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Bildirici Y, Kocaaga A, Karademir-Arslan CN, Yimenicioglu S. Evaluation of Molecular and Clinical Findings in Children With Neurofibromatosis Type 1: Identification of 15 Novel Variants. Pediatr Neurol 2023; 149:69-74. [PMID: 37806041 DOI: 10.1016/j.pediatrneurol.2023.08.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/25/2023] [Accepted: 08/26/2023] [Indexed: 10/10/2023]
Abstract
BACKGROUND 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.
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Affiliation(s)
- Yasar Bildirici
- Department of Pediatrics, Eskişehir City Hospital, Eskişehir, Turkey
| | - Ayca Kocaaga
- Department of Medical Genetics, Eskişehir City Hospital, Eskişehir, Turkey.
| | | | - Sevgi Yimenicioglu
- Department of Pediatric Neurology, Eskişehir City Hospital, Eskişehir, Turkey
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Leite Rocha D, Ashton-Prolla P, Rosset C. Reviewing the occurrence of large genomic rearrangements in patients with inherited cancer predisposing syndromes: importance of a comprehensive molecular diagnosis. Expert Rev Mol Diagn 2022; 22:319-346. [PMID: 35234551 DOI: 10.1080/14737159.2022.2049247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Hereditary cancer predisposition syndromes are caused by germline pathogenic or likely pathogenic variants in cancer predisposition genes (CPG). The majority of pathogenic variants in CPGs are point mutations, but large gene rearrangements (LGRs) are present in several CPGs. LGRs can be much more difficult to characterize and perhaps they may have been neglected in molecular diagnoses. AREAS COVERED We aimed to evaluate the frequencies of germline LGRs in studies conducted in different populations worldwide through a qualitative systematic review based on an online literature research in PubMed. Two reviewers independently extracted data from published studies between 2009 and 2020. In total, 126 studies from 37 countries and 5 continents were included in the analysis. The number of studies in different continents ranged from 3 to 48 and for several countries there was an absolute lack of information. Asia and Europe represented most of the studies, and LGR frequencies varied from 3.04 to 15.06% in different continents. MLPA was one of the methods of choice in most studies (93%). EXPERT OPINION The LGR frequencies found in this review reinforce the need for comprehensive molecular testing regardless of the population of origin and should be considered by genetic counseling providers.
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Affiliation(s)
- Débora Leite Rocha
- Laboratório de Medicina Genômica, Serviço de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre (HCPA), Rua Ramiro Barcelos, 2350, CEP: 90035-930, Porto Alegre, Rio Grande do Sul, Brazil
| | - Patrícia Ashton-Prolla
- Laboratório de Medicina Genômica, Serviço de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre (HCPA), Rua Ramiro Barcelos, 2350, CEP: 90035-930, Porto Alegre, Rio Grande do Sul, Brazil.,Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil. Av. Bento Gonçalves, 9500 - Prédio 43312 M, CEP: 91501-970, Caixa Postal 1505, Porto Alegre, Rio Grande do Sul, Brazil.,Serviço de Genética Médica, HCPA, Rio Grande do Sul, Brazil. Rua Ramiro Barcelos, 2350, CEP: 90035-930, Porto Alegre, Rio Grande do Sul, Brazil
| | - Clévia Rosset
- Laboratório de Medicina Genômica, Serviço de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre (HCPA), Rua Ramiro Barcelos, 2350, CEP: 90035-930, Porto Alegre, Rio Grande do Sul, Brazil
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Ece Solmaz A, Isik E, Atik T, Ozkinay F, Onay H. Mutation spectrum of the NF1 gene and genotype-phenotype correlations in Turkish patients: Seventeen novel pathogenic variants. Clin Neurol Neurosurg 2021; 208:106884. [PMID: 34418705 DOI: 10.1016/j.clineuro.2021.106884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 08/05/2021] [Accepted: 08/07/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVE Neurofibromatosis type 1 is one of the most common autosomal dominant diseases caused by heterozygous mutation in the NF1 gene. Wide spectrum of NF1-related clinical manifestations and mutation distribution makes genetic counselling difficult. METHODS The study enrolled 58 unrelated Turkish patients with clinically suspected NF1 referred to the Department of Medical Genetics. Individuals were eligible if they 1) met at least two of the main National Institutes of Health criteria or 2) had multiple café-au-lait macules as a child. RESULTS Fourty-one different disease-causing variants were identified in 42 (72.4%) individuals, including 17 novel variants. Twenty-four (58.2%) of the NF1 patients had de novo variants. Café-au-lait macules were observed in all patients (100%). Intracranial hamartoma was the second most common phenotype, found in 52.3% (22/42) of the patients. Other common manifestations were neurofibromas (35.7%), axillary or inguinal freckling (28.5%), and Lisch nodules (28.5%). Additionally, one patient had intra-abdominal malignant peripheral nerve sheath tumours and another patient underwent surgery for serous papillary ovarian cancer. CONCLUSION In conclusion, this study is one of the largest studies from Turkey to investigate the NF1 mutation spectrum and genotype-phenotype correlations.
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Affiliation(s)
- Asli Ece Solmaz
- Ege University Faculty of Medicine, Department of Medical Genetics, Izmir, Turkey.
| | - Esra Isik
- University Faculty of Medicine, Department of Pediatrics, Division of Pediatric Genetics, Izmir, Turkey
| | - Tahir Atik
- University Faculty of Medicine, Department of Pediatrics, Division of Pediatric Genetics, Izmir, Turkey
| | - Ferda Ozkinay
- University Faculty of Medicine, Department of Pediatrics, Division of Pediatric Genetics, Izmir, Turkey
| | - Huseyin Onay
- Ege University Faculty of Medicine, Department of Medical Genetics, Izmir, Turkey
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Deletion of the whole NF1 gene in a three-generation family with neurofibromatosis type 1. Neurol Sci 2021; 43:1295-1301. [PMID: 34089417 DOI: 10.1007/s10072-021-05353-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 05/27/2021] [Indexed: 02/05/2023]
Abstract
BACKGROUND Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous disorder characterized by café-au-lait macules (CALMs), skinfold freckling, Lisch nodules, and neurofibromas. It is associated with heterozygous mutations in the neurofibromatosis type 1 (NF1) gene. Whole NF1 deletion has been described in some cases, but most cases are sporadic, and familial forms are extremely rare. To date, only two-generation familial forms have been described. OBJECTIVE To describe a whole NF1 gene deletion in a three-generation family with neurofibromatosis type 1. METHODS Physical examinations, laboratory tests, structural neuroimaging studies, whole-exome sequencing, and multiplex ligation-dependent probe amplification analysis were carried out. RESULTS All the affected individuals within this three-generation family, including the 14-year-old female proband, her 40-year-old father, and 63-year-old grandmother, exhibited such typical manifestations of NF1 as CALMs and cutaneous neurofibromas, CALMs increased in size with age. The affected subjects had more localized hyperpigmentation and CALMs within the lesion areas, mainly in the chest, abdomen, waist, and back. In addition, learning disorder was observed in the proband, and brain MRI revealed abnormal high signal lesions in the brainstem. All the affected subjects had normal birth history and had no significant past medical history. Whole-exome sequencing and subsequent multiplex ligation-dependent probe amplification analysis identified deletion of the whole NF1 gene, co-segregating with the NF1 phenotype in an autosomal dominant pattern. CONCLUSIONS Our findings are the first to identify whole NF1 deletion in a three-generation family with autosomal dominant NF1 and broaden the understanding of the genetic spectrum of NF1-associated NF1.
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Evaluation of clinical findings and neurofibromatosis type 1 bright objects on brain magnetic resonance images of 60 Turkish patients with NF1 gene variants. Neurol Sci 2021; 42:2045-2057. [PMID: 33443663 DOI: 10.1007/s10072-020-04988-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 12/11/2020] [Indexed: 12/13/2022]
Abstract
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.
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Bianchessi D, Ibba MC, Saletti V, Blasa S, Langella T, Paterra R, Cagnoli GA, Melloni G, Scuvera G, Natacci F, Cesaretti C, Finocchiaro G, Eoli M. Simultaneous Detection of NF1, SPRED1, LZTR1, and NF2 Gene Mutations by Targeted NGS in an Italian Cohort of Suspected NF1 Patients. Genes (Basel) 2020; 11:genes11060671. [PMID: 32575496 PMCID: PMC7349720 DOI: 10.3390/genes11060671] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 06/12/2020] [Accepted: 06/16/2020] [Indexed: 12/30/2022] Open
Abstract
Neurofibromatosis type 1 (NF1) displays overlapping phenotypes with other neurocutaneous diseases such as Legius Syndrome. Here, we present results obtained using a next generation sequencing (NGS) panel including NF1, NF2, SPRED1, SMARCB1, and LZTR1 genes on Ion Torrent. Together with NGS, the Multiplex Ligation-Dependent Probe Amplification Analysis (MLPA) method was performed to rule out large deletions/duplications in NF1 gene; we validated the MLPA/NGS approach using Sanger sequencing on DNA or RNA of both positive and negative samples. In our cohort, a pathogenic variant was found in 175 patients; the pathogenic variant was observed in NF1 gene in 168 cases. A SPRED1 pathogenic variant was also found in one child and in a one year old boy, both NF2 and LZTR1 pathogenic variants were observed; in addition, we identified five LZTR1 pathogenic variants in three children and two adults. Six NF1 pathogenic variants, that the NGS analysis failed to identify, were detected on RNA by Sanger. NGS allows the identification of novel mutations in five genes in the same sequencing run, permitting unambiguous recognition of disorders with overlapping phenotypes with NF1 and facilitating genetic counseling and a personalized follow-up.
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Affiliation(s)
- Donatella Bianchessi
- Molecular Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy; (D.B.); (M.C.I.); (S.B.); (T.L.); (R.P.); (G.F.)
| | - Maria Cristina Ibba
- Molecular Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy; (D.B.); (M.C.I.); (S.B.); (T.L.); (R.P.); (G.F.)
| | - Veronica Saletti
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy; (V.S.); (G.M.)
| | - Stefania Blasa
- Molecular Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy; (D.B.); (M.C.I.); (S.B.); (T.L.); (R.P.); (G.F.)
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza dell’Ateneo Nuovo, 1, 20126 Milan, Italy
| | - Tiziana Langella
- Molecular Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy; (D.B.); (M.C.I.); (S.B.); (T.L.); (R.P.); (G.F.)
- Molecular Immunology Unit, Department of Research, Fondazione IRCCS Istituto Nazionale dei Tumori, Via Venezian, 20133 Milan, Italy
| | - Rosina Paterra
- Molecular Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy; (D.B.); (M.C.I.); (S.B.); (T.L.); (R.P.); (G.F.)
| | - Giulia Anna Cagnoli
- Medical Genetics Unit, Woman-Child-Newborn Department, Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, via Francesco Sforza 28, 20122 Milan, Italy; (G.A.C.); (F.N.); (C.C.)
| | - Giulia Melloni
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy; (V.S.); (G.M.)
| | - Giulietta Scuvera
- Pediatric Highly Intensive Care Unit, Università degli Studi di Milano, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, via Francesco Sforza 28, 20122 Milan, Italy;
| | - Federica Natacci
- Medical Genetics Unit, Woman-Child-Newborn Department, Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, via Francesco Sforza 28, 20122 Milan, Italy; (G.A.C.); (F.N.); (C.C.)
| | - Claudia Cesaretti
- Medical Genetics Unit, Woman-Child-Newborn Department, Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, via Francesco Sforza 28, 20122 Milan, Italy; (G.A.C.); (F.N.); (C.C.)
| | - Gaetano Finocchiaro
- Molecular Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy; (D.B.); (M.C.I.); (S.B.); (T.L.); (R.P.); (G.F.)
| | - Marica Eoli
- Molecular Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20133 Milan, Italy; (D.B.); (M.C.I.); (S.B.); (T.L.); (R.P.); (G.F.)
- Correspondence:
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Melloni G, Eoli M, Cesaretti C, Bianchessi D, Ibba MC, Esposito S, Scuvera G, Morcaldi G, Micheli R, Piozzi E, Avignone S, Chiapparini L, Pantaleoni C, Natacci F, Finocchiaro G, Saletti V. Risk of Optic Pathway Glioma in Neurofibromatosis Type 1: No Evidence of Genotype-Phenotype Correlations in A Large Independent Cohort. Cancers (Basel) 2019; 11:cancers11121838. [PMID: 31766501 PMCID: PMC6966666 DOI: 10.3390/cancers11121838] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 11/17/2019] [Accepted: 11/18/2019] [Indexed: 11/16/2022] Open
Abstract
The occurrence of optic pathway gliomas (OPGs) in children with neurofibromatosis type 1 (NF1) still raises many questions regarding screening and surveillance because of the lack of robust prognostic factors. Recent studies of an overall cohort of 381 patients have suggested that the genotype may be the main determinant of the development of OPG, with the risk being higher in patients harbouring NF1 mutations in the 5’ tertile and the cysteine/serine-rich domain. In an attempt to confirm this hypothesis, we used strict criteria to select a large independent cohort of 309 NF1 patients with defined constitutional NF1 mutations and appropriate brain images (255 directly enrolled and 54 as a result of a literature search). One hundred and thirty-two patients had OPG and 177 did not. The association of the position (tertiles and functional domains) and type of NF1 mutation with the development of OPG was analysed using the χ2 test and Fisher’s exact probability test; odds ratios (ORs) with 95% confidence intervals were calculated, and Bonferroni’s correction for multiple comparisons was applied; multiple logistic regression was also used to study genotype–phenotype associations further. Our findings show no significant correlation between the site/type of NF1 mutation and the risk of OPG, and thus do not support the hypothesis that certain constitutional mutations provide prognostic information in this regard. In addition, we combined our cohort with a previously described cohort of 381 patients for a total of 690 patients and statistically re-analysed the results. The re-analysis confirmed that there were no correlations between the site (tertile and domain) and the risk of OPG, thus further strengthening our conclusions.
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Affiliation(s)
- Giulia Melloni
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20121 Milan, Italy; (G.M.); (S.E.); (C.P.)
| | - Marica Eoli
- Molecular Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20121 Milan, Italy; (M.E.); (D.B.); (M.C.I.); (G.F.)
| | - Claudia Cesaretti
- Medical Genetics Unit, Woman-Child-Newborn Department, Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, via Francesco Sforza 28, 20122 Milan, Italy; (C.C.); (F.N.)
| | - Donatella Bianchessi
- Molecular Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20121 Milan, Italy; (M.E.); (D.B.); (M.C.I.); (G.F.)
| | - Maria Cristina Ibba
- Molecular Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20121 Milan, Italy; (M.E.); (D.B.); (M.C.I.); (G.F.)
| | - Silvia Esposito
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20121 Milan, Italy; (G.M.); (S.E.); (C.P.)
| | - Giulietta Scuvera
- Department of Pathophysiology and Transplantation, Pediatric Highly Intensive Care Unit, Università degli Studi di Milano, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, via Francesco Sforza 28, 20122 Milan, Italy;
| | - Guido Morcaldi
- Paediatric Neurology and Neuromuscular Disorders, University of Genoa and Istituto Giannina Gaslini, Via Gerolamo Gaslini 5, 16147 Genoa, Italy;
| | - Roberto Micheli
- Pediatric Neuropsychiatry, Spedali Civili of Brescia, Piazzale Spedali Civili 1, 25125 Brescia, Italy;
| | - Elena Piozzi
- Pediatric Department, ASST Grande Ospedale Metropolitano Niguarda, Piazza Ospedale Maggiore 3, 20162 Milan, Italy;
| | - Sabrina Avignone
- Neuroradiology Department, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, University of Milan, via Francesco Sforza 28, 20122 Milan, Italy;
| | - Luisa Chiapparini
- Neuroradiology Department, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20121 Milan, Italy;
| | - Chiara Pantaleoni
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20121 Milan, Italy; (G.M.); (S.E.); (C.P.)
| | - Federica Natacci
- Medical Genetics Unit, Woman-Child-Newborn Department, Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, via Francesco Sforza 28, 20122 Milan, Italy; (C.C.); (F.N.)
| | - Gaetano Finocchiaro
- Molecular Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20121 Milan, Italy; (M.E.); (D.B.); (M.C.I.); (G.F.)
| | - Veronica Saletti
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, 20121 Milan, Italy; (G.M.); (S.E.); (C.P.)
- Correspondence:
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Phenotypic expression of a spectrum of Neurofibromatosis Type 1 (NF1) mutations identified through NGS and MLPA. J Neurol Sci 2018; 395:95-105. [PMID: 30308447 DOI: 10.1016/j.jns.2018.10.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 09/06/2018] [Accepted: 10/02/2018] [Indexed: 12/17/2022]
Abstract
Neurofibromatosis Type 1 (NF1) is caused by mutations of the NF1 gene. The aim of this study was to identify the genetic causes underlying the disease, attempt possible phenotype/genotype correlations and add to the NF1 mutation spectrum. A screening protocol based on genomic DNA was established in 168 patients, encompassing sequencing of all coding exons and adjoining introns using a custom targeted next generation sequencing protocol and subsequent confirmation of findings with Sanger sequencing. MLPA was used to detect deletions/duplications and positive findings were confirmed by RNA analysis. All novel findings were evaluated according to ACMG Standards and guidelines for the interpretation of sequence variants with the aid of in-silico bioinformatic tools and family segregation analysis. A germline variant was identified in 145 patients (86%). In total 49 known and 70 novel variants in coding and non-coding regions were identified. Seven patients carried whole or partial gene deletions. NF1 patients, present with high phenotypic variability even in cases where the same germline disease causing variant has been identified. Our findings will contribute to a better knowledge of the genetic causes and the phenotypic expression related to the disease.
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Clinical and molecular characterization of 112 single-center patients with Neurofibromatosis type 1. Ital J Pediatr 2018; 44:45. [PMID: 29618358 PMCID: PMC5885309 DOI: 10.1186/s13052-018-0483-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 03/22/2018] [Indexed: 11/13/2022] Open
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.
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