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Patient 1 was a 48-year-old female presented with progressive headache for 1 year. Head CT showed multiple intracranial nodules. Dermatological examination showed multiple brown spots and subcutaneous nodules on the right abdomen in patient and her son. Whole exome and Sanger sequencing showed that the patient and her son carried the c. 1260 +3dupA mutation on exon 11 of the NF1 gene, caused to elongate by 14 bases GTAAAGTCCAAAAG. Patient 2 was a 17-year-old female presented with back prickling for three years. Physical examination showed wide facial distance between the eyes, a flat nasal bridge, masses of various sizes in the corners of the right mouth, lower lip and mandible, multiple brown rashes and subcutaneous nodules on the trunk and limbs, axillary and inguinal freckles. Her partents were normal. Dermatoscopy showed regular and well-defined brown grid-like pigmentation on the upper left side of the back. Histopathology of the tumor on the lateral side of the lower lip showed that there were a large number of spindle cells and scattered mast cells in the dermis. Whole exome sequencing showed the deletion of 1.37 Mb in the 17q11.2 region of the chromosome. All the above patients were diagnosed as neurofibromatosis type I. The skin lesion of Patient 1 was not specially treated, while the skin lesion of Patient 2 was surgically removed. Both cases were under follow-up. [ABSTRACT FROM AUTHOR]

The criteria for clinical diagnosis of neurofibromatosis type 1 (NF1) are not sensitive in young children. Recognition is easier when one of their parents has been diagnosed with this condition, and the causal mutation is known. We present a case of a girl with isolated café‐au‐lait spots, whose father was diagnosed with NF1. However, both were found to carry different de novo mutations in the NF1 gene. This possibility has significant implications for the diagnostic process and genetic counseling. [ABSTRACT FROM AUTHOR]

Neurofibromatosis-Noonan syndrome (NFNS), a rare autosomal-dominant hereditary disease, is characterized by clinical manifestations of both neurofibromatosis type 1 (NF1) and NS. We present a case of NFNS with short stature caused by a heterozygous nonsense variant of the NF1 gene. A 12-year-old boy was admitted because of short stature, numerous café-au-lait spots, low-set and posteriorly rotated ears, sparse eyebrows, broad forehead, and inverted triangular face. Cranial and spinal magnetic resonance imaging showed abnormal nodular lesions. Molecular analysis revealed a novel heterozygous c.6189 C > G (p.(Tyr2063*)) variant in the NF1 gene. The patient was not prescribed recombinant growth hormone (GH) therapy because exogenous GH may have enlarged the abnormal skeletal lesions. During follow-up, Lisch nodules were found in the ophthalmologic examination. NFNS, a variant form of NF1, is caused by heterozygous mutations in the NF1 gene. The mechanism of GH deficiency caused by NF1 is still unclear. Whether NFNS patients should be treated with exogenous GH remains controversial.

Background: Neurofibromatosis type 1 (NF1) is a unique, highly penetrant neuro-cutaneous disorder with a wide range of manifestations. Though the clinical diagnosis of NF1 is straight forward, there can be other disorders which mimic NF1, especially its cutaneous features. Here we describe the clinical and mutation spectrum of a series of individuals whose primary diagnosis was NF1 or NF1 related disorders. Methods: We have screened 29 unrelated individuals who fulfilled the clinical criteria of NF1. Whole exome sequencing (WES) was done in all individuals except one with suspected microdeletion syndrome with NF1 in whom Cytogenetic microarray (CMA) was done. Results: Out of 29 suspected patients, 25 had germline pathogenic/likely pathogenic variants involving NF1 gene. Five novel and 20 known variants in coding and non-coding regions were identified, among them 7 variants were deletions (28%), 7 nonsense (28%), 3 splice-site (12%), 4 missense (16%), 2 duplications (8%) and 2 (8%) were contiguous deletions. In those where NF1 variants were not detected, 3 had neurofibromatosis type 2 (NF2) and 1 rare autosomal recessive form of Elher Danlos syndrome. Conclusion: We hereby present the wide range of manifestations in different age groups and the mutation spectrum ranging from small scale variants to contiguous gene deletion syndromes involving NF1 gene. We highlight the usefulness of molecular testing and its importance in tumor surveillance and genetic counseling in this disorder.

Neurofibromatosis type 1 (NF1) is the most common neurocutaneous disease and is caused by mutations in the NF1 gene. The most common clinical features of NF1 are pigmentary abnormalities such as café-au-lait spots and inguinal or axillary freckling, cutaneous and plexiform neurofibromas, hamartomas of the iris, optic gliomas, and bone lesions. The aim of this retrospective study was to define the clinical and molecular characteristics of a pediatric sample of NF1, as well as the mutational spectrum and genotype-phenotype correlation. The study included 40 children with clinically suspected NF1. The patients were screened for NF1 mutations by DNA-based sequencing. In addition, all the patients were studied by multiplex ligation-dependent probe amplification (MLPA) to identify any duplications or deletions in NF1. The demographic, clinical, and genetic features of the children were characterized. A total of 40 children with NF1 were included. Of those, 28 were female and 12 were male. The mean age was 8.91 years. An NF1 variant was discovered in 28 of 40 patients (70%). Among these mutations, intronic mutations were the most frequently detected mutations; 15 of these variants had not been previously reported. Only one patient had a whole NF1 gene deletion. This study expands the spectrum of mutations in the NF1 gene. This study also showed that genetic screening using both next-generation sequencing and MLPA had a positive effect on diagnosis and genetic counseling in patients with suspected NF1. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 (NF1) is a clinically heterogeneous neurocutaneous disorder inherited in autosomal dominant manner. Approximately 5–10% of the cases are caused by NF1 microdeletions involving the NF1 gene and its flanking regions. Microdeletions, which lead to more severe clinical manifestations, can be subclassified into four different types (type 1, 2, 3 and atypical) according to their size, the genomic location of the breakpoints and the number of genes included within the deletion. Besides the prominent hallmarks of NF1, patients with NF1 microdeletions frequently exhibit specific additional clinical manifestations like dysmorphic facial features, macrocephaly, overgrowth, global developmental delay, cognitive disability and an increased risk of malignancies. It is important to identify the genes co-deleted with NF1, because they are likely to have an effect on the clinical manifestation. Multiplex ligation-dependent probe amplification (MLPA) and microarray analysis are the primary techniques for the investigation of NF1 microdeletions. However, based on previous research, optical genome mapping (OGM) could also serve as an alternative method to identify copy number variations (CNVs). Here, we present a case with NF1 microdeletion identified by means of OGM and demonstrate that this novel technology is a suitable tool for the identification and classification of the NF1 microdeletions. [ABSTRACT FROM AUTHOR]

Abstract Objective NF1 is a tumor suppressor gene that encodes the neurofibromin protein and negatively regulates Ras signaling. This study was aimed to investigate the molecular, clinical characteristics, and prognostic features of NF1 gene in EGFR mutant lung cancer patients. Method The next‐generation sequencing (NGS) was used to analyze the data from lung cancer patients in the Guangdong Lung Cancer Institute (GLCI) from June 2016 to December 2020. Results Somatic NF1 mutations were present in 4.2% (135/3220) of Chinese lung cancer patients. NF1 mutations where clearly enriched in older (p

Purpose of the study: Analysis of available data on geno-phenotypic correlations and atypical forms of neurofibromatosis type 1. Material and methods. We searched for relevant sources in the Scopus, Web of Science, PubMed systems, including publications from May 1993 to October 2021. Of the 318 studies we identified, 59 were used to write a systematic review. Results. We found studies describing atypical forms of neurofibromatosis type 1 with an erased course without manifestation of a tumor syndrome, which are caused by specific mutations in the NF1 gene (causing substitutions of amino acids in neurofibromin: p.Arg1038, p.Met1149, p.Arg1809, or deletion of amino acids: p.Met990del, p.Met992del). NF1 patients with microdeletions are characterized by more severe disease symptoms (more often facial dysmorphism, skeletal and cardiovascular abnormalities, learning difficulties, and symptomatic spinal neurofibromas). mutations of splicing sites and extended deletions of the NF1 gene are associated with early manifestation of tumors, mutations at the 5’-end of the gene, causing a shortening of the protein product, are associated with optic nerve gliomas. the mutation c.3721C>T (p.R1241*) correlated with structural brain damage, and c.6855C>A (p.Y2285*) with endocrine disorders. the manifestations of NF1, similar to lipomatosis and Jaffe-Campanacci syndrome, not associated with a specific type of mutation are described. Conclusion. In spite of pronounced clinical variability of the disease, even among members of the same family, several studies have described genotype-phenotype correlations. Therefore, the role of modifier genes and epigenetic factors in the pathogenesis of NF1 is assumed, since the neurofibromin protein has a complex structure with several functional domains. It has been shown that the severity of the tumor syndrome is influenced by the methylation characteristics of NF1 gene and adjacent areas. in addition, NF1 gene is associated with a variety of microRNAs. therefore, targeted therapy aimed at specific non-coding RNAs to restore normal expression of NF1 gene can become a promising treatment for NF1.

Objective: NF1 is a tumor suppressor gene that encodes the neurofibromin protein and negatively regulates Ras signaling. This study was aimed to investigate the molecular, clinical characteristics, and prognostic features of NF1 gene in EGFR mutant lung cancer patients. Method: The next‐generation sequencing (NGS) was used to analyze the data from lung cancer patients in the Guangdong Lung Cancer Institute (GLCI) from June 2016 to December 2020. Results: Somatic NF1 mutations were present in 4.2% (135/3220) of Chinese lung cancer patients. NF1 mutations where clearly enriched in older (p < 0.001), male (p < 0.001), and smoking (p < 0.001) patients. Patients with NF1 mutations were more likely to have TP53 (p = 0.003), BRAF (p = 0.001) and RASA1 (p = 0.026) mutations and mutually exclusive with EGFR mutations (p = 0.006). TP53 mutation had worsen prognosis in cases of NF1 mutant (p = 0.026) or EGFR/NF1 co‐mutant (p = 0.031) lung adenocarcinomas (LUAD) patients. There was no effect on overall survival (OS) in LUAD patients with and without NF1 mutations, even in LUAD driver‐gene negative patients. NF1/EGFR co‐mutation patients had a longer OS than a single mutation of either the EGFR gene (median OS: 47.7 m vs. 30.2 m, hazard ratio [95% CI], 0.47 [0.30–0.74], p = 0.004) or NF1 gene (47.7 m vs. 19.0 m, 0.44 [0.27–0.73], p = 0.003). Furthermore, NF1 mutations significantly prolonged OS in EGFR mutant/TP53 wild‐type LUAD patients (106.5 m vs. 25.5 m, 0.28 [0.13–0.59], p = 0.003) but not in patients with EGFR/TP53 co‐mutations (36.8 m vs. 30.2 m, 0.70 [0.39–1.26], p = 0.280). Conclusion: Our results indicated NF1 mutations served as a good prognostic factor in EGFR mutant/TP53 wild‐type lung cancer patients in this single‐center study. TP53 mutation was obviously enriched in NF1 mutant patients and had shorter OS. [ABSTRACT FROM AUTHOR]

Abstract Tobacco smoking is associated with increased risks of nearly 20 types of cancer. Although the association between smoking and gliomas, the most prevalent type of adult brain tumor, is still unconclusive, here, we found that the frequency of NF1 mutations was significantly increased in the glioma patients with smoking history compared to non-smoking patients (24% vs. 10%, P = 0.021). NF1 acts as a tumor suppressor gene is highly mutated in gliomas. The TCGA data analysis indicated that glioma patients carrying NF1 somatic mutations have worse overall survival (median survival time: smoking 19.9 months vs. non-smoking 36.8 month; P = 0.0018). In addition, we revealed that the NF1 and IDH1 mutations were mutually exclusive suggesting NF1 mutation has independent molecular mechanism involved in glioma biology.

Neurofibromatosis type 1 is the most common autosomal dominant tumor syndrome. The prevalence of the disease is 1 in 3000 people. Neurofibromatosis type 1 is characterized by the gradual appearance of signs of the disease and pronounced clinical polymorphism from erased and atypical forms to severe classical manifestations. The review is devoted to the consideration of diseases, the manifestations of which are significantly similar to neurofibromatosis type 1, and therefore, molecular diagnosis of the disease is an important method for differential diagnosis. To make a diagnosis of neurofibromatosis type 1, it is necessary to find mutations in the NF1 gene using sequencing. In 10% of cases, neurofibromatosis type 1 is caused by large deletions of the 17q11.2 locus, therefore, multiplex ligation-dependent probe amplification is also necessary. Typically, the initial manifestations of neurofibromatosis type 1 are multiple café-au-lait spots, which may be the only external signs of the disease for many years. Therefore, patients with neurofibromatosis type 1 may be mistakenly diagnosed with diseases for which these pigmentary changes are characteristic: Bloom, LEOPARD, Carney, Costello, Cowden, Legius, Nijmegen, Noonan, Peitz-Jägers, Silver-Russell, cardio-facio-cutaneous syndromes. The detection of subcutaneous tumors can become the basis for an incorrect diagnosis of the clinically similar Legius syndrome and multiple endocrine neoplasia. In addition, multiple lipomas are specific manifestations of Madelung or Dercum lipomatosis, familial angiolipomatosis, the etiology of which is considered unknown. Therefore, I assume that these diseases are atypical forms of neurofibromatosis type 1, since a number of authors have described the identification of mutations in NF1 gene in patients with multiple lipomatosis. Therefore, it is important to widely introduce into clinical practice the possibility of molecular genetic identification of the disease in order to identify cases of neurofibromatosis type 1 that do not meet the diagnostic criteria adopted by the NIH. It is promising to create a panel for the study of all genes, mutations in which can cause manifestations similar to neurofibromatosis. Early diagnosis of the disease is necessary for timely initiation of treatment and prevention of severe manifestations, since effective methods of antitumor therapy of neurofibromatosis type 1, such as inhibitors of mitogen-activated kinase, are being introduced into clinical practice.

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"Juvenile-like (hyperplastic/inflammatory) mucosal polyp" is a term proposed for rare benign mesenchymal lesions of the gastro-intestinal tract so far reported only in patients with type 1 neurofibromatosis (NF1). We report here a first sporadic case of NF1 -associated mucosal inflammatory polyp of the colon. The diagnosis was made in a 53-year old female patient with a large polypoid tumor of the cecum. The lesion was predominantly mucosal, made of fibroblast-like cells associated with inflammatory infiltrates rich in eosinophils and containing entrapped, distorted epithelial glands, responsible for the juvenile-like appearance. Whole exome sequencing showed a pathogenic variant of NF1. The patient had no evidence of NF1; no NF1 mutation was detected in normal tissues. Our observation may support the existence of juvenile-like inflammatory polyps associated with NF1 alterations, either germline or somatic. This justifies to test NF1 in difficult-to-classify gastrointestinal mesenchymal tumors. [ABSTRACT FROM AUTHOR]

Cases of neurofibromatosis type 1 (NF1)-associated medullary thyroid carcinoma (MTC) or C-cell hyperplasia are rarely associated with other endocrine tumors or cases with a multiple endocrine neoplasia type 2. In these patients, mutations were detected in the NF1 gene but no mutations were detected in the RET gene. Although vandetanib has been shown to improve progression-free survival in adults with advanced MTC, data in pediatric patients are limited. Herein, we report the use and outcome of vandetanib in a pediatric MTC case in which NF1 gene and RET proto-oncogen mutation were identified together.

Introduction. Neurofibromatosis type 1 (NF1) is the most common hereditary tumor syndrome (frequency of its occurrence in the world is 1 : 3000 of the population). The main clinical manifestations of the disease are multiple café-au-lait macules on the skin and neurofibromas, skeletal abnormalities and cognitive deficits. The disease is based on mutations in the oncosuppressor gene NF1. This disease is characterized by significant clinical polymorphism of manifestations, even among members of the same family. No geno-phenotypic correlations were found for NF1. Therefore, it is assumed that modifier genes are the cause of the varying expressiveness of the disease. Materials and methods. Clinical-epidemiological and molecular-genetic research of patients with NF1 in the Republic of Bashkortostan (RB) was carried out. Sequencing was used to search for intragenic mutations in 57 exons of the NF1 gene. Microsatellite analysis was used to detect the deletion of the entire gene.Results. The frequency of occurrence of NF1 in RB was 1 : 10153 of the population. Analysis of the clinical manifestations of NF1 in RB patients showed a lower incidence of brain cysts in patients born in mixed marriages, which indicates the protective role of mestization. In patients with NF1 who inherited the disease from the mother, a more frequent development of skeletal anomalies and facial dysmorphism was determined. We identified 1 deletion of the entire NF1 gene in 1 patient and 14 intragenic mutations (c.205-1G>C, с.1278G>A, c.1369_1370insGGGTC, с.1570G>A, с.1973_1974delTC, c.2806A>T, с.2991-1G>C, c.3158C>G, с.3526_3528delAGA, с.3826delC, с.4514+5G>A, с.4537С>Т, c.5758_5761delTTGA, с.6792С>A) in 20 patients with NF1. We determined the random distribution of the types of mutations and did not reveal the specific features of the NF1 clinic depending on the type of mutations.Conclusions. The protective role of crossbreeding in relation to brain cysts, as well as the predominance of skeletal anomalies in patients with NF1 inheritance from the mother, indicate the role of modifier genes in the pathogenesis of the disease. The identified mutations in the NF1 gene will allow us to perform prenatal prevention of NF1 in RB patients.

Abstract Background The mosaic form of neurofibromatosis type 1 (NF1) is called mosaic NF1 (MNF1). No specific MNF1 follow-up guidelines exist. It is debatable if patients with MNF1 should be clinically examined and undergo follow-up in accordance with the standard NF1 guidelines, as MNF1 patients more often may develop more benign phenotypes and thereby less disease-associated complications including cognitive impairment. We discussed the need for a specific MNF1 follow-up guideline with focus on frequency of plexiform neurofibromas and NF1-associated complications. Method A systematic retrospective data collection in a MNF1 cohort from one of two Danish national centers of NF1 Expertise was completed. Data collected included demographics, clinical features including NF1 diagnostic criteria and NF1-associated complications. Recent literature in the field was reviewed. Results We identified 17 patients with MNF1 with a median age of 37 years [4; 66]. Eleven (65%) were females. Five patients (30%) had a plexiform neurofibroma. The median age at detection of plexiform neurofibroma was 30 years [14; 60]. Nine (53%) had at least one NF1-related complication; scoliosis, hypertension, ADHD, learning disability, language delay, autism and delay in gross and fine motor function development. We reviewed nine articles. In total, 126 cases were described within three case-series. Nineteen (15%) had a plexiform neurofibroma and in total, 23 NF1-associated complications were reported including language delay, learning disability and skeletal abnormalities. Furthermore, from the literature it was evident that the diagnosing of MNF1 varies among physicians and across countries. Conclusion Patients with MNF1 present with plexiform neurofibromas and other NF1-related complications with a frequency requiring that follow-up of MNF1 patients should be in accordance with the standard NF1 guideline in both childhood and adulthood. Physicians should be aware of cognitive impairment as a complication to MNF1. To develop a specific MNF1 follow-up guideline, there is a need for an international consensus on the diagnostic criteria for MNF1 and a follow-up study conducted in a larger MNF1 cohort.

Neurofibromatosis Noonan syndrome (NFNS) is a rare RASopathy syndrome, resulting from NF1 gene mutations. NFNS is characterized by phenotypic features of both neurofibromatosis type 1 (NF1) and Noonan syndrome. Plexiform neurofibromas (PNFs) are an unusual finding in NFNS. A seven year-old girl with typical clinical features of NF1 was referred to our clinic due to short stature and abnormal genital appearance. Due to dysmorphic features, a clinical diagnosis of NFNS was considered in the patient and, following molecular analysis, revealed a novel heterozygous c.3052_3056delTTAGT (p.L1018X) variant in the NF1 gene. Although evaluation for genital virilization, including karyotype and hormonal studies were normal, imaging studies revealed a diffuse genital PNF. Although PNFs are seen rarely in NFNS, this should be considered in the differential diagnosis of genital virilization in these patients to prevent unnecessary testing.

Tobacco smoking is associated with increased risks of nearly 20 types of cancer. Although the association between smoking and gliomas, the most prevalent type of adult brain tumor, is still unconclusive, here, we found that the frequency of NF1 mutations was significantly increased in the glioma patients with smoking history compared to non-smoking patients (24% vs. 10%, P = 0.021). NF1 acts as a tumor suppressor gene is highly mutated in gliomas. The TCGA data analysis indicated that glioma patients carrying NF1 somatic mutations have worse overall survival (median survival time: smoking 19.9 months vs. non-smoking 36.8 month; P = 0.0018). In addition, we revealed that the NF1 and IDH1 mutations were mutually exclusive suggesting NF1 mutation has independent molecular mechanism involved in glioma biology. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 (NF1) is an inherited tumor predisposition syndrome. The high susceptibility to benign-malignant tumors and frequency of complications have revealed the importance of genetic molecular diagnosis and regular follow-up of patients. The aim of this study was to identify the genetic mutations that cause the disease and provide genotype/phenotype correlations. The patients with NF1 assessed in the genetic outpatient clinic between 2018 and 2020 were included in the study. The NF1 gene was analyzed by next generation sequencing (NGS) method. Patient's demografic features and the results of NF1 gene analysis were investigated retrospectively. Café au lait spots were present in all 40 patients included in the study. Lisch nodule was observed in 20%, optic glioma in 10%, neurofibroma in 12.5%, hamartoma in 10%, short stature in 10% of patients. Cranial MRI abnormalities were detected in 55% of patients. We detected four novel mutations which were not reported before in the literature; p.S2460*, p.Q1360sFS*20, p.K1457* and p.K918*.Prediction of complications that may arise in patients according to mutations and information about genotype-phenotype correlations can be helpful in the management of the disease. Early diagnosis, informing families about NF1 disease, providing genetic counseling, and regular follow-up of patients by a team of experts from different branches are important in terms of minimizing the mortality and morbidity of NF1. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 (NF1) is a tumor predisposition genetic disorder that directly affects more than 1 in 3,000 individuals worldwide. It results from mutations of the NF1 gene and shows almost complete penetrance. NF1 patients show high phenotypic variabilities, including cafe-au-lait macules, freckling, or other neoplastic or non-neoplastic features. Understanding the underlying mechanisms of the diversities of clinical symptoms might contribute to the development of personalized healthcare for NF1 patients. Currently, studies have shown that the different types of mutations in the NF1 gene might correlate with this phenomenon. In addition, genetic modifiers are responsible for the different clinical features. In this review, we summarize different genetic mutations of the NF1 gene and related genetic modifiers. More importantly, we focus on the genotype–phenotype correlation. This review suggests a novel aspect to explain the underlying mechanisms of phenotypic heterogeneity of NF1 and provides suggestions for possible novel therapeutic targets to prevent or delay the onset and development of different manifestations of NF1.

Neurofibromatosis type 1 (NF1) is a tumor predisposition genetic disorder that directly affects more than 1 in 3,000 individuals worldwide. It results from mutations of the NF1 gene and shows almost complete penetrance. NF1 patients show high phenotypic variabilities, including cafe-au-lait macules, freckling, or other neoplastic or non-neoplastic features. Understanding the underlying mechanisms of the diversities of clinical symptoms might contribute to the development of personalized healthcare for NF1 patients. Currently, studies have shown that the different types of mutations in the NF1 gene might correlate with this phenomenon. In addition, genetic modifiers are responsible for the different clinical features. In this review, we summarize different genetic mutations of the NF1 gene and related genetic modifiers. More importantly, we focus on the genotype–phenotype correlation. This review suggests a novel aspect to explain the underlying mechanisms of phenotypic heterogeneity of NF1 and provides suggestions for possible novel therapeutic targets to prevent or delay the onset and development of different manifestations of NF1. [ABSTRACT FROM AUTHOR]

Cases of neurofibromatosis type 1 (NF1)-associated medullary thyroid carcinoma (MTC) or C-cell hyperplasia are rarely associated with other endocrine tumors or cases with a multiple endocrine neoplasia type 2. In these patients, mutations were detected in the NF1 gene but no mutations were detected in the RET gene. Although vandetanib has been shown to improve progression-free survival in adults with advanced MTC, data in pediatric patients are limited. Herein, we report the use and outcome of vandetanib in a pediatric MTC case in which NF1 gene and RET proto-oncogen mutation were identified together. [ABSTRACT FROM AUTHOR]

Abstract Background 17q11.2 microdeletions, which include the neurofibromatosis type 1 (NF1) gene region, are responsible for the NF1 microdeletion syndrome, observed in 4.2% of all NF1 patients. Large deletions of the NF1 gene and its flanking regions are associated with a more severe NF1 phenotype than the NF1 general population. Case presentation We hereby describe the clinical and molecular features of two girls (aged 2 and 4 years, respectively), with non-mosaic atypical deletions. Patient 1 showed fifteen café-au-lait spots and axillary freckling, as well as a Lisch nodule in the left eye, strabismus, high-arched palate, malocclusion, severe kyphoscoliosis, bilateral calcaneovalgus foot, mild generalized hypotonia, hyperactivity and deficits of speech-related abilities. NF1 genomic rearrangements through multiplex ligation-dependent probe amplification (MLPA) detected an heterozygous deletion of the whole NF1 gene. Array comparative genomic hybridization (a-CGH) analysis defined a 17q11.2 deletion of about 1 Mb (breakpoints at positions 29,124,299 and 30,151,654), which involved different genes (partially CRLF3, ATAD5, TEFM, ADAP2, RNF135, OMG, EVI2B, EVI2A, RAB11FIP4), including NF1. Patient 2 showed growth and developmental delay, supravalvular pulmonary stenosis, twenty-five café-au-lait spots, axillary freckling, craniofacial dysmorphic features, short neck with pterygium, limb abnormalities and foci of neural dysplasia on brain magnetic resonance imaging (MRI). MLPA detected an heterozygous deletion of NF1, which was detailed by a-CGH indicating the positions 29,124,299 and 30,326,958 as its breakpoints, and which included aside from the genes deleted in Patient 1 also COPRS, UTP6 and partially SUZ12. Fluorescent in situ hybridization (FISH) analysis of the parents documented a de novo origin of the deletions in both cases. Conclusions The present report will likely provide further insights and a better characterization of NF1 microdeletion syndrome.

Von Recklinghausen’s disease (VRD) is a hereditary disease that occurs because of mutation in NF1 gene located on chromosome 17. About 25% of VRD patients are reported to suffer from gastrointestinal lesions varying from hyperplasia of the gut neural tissue, endocrine tumors of the duodenum and the periampullary region, and gastrointestinal stromal tumors. Herein, we describe a case of ampullary neuroendocrine tumor with unique histology and immunohistochemistry in a 35-year-old male patient with VRD, detailed review of literature.

Neurofibromatosis type 1 is a tumor predisposition syndrome inherited in autosomal dominant manner. Besides the intragenic loss-of-function mutations in NF1 gene, large deletions encompassing the NF1 gene and its flanking regions are responsible for the development of the variable clinical phenotype. These large deletions titled as NF1 microdeletions lead to a more severe clinical phenotype than those observed in patients with intragenic NF1 mutations. Around 5-10% of the cases harbor large deletion and four major types of NF1 microdeletions (type 1, 2, 3 and atypical) have been identified so far. They are distinguishable in term of their size and the location of the breakpoints, by the frequency of somatic mosaicism with normal cells not harboring the deletion and by the number of the affected genes within the deleted region. In our study genotype-phenotype analyses have been performed in 17 mostly pediatric patients with NF1 microdeletion syndrome identified by multiplex ligation-dependent probe amplification after systematic sequencing of the NF1 gene. Confirmation and classification of the NF1 large deletions were performed using array comparative genomic hybridization, where it was feasible. In our patient cohort 70% of the patients possess type-1 deletion, one patient harbors type-2 deletion and 23% of our cases have atypical NF1 deletion. All the atypical deletions identified in this study proved to be novel. One patient with atypical deletion displayed mosaicism. In our study NF1 microdeletion patients presented dysmorphic facial features, macrocephaly, large hands and feet, delayed cognitive development and/or learning difficulties, speech difficulties, overgrowth more often than patients with intragenic NF1 mutations. Moreover, neurobehavior problems, macrocephaly and overgrowth were less frequent in atypical cases compared to type-1 deletion. Proper diagnosis is challenging in certain patients since several clinical manifestations show age-dependency. Large tumor load exhibited more frequently in this type of disorder, therefore better understanding of genotype-phenotype correlations and progress of the disease is essential for individuals suffering from neurofibromatosis to improve the quality of their life. Our study presented additional clinical data related to NF1 microdeletion patients especially for pediatric cases and it contributes to the better understanding of this type of disorder. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 (NF1) is caused by mutations in the NF1 gene. This retrospective study aims to evaluate the clinical manifestations and brain magnetic resonance images (MRI) analysis in 60 genetically confirmed NF1 patients. The results of next-generation sequencing (NGS), Sanger sequencing, and MLPA of NF1 gene were evaluated. A total of 54 different variants were identified. Fourteen out of them were novel variants (25.9%). Patients who complied with NIH criteria had most frequently frameshift variants (11/32 patients), and those with only CALMs had missense variants (9/28 patients). Neurofibromatosis type 1 bright objects (NBOs) on T2-weighted MRI were detected in 42 patients (42/56; 75%). These brain lesions were detected mostly in basal ganglia and in cerebellar vermis. NBOs were detected more in the patients who complied with NIH criteria (80.6%) compared to those who were only CALMs (68%). While frameshift variants (33.3%) were the most common type variants in the patients who had NBOs, the most common variants were splicing (35.7%) and missense (35.7%) variants in the patients whose MRIs were normal. Frameshift variants (11/28 patients; 39.3%) were the most common in the patients with more than one brain locus involvement. Therefore, we consider that frameshift variants may be associated with increased incidence of NBOs and involvement of more than one brain locus. In addition, NBOs may occur less frequently in the patients with splicing variants. To our knowledge, this is the first study evaluated the relationship between NF1 gene variants and NBOs. Future studies may help us understand the etiology of NBOs. [ABSTRACT FROM AUTHOR]

Background: The mosaic form of neurofibromatosis type 1 (NF1) is called mosaic NF1 (MNF1). No specific MNF1 follow-up guidelines exist. It is debatable if patients with MNF1 should be clinically examined and undergo follow-up in accordance with the standard NF1 guidelines, as MNF1 patients more often may develop more benign phenotypes and thereby less disease-associated complications including cognitive impairment. We discussed the need for a specific MNF1 follow-up guideline with focus on frequency of plexiform neurofibromas and NF1-associated complications.Method: A systematic retrospective data collection in a MNF1 cohort from one of two Danish national centers of NF1 Expertise was completed. Data collected included demographics, clinical features including NF1 diagnostic criteria and NF1-associated complications. Recent literature in the field was reviewed.Results: We identified 17 patients with MNF1 with a median age of 37 years [4; 66]. Eleven (65%) were females. Five patients (30%) had a plexiform neurofibroma. The median age at detection of plexiform neurofibroma was 30 years [14; 60]. Nine (53%) had at least one NF1-related complication; scoliosis, hypertension, ADHD, learning disability, language delay, autism and delay in gross and fine motor function development. We reviewed nine articles. In total, 126 cases were described within three case-series. Nineteen (15%) had a plexiform neurofibroma and in total, 23 NF1-associated complications were reported including language delay, learning disability and skeletal abnormalities. Furthermore, from the literature it was evident that the diagnosing of MNF1 varies among physicians and across countries.Conclusion: Patients with MNF1 present with plexiform neurofibromas and other NF1-related complications with a frequency requiring that follow-up of MNF1 patients should be in accordance with the standard NF1 guideline in both childhood and adulthood. Physicians should be aware of cognitive impairment as a complication to MNF1. To develop a specific MNF1 follow-up guideline, there is a need for an international consensus on the diagnostic criteria for MNF1 and a follow-up study conducted in a larger MNF1 cohort. [ABSTRACT FROM AUTHOR]

Introduction: Griscelli syndrome type 2 (GS2) and neurofibromatosis type 1 (NF1) are both rare genetic disorders, but their coexistence has not been documented prior to this report., Case Presentation: We present the case of a 4-year-old girl initially diagnosed with GS2 due to albinism and immunodeficiency, and later with NF1, manifested by the development of multiple café-au-lait macules (CALMs) and MRI findings. The patient was the second child of consanguineous parents and exhibited symptoms early, with silver-gray hair at birth and subsequent health complications at 9 months. GS2 was confirmed via the identification of a homozygous frameshift variant in the RAB27A gene, and a de novo heterozygous splice site mutation in the NF1 gene established the NF1 diagnosis. Her treatment included hematopoietic stem cell transplantation and ongoing surveillance for NF1-associated complications., Discussion/conclusion: This case emphasizes the importance of considering the potential for concurrent rare genetic diseases in clinical evaluations, especially with progressive or evolving symptomatology., Competing Interests: The authors have no conflicts of interest to declare., (© 2024 S. Karger AG, Basel.)

We analyzed the clinical features and NF1 gene mutation in a Chinese pedigree of neurofibromatosis type 1 (NF1). Three members of this family were NF1 patients presenting with different clinical phenotypes and the others were asymptomatic. Exons of NF1 were amplified by polymerase chain reaction, sequenced, compared with a reference database. One novel NF1 frame-shift mutation c.703_704delTA, which resulted in a premature stop signal at codon 720 and the synthesis of truncated, was revealed. This mutation segregated with the NF1 members is likely responsible for the pathogenesis of NF1 in the family.

Abstract Background The aim of this retrospective study was to define clinical and molecular characteristics of a large sample of neurofibromatosis type 1 (NF1) patients, as well as to evaluate mutational spectrum and genotype-phenotype correlation. NF1 is a relatively common neurogenetic disorder (1:2500–1:3000 individuals). It is caused by mutations of the NF1 gene on chromosome 17ql1.2, with autosomal dominant pattern of inheritance and wide phenotypical variability. Café-au-lait spots (CALs), cutaneous and/or subcutaneous neurofibromas (CNFs/SCNFs), skinfold freckling, skeletal abnormalities, Lisch nodules of the iris and increased risk of learning and intellectual disabilities, as well as tumors of the nervous system and other organs are its main clinical features. Methods The preliminary group collected 168 subjects with clinical suspicion of NF1. They were evaluated following the National Institutes of Health (NIH) criteria for NF1, revised by Gutmann et al. 1997, integrated for 67 of them by molecular testing. According to these references, 112 of 168 patients were diagnosed as NF1. The sample was characterized by an equal sex ratio (57 males, 55 females) and age distribution ranging from 10 days to 60 years of age (mean age, 13 years). Results A wide spectrum of clinical features has been observed in our patients. Mutational analysis resulted positive in 51 cases (76%). Twenty-four mutations detected in our cohort have not been reported to date. Conclusions This study may contribute to a better definition of genotypic and phenotypic features of NF1 patients, with respect to further insights into the clinical characterization of the disease. In addition, an amplification of the spectrum of mutations in the NF1 gene has been documented.

Background: Neurofibromatosis (NF) is a genetic disorder, and neurofibromatosis types 1 and 2 have different genetic and clinical features. Herein, we present the clinical and genetic aspects of a patient carrying a constitutional NF1 gene mutation and whose neurocutaneous manifestations suggested a NF type 2 (NF2). Methods: A 55-year-old woman presented with headache and deterioration of vision. Physical examination and radiologic findings revealed multiple subcutaneous nodules and multiple intracranial and spinal masses which were suspected to be NF2. Results: Genomic DNA sequencing using a peripheral blood sample revealed a splicing mutation in the NF1 gene. Tumor resection and biopsy revealed intracranial meningiomas and paraspinal Schwannoma compatible with NF2. PCR-direct sequencing using tumor tissue samples showed pathogenic somatic mutation of the NF2 gene. Conclusions: We report a case of NF2 presenting with a pathogenic somatic mutation in the NF2 gene in a woman harboring a germline splicing mutation in the NF1 gene. This case emphasizes the importance of sequence analysis by using tumor tissues and the need to elucidate the role of a NF1 splicing mutation. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 is an autosomal dominant disorder which is characterized by multiple café-au-lait spots in the body, intertriginous freckles, Lisch nodules, neurofibroma, optic glioma and bone dysplasia. One of the clinical characteristics of Neurofibromatosis type 1 is the risk of benign and malignant tumor development. Optic gliomas, a type of astrocytoma, are the most common central nervous system complication in children with Neurofibromatosis type 1 and are seen in 10-15% of cases. In this case report, a patient with an optic glioma and a mutation that was not previously identified in the NF1 gene is presented in the light of the literature. Identification of new mutations that cause Neurofibromatosis type 1 disease and reporting of clinical findings caused by the mutations will allow a large proportion of genotypephenotype correlation. Early diagnosis has a great importance in terms of followup of patients for malignancies that may develop in the future. [ABSTRACT FROM AUTHOR]

Uncovering frequent motives of action by which variants impair 3′ splice site (3′ss) recognition and selection is essential to improve our understanding of this complex process. Through several mini‐gene experiments, we demonstrate that the pyrimidine (Y) to purine (R) transversion NM_000267.3(NF1):c.1722‐11T>G, although expected to weaken the polypyrimidine tract, causes exon skipping primarily by introducing a novel AG in the AG‐exclusion zone (AGEZ) between the authentic 3′ss AG and the branch point. Evaluation of 90 additional noncanonical intronic NF1 3′ss mutations confirmed that 63% of all mutations and 89% (49/55) of the single‐nucleotide variants upstream of positions ‐3 interrupt the AGEZ. Of these AGEZ‐interrupting mutations, 24/49 lead to exon skipping suggesting that absence of AG in this region is necessary for accurate 3′ss selection already in the initial steps of splicing. The analysis of 91 noncanonical NF1 3′ss mutations also shows that 90% either introduce a novel AG in the AGEZ, cause a Y>R transversion at position ‐3 or remove ≥2 Ys in the AGEZ. We confirm in a validation cohort that these three motives distinguish spliceogenic from splice‐neutral variants with 85% accuracy and, therefore, are generally applicable to select among variants of unknown significance those likely to affect splicing. [ABSTRACT FROM AUTHOR]

Neurofibromatosis Noonan syndrome (NFNS) is a rare RASopathy syndrome, resulting from NF1 gene mutations. NFNS is characterized by phenotypic features of both neurofibromatosis type 1 (NF1) and Noonan syndrome. Plexiform neurofibromas (PNFs) are an unusual finding in NFNS. A seven year-old girl with typical clinical features of NF1 was referred to our clinic due to short stature and abnormal genital appearance. Due to dysmorphic features, a clinical diagnosis of NFNS was considered in the patient and, following molecular analysis, revealed a novel heterozygous c.3052_3056delTTAGT (p.L1018X) variant in the NF1 gene. Although evaluation for genital virilization, including karyotype and hormonal studies were normal, imaging studies revealed a diffuse genital PNF. Although PNFs are seen rarely in NFNS, this should be considered in the differential diagnosis of genital virilization in these patients to prevent unnecessary testing. [ABSTRACT FROM AUTHOR]

Abstract Background Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder with equal sex incidence that is characterized by neurofibromas, café‐au‐lait macules, axillary freckling, optic pathway tumor, distinctive osseous lesion, and iris Lisch nodules. Inactivating variants in the NF1 gene have been identified to be correlated with NF1. This tumor suppressor gene is located at 17q11.2. Methods Ten affected NF1 probands and their available relatives from 10 unrelated Chinese families with neurofibromatosis type 1 were clinically studied. All of these probands mainly complained of osseous lesions. PCR was used to analyze and sequence the variants. We collected both laboratory and radiological information. Results We detected five novel pathogenic variants including two de novo variants in these 10 families: one missense variant, p.Cys709Arg(c.2125T>C), in exon 18 and four frameshift variants: p.Leu1459Profs*2(c.4436dupT) in exon 34; p.Lys99Argfs*4(c.296delA) in exon 4; p.Leu762Cysfs*2(c.2283delA) in exon 19; and p.Leu1522Ilefs*53(c.4562_4563dupAT) in exon 34. Conclusion Novel pathogenic variants in the NF1 gene in these families correlated with the phenotype and genotype and explained the clinical manifestations of these patients. The results help us to understand the genetic basis of patients with neurofibromatosis type 1 in China. Our study expands the pathogenic variant spectrum of the NF1 gene and may be helpful in genetic counseling and prenatal genetic diagnosis.

Objective: To summarize the gene therapy strategies for neurofibromatosis type 1 (NF1) and related research progress., Methods: The recent literature on gene therapy for NF1 at home and abroad was reviewed. The structure and function of the NF1 gene and its mutations were analyzed, and the current status as well as future prospects of the transgenic therapy and gene editing strategies were summarized., Results: NF1 is an autosomal dominantly inherited tumor predisposition syndrome caused by mutations in the NF1 tumor suppressor gene, which impair the function of the neurofibromin and lead to the disease. It has complex clinical manifestations and is not yet curable. Gene therapy strategies for NF1 are still in the research and development stage. Existing studies on the transgenic therapy for NF1 have mainly focused on the construction and expression of the GTPase-activating protein-related domain in cells that lack of functional neurofibromin, confirming the feasibility of the transgenic therapy for NF1. Future research may focus on split adeno-associated virus (AAV) gene delivery, oversized AAV gene delivery, and the development of new vectors for targeted delivery of full-length NF1 cDNA. In addition, the gene editing tools of the new generation have great potential to treat monogenic genetic diseases such as NF1, but need to be further validated in terms of efficiency and safety., Conclusion: Gene therapy, including both the transgenic therapy and gene editing, is expected to become an important new therapeutic approach for NF1 patients.

Neurofibromatosis type I (NF1) is a familial tumor syndrome with an autosomal‐dominant inheritance. NF1‐associated tumors often include neurofibromas, malignant peripheral nerve sheath tumors and pilocytic astrocytomas of the optic nerve. The presentation of NF1 patients with glioblastoma is a rare occurrence, with only a handful of cases reported in the literature. We report two cases of glioblastomas occurring in adults with NF1 and briefly review the relevant literature. [ABSTRACT FROM AUTHOR]

The finding of variants of uncertain significance (VUS) in the activity of a diagnostic genetic laboratory is a common issue, which is however provisional and needs to be periodically re-evaluated, due to the continuous advancements in our knowledge of the genetic diseases. Neurofibromatosis type 1, caused by the occurrence of heterozygous pathogenic NF1 variants, is a good model for studying the evolution of VUS, due to the widespread use of genetic testing for the disease, the constant enrichment of the international databases with NF1 variants and the full adult penetrance of the disease, which makes genotyping the parents a crucial step in the diagnostic workflow. The present study retrospectively reviewed and reinterpreted the genetic test results of NF1 in a diagnostic genetic laboratory in the period from January 1, 2000 to December 31, 2020. All the VUS were reinterpreted using the 2015 consensus standards and guidelines for the interpretation. Out of 589 NF1 genetic tests which were performed in the period, a total of 85 VUS were found and reinterpreted in 72 cases (84.7%): 21 (29.2%) were reclassified as benign/likely benign, whereas 51 (70.8%) were recoded as pathogenic/likely pathogenic with a significant trend distribution (Chi square test for trend p = 0.005). Synonymous VUS have mainly been reclassified as class 1 and 2 (7/8, 87.5%), whereas missense variants have been attributed to class 4 and 5 in 38 out of the 58 cases (65.5%). These findings underline an improvement in the classification of variants over time, suggesting that a reinterpretation of the genetic tests should be routinely performed to support the physicians in the clinical diagnosis of genetic diseases. [ABSTRACT FROM AUTHOR]

Background: Neurofibromatosis type 1 (NF1) is a unique, highly penetrant neuro-cutaneous disorder with a wide range of manifestations. Though the clinical diagnosis of NF1 is straight forward, there can be other disorders which mimic NF1, especially its cutaneous features. Here we describe the clinical and mutation spectrum of a series of individuals whose primary diagnosis was NF1 or NF1 related disorders., Methods: We have screened 29 unrelated individuals who fulfilled the clinical criteria of NF1. Whole exome sequencing (WES) was done in all individuals except one with suspected microdeletion syndrome with NF1 in whom Cytogenetic microarray (CMA) was done., Results: Out of 29 suspected patients, 25 had germline pathogenic/likely pathogenic variants involving NF1 gene. Five novel and 20 known variants in coding and non-coding regions were identified, among them 7 variants were deletions (28%), 7 nonsense (28%), 3 splice-site (12%), 4 missense (16%), 2 duplications (8%) and 2 (8%) were contiguous deletions. In those where NF1 variants were not detected, 3 had neurofibromatosis type 2 (NF2) and 1 rare autosomal recessive form of Elher Danlos syndrome., Conclusion: We hereby present the wide range of manifestations in different age groups and the mutation spectrum ranging from small scale variants to contiguous gene deletion syndromes involving NF1 gene. We highlight the usefulness of molecular testing and its importance in tumor surveillance and genetic counseling in this disorder., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors. Published by Elsevier Ltd.)

Neurofibromatosis-Noonan syndrome (NFNS), a rare autosomal-dominant hereditary disease, is characterized by clinical manifestations of both neurofibromatosis type 1 ( NF1 ) and NS. We present a case of NFNS with short stature caused by a heterozygous nonsense variant of the NF1 gene. A 12-year-old boy was admitted because of short stature, numerous café-au-lait spots, low-set and posteriorly rotated ears, sparse eyebrows, broad forehead, and inverted triangular face. Cranial and spinal magnetic resonance imaging showed abnormal nodular lesions. Molecular analysis revealed a novel heterozygous c.6189 C > G (p.(Tyr2063*)) variant in the NF1 gene. The patient was not prescribed recombinant growth hormone (GH) therapy because exogenous GH may have enlarged the abnormal skeletal lesions. During follow-up, Lisch nodules were found in the ophthalmologic examination. NFNS, a variant form of NF1 , is caused by heterozygous mutations in the NF1 gene. The mechanism of GH deficiency caused by NF1 is still unclear. Whether NFNS patients should be treated with exogenous GH remains controversial., Competing Interests: Conflict of interest: None declared, (©Copyright 2023 by Turkish Society for Pediatric Endocrinology and Diabetes / The Journal of Clinical Research in Pediatric Endocrinology published by Galenos Publishing House.)

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder primarily characterized by multiple café-au-lait macules, peripheral neurofibromas, skinfold freckling, and Lisch nodules. The causative genetic factor is the neurofibromin 1 gene (NF1), which encodes a Ras GTPase-activating protein called neurofibromin. NF1 variants may lead to loss of neurofibromin function and activation of downstream cell growth. This study aims to discover the disease-causing variants responsible for NF1 in two Han Chinese families by using exome sequencing combined with Sanger sequencing. A recurrent missense variant c.269T>C (p.Leu90Pro) and a novel nonsense variant c.2993dupA (p.Tyr998*) in the NF1 gene were identified. These variants co-segregated with the disorder in the pedigrees and were absent in the normal controls. The results broaden the NF1 mutation spectrum responsible for NF1. This may be helpful in genetic counseling, clinical management, and gene-targeted therapies for NF1. [ABSTRACT FROM AUTHOR]

Neurofibromatosis (NF) is a clinically heterogeneous autosomal dominant disorder. Three distinct forms have been identified: neurofibromatosis type 1 (NF1), type 2 (NF2) and schwannomatosis. In the present study, we report clinical and genetic findings in the NF1 and NF2 genes in a cohort of 27 Bulgarian patients, with 18 cases (67%) genetically verified. Both NF1 and NF2 genes were screened by Sanger sequencing on DNA samples. The Sanger negative samples were screened by Multiplex Ligation-dependent Probe Amplification (MLPA) for deletions and duplications. The results from genetic testing revealed three novel mutations and fifteen previously reported ones (13 in the NF1 gene and 2 in the NF2 gene). The novel variants in the NF1 gene are a splice site mutation c.4725-1G>A, a small deletion of five bases c.823delATCTT, p.Leu275ValfsTer14, and a single base duplication c.6547dupC, p.Arg2183ProfsTer11. The novel splice site mutation is manifested by multiple 'café au lait' macules and neurofibromas. Both novel out of frame mutations were found in patients with multiple 'café au lait' spots and focal epilepsy. A segmental neurofibromatosis (S NF1) is restricted to one or more body segments. Here we present a case with S NF1 caused by a somatic deletion of exons 1 to 12 of the NF1 gene which is manifested by multiple neurofibromas in the right hand. Two nonsense mutations are found in the NF2 gene. Our study adds three novel mutations to the NF1 mutation spectra and contributes to the clinical-genetic NF1-characterization. Here we report strikingly different phenotypic spectra caused by the same mutation in a single family. Our findings contribute to the genotype- phenotype correlations which are difficult to establish, due to the extremely complex NF phenotype being a combination of clinical features. [ABSTRACT FROM AUTHOR]