DTI). A machine learning algorithm determined the combination of features most predictive of progression.

RESULTS

Nineteen OPG patients with progression were matched to 19 OPG patients without progression. The mean time between most recent follow-up and most recently analyzed MRI was 3.5 ± 1.7 years. Eighty-three MRI studies and 532 extracted features were included. The predictive model achieved an accuracy of 86%, sensitivity of 89%, and specificity of 81%. Fractional anisotropy of the ORs was among the most predictive features (area under the curve 0.83, P < 0.05).

CONCLUSIONS

Our findings show that image analysis and machine learning can be applied to OPGs to generate a MRI-based predictive model with high accuracy. As OPGs grow along the visual pathway, the most predictive features relate to white matter changes as detected by DTI, especially within ORs.

Effect of age and neurofibromatosis type 1 status on white matter integrity in the optic radiations

Background

Adults with neurofibromatosis type 1 (NF1) have decreased white matter integrity, but differences in children with NF1 have not been described. Defining normal values for diffusion tensor imaging (DTI) measures, especially in the optic radiations, is important to the development of DTI as a potential biomarker of visual acuity in children with optic pathway glioma. This study examines the effect of age and NF1 status on DTI measures in children.

Methods

In this retrospective study, MR imaging including DTI was conducted in 93 children (40 children with NF1 and 53 healthy controls) between 0 and 14 years of age. Regression models of age, sex, and NF1 status on DTI measures were evaluated, and tract-based spatial statistics (TBSS) compared DTI measures in age-matched NF1 to non-NF1 cohorts.

Results

Fractional anisotropy, radial diffusivity, and mean diffusivity in white matter tracts of the optic radiations varied with age and were best modeled by a logarithmic function. Age-related DTI measure change was different in NF1 versus non-NF1 subjects. Normal values and 95% confidence intervals for age 0.5–12 years were derived for both groups. Differences in DTI measures between NF1 and non-NF1 groups at a range of ages were shown diffusely throughout the cerebral white matter using TBSS.

Conclusions

Children with NF1 demonstrate increased diffusion throughout the brain compared to children without NF1 suggesting a potentially altered developmental trajectory of optic radiation microstructure. Defining normal values for white matter integrity in children with NF1 may help target early intervention efforts in this vulnerable group.

Late morbidity and mortality in adult survivors of childhood glioma with neurofibromatosis type 1: report from the Childhood Cancer Survivor Study

Purpose

Neurofibromatosis type 1 (NF1) is associated with tumor predisposition and non-malignant health conditions. Whether survivors of childhood cancer with NF1 are at increased risk for poor long-term health outcomes is unknown.

Methods

147 5+ year survivors of childhood glioma with NF1 from the Childhood Cancer Survivor Study were compared to 2 629 non-NF1 glioma survivors and 5 051 siblings for late mortality, chronic health conditions, psychosocial, neurocognitive, and socioeconomic outcomes.

Results

Survivors with NF1 (age at diagnosis: 6.8±4.8 years) had greater cumulative incidence of late mortality 30 years after diagnosis (46.3%[95% confidence interval: 23.9%−62.2%]) compared to non-NF1 survivors (18.0%[16.1%−20.0%]) and siblings (0.9%[0.6%−1.2%]), largely due to subsequent neoplasms. Compared to survivors without NF1, those with NF1 had more severe/life-threatening chronic conditions at cohort entry (46.3%[38.1%−54.4%] vs. 30.8%[29.1%−32.6%]), but similar rates of new conditions during follow-up (Rate Ratio: 1.26 [0.90–1.77]). Survivors with NF1 were more likely to report psychosocial impairments, neurocognitive deficits, and socioeconomic difficulties compared to survivors without NF1.

Conclusion

Late mortality among glioma survivors with NF1 is twice that of other survivors, due largely to subsequent malignancies. Screening, prevention and early intervention for chronic health conditions, psychosocial and neurocognitive deficits may reduce long-term morbidity in this vulnerable population.

Sporadic and Familial Variants in NF1: An Explanation of the Wide Variability in Neurocognitive Phenotype?

Background: Cognitive impairment is the most common neurological manifestation in NF1 and occurs in 30–70% of NF1 cases. The onset and severity of each specific cognitive deficit varies greatly from child to child, with no apparent external causes. The wide variability of phenotype is the most complex aspect in terms of management and care. Despite multiple research, the mechanism underlying the high heterogeneity in NF1 has not yet been elucidated. While many studies have focused on the effects of specific and precise genetic mutations on the NF1 phenotype, little has been done on the impact of NF1 transmission (sporadic vs. familial cases). We used a complete neuropsychological evaluation designed to assess five large cognitive areas: general cognitive functions (WISC-IV and EVIP); reading skills (“L'Alouette,” ODEDYS-2 and Lobrot French reading tests); phonological process (ODEDYS-2 test); visual perceptual skills (JLO, Thurstone and Corsi block tests) and attention (CPT-II), as well as psychosocial adjustments (CBCL) to explore the impact of NF1 transmission on cognitive disease manifestation in 96 children affected by NF1 [55 sporadic cases (29♀, 26♂); 41 familial cases (24♀, 17♂)].

Results: Familial and Sporadic form of NF1 only differ in IQ expression. The families' socioeconomic status (SES) impacts IQ performance but not differently between sporadic and familial variants. However, SES is lower in familial variants than in the sporadic variant of NF1. No other cognitive differences emerge between sporadic and familial NF1.

Conclusions: Inheritance in NF1 failed to explain the phenotype variability in its entirety. IQ differences between groups seems in part linked to the environment where the child grows up. Children with NF1, and especially those that have early diagnoses (most often in inherited cases), must obtain careful monitoring from their early childhood, at home to strengthen investment in education and in school to early detect emerging academic problems and to quickly place them into care.

Trial Registration: IDRCB, IDRCB2008-A01444-51. Registered 19 January 2009.

Phakomatoses

Phakomatoses present with characteristic findings on the skin, central or peripheral nervous system, and tumors. Neurofibromatosis type 1 is the most common syndrome and is characterized by Café-au-lait macules, intertriginous freckling, Lisch nodules, and tumors including neurofibromas, malignant peripheral nerve sheath tumors, and gliomas. Tuberous Sclerosis Complex is characterized by benign hamartomas presenting with hypomelanotic macules, shagreen patches, angiofibromas, confetti lesions and tumors including cortical tubers, subependymal nodules, subependymal giant cell astrocytomas and tumors of the kidney, lung, and heart. Managing these disorders requires disease specific supportive care, tumor monitoring, surveillance for selected cancers, and treatment of comorbid conditions.

Neurofibromatosis 1 French national guidelines based on an extensive literature review since 1966

Neurofibromatosis type 1 is a relatively common genetic disease, with a prevalence ranging between 1/3000 and 1/6000 people worldwide. The disease affects multiple systems with cutaneous, neurologic, and orthopedic as major manifestations which lead to significant morbidity or mortality. Indeed, NF1 patients are at an increased risk of malignancy and have a life expectancy about 10-15 years shorter than the general population. The mainstay of management of NF1 is a patient-centered longitudinal care with age-specific monitoring of clinical manifestations, aiming at the early recognition and symptomatic treatment of complications as they occur. Protocole national de diagnostic et de soins (PNDS) are mandatory French clinical practice guidelines for rare diseases required by the French national plan for rare diseases. Their purpose is to provide health care professionals with guidance regarding the optimal diagnostic and therapeutic management of patients affected with a rare disease; and thus, harmonizing their management nationwide. PNDS are usually developed through a critical literature review and a multidisciplinary expert consensus. The purpose of this article is to present the French guidelines on NF1, making them even more available to the international medical community. We further dwelled on the emerging new evidence that might have therapeutic potential or a strong impact on NF1 management in the coming feature. Given the complexity of the disease, the management of children and adults with NF1 entails the full complement healthcare providers and communication among the various specialties.

A nationwide, population-based study of school grades, delayed graduation, and qualification for school years 10-12, in children with brain tumors in Sweden

BACKGROUND

As many as 95.7% of children diagnosed with a brain tumor will experience persistent late effects as adults. These include difficulties with general executive functions, lower IQ, and mental fatigue, which may negatively affect school performance.

METHODS

Through the Swedish Childhood Cancer Registry, we identified 475 children born between 1988 and 1996, diagnosed with a brain tumor before their 15th birthday. School grades in "Swedish," "mathematics," and "English," if their graduation was delayed, and qualification for school years 10-12 were compared with 2197 matched controls. Furthermore, we checked for interaction effects between sex and age at diagnosis, and possible effects of tumor grade (high or low) as well as parents' education.

RESULTS

Children treated for a brain tumor performed worse in the subjects compared to controls and also had delayed graduation to a greater extent. Fewer children treated for a brain tumor than controls qualified for school years 10-12. Children treated at a young age, especially females, and children whose parents have low education seem to be at particular risk. Unexpectedly, there were no differences in outcomes between survivors with high- and low-grade tumors.

CONCLUSIONS

It is important that schools provide regular pedagogical assessment and individualized support to meet the different needs of children treated for a brain tumor. Children treated for low-grade tumors do not perform better than children treated for high-grade tumors, despite the lighter treatment, and hence require the same attention and support.

Determination of Vitamin D Levels in Patients With Neurofibromatosis Type 1 in the Pediatric Age Group

Introduction:

Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant genetic disorders. Some clinical manifestations are present at birth, while some develop during childhood, and others can occur at any age. Given the early age at which patients develop clinical features, diagnosis is often made during childhood. The most prevalent features of NF1 are café au lait spots, dermal and plexiform neurofibromas, and learning disability. A variety of skeletal problems may be seen in NF1, including scoliosis, short stature, and pseudoarthrosis. Reduced skeletal bone mass has been documented to be a common phenomenon in children and adults with NF1. Decreased serum 25-hydroxyvitamin D (vitamin D) levels have been noted in adults and children with NF1 and have been reported to be inversely correlated with the number of dermal neurofibromas in adults. However, the actual correlation of vitamin D level to bone density and dermal neurofibroma number in children with NF1 remains unclear.

Objectives:

The primary objective of this study was to evaluate vitamin D levels among children and adolescents with NF1. The secondary objective was to describe the levels of vitamin D among children and adolescents with NF1, to verify in which age group there is a higher frequency of vitamin D alterations, and to explore vitamin D level correlations between age, gender, sun exposure, number of neurofibromas, and number of plexiform neurofibromas.

Methods:

This was an observational, cross-sectional, hospital-based study. We obtained a convenience sample of individuals with confirmed diagnosis of NF1 from patients attending the Medical Genetics Service of the IPPMG-UFRJ and Santa Casa de Misericórdia of Rio de Janeiro over a 24-month period. We evaluated vitamin D levels in blood samples of patients with NF1 by a chemiluminescent immunoassay method, and we correlated the results with gender, age, number of neurofibromas, number of plexiform neurofibromas, and satisfactory sun exposure.

Results:

Of the 55 patients, 28 (50.9%) were female and 27 (49.1%) were male. Patient ages ranged from a minimum of 1.2 to a maximum of 19.6 years (mean age 10.95 years) and the median was 11.11 years. Median and mean body mass index (BMI; z score) were -0.09 (minimum value -1.63 and maximum of 4.62) and 0.16, respectively. The mean value of vitamin D was 30.82 ng/mL (±12.31) and the median was 29 ng/mL (minimum value of 10.40 ng/mL and maximum of 79.19 ng/mL).

Conclusions:

The levels of vitamin D did not differ according to gender, age group, or the presence or number of cutaneous neurofibromas. Among patients with adequate sun exposure, there was a higher incidence of sufficient serum vitamin D levels. Patients with cutaneous neurofibromas in the 0 to 11 age group had a greater tendency to vitamin D sufficiency in relation to patients aged 11 to 19 years.

The Diagnosis and Management of Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1), NF2, and schwannomatosis are related, but distinct, tumor suppressor syndromes characterized by a predilection for tumors in the central and peripheral nervous systems. NF1 is one of the most common autosomal dominant conditions of the nervous system. NF1 has a high degree of variability in clinical presentation, which may include multiple neoplasms as well as cutaneous, vascular, bony, and cognitive features. Some of these manifestations overlap with other genetic conditions. Accurate diagnosis of NF1 is important for individualizing clinical care and genetic counseling. This article summarizes the clinical features, diagnostic work-up, and management of NF1.

A comparison of neuropsychological function between monozygotic twins with neurofibromatosis, type 1: A case report

Objective: Neurofibromatosis type 1 (NF-1) is an autosomal dominant genetic disorder that commonly presents with cognitive impairment and greater rates of learning disorders and academic difficulty compared to the general population. Investigations of neurological and physiological expression of NF-1 in monozygotic twins identified intrapair similarities and differences. Monozygotic twins with NF-1 have been found to have similar IQ scores as well as concordant diagnoses of attention-deficit/hyperactivity disorder and learning disabilities. There have been no previous reports on similarities and differences in neuropsychological profiles between monozygotic twins with NF-1. The purpose of this article is to examine the results of comprehensive neuropsychological evaluations for a pair of monozygotic twins with NF-1.Method: A pair of 19-year-old female, African-American monozygotic twins with NF-1 underwent neuropsychological evaluations in an outpatient clinic. Findings are reported following the CAse REport (CARE) guidelines.Results: The twins demonstrated similar impairment in processing speed, working memory, and attention span; however, differences also were found.Conclusions: Intrapair similarities and differences on neuropsychological assessment were found between monozygotic twins with NF-1. Primary deficits were suggestive of a frontal-subcortical pattern and could be consistent with remote neuroimaging. When differences did occur, performance was typically better for Twin A, who had also showed greater improvement on neuroimaging. Implications and directions for future research are discussed. Specifically, this case demonstrates the need for inclusion of neuropsychological assessment in studies of larger cohorts of monozygotic twins with NF-1 and correlation of neuropsychological findings with neuroimaging and postzygotic mutations.

Cerebellar radiological abnormalities in children with neurofibromatosis type 1: part 1 - clinical and neuroimaging findings

Background

Many children with neurofibromatosis type 1 (NF1) have focal abnormal signal intensities (FASI) on brain MRI, whose full clinical impact and natural history have not been studied systematically. Our aims are to describe the clinical and neuroradiological features in children with NF1 and cerebellar FASI, and report on the natural history of FASI that display atypical features such as enhancement and mass effect.

Method

A retrospective review of the hospital charts and brain MRIs was performed on children from Manitoba diagnosed between 1999 and 2008 with NF1, who also had cerebellar FASI on MRI.

Results

Fifty patients (mean age: 16.1y, minimum-maximum: 6.4 - 30y, 27 M) were identified. Mean duration of follow up was 10.1y. Developmental delay, learning disabilities, tumors, and visual signs occurred commonly. Cerebellar signs were not reported. Mean age of the patients at baseline MRI was 7.8 (SD: 4.5) years. FASI occurred in several brain locations and were rarely confined to the cerebellum. FASI displayed mass effect and enhancement infrequently but were associated with malignancy only once. The number of FASI at baseline MRI was significantly less in patients with attention deficient hyperactivity disorder and more if a first degree relative had NF1 or if they had decreased visual acuity.

Discussion

Patients with NF1 and cerebellar FASI do not have motor or consistent non-motor (e.g. developmental delay or learning disabilities) cerebellar features. The number of FASI may correlate with some clinical features. FASI may display enhancement and mass effect but they rarely become malignant.

Cerebellar radiological abnormalities in children with neurofibromatosis type 1: part 2 - a neuroimaging natural history study with clinical correlations

Background

Focal abnormal signal intensities (FASI) on brain MRI occur commonly in patients with neurofibromatosis type 1 (NF1). The natural history of cerebellar FASI and their correlation with clinical features have not been studied comprehensively. Our aims are to describe the natural history of cerebellar FASI on repeat MRI scans and correlate the findings with the clinical features in children with NF1 and cerebellar FASI.

Method

A retrospective review of 226 brain MRI scans and hospital charts was performed in 50 patients with cerebellar FASI, who were diagnosed with NF1 during their childhood between 1999 and 2008.

Results

Mean age at the end of the study period was 16.1 years. There were 27 males. Mean duration of clinical follow up was 10.1 years. Mean duration between the first and the last MRI was 6.6 years (n = 36, SD: 2.8 years). FASI were rarely confined to the cerebellum. The number of FASI was highest in early childhood and decreased significantly on subsequent MRI scans in most brain regions with the exception of the cerebrum, where a fewer number of patients with a smaller number of FASI were seen. Four patterns of change in FASI size over time were determined, none correlated with the clinical features.

Conclusions

In patients with NF1, the natural history of FASI including their number, age at onset, rate of size changes, and resolution if any, varies by brain region. FASI patterns of change over time showed no clinical correlate.

Tafa-2 plays an essential role in neuronal survival and neurobiological function in mice

Tafa is a family of small secreted proteins with conserved cysteine residues and restricted expression in the brain. It is composed of five highly homologous genes referred to as Tafa-1 to -5. Among them, Tafa-2 is identified as one of the potential genes responsible for intellectual deficiency in a patient with mild mental retardation. To investigate the biological function of Tafa-2 in vivo, Tafa-2 knockout mice were generated. The mutant mice grew and developed normally but exhibited impairments in spatial learning and memory in Morris water maze test and impairments in short- and long-term memory in novel object recognition test, accompanied with increased level of anxiety-like behaviors in open-field test and elevated plus maze test, and decreased level of depression-like behaviors in forced-swim test and tail-suspension test. Further examinations revealed that Tafa-2 deficiency causes severe neuronal reduction and increased apoptosis in the brain of Tafa-2-/- mice via downregulation of PI3K/Akt and MAPK/Erk pathways. Conformably, the expression levels of CREB target genes including BDNF, c-fos and NF1, and CBP were found to be reduced in the brain of Tafa-2-/- mice. Taken together, our data indicate that Tafa-2 may function as a neurotrophic factor essential for neuronal survival and neurobiological functions.

Investigation of retinal nerve fiber layer thickness and ganglion cell layer-inner plexiform layer thickness in patients with optic pathway gliomas

PURPOSE

This study aimed to compare the optical coherence tomography (OCT) findings of optic pathway glioma (OPG) patients (sporadic or secondary to neurofibromatosis type 1, NF1) with NF1 without OPG patients and healthy controls.

METHODS

This was a prospective, case-control study in which 27 patients (13 with OPGs and 14 with NF1 without OPGs) and 13 control subjects were included. The retinal nerve fiber layer (RNFL) thickness, macular thickness, and ganglion cell layer-inner plexiform layer (GCL-IPL) thickness findings measured using OCT and the results were compared between the groups.

RESULTS

The macular thickness was significantly lower in the OPG group than in the control group and the NF1 patients without OPGs group (p < 0.001). The GCL-IPL thickness was lower in OPG group than in the control group and the NF1 patients without OPG group (p < 0.001). The RNFL thickness was lower in the OPG group than in the control group and the NF1 patients without OPG group (p < 0.001). There was a statistically significantly negative correlation between the visual acuity (log of the minimum angle of resolution, logMAR) and all the other parameters (macular, RNFL, and GCL-IPL thicknesses). All the parameters were found to positively correlate with each other.

CONCLUSIONS

OCT measurements (macular thickness, RNFL, and GCL-IPL thicknesses) can be used to monitor the disease in those patients with suspected OPGs; however, this should be verified with a larger case series.

Neurodevelopmental disorders in children with neurofibromatosis type 1

Over the past several decades, neurofibromatosis type 1 (NF1) has become increasingly recognized as a neurodevelopmental disorder conferring increased risk for several important neurodevelopmental problems. In this review, we summarize the specific neurodevelopmental problems encountered in the context of NF1. These include impairments in general cognitive function, deficits in specific cognitive domains such as executive function and visuospatial processing and risk for specific learning disorders, impairments in attention and social skills and the overlap with attention-deficit-hyperactivity disorder and autism spectrum disorder, and the risk of developing other psychiatric conditions including anxiety and depression. Early recognition of these developmental impairments is important for the effective treatment of children with NF1, and further characterization is essential to improve our understanding of how mutations in the NF1 gene create the diversity of clinical neuropsychiatric symptomatology observed in this at-risk population.

Response inhibition in Attention deficit disorder and neurofibromatosis type 1 - clinically similar, neurophysiologically different

There are large overlaps in cognitive deficits occurring in attention deficit disorder (ADD) and neurodevelopmental disorders like neurofibromatosis type 1 (NF1). This overlap is mostly based on clinical measures and not on in-depth analyses of neuronal mechanisms. However, the consideration of such neuronal underpinnings is crucial when aiming to integrate measures that can lead to a better understanding of the underlying mechanisms. Inhibitory control deficits, for example, are a hallmark in ADD, but it is unclear how far there are similar deficits in NF1. We thus compared adolescent ADD and NF1 patients to healthy controls in a Go/Nogo task using behavioural and neurophysiological measures. Clinical measures of ADD-symptoms were not different between ADD and NF1. Only patients with ADD showed increased Nogo errors and reductions in components reflecting response inhibition (i.e. Nogo-P3). Early perceptual processes (P1) were changed in ADD and NF1. Clinically, patients with ADD and NF1 thus show strong similarities. This is not the case in regard to underlying cognitive control processes. This shows that in-depth analyses of neurophysiological processes are needed to determine whether the overlap between ADD and NF1 is as strong as assumed and to develop appropriate treatment strategies.

The Key Search Subtest of the Behavioural Assessment of the Dysexecutive Syndrome in Children (BADS-C) Instrument Reveals Impaired Planning Without External Constraints in Children With Neurofibromatosis Type 1

Studies of executive function and its relationship with brain T2-weighted hyperintensities in children with neurofibromatosis type 1 (NF1) have yielded inconsistent results. We examined 16 children with NF1 aged 8 to 15 years, of normal intelligence, and compared their findings to those of 16 siblings and 16 typically developing children using the Behavioural Assessment of the Dysexecutive Syndrome in Children (BADS-C). NF1 patients had an adequate overall score at BADS-C, but showed significantly lower performance than typical peers in the Key Search subtest. This is a task that must be solved without any given rules, in which subjects must devise a strategy and an efficient search pattern transferable to other similar real situations. The Key Search scores were not correlated with number and signal characteristics of T2-weighted hyperintensities. Planning without external indications is impaired in children with NF1 because they have to rely entirely on self-organization and monitoring; this study provides information for remediation programs designed to improve functioning in daily life.

Conflict processing in juvenile patients with neurofibromatosis type 1 (NF1) and healthy controls - Two pathways to success

Neurofibromatosis Type 1 (NF1) is a monogenetic autosomal-dominant disorder with a broad spectrum of clinical symptoms and is commonly associated with cognitive deficits. Patients with NF1 frequently exhibit cognitive impairments like attention problems, working memory deficits and dysfunctional inhibitory control. The latter is also relevant for the resolution of cognitive conflicts. However, it is unclear how conflict monitoring processes are modulated in NF1. To examine this question in more detail, we used a system neurophysiological approach combining high-density ERP recordings with source localisation analyses in juvenile patients with NF1 and controls during a flanker task. Behaviourally, patients with NF1 perform significantly slower than controls. Specifically on trials with incompatible flanker-target pairings, however, the patients with NF1 made significantly fewer errors than healthy controls. Yet, importantly, this overall successful conflict resolution was reached via two different routes in the two groups. The healthy controls seem to arrive at a successful conflict monitoring performance through a developing conflict recognition via the N2 accompanied by a selectively enhanced N450 activation in the case of perceived flanker-target conflicts. The presumed dopamine deficiency in the patients with NF1 seems to result in a reduced ability to process conflicts via the N2. However, NF1 patients show an increased N450 irrespective of cognitive conflict. Activation differences in the orbitofrontal cortex (BA11) and anterior cingulate cortex (BA24) underlie these modulations. Taken together, juvenile patients with NF1 and juvenile healthy controls seem to accomplish conflict monitoring via two different cognitive neurophysiological pathways.

Emerging genotype-phenotype relationships in patients with large NF1 deletions

The most frequent recurring mutations in neurofibromatosis type 1 (NF1) are large deletions encompassing the NF1 gene and its flanking regions (NF1 microdeletions). The majority of these deletions encompass 1.4-Mb and are associated with the loss of 14 protein-coding genes and four microRNA genes. Patients with germline type-1 NF1 microdeletions frequently exhibit dysmorphic facial features, overgrowth/tall-for-age stature, significant delay in cognitive development, large hands and feet, hyperflexibility of joints and muscular hypotonia. Such patients also display significantly more cardiovascular anomalies as compared with patients without large deletions and often exhibit increased numbers of subcutaneous, plexiform and spinal neurofibromas as compared with the general NF1 population. Further, an extremely high burden of internal neurofibromas, characterised by >3000 ml tumour volume, is encountered significantly, more frequently, in non-mosaic NF1 microdeletion patients than in NF1 patients lacking such deletions. NF1 microdeletion patients also have an increased risk of malignant peripheral nerve sheath tumours (MPNSTs); their lifetime MPNST risk is 16–26%, rather higher than that of NF1 patients with intragenic NF1 mutations (8–13%). NF1 microdeletion patients, therefore, represent a high-risk group for the development of MPNSTs, tumours which are very aggressive and difficult to treat. Co-deletion of the SUZ12 gene in addition to NF1 further increases the MPNST risk in NF1 microdeletion patients. Here, we summarise current knowledge about genotype–phenotype relationships in NF1 microdeletion patients and discuss the potential role of the genes located within the NF1 microdeletion interval whose haploinsufficiency may contribute to the more severe clinical phenotype.

Cell type-specific roles of RAS-MAPK signaling in learning and memory: Implications in neurodevelopmental disorders

The RAS-mitogen-activated protein kinase (MAPK) signaling pathway plays critical roles in brain function, including learning and memory. Mutations of molecules in the RAS-MAPK pathway are associated with a group of disorders called RASopathies, which include Noonan syndrome, neurofibromatosis type 1, Costello syndrome, Noonan syndrome with multiple lentigines, Legius syndrome, and cardio-facio-cutaneous syndrome. RASopathies share certain clinical symptoms, including craniofacial abnormalities, heart defects, delayed growth, and cognitive deficits such as learning disabilities, while each individual syndrome also displays unique phenotypes. Recent studies using mouse models of RASopathies showed that each disorder may have a distinct molecular and cellular etiology depending on the cellular specificity of the mutated molecules. Here, we review the cell-type specific roles of the regulators of the RAS-MAPK pathway in cognitive function (learning and memory) and their contribution to the development of RASopathies. We also discussed recent technical advances in analyzing cell type-specific transcriptomes and proteomes in the nervous system. Understanding specific mechanisms for these similar but distinct disorders would facilitate the development of mechanism-based individualized treatment for RASopathies.

Social functioning and facial expression recognition in children with neurofibromatosis type 1

BACKGROUND

This study examined social functioning and facial expression recognition (FER) in children with neurofibromatosis type 1 (NF1) compared to typically developing peers. Specifically, the current research aimed to identify hypothesised relationships between neurocognitive ability, FER and social functioning.

METHOD

Children, ages 8 to 16, with NF1 (n = 23) and typically developing peers (n = 23) were recruited during regularly scheduled clinic visits and through advertisements on an institutional clinical trials website, respectively. Participants completed a measure of FER, an abbreviated intelligence test and questionnaires regarding their quality of life and behavioural functioning. Parents were also asked to complete questionnaires regarding the social-emotional and cognitive functioning of their child.

RESULTS

As expected, there were significant differences between children with NF1 and typically developing peers across domains of social functioning and FER. Within the sample of children with NF1, there were no significant associations observed between cognitive measures, social functioning and facial recognition skills.

CONCLUSION

Children with NF1 exhibited high rates of social impairment and weak FER skills compared to controls. The absence of associations between FER with cognitive and social variables, however, suggests something unique about this skill in children with NF1. Theoretical comparisons are made to children with autism spectrum disorders, as this condition may serve as a potentially useful model in better understanding FER in children with NF1.

A randomized placebo-controlled lovastatin trial for neurobehavioral function in neurofibromatosis I

Objective

Lovastatin has been shown to reverse learning deficits in a mouse model of Neurofibromatosis Type 1 (NF1), a common monogenic disorder caused by a mutation in the Ras‐MAPK pathway and associated with learning disabilities. We conducted a randomized double‐blind placebo‐controlled trial to assess lovastatin's effects on cognition and behavior in patients with NF1.

Method

Forty‐four NF1 patients (mean age 25.7+/−11.6 years; 64% female) were randomly assigned to 14 weeks of lovastatin (N = 23; maximum dose of 80 mg/day for adult participants and 40 mg/day for children) or placebo (N = 21). Based on findings in the mouse model, primary outcome measures were nonverbal learning and working memory. Secondary outcome measures included verbal memory, attention, and self/parent‐reported behavioral problems, as well as tolerability of medication. Participants also underwent neuroimaging assessments at baseline and 14 weeks, to determine whether neural biomarkers were associated with treatment response. Linear mixed models assessed for differential treatment effects on outcome measures.

Results

Twelve participants dropped from the study prior to completion (8 placebo, 4 lovastatin), resulting in 32 completers (15 placebo, 17 lovastatin). Lovastatin was well‐tolerated, with no serious adverse events. Differential improvement favoring lovastatin treatment was observed for one primary (working memory; effect size f² = 0.70, P < 0.01) and two secondary outcome measures (verbal memory, f² = 0.19, P = 0.02, and adult self‐reported internalizing problems, f² = 0.26, P = 0.03). Exploratory moderator analyses revealed that higher baseline neural activity in frontal regions was associated with larger treatment effects.

Interpretation

These preliminary results suggest beneficial effects of lovastatin on some learning and memory functions, as well as internalizing symptoms in patients with NF1.

Neurofibromatosis as a gateway to better treatment for a variety of malignancies

The neurofibromatoses (NF) are a group of rare genetic disorders that can affect all races equally at an incidence from 1:3000 (NF1) to a log unit lower for NF2 and schwannomatosis. Since the research community is reporting an increasing number of malignant cancers that carry mutations in the NF genes, the general interest of both the research and pharma community is increasing and the authors saw an opportunity to present a novel, fresh approach to drug discovery in NF. The aim of the paper is to challenge the current drug discovery approach to NF, whereby existing targeted therapies that are either in the clinic or on the market for other disease indications are repurposed for NF. We offer a suggestion for an alternative drug discovery approach. In the new approach, selective and tolerable targeted therapies would be developed for NF and later expanded to patients with more complex diseases such as malignant cancer in which the NF downstream pathways are deregulated. The Children's Tumor Foundation, together with some other major NF funders, is playing a key role in funding critical initiatives that will accelerate the development of better targeted therapies for NF patients, while these novel, innovative treatments could potentially be beneficial to molecularly characterized cancer patients in which NF mutations have been identified.

Neuropsychological evaluation and parental assessment of behavioral and motor difficulties in children with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant multisystem disorder, with large inter and intrafamilial clinical variability and uncertain prognosis. In children with NF1 cognitive disorders, learning difficulties and behavioral problems are common. The present study aims to establish the neuropsychological and behavioral profiles of 78 patients with NF1, aged between 5 and 18 years, and to examine the relationship between these profiles and the transmission of NF1 (sporadic vs. familial), clinical manifestations, and environmental factors. We used several questionnaires completed by parents and neuropsychological tests. The results confirmed specific neuropsychological disabilities in children with NF1, especially involving visuospatial and fine motor skills, learning difficulties and behavioral problems. Cognitive difficulties were significantly more frequent in patients with familial than in those with sporadic NF1. All parental questionnaires were correlated with each other, but parental reports were not associated with FSIQ, SES, school status, and clinical manifestations of the disease. Neuropsychological tests were poorly related to parental reports of cognitive and behavioral difficulties.

Neurofibromatosis: part 2 – clinical management

Part 1 of this guideline addressed the differential diagnosis of the neurofibromatoses (NF): neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2) and schwannomatosis (SCH). NF shares some features such as the genetic origin of the neural tumors and cutaneous manifestations, and affects nearly 80 thousand Brazilians. Increasing scientific knowledge on NF has allowed better clinical management and reduced rate of complications and morbidity, resulting in higher quality of life for NF patients. Most medical doctors are able to perform NF diagnosis, but the wide range of clinical manifestations and the inability to predict the onset or severity of new features, consequences, or complications make NF management a real clinical challenge, requiring the support of different specialists for proper treatment and genetic counseling, especially in NF2 and SCH. The present text suggests guidelines for the clinical management of NF, with emphasis on NF1.

Neurofibromatosis Type 1 in a Pediatric Population: Ste-Justine's Experience

Background:

To date, few pediatric series of neurofibromatosis type 1 (NF-1) have been described in the literature even though it is the most frequently encountered phakomatosis.

Methods:

We reviewed 987 charts of pediatric patients with a presumptive diagnosis of NF-1 who were evaluated at Ste-Justine hospital from January 1, 1991 to July 31, 2002. Patients who presented with two or more cardinal criteria were diagnosed with NF-1. Clinical and laboratory data were retrospectively collected, including: demographics, neuroimaging and presence or absence of associated symptoms or signs of NF-1.

Results:

A total of 279 patients were diagnosed with NF-1. The mean age at diagnosis was 3.4 years. Ninety-nine percent of the patients had café au lait spots and 47% had a first degree relative with NF-1. Almost 60 percent (59.6%) of those seen by an ophthalmologist had Lisch nodules. Optic glioma was found in in 14.7%, cutaneous neurofibromas in 38.4%, plexiform neurofibromas in 24.7%, neurofibrosarcoma in 1.8%, learning disabilities in 39%, attention deficit disorder in 40.5%, osseous dysplasias in 7.2%, pseudoarthrosis in 3.6%, precocious puberty in 3.2% and short stature in 17.9%. Magnetic resonance, when performed, showed hyperintense T2 lesions in 87.1% of cases. The mean period of follow-up was 7.4 years.

Conclusion:

Neurofibromatosis type 1 is a multisystemic disorder associated with increased risk of malignancy. It can be diagnosed at a very young age and clinical follow-up is advised. To our knowledge, this is the largest single center study of NF-1 in a pediatric population.

Relations between fine motor skill and parental report of attention in young children with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is one of the most common genetic disorders presenting in approximately 1 in 3,500 live births. NF1 is a highly variable condition with a large number of complications. A common complication is neuropsychological problems, including developmental delays and learning difficulties that affect as many as 60% of patients. Research has suggested that school-aged children with NF1 often have poorer fine motor skills and are at greater risk for attention difficulties than the general population. Thirty-eight children with NF1 and 23 unaffected children between the ages of 4 and 6 years, who are enrolled in a study of early development in NF1, were included in the present study. Varying levels of fine motor functioning were examined (simple to complex fine motor tasks). For children with NF1, significant difficulties were demonstrated on lab-based mid-level and complex fine motor tasks, even after controlling for nonverbal reasoning abilities, but not on simple fine motor tasks. Parental report also indicated difficulties in everyday adaptive fine motor functioning. No significant correlations were found between complex fine motor ability and attention difficulties. This study provides much needed descriptive data on the early emergence of fine motor difficulties and attention difficulties in young children with NF1.

The impact of coexisting genetic mutations on murine optic glioma biology

BACKGROUND

Children with the neurofibromatosis type 1 (NF1) tumor predisposition syndrome are prone to the development of optic pathway gliomas resulting from biallelic inactivation of the NF1 gene. Recent studies have revealed the presence of other molecular alterations in a small portion of these NF1-associated brain tumors. The purpose of this study was to leverage Nf1 genetically engineered mouse strains to define the functional significance of these changes to optic glioma biology.

METHODS

Nf1+/- mice were intercrossed with Nf1(flox/flox) mice, which were then crossed with Nf1(flox/flox); GFAP-Cre mice, to generate Nf1(flox/mut); GFAP-Cre (FMC) mice. These mice were additionally mated with conditional KIAA1549:BRAF knock-in or Pten(flox/wt) mice to generate Nf1(flox/mut); f-BRAF; GFAP-Cre (FMBC) mice or Nf1(flox/mut); Pten(flox/wt); GFAP-Cre (FMPC) mice, respectively. The resulting optic gliomas were analyzed for changes in tumor volume, proliferation, and retinal ganglion cell loss.

RESULTS

While KIAA1549:BRAF conferred no additional biological properties on Nf1 optic glioma, FMPC mice had larger optic gliomas with greater proliferative indices and microglial infiltration. In addition, all 3 Nf1 murine optic glioma strains exhibited reduced retinal ganglion cell survival and numbers; however, FMPC mice had greater retinal nerve fiber layer thinning near the optic head relative to FMC and FMBC mice.

CONCLUSIONS

Collectively, these experiments demonstrate genetic cooperativity between Nf1 loss and Pten heterozygosity relevant to optic glioma biology and further underscore the value of employing genetically engineered mouse strains to define the contribution of discovered molecular alterations to brain tumor pathogenesis.

Neurocognitive profiles of learning disabled children with neurofibromatosis type 1

Neurofibromatosis 1 (NF1) is a genetic condition generally associated with intellectual deficiency and learning disabilities. Although there have been groundbreaking advances in the understanding of the molecular, cellular, and neural systems underlying learning deficits associated to NF1 in animal models, much remains to be learned about the spectrum of neurocognitive phenotype associated with the NF1 clinical syndrome. In the present study, 32 children with NF1 ranging from 7 to 14 years were evaluated with neurocognitive tests dedicated to assess basic capacities which are involved in reading and mathematical achievement. Deficits in lexical and phonological strategies and poor number facts retrieval were found underlying reading and arithmetic disorders, respectively. Additionally, efficiencies in lexical/phonological strategies and mental arithmetic were significant predictors of individual differences in reading attainment and math. However, deficits in core numeric capacities were not found in the sample, suggesting that it is not responsible for calculation dysfluency. The estimated prevalence of Developmental Dyscalculia was 18.8%, and the male:female ratio was 5:1. On the other hand, the prevalence of Developmental Dyslexia was almost 3 times as high (50%), and no gender differences were found (male: female ratio = 1:1). This study offers new evidence to the neurocognitive phenotype of NF1 contributing to an in depth understanding of this condition, but also to possible treatments for the cognitive deficits associated with NF1.

Handheld optical coherence tomography during sedation in young children with optic pathway gliomas

IMPORTANCE

Monitoring young children with optic pathway gliomas (OPGs) for visual deterioration can be difficult owing to age-related noncompliance. Optical coherence tomography (OCT) measures of retinal nerve fiber layer (RNFL) thickness have been proposed as a surrogate marker of vision but this technique is also limited by patient cooperation.

OBJECTIVE

To determine whether measures of circumpapillary RNFL thickness, acquired with handheld OCT (HH-OCT) during sedation, can differentiate between young children with and without vision loss from OPGs.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional analysis of a prospective observational study was conducted at a tertiary-care children's hospital. Children with an OPG (sporadic or secondary to neurofibromatosis type 1) who were cooperative for visual acuity testing, but required sedation to complete magnetic resonance imaging, underwent HH-OCT imaging of the circumpapillary RNFL while sedated.

MAIN OUTCOMES AND MEASURES

Area under the curve of the receiver operating characteristic, sensitivity, specificity, positive predictive value, and negative predictive value of the average and quadrant-specific RNFL thicknesses.

RESULTS

Thirty-three children (64 eyes) met inclusion criteria (median age, 4.8 years; range, 1.8-12.6 years). In children with vision loss (abnormal visual acuity and/or visual field), RNFL thickness was decreased in all quadrants compared with the normal-vision group (P < .001 for all comparisons). Using abnormal criteria of less than 5% and less than 1%, the area under the curve was highest for the average RNFL thickness (0.96 and 0.97, respectively) compared with specific anatomic quadrants. The highest discrimination and predictive values were demonstrated for participants with 2 or more quadrants meeting less than 5% (sensitivity = 93.3; specificity = 97.9; positive predictive value = 93.3; and negative predictive value = 97.9) and less than 1% (sensitivity = 93.3; specificity = 100; positive predictive value = 100; and negative predictive value = 98.0) criteria.

CONCLUSIONS AND RELEVANCE

Measures of RNFL thickness acquired with HH-OCT during sedation can differentiate between young children with and without vision loss from OPGs. For young children who do not cooperate with vision testing, HH-OCT measures may be a surrogate marker of vision. Longitudinal studies are needed to delineate the temporal relationship between RNFL decline and vision loss.