Mutations In NF1 Gene Research Articles

Generation of an induced pluripotent stem cell line from a type 1 neurofibromatosis patient with NF1 mutation

A human induced pluripotent stem cell (iPSC) line was generated from patient with type 1 neurofibromatosis (NF-1), carrying heterozygous mutation in NF1 gene. Peripheral blood mononuclear cells (PBMCs) were reprogrammed using non-integrating delivery of KFL4, OCT4, SOX2, BCL-XL and c-MYC. The iPSC line expresses pluripotency markers, displays a normal karyotype, and is able to differentiate into three germ layers in vitro. This iPSC line represents a valuable cell model for NF1 in humans.

The NF1 gene mutations and co-mutations in lung adenocarcinomas with brain metastasis.

The co-occurrence of lung adenocarcinoma and brain metastasis remains a significant cause of morbidity and mortality despite advancements in cancer treatment. The activity of neurofibromin, the product of Neurofibromatosis Type 1 gene (NF1), is crucial in regulating the RAS/MAPK pathway. The NF1 somatic mutations are significant in conditions such as melanoma, lung cancer, breast cancer, neuroblastoma, and central nervous system tumors. Therefore, this research aims to uncover the profile of NF1 mutations and co-mutations in patients with brain metastases from lung adenocarcinoma, shedding light on their role in the pathophysiology of metastatic lung cancer. In this study, a total of 131 (31 females, 90 males) patients diagnosed with metastatic lung adenocarcinoma who were examined in the Molecular Pathology Laboratory between 2019 and 2022 were retrospectively analyzed. The NF1 somatic mutations and co-mutations were evaluated using the NGS lung panel on the MiniSEQ NGS platform. The average age of the 131 patients (31 females, 90 males) retrospectively examined in the study was 62.05 years. The ages of the cases included in the study followed a normal distribution according to Kolmogorov-Smirnov test (P = 0.200). Lymph node metastasis was detected in 48 patients (36.6%), while distant organ metastasis was observed in 81 patients (61.83%). Metastases were more frequently seen in males. No statistically significant difference was found between metastases and gender (P > 0.05). Distant organ metastasis (n = 26, 19.8%) and NF1 mutations (n = 8/26, 30.77%) were most commonly observed in the brain. The most common NF1 pathogenic variants in brain metastases were c.2325 + 3A > G (p.M1205fs*12) (n = 6/26, 23.07%) and c.1400C > T (p.T4671) (n = 5/26, 19.23%). There was no statistically significant relationship observed between patients' age, gender, brain metastasis, and NF1 mutation types (respectively, P = 0.98, P = 0.63, and P = 0.87). The mutations that showed the most association with NF1 mutations in brain metastases were PTEN and TP53. Somatic NF1 mutations and co-mutations can play a critical driving force in metastatic lung adenocarcinoma and may contribute to treatment resistance. The mutational landscape of somatic NF1 mutations and co-mutations can provide new insights into the pathophysiology of metastatic lung cancer, especially those that have metastasized to the brain.

The Nf1-Q181X point mutation induces M2 macrophage polarization via the AKT/STAT pathway to promote smooth muscle cell proliferation and migration.

Increased case reports have shown that patients with NF1 have an increased risk of extensive vascular vasculopathy. Previous studies demonstrated the presence of macrophages and smooth muscle cells in the neoplastic intima of carotid arteries after injury in Nf1+/- mice. However, whether NF1 gene mutations affect macrophage polarization and macrophage-smooth muscle cell interactions remains to be elucidated. Scratch assay and transwell assay were utilized to detect cell migration ability. The dye 2',7'dichlorofluorescin diacetate and neutral red stain were used to assess intracellular ROS production and cell phagocytosis function, respectively. Proteins and mRNA expression were determined by western blot, RT-qPCR, and immunofluorescence. Finally, the macrophage (MAC) and vascular smooth muscle cell (VSMC) co-culture system was used to detect cellular crosstalk. Cell function assays confirmed that the Nf1-Q181X point mutation attenuated the phagocytosis of bone marrow-derived macrophages (BMDMs) and promoted the migration and ROS production of BMDMs. Moreover, we found that the Nf1-Q181X point mutation inhibited M1 but promoted M2 macrophage polarization by down-regulating p38, ERK, and JNK and up-regulating the Akt/STAT3 signaling pathway, respectively. Furthermore, in the MAC-VSMC co-culture system, we demonstrated that Nf1-Q181X point mutation-activated M2 BMDMs promoted proliferation and migration of VSMCs and induced the transformation of VSMCs from contractile phenotype to synthetic phenotype. The findings suggest that the Nf1-Q181X point mutation can mediate macrophage polarization and promote smooth muscle cell proliferation and migration, providing clinical clues for the treatment of NF1-complicated vasculopathy.

Succinate dehydrogenase A deficient renal cell carcinoma: A rare renal tumor distinct from typical Succinate dehydrogenase deficient renal cell carcinoma

Succinate dehydrogenase (SDH)-deficient renal cell carcinoma (RCC) is a rare subtype of RCC classified as a molecularly defined RCC in the fifth edition of the WHO. Most gene alterations in patients with SDH-deficient RCC involve the SDHB subunit, with less involvement of the SDHC, SDHA, and SDHD subunits. Four cases of SDHA-deficient RCC have been reported in the literature, of which one case was associated with an NF2 gene mutation. Herein, we report six novel SDHA-deficient RCC cases, including two cases with NF2 gene mutations. In contrast to the typical morphology of SDH-deficient RCC, the six tumors mainly displayed glandular, sheet-like, or papillary growth patterns with prominent nucleoli (Grades 2–3), among which two cases with NF2 mutations had prominent nucleoli (Grade 3), large transparent vacuoles in the cytoplasm, and a large number of lymphocytes in the stroma. Six tumors showed negative immunohistochemical staining for SDHA and SDHB, and three cases presented with high expression of PD-L1. Second-generation sequencing revealed novel pathogenic somatic SDHA gene mutation and NF2 gene mutations in six and two tumors, respectively. Follow-up data were collected for the six patients with a follow-up time ranging from 7 to 268 months, and all six patients have survived to date. One patient received targeted therapy for tumor metastasis to the lungs after seven months, and another patient with an NF2 gene mutation received immunotherapy for lymph node metastasis revealed during surgery. SDHA-deficient RCCs with NF2 gene mutations have the ability to metastasize but might respond well to immunotherapy. For the first time, we report the largest number of SDHA-deficient RCC cases and comprehensively investigate their clinicopathological and molecular features to provide important guidance for diagnosis and clinical immunotherapy.

Multimodal Imaging of Choroidal Nodules in Neurofibromatosis Type I.

To clarify the possibilities and role of posterior segment imaging in patients with neurofibromatosis type I (NF1), and to show the prevalence of this disease in the pediatric population in Slovakia. Until recently, ophthalmologic consultations in patients with NF1 were limited mainly to the observation of Lisch nodules of the iris and the presence of optic nerve glioma. However, advances in imaging capabilities have made it possible to investigate and describe new f indings concerning the ocular manifestations of this disease. Between October 2020 and November 2021, we examined the anterior and posterior segment of 76 eyes (38 children – 12 boys and 26 girls) with genetically confirmed NF1 gene mutation at our clinic. The age of the patients ranged from 4 to 18 years. The anterior segment was checked for the presence of Lisch nodules biomicroscopically with a slit lamp. On the posterior segment, the presence of choroidal nodules was checked by various imaging methods – fundus camera, infrared confocal selective laser ophthalmoscopy, MultiColor imaging, OCT, and OCT angiography. All the patients had magnetic resonance imaging performed in order to detect potential optic nerve gliomas for the purpose of diagnosis. We observed the correlation between the patients’ age, presence of Lisch nodules and the presence of choroidal nodules. Eight patients also had other manifestations of the disease – optic nerve gliomas or microvascular changes (so-called “corkscrew” vessels). Out of 38 patients, Lisch iris nodules were present in 20 patients (53%) and choroidal nodules in 24 patients (63%). There was no positive correlation between the presence of these two manifestations within the same patient or eye, but there is a clear correlation between the presence of choroidal nodules and patient age. The results suggest that a previously unknown ocular manifestation of neurofibromatosis type I, namely choroidal nodules, has a higher prevalence than Lisch nodules also in the pediatric population and can be easily visualized using various imaging modalities. It will be important to include follow-up observation of this finding among the standard controls for ocular findings in NF1, and it will be very interesting to correlate this f inding with the exact NF1 mutation

MODL-07. NF1 MUTATION IN OLIGODENDROCYTE PRECURSOR CELLS INDUCES PRENEOPLASTIC LESIONS IN THE BRAIN

Abstract Oligodendrocyte precursor cells (OPCs) are progenitor cells that give rise to oligodendrocytes in the central nervous system throughout the lifespan. Transcriptomic and lineage tracing studies suggest that OPCs may be the putative cell of origin for many gliomas in children and adults. While children with the neurofibromatosis type 1 (NF1) cancer predisposition syndrome typically develop optic pathway and brainstem gliomas, as many as 50% of children develop gliomas in other brain regions using radiologic criteria. Relevant to these gliomas, discrete patches of hyperdense OPCs were found in the brains of Nf1+/- mice. The OPCs within the lesions display a transient increase in proliferation and hypercellularity. When the brains of mice carrying different heterozygous NF1 patient derived germline Nf1 gene mutations were examined, hyperdense OPC lesions were only seen in mice whose Nf1 mutations also predispose to optic gliomas. Mechanistically, monoallelic KRAS hyperactivation also results in similar OPC hyperdense lesions. Moreover, OPC-specific Nf1-heterozygous mice display similar lesions, while OPC-specific Nf1-knockout results in generalized OPC hyperdensity throughout the entire brain. Taken together, these data suggest the existence of a preneoplastic state conferred by Nf1 mutation in OPCs and establish a tractable model system to explore the transition to glioma in children with NF1.

Molecular profiles of different PD-L1 expression in patients with esophageal squamous cell carcinoma

ABSTRACT Background PD-1/PD-L1 inhibitors are approved treatments for patients with esophageal squamous cell carcinoma (ESCC). The present investigation aspired to explore the interrelation between molecular phenotype and PD-L1 expression in ESCC. Methods PD-L1 testing and targeted next-generation sequencing (NGS) were performed on tumoral tissues from 139 ESCC patients. Tumor-infiltrating lymphocytes (TILs) were scrutinized using a tyramide signal amplification system combined with immunohistochemistry. Results Among enrolled patients, 36.7% displayed high PD-L1 expression (combined positive score [CPS] ≥10). BRCA1 and NF1 gene mutations were significantly associated with high PD-L1 expression (p < .05) while TGFβ pathway alterations were linked to low PD-L1 expression (p = .02). High copy number instability (CNI) and copy number alterations (CNA) were correlated with low PD-L1 expression. Patients with CDKN2A deletion exhibited higher PD-L1 expression. Varying types of TILs were observed across different PD-L1 expression groups. The ratio of CD8+PD-L1+ T cells and CD8+PD-1+ T cells to CD8+ T cells remained comparable in both tumoral and stromal regions, but the ratio of CD68+PD-L1+ macrophages to CD68+ macrophages was higher than the ratio of CD68+PD-1+ macrophages to CD68+ macrophages. CPS was significantly correlated with PD-L1+ lymphocytes and CD68+ macrophages in the tumoral region. CD8+ T cell infiltration was positively correlated with PD-1+ cells in both tumoral and stromal regions. Conclusion In this study, we presented the prevalence rates of PD-L1 expression in Chinese ESCC patients. The association of genetic profiles with PD-L1 expression levels also provide the clue that genomic phenotype may interact with the immunologic phenotype in ESCC.

INTEGRATIVE ANALYSIS OF DIFFERENTIALLY REGULATED PROTEINS IN MENINGIOMA

Abstract AIMS Meningiomas are common primary intracranial tumours that arise from meninges. loss of chromosome 22q is common genetic event observed in meningiomas. About 50% of meningiomas harbour mutations in NF2 gene that resides on chromosome 22. Moreover, frequent mutations have been observed in AKT1, KLF4, TRAF7, and SMO genes. Meningiomas are divided into different genomic subgroups that express unique proteomic profiles. This study aims to investigate genomic background of meningioma and to determine the impact of mutations on underlying protein expression to identify druggable targets. METHOD Total 96 meningioma samples were sequenced using Illumina TruSight Oncology 500 panel. The raw sequence data was analyzed using TSO500 App. The variant data was annotated using Cancer Genome Interpreter and ANNOVAR. Clinical enrichment analysis was performed to investigate common pathways. Genomic data was correlated with LC-MS based proteomic data to determine variants effect on downstream processes. RESULTS Results showed an average of 1083 total and 7 driver mutations per sample. NF2 gene was found among highly mutated genes in tumour samples. Almost all NF2 mutations were frameshift, splice site and nonsense mutations, previously reported to be associated with high rate of multiple and recurring meningiomas. Additionally, driver mutations were identified in known meningioma genes including AKT1, KLF4, and TRAF7 along with previously unpublished mutations in ERBB2, MET, ARID5B, etc. The results correlate with tumour location, grade, and histopathological subtype. CONCLUSIONS The study identified common as well as unique driver mutations in meningioma samples. After functional validation, novel driver mutations could further enhance personalized treatment for meningioma patients.

Recurrent CYP2A6 gene mutation in biphasic hyalinizing psammomatous renal cell carcinoma: Additional support of three cases.

Biphasic hyalinizing psammomatous renal cell carcinoma (BHP RCC) with NF2 gene mutations is a newly described provisional category of renal cell carcinoma (RCC). Here we described three additional cases of BHP RCC with CYP2A6 gene mutation besides NF2 gene. The carcinomas were predominantly unencapsulated, and two of them had a rounded, nodular interface with the native kidney while one had perirenal adipose tissue invasion. Histopathologically, all neoplasms had a characteristic biphasic appearance of smaller cells clustering around basement membrane material within larger acini, forming pseudorosettes or a glomeruloid pattern. The smaller cells were focally spindle-shaped in two carcinomas. Psammoma bodies were shown in two carcinomas. Cellular necrosis and perineural invasion was identified in one case. Immunohistochemically, Vimentin, EMA, P504s were extensively expressed while RCC and CD10 were only expressed in larger cells. CK7 was positive in one tumor. CYP2A6 gene mutation (CYP2A6 NM_000762.6: exon4:c.A580G:p.K194E) was revealed in three tumors by Whole-genome exome sequencing, which was further confirmed by Sanger sequencing. Only one case harbored a somatic termination mutation in NF2 gene. NF2 promoter methylation was observed in the other two cases. Clinically, one patient died of disease with widespread bone metastases confirmed by biopsy at the ninth month after surgery but the other two patients had no evidence of recurrence or metastases (follow-up period 9-90 months). Our findings validated previously described clinicopathological features and NF2 gene mutation or promoter methylation of BHP RCC. In addition, we reported different IHC pattern of BHP RCC and further revealed the recurrent CYP2A6 genetic alteration.

Abstract IA014: Mass spectrometry and RNAseq based discovery of frameshift neoantigens and cryptic neoantigens from malignant peripheral nerve sheath tumors for prophylactic vaccines

Abstract Neurofibromatosis type 1 (NF1) syndrome is an autosomal, dominant tumor predisposition syndrome caused by loss-of-function mutations of NF1 gene encoding neurofibromin. Loss of the non-mutant allele of NF1 in a rare Schwann cell or precursor leads to benign plexiform neurofibromas. The main cause of death among NF1 patients is the malignant peripheral nerve sheath tumor (MPNST), a highly aggressive soft tissue sarcoma that most likely develops from plexiform neurofibroma, in particular the so-called “atypical” plexiform neurofibroma. Approximately half of MPNSTs are NF1-associated, and NF1 patients have ~15% lifetime risk of developing this terrible cancer. NF1 patients could greatly benefit from prophylactic vaccination that would prevent the malignant transformation to MPNSTs. We hypothesize that malignant transformation leads to the expression of recurrent alternately processed transcripts, such as transcriptionally-induced chimeras, that could express neoantigens and be used as targets for prophylactic vaccines. Such transcripts can be translated to produce novel peptides downstream of frameshift mutations caused by coding exon read-through into introns, mis-splicing from a coding exon to a non-canonical splice acceptors or splice acceptors in other genes. In most cases, a premature termination codon (PTC) will be rapidly encountered by the ribosome translating such transcripts. Therefore, we furthermore hypothesize that these alternately processed transcripts can express what we call “cryptic” neoantigens when treated with drugs that suppress utilization of premature codons such as Ataluren or gentamicin. In such a way, we could administer a prophylactic vaccine and induce conditionally active immune response that would eliminate nascent tumors only when drug treatment is used. We have developed a PTC suppression read-through reporter which results in presentation of the SIINFEKL peptide on C57BL6/J tumor cells. We developed a bioinformatic algorithm that takes deep RNA-seq data and identifies candidate neoepitopes encoded by non-normally processed or mutant mRNAs called Identifying and Verifying Immunogenic Neoepitopes and Neojunctions (IVINN). We have also achieved successful purification of human HLA Class I complex using an anti-pan HLA antibody column, and bound peptides have been isolated and identified by liquid chromatography tandem mass spectrometry (LC-MS/MS). We plan to utilize these approaches for mouse model and human MPNST patient derived xenografts. Citation Format: David A. Largaespada. Mass spectrometry and RNAseq based discovery of frameshift neoantigens and cryptic neoantigens from malignant peripheral nerve sheath tumors for prophylactic vaccines [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA014.

A novel NF1 mutation in a pediatric patient with renal artery aneurysm

BackgroundNeurofibromatosis type 1 (NF1) is a neurocutaneous syndrome, due to heterozygous pathogenic variants in NF1 gene. The main clinical manifestations are multiple café au lait spots, axillary and inguinal freckling, cutaneous and plexiform neurofibromas, optic glioma, Lisch nodules and osseous lesions, such as sphenoid and tibial dysplasia. Vasculopathy is another feature of NF1; it consists of stenosis, aneurysms, and arteriovenous malformations, frequently involving renal arteries.Case presentationWe report on a 9-year-old girl with a novel mutation in NF1 gene and renal artery aneurysm, treated by coil embolization and complicated with hypertension.ConclusionVasculopathy is a complication of NF1, affecting from 0.4 to 6.4% of patients with NF1. Among the vascular abnormalities, renal artery aneurysm is a rare manifestation, with only a few cases regarding adult patients and no pediatric reports described in current literature. The finding of a vascular abnormality in a specific site requires the evaluation of the entire vascular system because multiple vessels could be involved at the same time.

NEUROFIBROMATOSIS ASSOCIATED DIFFUSE CYSTIC LUNG DISEASE

Neurobromatosis is an autosomal dominant disorder of neuroectodermal and mesenchymal origin, also known as Von Rechlinghausen disorder. It can also occur inherited or sporadically. A mutation of NF1 gene on chromosome 17q11.2 has been recognized as a disease prompter, and the spectrum of clinical phenotype is wide because of gene complexity, size and diversity of exons. In our article we are presenting a case of neurobromatosis associated with diffuse cystic lung disease.

Abstract 4000: ERBB4 is sufficient and necessary for proliferation of BRAF WT melanoma cell lines

Abstract Approximately 50% of metastatic melanomas possess wild-type (WT) BRAF alleles. These BRAF-WT tumors are a significant clinical problem, despite the fact that these tumors commonly possess mutations in NF1 or RAS genes, as there are no targeted therapeutics for these tumors. Here we demonstrate that ERBB4 is sufficient and necessary for proliferation of BRAF WT melanoma cell lines, suggesting that disrupting ERBB4 signaling may be effective against BRAF WT melanomas. ERBB4 (HER4) is a member of the ERBB family of receptor tyrosine kinases, which includes the epidermal growth factor receptor (EGFR/ERBB1/HER1), ERBB2 (Neu/HER2), and ERBB3 (HER3). EGFR and ERBB2 are validated targets in a variety of solid tumors, whereas the roles that ERBB4 plays in human malignancies are ambiguous. Our previous in silico analyses of BRAF-WT tumor genomes in The Cancer Genome Atlas skin cutaneous melanoma (TCGA-SKCM) dataset suggest that ERBB4 mutation or overexpression cooperates with NF1 or RAS gene mutations to drive melanomas via activation of the PI3 kinase/AKT signaling pathway. These in silico analyses have also enabled us to prioritize the ERBB4 mutants found in BRAF-WT melanomas. We have tested this hypothesis using a panel of human BRAF-WT melanoma cell lines. We have shown that expression of wild-type ERBB4 causes increased clonogenic proliferation, whereas expression of a dominant-negative ERBB4 mutant (K751M) causes decreased clonogenic proliferation. These data indicate that ERBB4 is sufficient and necessary for clonogenic proliferation of BRAF-WT melanoma cell lines. Analgous studies are testing whether ERBB4 regulates anchorage independence in semi-solid medium and proliferation rates and saturation density in culture dishes. The BRAF-WT melanoma cell lines endogenously express ERBB4 ligands, EGFR, and ERBB2. Moreover, ERBB4 homodimers function as tumor suppressors, whereas ERBB4-EGFR and ERBB4-ERBB2 heterodimers are oncogenic. Thus, we are using gene silencing and pharmacologic tools to determine whether endogenous ERBB4 ligands, endogenous EGFR, or endogenous ERBB2 is required for the oncogenic activity of ERBB4. Furthermore, we are determining whether prioritized ERBB4 mutants found in BRAF-WT melanomas exhibit greater signaling and oncogenic activities than WT ERBB4. Consequently, these experiments will establish a functional role for ERBB4 mutations and expression in BRAF-WT melanomas and will identify potential strategies for disrupting oncogenic ERBB4 signaling in these tumors. Citation Format: Lauren M. Lucas, Vipasha Dwivedi, Rania H. Mohamedelhassan, Erin L. Harrell, Connor M. Kelley, Elizabeth L. Knerr, Jessica A. Markham, David J. Riese. ERBB4 is sufficient and necessary for proliferation of BRAF WT melanoma cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4000.

Neuronal hyperexcitability drives central and peripheral nervous system tumor progression in models of neurofibromatosis-1

Neuronal activity is emerging as a driver of central and peripheral nervous system cancers. Here, we examined neuronal physiology in mouse models of the tumor predisposition syndrome Neurofibromatosis-1 (NF1), with different propensities to develop nervous system cancers. We show that central and peripheral nervous system neurons from mice with tumor-causing Nf1 gene mutations exhibit hyperexcitability and increased secretion of activity-dependent tumor-promoting paracrine factors. We discovered a neurofibroma mitogen (COL1A2) produced by peripheral neurons in an activity-regulated manner, which increases NF1-deficient Schwann cell proliferation, establishing that neurofibromas are regulated by neuronal activity. In contrast, mice with the Arg1809Cys Nf1 mutation, found in NF1 patients lacking neurofibromas or optic gliomas, do not exhibit neuronal hyperexcitability or develop these NF1-associated tumors. The hyperexcitability of tumor-prone Nf1-mutant neurons results from reduced NF1-regulated hyperpolarization-activated cyclic nucleotide-gated (HCN) channel function, such that neuronal excitability, activity-regulated paracrine factor production, and tumor progression are attenuated by HCN channel activation. Collectively, these findings reveal that NF1 mutations act at the level of neurons to modify tumor predisposition by increasing neuronal excitability and activity-regulated paracrine factor production.

Clinical Masks of Neurofibromatosis Type 1

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.

The role of mutations in &lt;i&gt;NF1&lt;/i&gt; gene in sporadic carcinogenesis

The review article presents data on somatic inactivation of NF1 gene as a cause of sporadic malignant neoplasms. The re- lationship between the features of specific tumors in neurofibromatosis type 1 and specific types of sporadic neoplasms, in which mutations in NF1 gene are found, are presented. Evidence for the role of somatic mutations in NF1 gene in the development of chemoresistance in melanoma, neuroblastoma, ovarian and breast cancer, and lung cancer is described (only if there are no mutations of known protooncogenes). To overcome the resistance of these neoplasms, inhibitors of mitogen-activated protein kinase have been proposed, the effectiveness of which has been proven in the treatment of plexiform neurofibromas. The review presents evidence of the relationship between NF1 and microRNA, which can be used for targeted therapy of both neurofibromatosis type 1 and sporadic neoplasms with mutations of this gene. Prospects for gene therapy of these diseases are considered.

A CASE REPORT ON NEUROFIBROMATOSIS TYPE 1 IN CHILDREN

Neurofibromatosis1 is an autosomal dominant neurocutaneous disorder occurs due to mutation of NF1 gene on chromosome 172. It affects 1 in 3000 births.There is no sex or racial predilection. It is a multiorgan disease affecting nervous system ,skin and bones. Most cases with NF1 develop hyperpigmented cutaneous macule (café au lait macules),skinfold freckling,lisch nodules and dermal neurofibroma1 Here, we present a case of 4 year old boys with NF1. He was seen by many ophthalmologist outside and was diagnosed with congenital ptosis and reffered to our institute for ptosis management. Ptosis and deterioration of vision is an uncommon presentation.He presented with multiple cutaneous macules,plexiform neurofibroma, ptosis and sphenoid wing dysplasia on imaging. Here, we present a cse report on neurofibrmatosis(NF1) in a four year old child presenting in this mode. The diagnosis of NF1 was made according to the diagnostic criteria laid by National Institute of Health Consensus Development Conference1.

Clinical and radiological features of orbito-temporal neurofibromatosis

Neurofibromatosis- 1 (NF- 1) is an autosomal dominant condition belonging to the well-known group of neurocutaneous syndromes. It affects 1 in 3500 persons. It is caused by a mutation in the neurofibromin gene localized to chromosome 17q11.2. which codes for a protein involved in the normal cell cycle regulation. Therefore NF-1 gene mutations predispose the individual to various benign and malignant tumors. The diagnosis of NF-1 remains largely clinical, given its characteristic lesions. Here we describe one such case with hallmark lesions of NF-1. A 12-year-old boy presented with a slow-growing and progressive right upper lid mass causing severe drooping, vision impairment and facial disfiguration. On detailed ophthalmic examination he was found to have severe ptosis, Lisch nodules and keratoconus. A systemic examination revealed café au lait spots and axillary freckling. Radiological imaging showed sphenoid wing dysplasia, encephalocele and optic pathway glioma. The patient was taken up for debulking surgery and a referral to the neurosurgery department was sent. He has been on follow up for last 12 months. This case first presented to an ophthalmology clinic and thus, as an ophthalmologist, keeping in mind the associated intraorbital and intracranial pathology can be life-saving. A multidisciplinary approach is needed in the management of such severe cases of NF-1.

Genotype-Phenotype Associations in Patients With Type-1, Type-2, and Atypical NF1 Microdeletions.

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.

Implications of mosaicism in variant interpretation: A case of a de novo homozygous NF1 variant

Neurofibromatosis type 1 is a common multisystem autosomal dominant syndrome caused by pathogenic heterozygous variants in the neurofibromin gene (NF1). It is associated with a substantially increased cancer risk. Mosaicism for NF1 has been clinically well-established for “second hit” variants in skin lesions and tumor tissues. Here, we report on a 3-month-old boy with multiple café au lait macules (CAMs) and juvenile myelomonocytic leukemia (JMML) who was found to carry a previously established pathogenic NF1 variant (c.586+5G>A), as revealed by whole-exome sequencing. Surprisingly, however, this variant was detected in the homozygous state in the patient and was absent in the parents and siblings. Deep sequencing of this variant using blood, buccal swabs and skin samples was performed. As expected for an NF1 gene mutation promoting JMML, the variant was detected in 90.6% of the blood DNA reads, in sharp contrast to the mere 5% and 0.74% of reads in the saliva- and skin fibroblast-derived DNA, respectively. Our analysis, therefore, confirmed postzygotic origin of the variant followed by a mitotic event resulting in its homozygosity, although we could not differentiate between the possibilities of a gene conversion and mitotic crossover. Apparently de novo homozygous variants should trigger a careful investigation into mosaicism to achieve accurate interpretation.