Moyamoya syndrome in children with neurofibromatosis type 1: Italian-French experience

Vascular Abnormalities and Neurofibromatosis Type 1: A Paediatric Case Series

Neurofibromatosis type 1 (NF1) is a multisystemic neurocutaneous disease caused by a heterozygous mutation of the NF1 gene that encodes neurofibromin. Complications include vascular and neurologic abnormalities such as moyamoya syndrome, a cerebrovascular disorder with progressive occlusion of the large intracranial arteries, leading to ischemic events and the formation of abnormal vascular networks. Stenosis of the renal artery is another frequent complication of neurofibromatosis type 1, and it represents the most common cause of secondary hypertension in these patients. The purpose of the article is to describe the clinical manifestations of neurofibromatosis type 1 vasculopathy in 4 patients presenting with a wide range of neurologic and reno-vascular manifestations, as well as to examine current diagnostic management and follow-up, current therapeutic options, and to discuss further perspectives in terms of screening, diagnosis, and treatment.

Outcomes of surgical revascularization for pediatric moyamoya disease and syndrome

PURPOSE

Moyamoya disease and syndrome represent rare entities characterized by progressive stenosis and/or occlusion of the intracranial blood vessels. We present our series of patients with moyamoya disease and syndrome stratified by underlying disease and analyze differences in presentation and outcome following surgical revascularization.

METHODS

This was an Institutional Review Board (IRB) approved, retrospective review of all patients surgically revascularized by the senior author (SNM) while at Children's National Hospital in Washington, DC. Demographic data, presenting symptoms and severity, surgical details, and functional and radiographic outcomes were obtained and analyzed for differences among the underlying cohorts of moyamoya disease and syndrome as well as by unilateral or bilateral disease and index or non-index surgeries.

RESULTS

Twenty-two patients were identified with the following underlying diseases: six with idiopathic moyamoya disease, six with sickle cell anemia, five with trisomy 21, and five with neurofibromatosis type 1. Thirty hemispheres were revascularized with a significantly reduced rate of stroke from 3.19 strokes/year (SD = 3.10) to 0.13 strokes/year (SD = 0.25), p = 0.03. When analyzed by underlying cause of moyamoya syndrome, patients with neurofibromatosis type 1 were found to be significantly less likely than the other subtypes of moyamoya syndrome to have had either a clinical stroke (0.0% neurofibromatosis type 1 vs. 100.0% sickle cell, 60.0% trisomy 21, or 83.3% moyamoya disease, p < 0.01) or radiographic stroke (0.0% neurofibromatosis type 1 vs. 100.0% sickle cell, 60.0% trisomy 21, or 83.3% moyamoya disease, p < 0.01) at time of presentation. Patients with moyamoya syndrome associated with sickle cell disease were more likely to present with clinical and radiographic strokes. Additionally, patients with bilateral disease demonstrated no difference in final functional outcome compared to patients with unilateral disease (mRS 0.73 (SD = 1.33) vs. 1.29 (SD = 1.60), p = 0.63).

CONCLUSION

Indirect surgical revascularization decreases stroke risk for pediatric patients with different forms of moyamoya disease and moyamoya syndrome. Additionally, these data suggest that sickle cell anemia-associated moyamoya syndrome may represent a more aggressive variant, while neurofibromatosis type 1 may represent a more benign variant.

A Comprehensive Overview of NF1 Mutations in Iranian Patients

Neurofibromatosis type 1 (NF1) is a genetic disorder caused by mutations in the NF1 gene. This disorder shows nearly complete penetrance and high phenotypic variability. We used the whole-exome sequencing technique to identify mutations in 32 NF1 cases from 22 Iranian families. A total of 31 variants, including 30 point mutations and one large deletion, were detected. In eight cases, variants were inherited, while they were sporadic in the remaining. Seven novel variants, including c.5576 T > G, c.6658_6659insC, c.2322dupT, c.92_93insAA, c.4360C > T, c.3814C > T, and c.4565_4566delinsC, were identified. The current study is the largest in terms of the sample size of Iranian NF1 cases with identified mutations. The results can broaden the spectrum of NF1 mutations and facilitate the process of genetic counseling in the affected families.

Cerebral Vasculopathy in Children with Neurofibromatosis Type 1

Cerebrovascular abnormalities are a severe and often underrecognized complication of childhood neurofibromatosis type 1 (NF1). There are no prospective studies of cerebral vasculopathy in NF1; thus, the estimated frequency of vasculopathy varies between studies. The data is difficult to interpret due to the retrospective data collection and variability in whether imaging is done based on screening/surveillance or due to acute neurologic symptoms. The prevalent NF1-associated cerebral vasculopathy is moyamoya syndrome (MMS). Vascular changes can present without symptoms or with acute TIA or stroke-like symptoms or a range of progressive neurologic deficits. Advanced imaging may enhance sensitivity of neuroimaging in children. Medical and/or surgical interventions may prevent short- and long-term complications. Challenges for establishment of a screening protocol for cerebral vasculopathy in children with NF1 include the relatively large number of patients with NF1, the potential need for sedation to achieve quality imaging and the broad age range at time of detection for cerebral vascular changes. The goal of this review is to present the epidemiology, clinical presentation, imaging features and medical/surgical management of cerebral arteriopathies 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.

Moyamoya Vasculopathy in Neurofibromatosis Type 1 Pediatric Patients: The Role of Rare Variants of RNF213

Neurofibromatosis type 1 (NF1) is a neurocutaneous disorder caused by mutations in NF1 gene, coding for neurofibromin 1. NF1 can be associated with Moyamoya disease (MMD), and this association, typical of paediatric patients, is referred to as Moyamoya syndrome (MMS). MMD is a cerebral arteriopathy characterized by the occlusion of intracranial arteries and collateral vessel formation, which increase the risk of ischemic and hemorrhagic events. RNF213 gene mutations have been associated with MMD, so we investigated whether rare variants of RNF213 could act as genetic modifiers of MMS phenotype in a pediatric cohort of 20 MMS children, 25 children affected by isolated MMD and 47 affected only by isolated NF1. By next-generation re-sequencing (NGS) of patients' DNA and gene burden tests, we found that RNF213 seems to play a role only for MMD occurrence, while it does not appear to be involved in the increased risk of Moyamoya for MMS patients. We postulated that the loss of neurofibromin 1 can be enough for the excessive proliferation of vascular smooth muscle cells, causing Moyamoya arteriopathy associated with NF1. Further studies will be crucial to support these findings and to elucidate the possible role of other genes, enhancing our knowledge about pathogenesis and treatment of MMS.

Neurofibromatosis Type 1: Pediatric Aspects and Review of Genotype-Phenotype Correlations

Neurofibromatosis type 1 (NF1) is an autosomal dominant condition, with a birth incidence of approximately 1:2000-3000, caused by germline pathogenic variants in NF1, a tumor suppressor gene encoding neurofibromin, a negative regulator of the RAS/MAPK pathway. This explains why NF1 is included in the group of RASopathies and shares several clinical features with Noonan syndrome. Here, we describe the main clinical characteristics and complications associated with NF1, particularly those occurring in pediatric age. NF1 has complete penetrance and shows wide inter- and intrafamilial phenotypic variability and age-dependent appearance of manifestations. Clinical presentation and history of NF1 are multisystemic and highly unpredictable, especially in the first years of life when penetrance is still incomplete. In this scenario of extreme phenotypic variability, some genotype-phenotype associations need to be taken into consideration, as they strongly impact on genetic counseling and prognostication of the disease. We provide a synthetic review, based on the most recent literature data, of all known genotype-phenotype correlations from a genetic and clinical perspective. Molecular diagnosis is fundamental for the confirmation of doubtful clinical diagnoses, especially in the light of recently revised diagnostic criteria, and for the early identification of genotypes, albeit few, that correlate with specific phenotypes.

RASopathy Cohort of Patients Enrolled in a Brazilian Reference Center for Rare Diseases: A Novel Familial LZTR1 Variant and Recurrent Mutations

Purpose

Noonan syndrome and related disorders are genetic conditions affecting 1:1000-2000 individuals. Variants causing hyperactivation of the RAS/MAPK pathway lead to phenotypic overlap between syndromes, in addition to an increased risk of pediatric tumors. DNA sequencing methods have been optimized to provide a molecular diagnosis for clinical and genetic heterogeneity conditions. This work aimed to investigate the genetic basis in RASopathy patients through Next Generation Sequencing in a Reference Center for Rare Diseases (IFF/Fiocruz) and implement the precision medicine at a public health institute in Brazil.

Patients and Methods

This study comprises 26 cases with clinical suspicion of RASopathies. Sanger sequencing was used to screen variants in exons usually affected in the PTPN11 and HRAS genes for cases with clinical features of Noonan and Costello syndrome, respectively. Posteriorly, negative and new cases with clinical suspicion of RASopathy were analyzed by clinical or whole-exome sequencing.

Results

Molecular analysis revealed recurrent variants and a novel LZTR1 missense variant: 24 unrelated individuals with pathogenic variants [PTPN11(11), NF1(2), SOS1(2), SHOC2(2), HRAS(1), BRAF(1), LZTR (1), RAF1(1), KRAS(1), RIT1(1), a patient with co-occurrence of PTPN11 and NF1 mutations (1)]; familial cases carrying a known pathogenic variant in PTPN11 (mother-two children), and a previously undescribed paternally inherited variant in LZTR1. The comparative modeling analysis of the novel LZTR1 variant p.Pro225Leu showed local and global changes in the secondary and tertiary structures, showing a decrease of about 1% in the β-sheet content. Furthermore, evolutionary conservation indicated that Pro225 is in a highly conserved region, as observed for known dominant pathogenic variants in this protein.

Conclusion

Bringing precision medicine through NGS towards congenital syndromes promotes a better understanding of complex clinical and/or undiagnosed cases. The National Policy for Rare Diseases in Brazil emphasizes the importance of incorporating and optimizing diagnostic methodologies in the Unified Brazilian Health System (SUS). Therefore, this work is an important step for the NGS inclusion in diagnostic genetic routine in the public health system.

Characteristics of Moyamoya Syndrome in Pediatric Patients With Neurofibromatosis Type 1

BACKGROUND

Moyamoya syndrome (MMS) is a progressive cerebral arteriopathy with increased incidence in children with neurofibromatosis type 1 (NF1). Despite the potential for significant neurological morbidity including stroke, little is known about the natural history, and no guidelines exist for screening and management of NF1-associated MMS.

METHODS

We identified 152 literature cases of children aged ≤18 years with NF1-associated MMS. A meta-analysis was performed evaluating clinical and neuroimaging findings and patient outcomes. Data from 19 patients with NF1-associated MMS from our center treated from January 1995 to July 2020 were abstracted via chart review and similarly analyzed for clinical and neuroimaging features.

RESULTS

Meta-analysis of literature cases showed a median age of MMS diagnosis of 6 years (interquartile range 3 to 10.8 years). Optic pathway gliomas were more common in patients with MMS (42%) compared with historical prevalence. Stroke or transient ischemic attack (TIA) was present at diagnosis in 46%. TIA and stroke were more common in patients with bilateral versus unilateral MMS (62% vs 34%, P = 0.001) and in children aged <4 years versus those aged ≥4 years (61% vs 40%, P = 0.02). Compared with the literature cases, our cohort was more frequently asymptomatic (42% vs 25%) and less likely to present with TIA or stroke (32% vs 46%) at diagnosis.

CONCLUSIONS

These data suggest there is an aggressive form of MMS in children with NF1 <4 years of age. Therefore, early screening should be considered to facilitate early detection and treatment of cerebral arteriopathy.

Genotype-Phenotype Correlations in Neurofibromatosis Type 1: Identification of Novel and Recurrent NF1 Gene Variants and Correlations with Neurocognitive Phenotype

Neurofibromatosis type 1 (NF1) is one of the most common genetic tumor predisposition syndrome, caused by mutations in the NF1. To date, few genotype-phenotype correlations have been discerned in NF1, due to a highly variable clinical presentation. We aimed to study the molecular spectrum of NF1 and genotype-phenotype correlations in a monocentric study cohort of 85 NF1 patients (20 relatives, 65 sporadic cases). Clinical data were collected at the time of the mutation analysis and reviewed for accuracy in this investigation. An internal phenotypic categorization was applied. The 94% of the patients enrolled showed a severe phenotype with at least one systemic complication and a wide range of associated malignancies. Spine deformities were the most common complications in this cohort. We also reported 66 different NF1 mutations, of which 7 are novel mutations. Correlation analysis identified a slight significant inverse correlation between age at diagnosis and delayed acquisition of psychomotor skills with residual multi-domain cognitive impairment. Odds ratio with 95% confidence interval showed a higher prevalence of learning disabilities in patients carrying frameshift mutations. Overall, our results aim to offer an interesting contribution to studies on the genotype–phenotype of NF1 and in genetic management and counselling.

Alternative RNA Splicing Defects in Pediatric Cancers: New Insights in Tumorigenesis and Potential Therapeutic Vulnerabilities

BACKGROUND

Compared to adult cancers, pediatric cancers are uniquely characterized by a genomically stable landscape and lower tumor mutational burden. However, alternative splicing, a global cellular process that produces different mRNA/protein isoforms from a single mRNA transcript, has been increasingly implicated in the development of pediatric cancers.

DESIGN

We review the current literature on the role of alternative splicing in adult cancer, cancer predisposition syndromes, and pediatric cancers. We also describe multiple splice variants identified in adult cancers and confirmed through comprehensive genomic profiling in our institutional cohort of rare, refractory and relapsed pediatric and adolescent young adult cancer patients. Finally, we summarize the contributions of alternative splicing events to neoantigens and chemoresistance and prospects for splicing-based therapies.

RESULTS

Published dysregulated splicing events can be categorized as exon inclusion, exon exclusion, splicing factor upregulation, or splice site alterations. We observe these phenomena in cancer predisposition syndromes (Lynch syndrome, Li-Fraumeni syndrome, CHEK2) and pediatric leukemia (B-ALL), sarcomas (Ewing sarcoma, rhabdomyosarcoma, osteosarcoma), retinoblastoma, Wilms tumor, and neuroblastoma. Within our institutional cohort, we demonstrate splice variants in key regulatory genes (CHEK2, TP53, PIK3R1, MDM2, KDM6A, NF1) that resulted in exon exclusion or splice site alterations, which were predicted to impact functional protein expression and promote tumorigenesis. Differentially spliced isoforms and splicing proteins also impact neoantigen creation and treatment resistance, such as imatinib or glucocorticoid regimens. Additionally, splice-altering strategies with the potential to change the therapeutic landscape of pediatric cancers include antisense oligonucleotides, adeno-associated virus gene transfers, and small molecule inhibitors.

CONCLUSIONS

Alternative splicing plays a critical role in the formation and growth of pediatric cancers, and our institutional cohort confirms and highlights the broad spectrum of affected genes in a variety of cancers. Further studies that elucidate the mechanisms of disease-inducing splicing events will contribute toward the development of novel therapeutics.

Pediatric Moyamoya Disease and Syndrome in Italy: A Multicenter Cohort

BACKGROUND

Moyamoya is a rare progressive cerebral arteriopathy, occurring as an isolated phenomenon (moyamoya disease, MMD) or associated with other conditions (moyamoya syndrome, MMS), responsible for 6-10% of all childhood strokes and transient ischemic attacks (TIAs).

METHODS

We conducted a retrospective multicenter study on pediatric-onset MMD/MMS in Italy in order to characterize disease presentation, course, management, neuroradiology, and outcome in a European country.

RESULTS

A total of 65 patients (34/65 women) with MMD (27/65) or MMS (38/65) were included. About 18% (12/65) of patients were asymptomatic and diagnosed incidentally during investigations performed for an underlying condition (incMMS), whereas 82% (53/65) of patients with MMD or MMS were diagnosed due to the presence of neurological symptoms (symptMMD/MMS). Of these latter, before diagnosis, 66% (43/65) of patients suffered from cerebrovascular events with or without other manifestations (ischemic stroke 42%, 27/65; TIA 32%, 21/65; and no hemorrhagic strokes), 18% (12/65) of them reported headache (in 4/12 headache was not associated with any other manifestation), and 26% (17/65) of them experienced multiple phenotypes (≥2 among: stroke/TIA/seizures/headache/others). Neuroradiology disclosed ≥1 ischemic lesion in 67% (39/58) of patients and posterior circulation involvement in 51% (30/58) of them. About 73% (47/64) of patients underwent surgery, and 69% (45/65) of them received aspirin, but after diagnosis, further stroke events occurred in 20% (12/61) of them, including operated patients (11%, 5/47). Between symptom onset and last follow-up, the overall patient/year incidence of stroke was 10.26% (IC 95% 7.58-13.88%). At last follow-up (median 4 years after diagnosis, range 0.5-15), 43% (26/61) of patients had motor deficits, 31% (19/61) of them had intellectual disability, 13% (8/61) of them had epilepsy, 11% (7/61) of them had behavioral problems, and 25% (13/52) of them had mRS > 2. The proportion of final mRS > 2 was significantly higher in patients with symptMMD/MMS than in patients with incMMS (p = 0.021). Onset age <4 years and stroke before diagnosis were significantly associated with increased risk of intellectual disability (p = 0.0010 and p = 0.0071, respectively) and mRS > 2 at follow-up (p = 0.0106 and p = 0.0009, respectively).

CONCLUSIONS

Moyamoya is a severe condition that may affect young children and frequently cause cerebrovascular events throughout the disease course, but may also manifest with multiple and non-cerebrovascular clinical phenotypes including headache (isolated or associated with other manifestations), seizures, and movement disorder. Younger onset age and stroke before diagnosis may associate with increased risk of worse outcome (final mRS > 2).

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.

Clinical variability of neurofibromatosis 1: A modifying role of cooccurring PTPN11 variants and atypical brain MRI findings

Neurofibromatosis 1 (NF1) is a disorder characterized by variable expressivity caused by loss-of-function variants in NF1, encoding neurofibromin, a protein negatively controlling RAS signaling. We evaluated whether concurrent variation in proteins functionally linked to neurofibromin contribute to the variable expressivity of NF1. Parallel sequencing of a RASopathy gene panel in 138 individuals with molecularly confirmed clinical diagnosis of NF1 identified missense variants in PTPN11, encoding SHP2, a positive regulator of RAS signaling, in four subjects from three unrelated families. Three subjects were heterozygous for a gain-of-function variant and showed a severe expression of NF1 (developmental delay, multiple cerebral neoplasms and peculiar cortical MRI findings), and features resembling Noonan syndrome (a RASopathy caused by activating variants in PTPN11). Conversely, the fourth subject, who showed an attenuated presentation, carried a previously unreported PTPN11 variant that had a hypomorphic behavior in vitro. Our findings document that functionally relevant PTPN11 variants occur in a small but significant proportion of subjects with NF1 modulating disease presentation, suggesting a model in which the clinical expression of pathogenic NF1 variants is modified by concomitant dysregulation of protein(s) functionally linked to neurofibromin. We also suggest targeting of SHP2 function as an approach to treat evolutive complications of NF1.

Association between neurofibromatosis type 1 and cerebrovascular diseases in children: A systematic review

BACKGROUND

Neurofibromatosis type 1 (NF-1) is an autosomal dominant disease that affects one in every 3000 individuals. This disease can present a wide range of clinical manifestations, ranging from skin abnormalities to severe vascular damage. Although not commonly recognized in the context of NF-1, cerebrovascular disease (CVD), can be often present since childhood and diagnosed just later in life. When present, NF-1-associated CVD clinical manifestations may include headache, cognitive deficits and ultimately aneurysm rupture, causing death. Thus, CVD plays an important role in the clinical manifestations, disease severity and prognosis of patients with NF-1. This systematic review aims to summarize the body of evidence linking NF-1 and CVD in children.

METHODS

Two independent investigators performed a systematic review on the PubMed and EMBASE search platforms, using the following key terms: "neurofibromatosis type 1", "Von Recklinghausen's disease", "children", "adolescents", "stroke", "Moyamoya disease", "vascular diseases", "cerebrovascular disorders", "aneurysm" and "congenital abnormalities". Studies focused on assessing the development of CVD in children with NF-1 were included.

RESULTS

Seven studies met the inclusion criteria. Twelve different clinical manifestations have been associated with cerebrovascular changes in children with NF-1; 44,5% of diagnosed patients were asymptomatic.

CONCLUSION

The available evidence suggests that CVDs are related with the progression of NF-1, even in the absence of a clear clinical manifestation. In addition, improved prognosis was observed when imaging tests were performed to screen for cerebrovascular alterations early during the clinical investigation. Early diagnosis of CVD in NF-1 patients foster implementation of timely interventions, directly impacting clinical outcomes.

Moyamoya disease versus moyamoya syndrome: comparison of presentation and outcome in 338 hemispheres

OBJECTIVE

Phenotypic differences between moyamoya disease (MMD) and moyamoya syndrome (MMS) remain unclear. The purpose of this study was to evaluate whether such differences exist when presentation, procedure-related, and outcome variables are compared quantitatively.

METHODS

The study cohort included 185 patients with moyamoya presenting to the Johns Hopkins Medical Institutions between 1994 and 2015. Baseline demographic, angiographic, and clinical characteristics were compared between patients with MMS and MMD, in addition to procedure-related complications and length of stay (LOS) after surgery. Stroke-free survival was compared between both disease variants after diagnosis. Kaplan-Meier analysis and Cox proportional hazards regression were used to compare stroke-free survival between surgically treated and conservatively managed hemispheres in both types of disease, while evaluating interaction between disease variant and management.

RESULTS

The cohort consisted of 137 patients with MMD (74%) with a bimodal age distribution and 48 patients with MMS (26%) who were mostly under 18 years of age (75%). Underlying diseases included sickle cell disease (48%), trisomy 21 (12%), neurofibromatosis (23%), and other disorders (17%). Patients with MMS were younger (p < 0.001) and less likely to be female (p = 0.034). Otherwise, baseline characteristics were statistically comparable. The rate of surgical complications was 33% in patients with MMD and 16% in patients with MMS (p = 0.097). Both groups of patients had a similar LOS after surgery (p = 0.823). Survival analysis (n = 330 hemispheres) showed similar stroke-free survival after diagnosis (p = 0.856) and lower stroke hazard in surgically managed patients in both MMD (hazard ratio [HR] 0.29, p = 0.028) and MMS (HR 0.62, p = 0.586). The disease variant (MMD vs MMS) did not affect the relationship between management approach (surgery vs conservative) and stroke hazard (p = 0.787).

CONCLUSIONS

MMD and MMS have largely comparable clinical and angiographic phenotypes with analogously favorable responses to surgical revascularization.

Moyamoya syndrome in a child with Legius syndrome: Introducing a cerebral vasculopathy to the SPRED1 phenotype?

Legius syndrome is a disorder of the RAS and mitogen-activated protein kinase (MAPK) pathway first described in 2007 by Eric Legius, et al., that has been considered a milder phenotype than reported in the RASopathy neurofibromatosis type 1 (NF1). However, with approximately 200 cases reported in the literature, the Legius syndrome phenotype remains to be fully characterized. We report a child who presented with moyamoya syndrome and who has Legius syndrome due to a pathogenic variant in SPRED1. Vascular complications such as moyamoya syndrome have been reported in NF1. However, this association has not been reported in Legius syndrome. This child's case may represent an expansion of the clinical phenotype of Legius syndrome, and further study is needed. We emphasize the importance of obtaining neuroimaging studies in patients with Legius syndrome who present with new neurologic deficits.

Epilepsy in NF1: a systematic review of the literature

Epilepsy is one of the possible neurological manifestations of the neurofibromatosis type 1 (NF1) that represents the most common neurocutaneous disorder. We performed a systematic review of the literature on epilepsy associated with NF1 since 1995 in order to better define prevalence and describe type and causes of seizures. Data on type, nature of studies, number of patients, gender, and inheritance of NF1 were recorded as well as data on causes, type, EEGs, brain imaging, intellectual disability (ID), surgical treatment, and outcome of epilepsy. We identified a total of 141 references through the literature search of Pubmed and Embase. After screening, 42 records were identified, including 11617 individuals with NF1 (53% of males). Overall prevalence was estimated at 5.4% lifelong with values that seemed to be slightly lower in children, 3.7% (p 0.0016). Neither gender differences nor correlation with NF1 inheritance was found. Focal with or without bilateral tonic-clonic seizures were the most common seizure type encountered (60.9%). Structural causes were identified in half of cases (114/226). Low-grade gliomas were the most frequent associated lesions followed by mesial temporal sclerosis, malformation of cortical development, dysembryoplastic neuroepithelial tumor, and cerebrovascular lesions. In these cases, the surgical approach improved the epileptic outcome. Prevalence of epilepsy is higher in subjects with NF1 respect of the general population, with values apparently significantly lower in pediatric age. Brain tumors and cytoarchitectural abnormalities are the most frequent causes of epilepsy in this population, although many other brain complications should be taken in account.

Multimodal evaluation of the cerebrovascular reserve in Neurofibromatosis type 1 patients with Moyamoya syndrome

Purpose

Moyamoya syndrome (MMS) is a rare intracranial arterial vasculopathy which can occur in neurofibromatosis type 1 (NF1) disease, representing a cause of cerebrovascular reserve (CVR) impairment, possibly leading to ischemic stroke. Here, we evaluated noninvasive imaging techniques used to assess CVR in MMS patients, describing clinical and imaging findings in patients affected by MMS-NF1.

Methods

Following strict inclusion and exclusion criteria, in this retrospective observational study, we evaluated imaging data of nine consecutive MMS-NF1 patients (M/F = 5/4, mean age: 12.6 ± 4.0). Subjects underwent a multimodal evaluation of cerebral vascular status, including intracranial arterial MR Angiography (MRA), MRI perfusion with dynamic susceptibility contrast (DSC) technique, and 99mTc-hexamethylpropyleneamine oxime (HMPAO) SPECT.

Results

In 8 out 9 patients (88.8%, 6/8 symptomatic), time-to-peak maps were correlated with the involved cerebral hemisphere, while in 6 out 9 patients (66.6%, 5/6 symptomatic), mean transit time (MTT) maps showed correspondence with the affected cerebrovascular territories. Cerebral blood flow (CBF) calculated using DSC perfusion failed to detect the hypoperfused regions instead identified by SPECT-CBF in all patients, while MTT maps overlapped with SPECT-CBF data in all cases and time-to-peak maps in 60.0%.

Conclusions

Although SPECT imaging still represents the gold standard for CBF assessment, our results suggest that data obtained using DSC perfusion technique, and in particular MTT maps, might be a very useful and noninvasive tool for evaluating hemodynamic status in MMS-NF1 patients.

Electronic supplementary material

The online version of this article (10.1007/s10072-020-04574-4) contains supplementary material, which is available to authorized users.

Retrospective Multicentric Study on Non-Optic CNS Tumors in Children and Adolescents with Neurofibromatosis Type 1

s: The natural history of non-optic central nervous system (CNS) tumors in neurofibromatosis type 1 (NF1) is largely unknown. Here, we describe prevalence, clinical presentation, treatment, and outcome of 49 non-optic CNS tumors observed in 35 pediatric patients (0-18 years). Patient- and tumor-related data were recorded. Overall survival (OS) and progression-free survival (PFS) were evaluated. Eighteen patients (51%) harbored an optic pathway glioma (OPG) and eight (23%) had multiple non-optic CNS lesions. The majority of lesions (37/49) were managed with a wait-and-see strategy, with one regression and five reductions observed. Twenty-one lesions (42.9%) required surgical treatment. Five-year OS was 85.3%. Twenty-four patients progressed with a 5-year PFS of 41.4%. Patients with multiple low-grade gliomas progressed earlier and had a lower 5-year PFS than those with one lesion only (14.3% vs. 57.9%), irrespective of OPG co-presence. Non-optic CNS tumors are common in young patients with NF1. Neither age and symptoms at diagnosis nor tumor location influenced time to progression in our series. Patients with multiple lesions tended to have a lower age at onset and to progress earlier, but with a good OS.

Clinical and Genetic Findings in Children with Neurofibromatosis Type 1, Legius Syndrome, and Other Related Neurocutaneous Disorders

Pigmentary manifestations can represent an early clinical sign in children affected by Neurofibromatosis type 1 (NF1), Legius syndrome, and other neurocutaneous disorders. The differential molecular diagnosis of these pathologies is a challenge that can now be met by combining next generation sequencing of target genes with concurrent second-level tests, such as multiplex ligation-dependent probe amplification and RNA analysis. We clinically and genetically investigated 281 patients, almost all pediatric cases, presenting with either NF1 (n = 150), only pigmentary features (café au lait macules with or without freckling; (n = 95), or clinical suspicion of other RASopathies or neurocutaneous disorders (n = 36). The causative variant was identified in 239 out of the 281 patients analyzed (85.1%), while 42 patients remained undiagnosed (14.9%). The NF1 and SPRED1 genes were mutated in 73.3% and 2.8% of cases, respectively. The remaining 8.9% carried mutations in different genes associated with other disorders. We achieved a molecular diagnosis in 69.5% of cases with only pigmentary manifestations, allowing a more appropriate clinical management of these patients. Our findings, together with the increasing availability and sharing of clinical and genetic data, will help to identify further novel genotype–phenotype associations that may have a positive impact on patient follow-up.

Caring for children with neurofibromatosis type 1

This article discusses the variable physical manifestations of neurofibromatosis type 1 among children in terms of presentation, disease severity, and prognosis, and addresses appropriate nursing interventions and patient teaching.

Microduplication of 15q13.3 and Microdeletion of 18q21.32 in a Patient with Moyamoya Syndrome

Moyamoya angiopathy (MA) is a cerebrovascular disease determining a progressive stenosis of the terminal part of the internal carotid arteries (ICAs) and their proximal branches and the compensatory development of abnormal “moyamoya” vessels. MA occurs as an isolated cerebral angiopathy (so-called moyamoya disease) or in association with various conditions (moyamoya syndromes) including several heritable conditions such as Down syndrome, neurofibromatosis type 1 and other genomic defects. Although the mechanism that links MA to these genetic syndromes is still unclear, it is believed that the involved genes may contribute to the disease susceptibility. Herein, we describe the case of a 43 years old woman with bilateral MA and peculiar facial characteristics, having a 484-kb microduplication of the chromosomal region 15q13.3 and a previously unreported 786 kb microdeletion in 18q21.32. This patient may have a newly-recognized genetic syndrome associated with MA. Although the relationship between these genetic variants and MA is unclear, our report would contribute to widening the genetic scenario of MA, in which not only genic mutation, but also genome unbalances are possible candidate susceptibility factors.

Whole exome sequencing identifies MRVI1 as a susceptibility gene for moyamoya syndrome in neurofibromatosis type 1

Background and purpose

Moyamoya angiopathy is a progressive cerebral vasculopathy. The p.R4810K substitution in RNF213 has previously been linked to moyamoya disease in Asian populations. When associated with other medical conditions, such as neurofibromatosis type 1, this vasculopathy is frequently reported as moyamoya syndrome. Intriguingly, most cases of moyamoya-complicated neurofibromatosis type 1 have been described in Caucasians, inverting the population ratio observed in Asians, although prevalence of neurofibromatosis type 1 is constant worldwide. Our aim was to investigate whether, among Caucasians, additive genetic factors may contribute to the occurrence of moyamoya in neurofibromatosis type 1.

Methods

Whole exome sequencing was carried out on an Italian family with moyamoya-complicated neurofibromatosis type 1 to identify putative genetic modifiers independent of the NF1 locus and potentially involved in moyamoya pathogenesis. Results were validated in an unrelated family of German ancestry.

Results

We identified the p.P186S substitution (rs35857561) in MRVI1 that segregated with moyamoya syndrome in both the Italian and German family.

Conclusions

The rs35857561 polymorphism in MRVI1 may be a genetic susceptibility factor for moyamoya in European patients with neurofibromatosis type 1. MRVI1 is a functional partner of ITPR1, PRKG1 and GUCY1A3, which are involved in response to nitric oxide. Mutations in GUCY1A3 have been recently linked to a recessive syndromic form of moyamoya with esophageal achalasia.

Whole Exome Sequencing Reveals a Monogenic Cause of Disease in ≈43% of 35 Families With Midaortic Syndrome

Midaortic syndrome (MAS) is a rare cause of severe childhood hypertension characterized by narrowing of the abdominal aorta in children and is associated with extensive vascular disease. It may occur as part of a genetic syndrome, such as neurofibromatosis, or as consequence of a pathological inflammatory disease. However, most cases are considered idiopathic. We hypothesized that in a high percentage of these patients, a monogenic cause of disease may be detected by evaluating whole exome sequencing data for mutations in 1 of 38 candidate genes previously described to cause vasculopathy. We studied a cohort of 36 individuals from 35 different families with MAS by exome sequencing. In 15 of 35 families (42.9%), we detected likely causal dominant mutations. In 15 of 35 (42.9%) families with MAS, whole exome sequencing revealed a mutation in one of the genes previously associated with vascular disease (NF1, JAG1, ELN, GATA6, and RNF213). Ten of the 15 mutations have not previously been reported. This is the first report of ELN, RNF213, or GATA6 mutations in individuals with MAS. Mutations were detected in NF1 (6/15 families), JAG1 (4/15 families), ELN (3/15 families), and one family each for GATA6 and RNF213 Eight individuals had syndromic disease and 7 individuals had isolated MAS. Whole exome sequencing can provide conclusive molecular genetic diagnosis in a high fraction of individuals with syndromic or isolated MAS. Establishing an etiologic diagnosis may reveal genotype/phenotype correlations for MAS in the future and should, therefore, be performed routinely in MAS.

Seizures in children with neurofibromatosis type 1: is neurofibromatosis type 1 enough?

BACKGROUND

Neurofibromatosis type 1 (NF1) is related to a generally increased prevalence of seizures. The mechanism underlying the increased predisposition to seizures has not been fully elucidated. The aim of the study was to evaluate the role of NF1 in seizures pathogenesis in a cohort of children with NF1 and seizures.

METHODS

The medical records of 437 children (0-18 years old) with NF1 were reviewed. All children with at least one afebrile seizure were included. Demographic, clinical, neurological, NF1 mutation status, and EEG data were collected along with brain magnetic resonance imaging. Depending on etiology, structural seizures have been identified and were further classified as NF1 related or not.

RESULTS

Nineteen patients (4.3%; 13 males) were included. NF1 was inherited in 7 (37.5%), with 3 maternal forms. Ten children with structural seizures were identified. Seven forms were identified someway related to NF1, two of which were associated to 17q11.2 microdeletion and hypoxic-ischemic encephalopathy. Any brain lesion that could explain seizures was found in nine patients, two third of these patients had a familiar history of epilepsy.

CONCLUSIONS

Our results suggest seizures are more frequent in NF1 children (4.3%) than in general pediatric population (0.3-0.5%) and that are someway related to NF1 in half of patients. Facing seizures in NF1, the clinician should first exclude brain tumors but also other, and rarer NF1-related scenarios, such as hydrocephalous and vasculopathies. Children with non-structural seizures frequently had a family history of epilepsy, raising questions about the pathogenic role of NF1. They should be approached as for the general population.

Adult-Onset Hemorrhagic Quasi-Moyamoya Disease with Unilateral Steno-occlusive Lesion in a Patient with Neurofibromatosis Type 1

BACKGROUND

Quasi-moyamoya disease is a condition that occurs in association with a specific underlying condition or disease such as atherosclerotic disease or neurofibromatosis type 1 (NF1). Pediatric cases are frequently reported, and an ischemic and bilateral presentation is more common than a hemorrhagic and unilateral presentation.

CLINICAL PRESENTATION

A 39-year-old woman previously diagnosed with NF1 presented to our department with nausea and left hemiparesis. She was diagnosed with right temporal intracerebral hemorrhage by initial computed tomography. Subsequent angiography showed an occlusion of the terminal portion of the right internal carotid artery, and magnetic resonance imaging showed multiple flow voids in the right basal ganglia, suggesting quasi-moyamoya disease. The hematoma was surgically removed, and her neurological condition improved after the operation.

CONCLUSIONS

This is the first reported case of quasi-moyamoya disease with a rare combination of characteristics, including an adult-onset, hemorrhagic presentation and a unilateral lesion in a patient previously diagnosed with NF1.

Juvenile Moyamoya and Craniosynostosis in a Child with Deletion 1p32p31: Expanding the Clinical Spectrum of 1p32p31 Deletion Syndrome and a Review of the Literature

Moyamoya angiopathy (MA) is a rare cerebrovascular disorder characterised by the progressive occlusion of the internal carotid artery. Its aetiology is uncertain, but a genetic background seems likely, given the high MA familial rate. To investigate the aetiology of craniosynostosis and juvenile moyamoya in a 14-year-old male patient, we performed an array-comparative genomic hybridisation revealing a de novo interstitial deletion of 8.5 Mb in chromosome region 1p32p31. The deletion involved 34 protein coding genes, including NF1A, whose haploinsufficiency is indicated as being mainly responsible for the 1p32-p31 chromosome deletion syndrome phenotype (OMIM 613735). Our patient also has a deleted FOXD3 of the FOX gene family of transcription factors, which plays an important role in neural crest cell growth and differentiation. As the murine FOXD3^−/− model shows craniofacial anomalies and abnormal common carotid artery morphology, it can be hypothesised that FOXD3 is involved in the pathogenesis of the craniofacial and vascular defects observed in our patient. In support of our assumption, we found in the literature another patient with a syndromic form of MA who had a deletion involving another FOX gene (FOXC1). In addition to describing the clinical history of our patient, we have reviewed all of the available literature concerning other patients with a 1p32p31 deletion, including cases from the Decipher database, and we have also reviewed the genetic disorders associated with MA, which is a useful guide for the diagnosis of syndromic form of MA.