scholarly journals Current Aspects on the Pathophysiology of Bone Metabolic Defects during Progression of Scoliosis in Neurofibromatosis Type 1

2022 ◽  
Vol 11 (2) ◽  
pp. 444
Author(s):  
Angelos Kaspiris ◽  
Olga D. Savvidou ◽  
Elias S. Vasiliadis ◽  
Argyris C. Hadjimichael ◽  
Dimitra Melissaridou ◽  
...  

Neurofibromatosis type 1 (NF1), which is the most common phacomatoses, is an autosomal dominant disorder characterized by clinical presentations in various tissues and organs, such as the skin, eyes and nervous and skeletal systems. The musculoskeletal implications of NF1 include a variety of deformities, including scoliosis, kyphoscoliosis, spondylolistheses, congenital bony bowing, pseudarthrosis and bone dysplasia. Scoliosis is the most common skeletal problem, affecting 10–30% of NF1 patients. Although the pathophysiology of spinal deformities has not been elucidated yet, defects in bone metabolism have been implicated in the progression of scoliotic curves. Measurements of Bone Mineral Density (BMD) in the lumbar spine by using dual energy absorptiometry (DXA) and quantitative computer tomography (QCT) have demonstrated a marked reduction in Z-score and osteoporosis. Additionally, serum bone metabolic markers, such as vitamin D, calcium, phosphorus, osteocalcin and alkaline phosphatase, have been found to be abnormal. Intraoperative and histological vertebral analysis confirmed that alterations of the trabecular microarchitecture are associated with inadequate bone turnover, indicating generalized bone metabolic defects. At the molecular level, loss of function of neurofibromin dysregulates Ras and Transforming Growth factor-β1 (TGF-β1) signaling and leads to altered osteoclastic proliferation, osteoblastic activity and collagen production. Correlation between clinical characteristics and molecular pathways may provide targets for novel therapeutic approaches in NF1.

Author(s):  
O Tezol ◽  
Y Balcı ◽  
M Alakaya ◽  
B Gundogan ◽  
EC Cıtak

Introduction: Neurofibromatosis type 1 (NF 1) is an autosomal dominant neurocutaneous disease characterised by multisystemic involvement, including bone tissue. Deformities and reduced bone mass are the main bone manifestations in NF1. Quantitative computed tomography (QCT) provides true volumetric bone mineral density (BMD) measurement. This study aimed to evaluate bone metabolism parameters and BMD in children with NF1 using QCT. Methods: The data of 52 paediatric NF1 patients (23 female, 29 male) was evaluated retrospectively. We investigated anthropometric measurements, biochemical parameters like total calcium, phosphate, magnesium, alkaline phosphatase, 25-hydroxyvitamin D (25OHD), parathyroid hormone, calcitonin, urinary calcium/creatinine ratio, and QCT parameters like lumbar trabecular and cortical BMD, trabecular area and cortical thickness. Comparisons of gender and puberty status were performed. Results: 25% of patients had skeletal deformities and 42.3% had 25OHD inadequacy (< 20 ng/mL). The frequency of 25OHD inadequacy was significantly higher in pubertal/postpubertal patients than prepubertal patients (61.9% vs. 29.0%, p = 0.019). Trabecular BMD Z-score was < −2.0 in 11.5% of patients; all with low BMD were at the pubertal/postpubertal stage. There was a significant negative correlation between age and trabecular Z-score (r = −0.41, p = 0.003). Mean cortical BMD was statistically similar between the genders and puberty groups. Puberty status, anthropometric Z-scores, and biochemical and QCT parameters were statistically similar between the genders (p > 0.05). Conclusion: Paediatric NF1 patients may present with low BMD and 25OHD inadequacy, especially at puberty. QCT may be a useful tool to evaluate trabecular and cortical bone separately in NF1 patients.


2020 ◽  
Vol 13 (1) ◽  
pp. e227379
Author(s):  
Gustavo Ferrer ◽  
Alwiya Omar Saleh ◽  
Henry D Tazelaar ◽  
Andrea V Arrossi

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder with multiple systemic manifestations. Pulmonary involvement has been reported in the form of interstitial fibrosis, emphysema, pulmonary hypertension and thoracic neoplasm. We report a case of desquamative interstitial pneumonia in a non-smoker with NF1.


2016 ◽  
Vol 62 (1) ◽  
pp. 155-158
Author(s):  
Raluca-Monica Pop ◽  
Radu Mircea Neagoe ◽  
Melinda Kolcsar ◽  
Ionela Paşcanu

AbstractBackground: Neurofibromatosis type 1 is an autosomal dominant disorder associated with multiple neoplasms particularly those of ectodermal origin. Various endocrine pathologies are often present, among them, hyperparathyroidism and follicular thyroid lesion are very rare described and their coincidence in the same patient has not been described in the literature reviewed.Subject: A 59-years-old woman with clinical manifestation of neurofibromatosis type 1 developed dysphagia, dysphonia, choking sensation. Physical and imagistic examination revealed a multinodular goiter with microfollicular lesion on fine needle aspiration biopsy (FNAB), elevated parathormone levels and severe osteoporosis. The surgically removed thyroid contained a nodule with follicular architecture of uncertain malignant potential; the parathyroid tissue appeared normal.Discussion and conclusion: This case serves as a reminder to look for non-neurogenic tumors in patients with neurofibromatosis. Clinicians must be aware of the diverse clinical features of this genetic disorder.


2017 ◽  
Vol 21 (5) ◽  
pp. 379-382 ◽  
Author(s):  
Irene Lara-Corrales ◽  
Mitra Moazzami ◽  
Maria Teresa García-Romero ◽  
Elena Pope ◽  
Patricia Parkin ◽  
...  

Background: Neurofibromatosis type 1 (NF1) is a neurocutaneous disorder caused by loss-of-function mutation in the NF1 gene. Segmental or mosaic NF1 (MNF) is an uncommon presentation of the NF1 result of postzygotic mutations that present with subtle localised clinical findings. Objectives: Our study’s objectives were to describe the clinical characteristics of children with MNF. Methods: We conducted a cross-sectional study of children diagnosed with MNF at the Hospital for Sick Children in Toronto, Canada, from January 1992 to September 2012. Data were abstracted from health records and analysed using a standardised data collection form approved by our hospital Research Ethics Board. Results: We identified 60 patients with MNF; 32 of 60 (53.3%) were female. Mean ± SD age at first assessment was 10.6 ± 4.6 years. The most common initial physical manifestation in 39 of 60 (65.0%) patients was localised pigmentary changes only, followed by plexiform neurofibromas only in 10 of 60 (16.7%) and neurofibromas only in 9 of 60 (15.0%). Unilateral findings were seen in 46 of 60 (76.7%) patients. Most common associations identified included learning disabilities (7/60; 12%) and bony abnormalities (6/60; 10.0%). Conclusions: MNF is an underrecognised condition with potential implications for patients. Children mostly present with pigmentary anomalies only. Most patients do not develop associated findings or complications before adulthood, but long-term follow-up will help determine outcomes and possible associations. Recognition and confirmation of the diagnosis is important to provide follow-up and genetic counselling to patients.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Valentina Botero ◽  
Bethany A. Stanhope ◽  
Elizabeth B. Brown ◽  
Eliza C. Grenci ◽  
Tamara Boto ◽  
...  

AbstractNeurofibromatosis type 1 is a chronic multisystemic genetic disorder that results from loss of function in the neurofibromin protein. Neurofibromin may regulate metabolism, though the underlying mechanisms remain largely unknown. Here we show that neurofibromin regulates metabolic homeostasis in Drosophila via a discrete neuronal circuit. Loss of neurofibromin increases metabolic rate via a Ras GAP-related domain-dependent mechanism, increases feeding homeostatically, and alters lipid stores and turnover kinetics. The increase in metabolic rate is independent of locomotor activity, and maps to a sparse subset of neurons. Stimulating these neurons increases metabolic rate, linking their dynamic activity state to metabolism over short time scales. Our results indicate that neurofibromin regulates metabolic rate via neuronal mechanisms, suggest that cellular and systemic metabolic alterations may represent a pathophysiological mechanism in neurofibromatosis type 1, and provide a platform for investigating the cellular role of neurofibromin in metabolic homeostasis.


2012 ◽  
Vol 19 (6) ◽  
pp. 817-825 ◽  
Author(s):  
Maya B Lodish ◽  
Urania Dagalakis ◽  
Ninet Sinaii ◽  
Ethan Bornstein ◽  
AeRang Kim ◽  
...  

Concern for impaired bone health in children with neurofibromatosis type 1 (NF-1) has led to increased interest in bone densitometry in this population. Our study assessed bone mineral apparent density (BMAD) and whole-body bone mineral content (BMC)/height in pediatric patients with NF-1 with a high plexiform neurofibroma burden. Sixty-nine patients with NF-1 (age range 5.2–24.8; mean 13.7±4.8 years) were studied. Hologic dual-energy X-ray absorptiometry scans (Hologic, Inc., Bedford, MA, USA) were performed on all patients. BMD was normalized to derive a reference volume by correcting for height through the use of the BMAD, as well as the BMC. BMAD of the lumbar spine (LS 2–4), femoral neck (FN), and total body BMC/height were measured and Z-scores were calculated. Impaired bone mineral density was defined as a Z-score ≤−2. Forty-seven percent of patients exhibited impaired bone mineral density at any bone site, with 36% at the LS, 18% at the FN, and 20% total BMC/height. BMAD Z-scores of the LS (−1.60±1.26) were more impaired compared with both the FN (−0.54±1.58; P=0.0003) and the whole-body BMC/height Z-scores (−1.16±0.90; P=0.036). Plexiform neurofibroma burden was negatively correlated with LS BMAD (rs=−0.36, P=0.01). In pediatric and young adult patients with NF-1, LS BMAD was more severely affected than the FN BMAD or whole-body BMC/height.


Genes ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 839
Author(s):  
Larissa Brussa Reis ◽  
Andreia Carina Turchetto-Zolet ◽  
Maievi Fonini ◽  
Patricia Ashton-Prolla ◽  
Clévia Rosset

Neurofibromatosis type 1 (NF1) is a cancer predisposition syndrome that results from dominant loss-of-function mutations mainly in the NF1 gene. Large rearrangements are present in 5–10% of affected patients, generally encompass NF1 neighboring genes, and are correlated with a more severe NF1 phenotype. Evident genotype–phenotype correlations and the importance of the co-deleted genes are difficult to establish. In our study we employed an evolutionary approach to provide further insights into the understanding of the fundamental function of genes that are co-deleted in subjects with NF1 microdeletions. Our goal was to access the ortholog and paralog relationship of these genes in primates and verify if purifying or positive selection are acting on these genes. Fourteen genes were analyzed in twelve mammalian species. Of these, four and ten genes showed positive selection and purifying selection, respectively. The protein, RNF135, showed three sites under positive selection at the RING finger domain, which may have been selected to increase efficiency in ubiquitination routes in primates. The phylogenetic analysis suggests distinct evolutionary constraint between the analyzed genes. With these analyses, we hope to help clarify the correlation of the co-deletion of these genes and the more severe phenotype of NF1.


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