Consensus-Based Best Practice Guidelines for the Management of Spinal Deformity and Associated Tumors in Pediatric Neurofibromatosis Type 1: Screening and Surveillance, Surgical Intervention, and Medical Therapy.

BACKGROUND: Spinal conditions, such as scoliosis and spinal tumors, are prevalent in neurofibromatosis type 1 (NF1). Despite the recognized importance of their early detection and treatment, there remain knowledge gaps in how to approach these manifestations. The purpose of this study was to utilize the experience of a multidisciplinary committee of experts to establish consensus-based best practice guidelines (BPGs) for spinal screening and surveillance, surgical intervention, and medical therapy in pediatric patients with NF1. METHODS: Using the results of a prior systematic review, 10 key questions that required further assessment were first identified. A committee of 20 experts across medical specialties was then chosen based on their clinical experience with spinal deformity and tumors in NF1. These were 9 orthopaedic surgeons, 4 neuro-oncologists/oncologists, 3 neurosurgeons, 2 neurologists, 1 pulmonologist, and 1 clinical geneticist. An initial online survey on current practices and opinions was conducted, followed by 2 additional surveys via a formal consensus-based modified Delphi method. The final survey involved voting on agreement or disagreement with 35 recommendations. Items reaching consensus (≥70% agreement or disagreement) were included in the final BPGs. RESULTS: Consensus was reached for 30 total recommendations on the management of spinal deformity and tumors in NF1. These were 11 recommendations on screening and surveillance, 16 on surgical intervention, and 3 on medical therapy. Five recommendations did not achieve consensus and were excluded from the BPGs. CONCLUSION: We present a set of consensus-based BPGs comprised of 30 recommendations for spinal screening and surveillance, surgical intervention, and medical therapy in pediatric NF1.

Updated diagnostic criteria and nomenclature for neurofibromatosis type 2 and schwannomatosis: An international consensus recommendation.

PURPOSE: Neurofibromatosis type 2 (NF2) and schwannomatosis (SWN) are genetically distinct tumor predisposition syndromes with overlapping phenotypes. We sought to update the diagnostic criteria for NF2 and SWN by incorporating recent advances in genetics, ophthalmology, neuropathology, and neuroimaging. METHODS: We used a multistep process, beginning with a Delphi method involving global disease experts and subsequently involving non-neurofibromatosis clinical experts, patients, and foundations/patient advocacy groups. RESULTS: We reached consensus on the minimal clinical and genetic criteria for diagnosing NF2 and SWN. These criteria incorporate mosaic forms of these conditions. In addition, we recommend updated nomenclature for these disorders to emphasize their phenotypic overlap and to minimize misdiagnosis with neurofibromatosis type 1. CONCLUSION: The updated criteria for NF2 and SWN incorporate clinical features and genetic testing, with a focus on using molecular data to differentiate the 2 conditions. It is likely that continued refinement of these new criteria will be necessary as investigators study the diagnostic properties of the revised criteria and identify new genes associated with SWN. In the revised nomenclature, the term "neurofibromatosis 2" has been retired to improve diagnostic specificity.

Caregivers of individuals with Rubinstein-Taybi syndrome: Perspectives, experiences, and relationships with medical professionals.

Rubinstein-Taybi syndrome (RTS) is a rare genetic disorder. Family-centered care (FCC) is a healthcare delivery approach that aims to create an equal partnership between caregivers and providers. FCC has been shown to improve parental wellbeing, their knowledge of the condition and care, and improve their feelings of self-efficacy and personal control. The purpose of this study was to explore the healthcare experiences of family caregivers of children and adults with RTS to understand the issues they encounter when working with medical professionals and to examine their perspectives on how to improve FCC. Primary family caregivers of individuals with RTS took an online mixed-method survey that contained three primary components: a demographic survey, the Measures of Processes of Care-20 (MPOC-20) [a measure of the FCC an individual feels they receive], and a qualitative assessment of negative and positive interactions with medical professionals and priority areas for improvement. Qualitative data were analyzed using thematic analysis. Quantitative data were analyzed with descriptive statistics. An analysis of variance test was used to determine whether values statistically differed between different-age groups of individuals with RTS being cared for. Sixty-three caregivers completed the survey. The average score of the Providing General Information subscale of the MPOC-20 was 3.18, lower than that seen in other studies. The average scores of the other subscales of the MPOC-20 ranged from 4.60 to 5.02, comparable to other studies of caregivers of children with other medical conditions. All aspects of FCC were ranked as important by caregivers. There were no differences in MPOC-20 values between those caring for the individuals with RTS in different-age groups reviewed. In the qualitative responses, parents noted that experiences with medical professionals would be improved if healthcare providers actively provided FCC, collaborated with parents and other providers, respected caregivers' time and breadth of knowledge and lived experience, gave a more balanced description of the condition, showed greater respect toward their loved ones and included them in the conversation, and made an effort to learn about RTS. The changes that parents would like to see in their child's care were not specific to one discipline and could be implemented by all healthcare specialists. While caregivers report that they receive moderate levels of FCC, they indicated that areas of FCC could be improved.

Revised diagnostic criteria for neurofibromatosis type 1 and Legius syndrome: an international consensus recommendation.

PURPOSE: By incorporating major developments in genetics, ophthalmology, dermatology, and neuroimaging, to revise the diagnostic criteria for neurofibromatosis type 1 (NF1) and to establish diagnostic criteria for Legius syndrome (LGSS). METHODS: We used a multistep process, beginning with a Delphi method involving global experts and subsequently involving non-NF experts, patients, and foundations/patient advocacy groups. RESULTS: We reached consensus on the minimal clinical and genetic criteria for diagnosing and differentiating NF1 and LGSS, which have phenotypic overlap in young patients with pigmentary findings. Criteria for the mosaic forms of these conditions are also recommended. CONCLUSION: The revised criteria for NF1 incorporate new clinical features and genetic testing, whereas the criteria for LGSS were created to differentiate the two conditions. It is likely that continued refinement of these new criteria will be necessary as investigators (1) study the diagnostic properties of the revised criteria, (2) reconsider criteria not included in this process, and (3) identify new clinical and other features of these conditions. For this reason, we propose an initiative to update periodically the diagnostic criteria for NF1 and LGSS.

Are Some Randomized Clinical Trials Impossible?

Congenital tibial pseudarthrosis is a rare condition seen in neurofibromatosis type 1 (NF1), and treatment is complex. A randomized, placebo-controlled trial of bone morphogenetic protein (rhBMP-2; INFUSE bone graft) at time of tibial surgery was developed by the Neurofibromatosis Clinical Trials Consortium. Patients were randomized to receive rhBMP-2 that would, or would not, be added to the standard surgical procedure consisting of resection of pseudarthrosis tissue, insertion of a rigid intramedullary rod, and placement of autogenous iliac crest bone graft. Despite involvement of 16 centers with wide experience with NF1 orthopaedic management, only 5 patients (of 54 required) were able to be enrolled in the study during a 3-year time period. Because of the inability to recruit sufficient patients, this study was closed in June 2019, with plans to terminate. The obstacles that were encountered during the study are summarized. The authors question whether a randomized, placebo-controlled trial of a rare pediatric orthopaedic condition is possible to accomplish. Recommendations are provided to guide future studies of orthopaedic manifestations of NF1.Level of Evidence: Level V.

Neurofibromatosis Type 2 (NF2) and the Implications for Vestibular Schwannoma and Meningioma Pathogenesis.

Patients diagnosed with neurofibromatosis type 2 (NF2) are extremely likely to develop meningiomas, in addition to vestibular schwannomas. Meningiomas are a common primary brain tumor; many NF2 patients suffer from multiple meningiomas. In NF2, patients have mutations in the NF2 gene, specifically with loss of function in a tumor-suppressor protein that has a number of synonymous names, including: Merlin, Neurofibromin 2, and schwannomin. Merlin is a 70 kDa protein that has 10 different isoforms. The Hippo Tumor Suppressor pathway is regulated upstream by Merlin. This pathway is critical in regulating cell proliferation and apoptosis, characteristics that are important for tumor progression. Mutations of the NF2 gene are strongly associated with NF2 diagnosis, leading to benign proliferative conditions such as vestibular schwannomas and meningiomas. Unfortunately, even though these tumors are benign, they are associated with significant morbidity and the potential for early mortality. In this review, we aim to encompass meningiomas and vestibular schwannomas as they pertain to NF2 by assessing molecular genetics, common tumor types, and tumor pathogenesis.

The Use of MEK Inhibitors in Neurofibromatosis Type 1-Associated Tumors and Management of Toxicities.

Early-phase clinical trials using oral inhibitors of MEK, the mitogen-activated protein kinase kinase, have demonstrated benefit for patients with neurofibromatosis type 1 (NF1)-associated tumors, particularly progressive low-grade gliomas and plexiform neurofibromas. Given this potential of MEK inhibition as an effective medical therapy, the use of targeted agents in the NF1 population is likely to increase substantially. For clinicians with limited experience prescribing MEK inhibitors, concern about managing these treatments may be a barrier to use. In this manuscript, the Clinical Care Advisory Board of the Children's Tumor Foundation reviews the published experience with MEK inhibitors in NF1 and outlines recommendations for side-effect management, as well as monitoring guidelines. These recommendations can serve as a beginning framework for NF providers seeking to provide the most effective treatments for their patients. IMPLICATIONS FOR PRACTICE: Neurofibromatosis type 1 (NF1) clinical care is on the cusp of a transformative shift. With the success of recent clinical trials using MEK inhibitors, an increasing number of NF1 patients are being treated with MEK inhibitors for both plexiform neurofibromas and low-grade gliomas. The use of MEK inhibitors is likely to increase substantially in NF1. Given these changes, the Clinical Care Advisory Board of the Children's Tumor Foundation has identified a need within the NF1 clinical community for guidance for the safe and effective use of MEK inhibitors for NF1-related tumors. This article provides a review of the published experience of MEK inhibitors in NF1 and provides recommendations for monitoring and management of side effects.

Examination of the genetic factors underlying the cognitive variability associated with neurofibromatosis type 1.

PURPOSE: Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder associated with cognitive deficits. The NF1 cognitive phenotype is generally considered to be highly variable, possibly due to the observed T2-weighted hyperintensities, loss of heterozygosity, NF1-specific genetic modifiers, or allelic imbalance. METHODS: We investigated cognitive variability and assessed the contribution of genetic factors by performing a retrospective cohort study and a monozygotic twin case series. We included data of 497 children with genetically confirmed NF1 and an IQ assessment, including 12 monozygotic twin and 17 sibling sets. RESULTS: Individuals carrying an NF1 chromosomal microdeletion showed significant lower full-scale IQ (FSIQ) scores than individuals carrying intragenic pathogenic NF1 variants. For the intragenic subgroup, the variability in cognitive ability and the correlation of IQ between monozygotic NF1 twin pairs or between NF1 siblings is similar to the general population. CONCLUSIONS: The variance and heritability of IQ in individuals with NF1 are similar to that of the general population, and hence mostly driven by genetic background differences. The only factor that significantly attenuates IQ in NF1 individuals is the NF1 chromosomal microdeletion genotype. Implications for clinical management are that individuals with intragenic NF1 variants that score <1.5-2 SD below the mean of the NF1 population should be screened for additional causes of cognitive disability.

Copb2 is essential for embryogenesis and hypomorphic mutations cause human microcephaly.

Primary microcephaly is a congenital brain malformation characterized by a head circumference less than three standard deviations below the mean for age and sex and results in moderate to severe mental deficiencies and decreased lifespan. We recently studied two children with primary microcephaly in an otherwise unaffected family. Exome sequencing identified an autosomal recessive mutation leading to an amino acid substitution in a WD40 domain of the highly conserved Coatomer Protein Complex, Subunit Beta 2 (COPB2). To study the role of Copb2 in neural development, we utilized genome-editing technology to generate an allelic series in the mouse. Two independent null alleles revealed that Copb2 is essential for early stages of embryogenesis. Mice homozygous for the patient variant (Copb2R254C/R254C) appear to have a grossly normal phenotype, likely due to differences in corticogenesis between the two species. Strikingly, mice heterozygous for the patient mutation and a null allele (Copb2R254C/Zfn) show a severe perinatal phenotype including low neonatal weight, significantly increased apoptosis in the brain, and death within the first week of life. Immunostaining of the Copb2R254C/Zfnbrain revealed a reduction in layer V (CTIP2+) neurons, while the overall cell density of the cortex is unchanged. Moreover, neurospheres derived from animals with Copb2 variants grew less than control. These results identify a general requirement for COPB2 in embryogenesis and a specific role in corticogenesis. We further demonstrate the utility of CRISPR-Cas9 generated mouse models in the study of potential pathogenicity of variants of potential clinical interest.

Activity of Selumetinib in Neurofibromatosis Type 1-Related Plexiform Neurofibromas.

BACKGROUND: Effective medical therapies are lacking for the treatment of neurofibromatosis type 1-related plexiform neurofibromas, which are characterized by elevated RAS-mitogen-activated protein kinase (MAPK) signaling. METHODS: We conducted a phase 1 trial of selumetinib (AZD6244 or ARRY-142886), an oral selective inhibitor of MAPK kinase (MEK) 1 and 2, in children who had neurofibromatosis type 1 and inoperable plexiform neurofibromas to determine the maximum tolerated dose and to evaluate plasma pharmacokinetics. Selumetinib was administered twice daily at a dose of 20 to 30 mg per square meter of body-surface area on a continuous dosing schedule (in 28-day cycles). We also tested selumetinib using a mouse model of neurofibromatosis type 1-related neurofibroma. Response to treatment (i.e., an increase or decrease from baseline in the volume of plexiform neurofibromas) was monitored by using volumetric magnetic resonance imaging analysis to measure the change in size of the plexiform neurofibroma. RESULTS: A total of 24 children (median age, 10.9 years; range, 3.0 to 18.5) with a median tumor volume of 1205 ml (range, 29 to 8744) received selumetinib. Patients were able to receive selumetinib on a long-term basis; the median number of cycles was 30 (range, 6 to 56). The maximum tolerated dose was 25 mg per square meter (approximately 60% of the recommended adult dose). The most common toxic effects associated with selumetinib included acneiform rash, gastrointestinal effects, and asymptomatic creatine kinase elevation. The results of pharmacokinetic evaluations of selumetinib among the children in this trial were similar to those published for adults. Treatment with selumetinib resulted in confirmed partial responses (tumor volume decreases from baseline of ≥20%) in 17 of the 24 children (71%) and decreases from baseline in neurofibroma volume in 12 of 18 mice (67%). Disease progression (tumor volume increase from baseline of ≥20%) has not been observed to date. Anecdotal evidence of decreases in tumor-related pain, disfigurement, and functional impairment was observed. CONCLUSIONS: Our early-phase data suggested that children with neurofibromatosis type 1 and inoperable plexiform neurofibromas benefited from long-term dose-adjusted treatment with selumetinib without having excess toxic effects. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT01362803 .).

Substantial pain burden in frequency, intensity, interference and chronicity among children and adults with neurofibromatosis Type 1.

Tumor growths, migraine headaches, and other health-related complications reported in patients with neurofibromatosis type 1 (NF1) are often associated with pain. Thus, this study sought to describe and quantify the pain experience in children and young adults with NF1. Surveys were administered to 49 participants (28 children and 21 adults), ages 8 through 40 years. The survey included the Numeric Rating Scale 11 (NRS11) to assess pain intensity and the Patient Reported Outcomes Measurement Information System (PROMIS) to assess pain interference. A supplemental survey was created to measure pain frequency, chronicity, quality, and location. Results suggest pain is not only present in 55% of the cohort, but that it can begin at early ages. Pain was chronic in 35% of participants, with 41% reporting the use of medication to manage pain symptoms. Common sources of pain included migraine headaches and NF-related tumors. Pain was described as having neuropathic features (i.e., burning, tingling, numbness, or itching), and was localized to the head, back, and extremities. Further, subsets of participants reported moderate-to-severe pain intensity, high frequency of pain, and interference of pain in daily activities. Continued investigation of the pain experience in a multisystem disorder, such as NF1, remains essential to providing guidance in the setting of complex pain management.

Mutations in PIEZO2 cause Gordon syndrome, Marden-Walker syndrome, and distal arthrogryposis type 5.

Gordon syndrome (GS), or distal arthrogryposis type 3, is a rare, autosomal-dominant disorder characterized by cleft palate and congenital contractures of the hands and feet. Exome sequencing of five GS-affected families identified mutations in piezo-type mechanosensitive ion channel component 2 (PIEZO2) in each family. Sanger sequencing revealed PIEZO2 mutations in five of seven additional families studied (for a total of 10/12 [83%] individuals), and nine families had an identical c.8057G>A (p.Arg2686His) mutation. The phenotype of GS overlaps with distal arthrogryposis type 5 (DA5) and Marden-Walker syndrome (MWS). Using molecular inversion probes for targeted sequencing to screen PIEZO2, we found mutations in 24/29 (82%) DA5-affected families and one of two MWS-affected families. The presence of cleft palate was significantly associated with c.8057G>A (Fisher's exact test, adjusted p value < 0.0001). Collectively, although GS, DA5, and MWS have traditionally been considered separate disorders, our findings indicate that they are etiologically related and perhaps represent variable expressivity of the same condition.

Analysis of copy number variants in 11 pairs of monozygotic twins with neurofibromatosis type 1.

Phenotypic variability among individuals with neurofibromatosis type 1 (NF1) has long been a challenge for clinicians and an enigma for researchers. Members of the same family and even identical twins with NF1 often demonstrate variable disease expression. Many mechanisms for this variability have been proposed. We have performed an exploratory study of copy number variants (CNVs) as a possible source of phenotypic variability in NF1. We enrolled 11 pairs of monozygotic (MZ) twins with NF1 and their parents, catalogued their clinical characteristics, and utilized a single nucleotide polymorphism (SNP) microarray to identify CNVs in blood and saliva. The 11 twin pairs showed high concordance for presence and number of café-au-lait spots, cutaneous neurofibromas, IQ, and ADHD. They were more likely to be discordant for optic pathway glioma, plexiform neurofibromas, skeletal manifestations, and malignancy. Microarray analysis identified a total of 81 CNVs meeting our conservative criteria, 37 of which overlap known genes. Of interest, three CNVs were previously unreported. Microarray analysis failed to ascertain any CNV differences within twin pairs, between twins and parents, or between tissues in any one individual. Results of this small pilot study did not demonstrate any de novo CNV events in our MZ twin pairs, nor were de novo CNVs overrepresented in these individuals with NF1. A much larger sample size would be needed to form any conclusions about the role of CNVs in NF1 variable expressivity. Alternative explanations for discordant phenotypes include epigenetic changes, smaller genetic alterations, or environmental factors. © 2016 Wiley Periodicals, Inc.

The Use of Magnetic Resonance Imaging Screening for Optic Pathway Gliomas in Children with Neurofibromatosis Type 1.

OBJECTIVE: To evaluate the utility of screening brain/orbital magnetic resonance imaging (MRI) in a large population of children with neurofibromatosis type 1 (NF1) over a 20-year period. STUDY DESIGN: A retrospective analysis of clinical and imaging data from children with NF1 seen at a single center between 1990 and 2010 was performed. RESULTS: During the 20-year study period, 826 individuals with NF1 (402 females, 424 males) ages 1-9 years were screened for optic pathway gliomas (OPGs) using brain/orbital MRI; 18% were identified with OPGs with a median age at detection of 3 years. Fifteen percent of patients with OPGs had radiologic or clinical progression requiring therapy. Children with chiasmatic and postchiasmatic tumors were more likely to require therapy compared with patients with prechiasmatic OPGs (P < .0001). Patients with visual deficits at the time of diagnosis were more likely to experience visual decline despite therapy when compared with patients treated based on radiologic progression (P < .012). CONCLUSIONS: Our findings confirm that chiasmatic and postchiasmatic OPG in children with NF1 have the highest risk for progression and vision loss. Early identification of OPG by screening MRI prior to the development of vision loss may lead to improved visual outcomes. Children with negative brain and orbital MRI screening at age 15 months or later did not develop symptomatic OPGs.

A novel dominant COL11A1 mutation resulting in a severe skeletal dysplasia.

Mutations in the type XI collagen alpha-1 chain gene (COL11A1) cause a change in protein structure that alters its interactions with collagens II and V, resulting in abnormalities in cartilage and ocular vitreous. The most common type XI collagenopathies are dominantly inherited Stickler or Marshall syndromes, while severe recessive skeletal dysplasias, such as fibrochondrogenesis, occur less frequently. We describe a family with a severe skeletal dysplasia caused by a novel dominantly inherited COL11A1 mutation. The siblings each presented with severe myopia, hearing loss, micromelia, metaphyseal widening of the long bones, micrognathia, and airway compromise requiring tracheostomy. The first child lived for over 2 years, while the second succumbed at 5 months of age. Their mother has mild rhizomelic shortening of the limbs, brachydactyly, and severe myopia. Sequencing of COL11A1 revealed a novel deleterious heterozygous mutation in COL11A1 involving the triple helical domain in both siblings, and a mosaic mutation in their mother, indicating germline mosaicism with subsequent dominant inheritance. These are the first reported individuals with a dominantly inherited mutation in COL11A1 associated with a severe skeletal dysplasia. The skeletal involvement is similar to, yet milder than fibrochondrogenesis and allowed for survival beyond the perinatal period. These cases highlight both a novel dominant COL11A1 mutation causing a significant skeletal dysplasia and the phenotypic heterogeneity of collagenopathies.

CTF meeting 2012: Translation of the basic understanding of the biology and genetics of NF1, NF2, and schwannomatosis toward the development of effective therapies.

The neurofibromatoses (NF) are autosomal dominant genetic disorders that encompass the rare diseases NF1, NF2, and schwannomatosis. The NFs affect more people worldwide than Duchenne muscular dystrophy and Huntington's disease combined. NF1 and NF2 are caused by mutations of known tumor suppressor genes (NF1 and NF2, respectively). For schwannomatosis, although mutations in SMARCB1 were identified in a subpopulation of schwannomatosis patients, additional causative gene mutations are still to be discovered. Individuals with NF1 may demonstrate manifestations in multiple organ systems, including tumors of the nervous system, learning disabilities, and physical disfigurement. NF2 ultimately can cause deafness, cranial nerve deficits, and additional severe morbidities caused by tumors of the nervous system. Unmanageable pain is a key finding in patients with schwannomatosis. Although today there is no marketed treatment for NF-related tumors, a significant number of clinical trials have become available. In addition, significant preclinical efforts have led to a more rational selection of potential drug candidates for NF trials. An important element in fueling this progress is the sharing of knowledge. For over 20 years the Children's Tumor Foundation has convened an annual NF Conference, bringing together NF professionals to share novel findings, ideas, and build collaborations. The 2012 NF Conference held in New Orleans hosted over 350 NF researchers and clinicians. This article provides a synthesis of the highlights presented at the conference and as such, is a "state-of-the-field" for NF research in 2012.

Sirolimus for non-progressive NF1-associated plexiform neurofibromas: an NF clinical trials consortium phase II study.

BACKGROUND: Patients with Neurofibromatosis Type 1 (NF1) have an increased risk of developing tumors of the central and peripheral nervous system, including plexiform neurofibromas (PN), which are benign nerve sheath tumors that are among the most debilitating complications of NF1. There are no standard treatment options for PN other than surgery, which is often difficult due to the extensive growth and invasion of surrounding tissues. Mammalian Target of Rapamycin (mTOR) acts as a master switch of cellular catabolism and anabolism and controls protein translation, angiogenesis, cell motility, and proliferation. The NF1 tumor suppressor, neurofibromin, regulates the mTOR pathway activity. Sirolimus is a macrolide antibiotic that inhibits mTOR activity. PROCEDURE: We conducted a 2-stratum phase II clinical trial. In stratum 2, we sought to determine whether the mTOR inhibitor sirolimus in subjects with NF1 results in objective radiographic responses in inoperable PNs in the absence of documented radiographic progression at trial entry. RESULTS: No subjects had better than stable disease by the end of six courses. However, the children's self-report responses on health-related quality of life questionnaires indicated a significant improvement in the mean scores of the Emotional and School domains from baseline to 6 months of sirolimus. CONCLUSIONS: This study efficiently documented that sirolimus does not cause shrinkage of non-progressive PNs, and thus should not be considered as a treatment option for these tumors. This study also supports the inclusion of patient-reported outcome measures in clinical trials to assess areas of benefit that are not addressed by the medical outcomes.

Fractures in children with neurofibromatosis type 1 from two NF clinics.

Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder with osseous abnormalities occurring in up to one-third of patients. Several studies have documented osteopenia in both children and adults with NF1; however, the significance of lower bone mineral density (BMD) in relationship to fracture incidence is not well elucidated in NF1, particularly in children. We undertook a retrospective study to determine prevalence and location of fractures in children and adolescents with NF1, ages 5-20 years, using a standardized questionnaire. We surveyed 256 individuals with NF1 from two multidisciplinary NF centers and 178 controls without NF1 of similar ages and sex. Participants with known long bone dysplasia (LBD) were analyzed separately. Data collected included numbers and location of fractures, dietary calcium intake, and physical activity levels. There was no difference in prevalence of ever having a fracture between the NF1 group without LBD (22%) and the control group (25%); median number of fractures also did not differ. There were significant differences in fracture location with a higher frequency of fractures of the lower extremities in NF1 individuals without LBD compared to controls. Both NF1 cohorts had lower rates of physical activity than controls (P < 0.0001). Our data demonstrate that the likelihood of having had a fracture is not higher in young NF1 individuals without LBD in comparison to healthy controls. The lower physical activity level may have a "protective effect" for those with NF1, thus keeping their fracture incidence lower than expected for their relative degree of osteopenia.

Approaches to treating NF1 tibial pseudarthrosis: consensus from the Children's Tumor Foundation NF1 Bone Abnormalities Consortium.

BACKGROUND: Neurofibromatosis 1 (NF1) is an autosomal dominant disorder with various skeletal abnormalities occurring as part of a complex phenotype. Tibial dysplasia, which typically presents as anterolateral bowing of the leg with subsequent fracture and nonunion (pseudarthrosis), is a serious but infrequent osseous manifestation of NF1. Over the past several years, results from clinical and experimental studies have advanced our knowledge of the role of NF1 in bone. On the basis of current knowledge, we propose a number of concepts to consider as a theoretical approach to the optimal management of tibial pseudarthrosis. METHODS: A literature review for both clinical treatment and preclinical models for tibial dysplasia in NF1 was performed. Concepts were discussed and developed by experts who participated in the Children's Tumor Foundation sponsored International Bone Abnormalities Consortium meeting in 2011. RESULTS: Concepts for a theoretical approach to treating tibial pseudarthrosis include: bone fixation appropriate to achieve stability in any given case; debridement of the "fibrous pseudarthrosis tissue" between the bone segments associated with the pseudarthrosis; creating a healthy vascular bed for bone repair; promoting osteogenesis; controlling overactive bone resorption (catabolism); prevention of recurrence of the "fibrous pseudarthrosis tissue"; and achievement of long-term bone health to prevent recurrence. CONCLUSIONS: Clinical trials are needed to assess effectiveness of the wide variation of surgical and pharmacologic approaches currently in practice for the treatment of tibial pseudarthrosis in NF1. LEVEL OF EVIDENCE: Level V, expert opinion.

Motor Function and Physiology in Youth With Neurofibromatosis Type 1.

BACKGROUND: Neurofibromatosis type 1 (NF1) is a genetic neurocutaneous disorder commonly associated with motor and cognitive symptoms that greatly impact quality of life. Transcranial magnetic stimulation (TMS) can quantify motor cortex physiology, reflecting the basis for impaired motor function as well as, possibly, clues for mechanisms of effective treatment. We hypothesized that children with NF1 have impaired motor function and altered motor cortex physiology compared to typically developing (TD) control children and children with attention-deficit/hyperactivity disorder (ADHD). METHODS: Children aged 8-17 years with NF1 (n = 21) were compared to children aged 8-12 years with ADHD (n = 59) and TD controls (n = 88). Motor development was assessed using the Physical and Neurological Examination for Subtle Signs (PANESS) scale. The balance of inhibition and excitation in motor cortex was assessed using the TMS measures short-interval cortical inhibition (SICI) and intracortical facilitation (ICF). Measures were compared by diagnosis and tested using bivariate correlations and regression for association with clinical characteristics. RESULTS: In NF1, ADHD severity scores were intermediate between the ADHD and TD cohorts, but total PANESS scores were markedly elevated (worse) compared to both (P < 0.001). Motor cortex ICF (excitatory) was significantly lower in NF1 than in TD and ADHD (P < 0.001), but SICI (inhibitory) did not differ. However, in NF1, better PANESS scores correlated with lower SICI ratios (more inhibition; ρ = 0.62, P = 0.003) and lower ICF ratios (less excitation; ρ = 0.38, P = 0.06). CONCLUSIONS: TMS-evoked SICI and ICF may reflect processes underlying abnormal motor function in children with NF1.