Minor disease features in neurofibromatosis type 1 (NF1) and their possible value in diagnosis of NF1 in children < or = 6 years and clinically suspected of having NF1. Neurofibromatosis team of Sophia Children's Hospital

Nf1 in heart development: a potential causative gene for congenital heart disease: a narrative review

Congenital heart disease is the most frequent congenital disorder, affecting a significant number of live births. Gaining insights into its genetic etiology could lead to a deeper understanding of this condition. Although the Nf1 gene has been identified as a potential causative gene, its role in congenital heart disease has not been thoroughly clarified. We searched and summarized evidence from cohort-based and experimental studies on the issue of Nf1 and heart development in congenital heart diseases from various databases. Available evidence demonstrates a correlation between Nf1 and congenital heart diseases, mainly pulmonary valvar stenosis. The mechanism underlying this correlation may involve dysregulation of epithelial-mesenchymal transition (EMT). The Nf1 gene affects the EMT process via multiple pathways, including directly regulating the expression of EMT-related transcription factors and indirectly regulating the EMT process by regulating the MAPK pathway. This narrative review provides a comprehensive account of the Nf1 involvement in heart development and congenital cardiovascular diseases in terms of epidemiology and potential mechanisms. RAS signaling may contribute to congenital heart disease independently or in cooperation with other signaling pathways. Efficient management of both NF1 and cardiovascular disease patients would benefit from further research into these issues.

Neurological manifestations of neurofibromatosis type 1: our experience

INTRODUCTION

Neurofibromatosis type 1 (NF1) is a progressive multisystem disorder following an autosomal dominant inheritance pattern that presents with multiple neurological manifestations.

METHODS

We reviewed medical histories of patients with NF1 followed up at our hospital's paediatric neurology department from May 1990 to 31 December 2018. We collected data on neurological symptoms.

RESULTS

A total of 128 patients with NF1 were identified. Mean age (SD) at NF1 diagnosis was 4.43 (3.38) years (range, 0.5-14.5 years). There was a slight female predominance (53.1%). Macrocephaly (head circumference over 2 SDs above average for age) was present in 37.5% of cases. Attention-deficit/hyperactivity disorder was recorded in 28.9% of patients (37): combined type in 20 patients, predominantly inattentive in 15, and predominantly impulsive/hyperactive in 2. Other manifestations included headache (18.6%), cognitive impairment (7.8%), motor deficit (6.2%), and epilepsy (4.68%). Brain MRI was performed in 85 patients, revealing T2-weighted hyperintensities in the basal ganglia and/or cerebellum in 60 patients (70.5%), Chiari malformation type 1 in 4 cases, and arachnoid cysts in 3. Optic nerve gliomas were identified by MRI in 22 patients (25.8%). Other MRI findings included plexiform neurofibromas (9.3%) and central nervous system gliomas (3.1%).

CONCLUSIONS

The neurological manifestations identified in our sample are consistent with those reported in the literature. Effective transfer strategies from paediatric neurology departments and subsequent clinical follow-up by adult neurology departments are needed to prevent loss to follow-up in adulthood.

Multidisciplinary neurocutaneous syndrome clinics: a systematic review and institutional experience

OBJECTIVE

Neurocutaneous syndromes have variable multisystem involvement. The multiorgan involvement, potential pathologies, and various treatment options necessitate collaboration and open discussion to ensure optimal treatment in any given patient. These disorders provide quintessential examples of chronic medical conditions that require a lifelong, multidisciplinary approach. The objectives of this study were to 1) perform a systematic review, thoroughly assessing different multidisciplinary clinic layouts utilized in centers worldwide; and 2) characterize an institutional experience with the management of these conditions, focusing on the patient demographics, clinical presentation, complications, and therapeutic strategies seen in a patient population.

METHODS

A systematic review of studies involving multidisciplinary clinics and their reported structure was performed according to PRISMA guidelines using the PubMed database. Then a retrospective chart review of patients enrolled in the Oklahoma Children’s Hospital Neurocutaneous Syndromes Clinic was conducted.

RESULTS

A search of the PubMed database yielded 251 unique results. Of these, 15 papers were included in the analysis, which identified 16 clinics that treated more than 2000 patients worldwide. The majority of these clinics treated patients with neurofibromatosis (13/16). The remaining clinics treated patients with von Hippel–Lindau syndrome (n = 1), tuberous sclerosis complex (n = 1), and multiple neurocutaneous syndromes (n = 1). The most commonly represented subspecialties in these clinics were genetics (15/16) and neurology (13/16). Five clinics (31%) solely saw pediatric patients, 10 clinics saw a combination of children and adults, and the final clinic had separate pediatric and adult clinics. The retrospective chart review of the Neurocutaneous Syndromes Clinic demonstrated that 164 patients were enrolled and seen in the clinic from April 2013 to December 2021. Diagnoses were made based on clinical findings or results of genetic testing; 115 (70%) had neurofibromatosis type 1, 9 (5.5%) had neurofibromatosis type 2, 35 (21%) had tuberous sclerosis complex, 2 (1%) had von Hippel–Lindau syndrome, 2 (1%) had Gorlin syndrome, and the remaining patient (0.6%) had Aarskog-Scott syndrome. Patient demographics, clinical presentation, complications, and therapeutic strategies are also discussed.

CONCLUSIONS

To the best of the authors’ knowledge, this is the first detailed description of a comprehensive pediatric neurocutaneous clinic in the US that serves patients with multiple syndromes. There is currently heterogeneity between described multidisciplinary clinic structures and practices. More detailed accounts of clinic compositions and practices along with patient data and outcomes are needed in order to establish the most comprehensive and efficient multidisciplinary approach for neurocutaneous syndromes.

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.

Disruption of Critical Period Plasticity in a Mouse Model of Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is a common monogenic neurodevelopmental disorder associated with physical and cognitive problems. The cognitive issues are thought to arise from increased release of the neurotransmitter GABA. Modulating the signaling pathways causing increased GABA release in a mouse model of NF1 reverts deficits in hippocampal learning. However, clinical trials based on these approaches have so far been unsuccessful. We therefore used a combination of slice electrophysiology, in vivo two-photon calcium imaging, and optical imaging of intrinsic signal in a mouse model of NF1 to investigate whether cortical development is affected in NF1, possibly causing lifelong consequences that cannot be rescued by reducing inhibition later in life. We find that, in NF1 mice of both sexes, inhibition increases strongly during the development of the visual cortex and remains high. While this increase in cortical inhibition does not affect spontaneous cortical activity patterns during early cortical development, the critical period for ocular dominance plasticity is shortened in NF1 mice due to its early closure but unaltered onset. Notably, after environmental enrichment, differences in inhibitory innervation and ocular dominance plasticity between NF1 mice and WT littermates disappear. These results provide the first evidence for critical period dysregulation in NF1 and suggest that treatments aimed at normalizing levels of inhibition will need to start at early stages of development.SIGNIFICANCE STATEMENT Neurofibromatosis type 1 is associated with cognitive problems for which no treatment is currently available. This study shows that, in a mouse model of neurofibromatosis type 1, cortical inhibition is increased during development and critical period regulation is disturbed. Rearing the mice in an environment that stimulates cognitive function overcomes these deficits. These results uncover critical period dysregulation as a novel mechanism in the pathogenesis of neurofibromatosis type 1. This suggests that targeting the affected signaling pathways in neurofibromatosis type 1 for the treatment of cognitive disabilities may have to start at a much younger age than has so far been tested in clinical trials.

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.

Macrocephaly Is Not a Predictor of Optic Pathway Glioma Development or Treatment in Neurofibromatosis Type 1

Neurofibromatosis type 1 is a common neurogenetic disorder characterized by significant clinical variability. As such, numerous studies have focused on identifying clinical, radiographic, or molecular biomarkers that predict the occurrence or progression of specific clinical features in individuals with neurofibromatosis type 1. One of these clinical biomarkers, macrocephaly, has been proposed as a prognostic factor for optic pathway glioma development. In the current study, the authors demonstrate that macrocephaly is not associated with the development of these brain tumors or the need to institute treatment for clinical progression. These findings suggest that macrocephaly is not a robust biomarker of optic pathway glioma formation or progression in children with neurofibromatosis type 1.

Nevus anemicus: a distinctive cutaneous finding in neurofibromatosis type 1

Nevus anemicus (NA) is a cutaneous anomaly characterized by pale, well-defined patches with limited vascularization after rubbing. They are largely known to be associated with neurofibromatosis 1 (NF1) and have received little attention in the literature until recently. We sought to characterize the prevalence and clinical features of patients with NA and NF1. We conducted an observational prospective study of 99 children with NF1 at the Hospital Niño Jesús, Madrid, Spain, from January 1, 2012, through July 31, 2013, and reviewed three other series of patients with NF1 and NA recently reported. The prevalence of NA in children with NF1 ranged from 8.8% to 51%, being much more prevalent at younger ages. Prospective studies yielded a higher prevalence than retrospective studies. NA was located most commonly on the trunk, particularly on the anterior chest wall, and was often multiple. Patients with segmental NF1 or isolated café au lait spots rarely had NA, and NA was absent in other genodermatoses. The collection of data was not homogeneous in all studies. NA has a high prevalence in individuals with NF1 patients but seems to be absent in connection with other genodermatoses, therefore its presence can assist in the diagnosis of suspected cases of NF1. The subtle clinical appearance of NA makes its detection difficult, and physicians involved in the care of children with NF1 must be aware of its possible presence and significance.

Bilateral and Symmetrical Anteromedial Bowing of the Lower Limbs in a Patient with Neurofibromatosis Type-I

An 8-year-old girl was referred to our department because of generalized bowing of long bones (radii, ulnae, and femora) and significant bilateral and symmetrical posteromedial bowing of the tibiae and fibulae. The femora were laterally bowed whereas the tibiae and fibulae showed posteromedial bowing between the middle and distal thirds of the tibia with posterior cortical thickening effectively causing the development of bilateral congenital anterolateral bowing of the tibiae and fibulae. We referred to closing-wedge osteotomy of the left tibia along with fibular osteotomy in order to realign the deformity. Due to the delayed appearance of skin stigmata in her early life, the diagnosis of neurofibromatosis was ruled out. At the age of 9 years, café-au-lait spots and axillary freckling were apparent. Genetic tests confirmed von Recklinghausen disease (neurofibromatosis type-I (NF1)) (gene has been localised to 17q22). Interestingly, bilateral and symmetrical anteromedial bowing of the tibiae and fibulae has not been described in patients with NF-I.

Neurofibromatosis: chronological history and current issues

Neurofibromatosis, which was first described in 1882 by Von Recklinghausen, is a genetic disease characterized by a neuroectodermal abnormality and by clinical manifestations of systemic and progressive involvement which mainly affect the skin, nervous system, bones, eyes and possibly other organs. The disease may manifest in several ways and it can vary from individual to individual. Given the wealth of information about neurofibromatosis, we attempted to present this information in different ways. In the first part of this work, we present a chronological history, which describes the evolution of the disease since the early publications about the disorder until the conclusion of this work, focusing on relevant aspects which can be used by those wishing to investigate this disease. In the second part, we present an update on the various aspects that constitute this disease.

Pediatric neurofibromatosis 1 and parental stress: a multicenter study

BACKGROUND

Neurofibromatosis 1 (NF1) is a complex and multifaceted neurocutaneous syndrome with many and varied comorbidities. The literature about the prevalence and degree of maternal stress and the impact of NF1 in the parent-child interaction is still scant. The aim of this study was to evaluate the prevalence of maternal stress in a large pediatric sample of individuals affected by NF1.

METHODS

Thirty-seven children (19 boys, 18 girls) of mean age 7.86±2.94 (range 5-11) years affected by typical NF1 and a control group comprising 405 typically developing children (207 boys, 198 girls; mean age 8.54±2.47 years) were included in this study. To assess parental stress, the mothers of all individuals (NF1 and comparisons) filled out the Parenting Stress Index-Short Form test.

RESULTS

The two study groups were comparable for age (P=0.116), gender (P=0.886), and body mass index adjusted for age (P=0.305). Mothers of children affected by NF1 reported higher mean Parenting Stress Index-Short Form scores on the Parental Distress domain (P<0.001), Difficult Child domain (P<0.001), and Total Stress domain than the mothers of typically developing children (controls) (P<0.001). No significant differences between the two groups were found for the Parent-Child Dysfunctional Interaction domain (P=0.566) or Defensive Responding domain scores (P=0.160).

CONCLUSION

NF1 is considered a multisystemic and complex disease, with many still unrecognized features in pediatric patients and in their families. In this light, our findings about the higher levels of maternal stress highlight the importance of considering the environmental aspects of NF1 management in developmental age.

Elevated head circumference-to-height ratio is an early and frequent feature in children with neurofibromatosis type 1

BACKGROUND/AIMS

Children with neurofibromatosis type 1 (NF1) tend to be macrocephalic and short. Our aim was to define the incidence and diagnostic accuracy of elevated head circumference-to-height ratio (HCHR) in children with NF1 and to assess if elevated HCHR would facilitate early diagnosis of NF1.

METHODS

Retrospective analysis of growth and health data of 80 NF1 patients aged 0-7 years was performed. The incidence and diagnostic accuracy of elevated HCHR for NF1 was analyzed using receiver operating characteristic curves.

RESULTS

The median age when the first elevated (≥2.0 SDS) HCHR value was detected was 0.3 years (range 0.0-5.3). At the median age of diagnosis (3.6 years), 53.8% of NF1 children exhibited elevated HCHR. The diagnostic accuracy of HCHR alone was 0.78 (95% CI 0.72-0.84), but in comparison with the seven National Institutes of Health diagnostic criteria for NF1, elevated HCHR was the second most prevalent feature.

CONCLUSION

Elevated HCHR is an early and frequent feature in NF1 children. Taking HCHR into account would facilitate the early detection of NF1.

Nutraceuticals safety and efficacy in migraine without aura in a population of children affected by neurofibromatosis type I

Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant disorders with a prevalence of one in 4,000 people worldwide, associated with many neurological comorbidities, such as headache. Despite the high prevalence of headache in this population, little data exist regarding the classification of headaches experienced by patients with NF1. Aim of this study is to verify the efficacy and safety of a nutraceutical complex containing Ginkgolide B/Coenzyme Q10/Riboflavin/Magnesium for prophylaxis in a sample of children affected by NF1 presenting migraine without aura. Ginkgolide B/Coenzyme Q10/Riboflavin/Magnesium complex was orally administered twice a day for 6 months, to 18 school-aged patients with NF1 and presenting symptoms of migraine without aura (10 M, mean age 8.4 ± 1.65). Each patient kept a journal to record: number, intensity (according VAS scale), duration of attacks and concomitant symptoms. In addition, the PedMIDAS scale was administered to assess migraine-related disability. To verify the efficacy of the association, we tested the starting frequency (T0) of headache after 6 months (T1) and then we calculated the migraine frequency delta percentage to express the decrease in monthly frequency. After treatment, a reduction was reported (p < 0.001) in all migraine outcomes (frequency, duration, intensity, and grade of disability). In conclusion, the present study should be considered as the first report on the efficacy and safety of nutraceutical complex containing Ginkgolide B/Coenzyme Q10/Riboflavin/Magnesium for the prophylaxis of migraine in children affected by NF1. Our findings suggest that headache symptoms should be considered a therapeutic target independent of primary disorder.

Neurofibromatosis type 1 and infantile spasms

BACKGROUND

There is no agreement on the prevalence, natural history and outcome of infantile spasms (IS) in neurofibromatosis type 1 (NF1). By contrast, its prevalence and outcome are well characterised in the setting of other neurocutaneous disorders (e.g. tuberous sclerosis).

MATERIALS AND METHODS

The aim of the present study was to try to establish a genotype-phenotype correlation in IS in the setting of NF1. A retrospective (years 1990-2000) and prospective (years 2000-2006) study in three paediatric centres in Italy were taken as referral populations for: (1) children with NF1 and (2) neurological problems in childhood.

RESULTS

Ten NF1 patients have had IS. The calculated population-based: (1) prevalence of IS in NF1 (0.76%) was higher than the reported frequency of IS in the general population (0.02-0.05%) and (2) frequency of NF1 in the IS series in two out of three centres (0.62-0.90%) was lower than the estimated frequencies in the literature (1.5-3.0%). Patients had psychomotor delay preceding the spasms (50%), symmetrical spasms (50%), typical (80%) and modified (20%) hypsarrhythmia and foci of spikes and waves and a good response to corticosteroid treatment (50%). Outcome was good in 30%. Imaging revealed high-signal foci in atypical locations (sub-cortical and central brain regions). Deoxyribonucleic acid analysis revealed three novel NF1 gene mutations without genotype-phenotype correlation.

CONCLUSION

Even though the combination of IS and NF1 does not seem to be coincidental, it is certainly an unusual event in NF1--rarer than in other neurocutaneous disorders. Spasms in NF1 are not associated with specific genetic defects.

Impact of neurofibromatosis type 1 on school performance

School functioning of 86 Dutch neurofibromatosis type 1 children (7-17 years) using teacher questionnaires was analyzed to determine the impact of neurofibromatosis type 1 on school performance. In all, 75% of the neurofibromatosis type 1 children performed more than 1 standard deviation below grade peers in at least one of the domains of spelling, mathematics, technical reading or comprehensive reading. Furthermore, neurofibromatosis type 1 children had a 4-fold increased risk for attending special education and a 6-fold increased risk for receiving remedial teaching for learning, behavior, speech, or motor problems. Children without apparent learning disabilities still frequently displayed neuropsychological deficits. Only 10% of the children did not show any school-functioning problems. Finally, it was found that the clinical severity of neurofibromatosis type 1 correlated with the cognitive deficits. Taken together, it was shown that neurofibromatosis type 1 has profound impact on school performance. Awareness of these problems may facilitate timely recognition and appropriate support.

Role of Maxillofacial Surgery in Patients With Neurofibromatosis Type I

Neurofibromas are a clinical manifestation of neurofibromatos is type I (NF1). Management of these tumors remains a challenge for the clinician. The goal of the present study is to point out treatment guidelines for these lesions. Eighteen patients diagnosed with NF1 and presenting lesions of the craniomaxillofacial district were included in the study. On the basis of clinical evidence and patient's expectations, only six patients of this group underwent surgery. All patients that had no surgery were included in a follow-up protocol to evaluate progression of disease. Four patients who underwent surgery had good functional/aesthetic results, whereas two patients had incomplete rehabilitation.

An absence of cutaneous neurofibromas associated with a 3-bp inframe deletion in exon 17 of the NF1 gene (c.2970-2972 delAAT): evidence of a clinically significant NF1 genotype-phenotype correlation

Neurofibromatosis type 1 (NF1) is characterized by cafe-au-lait spots, skinfold freckling, and cutaneous neurofibromas. No obvious relationships between small mutations (<20 bp) of the NF1 gene and a specific phenotype have previously been demonstrated, which suggests that interaction with either unlinked modifying genes and/or the normal NF1 allele may be involved in the development of the particular clinical features associated with NF1. We identified 21 unrelated probands with NF1 (14 familial and 7 sporadic cases) who were all found to have the same c.2970-2972 delAAT (p.990delM) mutation but no cutaneous neurofibromas or clinically obvious plexiform neurofibromas. Molecular analysis identified the same 3-bp inframe deletion (c.2970-2972 delAAT) in exon 17 of the NF1 gene in all affected subjects. The Delta AAT mutation is predicted to result in the loss of one of two adjacent methionines (codon 991 or 992) ( Delta Met991), in conjunction with silent ACA-->ACG change of codon 990. These two methionine residues are located in a highly conserved region of neurofibromin and are expected, therefore, to have a functional role in the protein. Our data represent results from the first study to correlate a specific small mutation of the NF1 gene to the expression of a particular clinical phenotype. The biological mechanism that relates this specific mutation to the suppression of cutaneous neurofibroma development is unknown.

Academic Impairment is the Most Frequent Complication of Neurofibromatosis Type-1 (NF1) in Children

Neurofibromatosis type-1 (NF1) is a common genetic disorder associated with a variety of medical complications, cognitive impairments, and behavioral problems. One hundred and sixteen patients with NF1 (62 males, 54 females; mean age 12.4 years) and 80 typically developing children of the same ages (46 males, 34 females; mean age 11.5 years) were studied in terms of complications and learning impairment (one or more grade repetitions or school exclusion). Seventy of 116 patients had significant learning impairment. Classical complications were present in 53 patients including the three.

Neurocutaneous syndromes: behavioral features

Neurocutaneous syndromes are disorders characterized by a neurological abnormality and cutaneous manifestations. Three of the more common neurocutaneous syndromes are Sturge-Weber syndrome, tuberous sclerosis, and neurofibromatosis. This review focuses on the cognitive and behavioral features of these syndromes.

Prospective evaluation of the brain in asymptomatic children with neurofibromatosis type 1: relationship of macrocephaly to T1 relaxation changes and structural brain abnormalities

BACKGROUND AND PURPOSE

Mutation of the neurofibromatosis type 1 (NF-1) gene may be associated with abnormal growth control in the brain. Because macrocephaly could be a sign of abnormal brain development and because 30% to 50% of children with NF-1 display macrocephaly in the absence of hydrocephalus, we sought to determine the relationship between macrocephaly and other brain abnormalities in young subjects with NF-1. These subjects were free of brain tumor, epilepsy, or other obvious neurologic problems.

METHODS

We prospectively screened 18 neurologically asymptomatic subjects with NF-1, ages 6 to 16 years, using clinical measures, psychometric testing, conventional MR imaging, and quantitative MR imaging to measure T1.

RESULTS

Cranial circumference was 2 or more SDs above the age norm in seven (39%) of 18 subjects, a frequency of macrocephaly 17-fold higher than normal. Conventional MR imaging showed abnormalities in all 18 children, although there were more extensive abnormalities in subjects with macrocephaly. Macrocephaly in NF-1 was associated with enlargement of multiple brain structures, and brain T1 in macrocephalic subjects was reduced with respect to controls in the genu, frontal white matter, caudate, putamen, thalamus, and cortex. In normocephalic subjects, T1 was reduced only in the genu and splenium. Volumetric analysis showed that macrocephaly was associated specifically with enlargement of white matter volume.

CONCLUSION

Neurologically asymptomatic children with NF-1 showed macrocephaly, cognitive deficit, enlarged brain structures, and abnormally low brain T1. Macrocephaly in children with NF-1 may be associated with characteristic alterations in brain development, marked by more widespread and significant changes in T1, greater enlargement of midline structures, and greater volume of white matter.

Behavioral phenotype of neurofibromatosis, type 1

Neurofibromatosis, type 1 (NF1) is a very common inherited disorder that was first described in the late 19th century. NF1 is associated with a myriad of behavioral manifestations in addition to its frequent and often severe medical and physical complications. Learning disability, cognitive impairment, emotional and psychosocial difficulties have been reported so frequently in neurofibromatosis that these are often considered hallmarks. This report briefly introduces the medical and physical characteristics of NF1. We then detail the behavioral manifestations of NF1 with additional discussion of possible etiologies for the high incidence of these behavioral difficulties. MRDD Research Reviews 2000;6:117-124.

Use of the national institutes of health criteria for diagnosis of neurofibromatosis 1 in children

OBJECTIVE

The National Institutes of Health (NIH) Diagnostic Criteria for neurofibromatosis 1 (NF1) are very useful clinically, but some individuals who are later shown to have NF1 cannot be diagnosed in early childhood using these criteria. The aim of this study is to determine the value of the NIH Diagnostic Criteria for NF1 in early childhood, to determine the age at which diagnosis can confidently be made, and to clarify the age at onset of the cardinal clinical features used in the NIH Diagnostic Criteria.

METHODS

We studied 1893 NF1 patients under 21 years old from the National Neurofibromatosis Foundation International Database to determine the age at which the features included in the NIH Diagnostic Criteria appear.

RESULTS

Approximately 46% of sporadic NF1 cases fail to meet the NIH Diagnostic Criteria by 1 year of age. Nearly all (97%; 95% confidence interval: 94-98) NF1 patients meet the criteria for diagnosis by 8 years old, and all do so by 20 years old. The usual order of appearance of the clinical features listed as NIH criteria is café-au-lait macules, axillary freckling, Lisch nodules, and neurofibromas. Symptomatic optic glioma is usually diagnosed by 3 years old, and characteristic osseous lesions are usually apparent within the first year of life.

CONCLUSION

The diagnosis of NF1 cannot always be made in young children using the NIH Diagnostic Criteria. Modification of these criteria may be necessary for children under 8 years old.