scholarly journals Atypical NF1 Microdeletions: Challenges and Opportunities for Genotype/Phenotype Correlations in Patients with Large NF1 Deletions

Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1639
Author(s):  
Hildegard Kehrer-Sawatzki ◽  
Ute Wahlländer ◽  
David N. Cooper ◽  
Victor-Felix Mautner
Keyword(s):  
Developmental Delay ◽  
Cognitive Abilities ◽  
Clinical Manifestations ◽  
Gene Mutations ◽  
Neurofibromatosis Type ◽  
Global Developmental Delay ◽  
Protein Coding ◽  
Protein Coding Genes ◽  
Nf1 Gene

Patients with neurofibromatosis type 1 (NF1) and type 1 NF1 deletions often exhibit more severe clinical manifestations than patients with intragenic NF1 gene mutations, including facial dysmorphic features, overgrowth, severe global developmental delay, severe autistic symptoms and considerably reduced cognitive abilities, all of which are detectable from a very young age. Type 1 NF1 deletions encompass 1.4 Mb and are associated with the loss of 14 protein-coding genes, including NF1 and SUZ12. Atypical NF1 deletions, which do not encompass all 14 protein-coding genes located within the type 1 NF1 deletion region, have the potential to contribute to the delineation of the genotype/phenotype relationship in patients with NF1 microdeletions. Here, we review all atypical NF1 deletions reported to date as well as the clinical phenotype observed in the patients concerned. We compare these findings with those of a newly identified atypical NF1 deletion of 698 kb which, in addition to the NF1 gene, includes five genes located centromeric to NF1. The atypical NF1 deletion in this patient does not include the SUZ12 gene but does encompass CRLF3. Comparative analysis of such atypical NF1 deletions suggests that SUZ12 hemizygosity is likely to contribute significantly to the reduced cognitive abilities, severe global developmental delay and facial dysmorphisms observed in patients with type 1 NF1 deletions.

scholarly journals Classification of NF1 microdeletions and its importance for establishing genotype/phenotype correlations in patients with NF1 microdeletions

2021 ◽  
Author(s):  
Hildegard Kehrer-Sawatzki ◽  
David N. Cooper
Keyword(s):  
Severe Disease ◽  
Neurofibromatosis Type ◽  
Global Developmental Delay ◽  
Cognitive Disability ◽  
Microdeletion Syndrome ◽  
Protein Coding ◽  
Large Deletions ◽  
Increased Risk ◽  
Flanking Regions

AbstractAn estimated 5–11% of patients with neurofibromatosis type-1 (NF1) harbour large deletions encompassing the NF1 gene and flanking regions. These NF1 microdeletions are subclassified into type 1, 2, 3 and atypical deletions which are distinguishable from each other by their extent and by the number of genes included within the deletion regions as well as the frequency of mosaicism with normal cells. Most common are type-1 NF1 deletions which encompass 1.4-Mb and 14 protein-coding genes. Type-1 deletions are frequently associated with overgrowth, global developmental delay, cognitive disability and dysmorphic facial features which are uncommon in patients with intragenic pathogenic NF1 gene variants. Further, patients with type-1 NF1 deletions frequently exhibit high numbers of neurofibromas and have an increased risk of malignant peripheral nerve sheath tumours. Genes located within the type-1 NF1 microdeletion interval and co-deleted with NF1 are likely to act as modifiers responsible for the severe disease phenotype in patients with NF1 microdeletions, thereby causing the NF1 microdeletion syndrome. Genotype/phenotype correlations in patients with NF1 microdeletions of different lengths are important to identify such modifier genes. However, these correlations are critically dependent upon the accurate characterization of the deletions in terms of their extent. In this review, we outline the utility as well as the shortcomings of multiplex ligation-dependent probe amplification (MLPA) to classify the different types of NF1 microdeletion and indicate the importance of high-resolution microarray analysis for correct classification, a necessary precondition to identify those genes responsible for the NF1 microdeletion syndrome.

scholarly journals Legius Syndrome in a 13 Month Old Boy: A Case Report

2017 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Learning Disabilities ◽  
Case Report ◽  
Developmental Delay ◽  
Neurofibromatosis Type 1 ◽  
Autosomal Dominant ◽  
Clinical Manifestations ◽  
Neurofibromatosis Type ◽  
Café Au Lait Spots ◽  
Legius Syndrome

Legius syndrome is autosomal dominant and caused by mutations in the SPRED1 gene. Clinical manifestations include multiple cafe-au-lait spots, axillary/ inguinal freckling and a degree of macrocephaly, without the non-pigmentary signs of neurofibromatosis type 1 (NF1). Learning disabilities, developmental delay and ADHD are also known.

scholarly journals Neurofibromatosis Type 1 Gene Alterations Define Specific Features of a Subset of Glioblastomas

2021 ◽  
Vol 23 (1) ◽  
pp. 352
Author(s):  
Maximilian Scheer ◽  
Sandra Leisz ◽  
Eberhard Sorge ◽  
Olha Storozhuk ◽  
Julian Prell ◽  
...  
Keyword(s):  
Neurofibromatosis Type 1 ◽  
Gene Mutations ◽  
Neurofibromatosis Type ◽  
Loss Of Function ◽  
Malignant Tumours ◽  
Cellular Mechanisms ◽  
Rich Domain ◽  
Nf1 Gene ◽  
Gene Alterations

Neurofibromatosis type 1 (NF1) gene mutations or alterations occur within neurofibromatosis type 1 as well as in many different malignant tumours on the somatic level. In glioblastoma, NF1 loss of function plays a major role in inducing the mesenchymal (MES) subtype and, therefore defining the most aggressive glioblastoma. This is associated with an immune signature and mediated via the NF1–MAPK–FOSL1 axis. Specifically, increased invasion seems to be regulated via mutations in the leucine-rich domain (LRD) of the NF1 gene product neurofibromin. Novel targets for therapy may arise from neurofibromin deficiency-associated cellular mechanisms that are summarised in this review.

scholarly journals Impacts of NF1 Gene Mutations and Genetic Modifiers in Neurofibromatosis Type 1

2021 ◽  
Vol 12 ◽  
Author(s):  
Wei Wang ◽  
Cheng-Jiang Wei ◽  
Xi-Wei Cui ◽  
Yue-Hua Li ◽  
Yi-Hui Gu ◽  
...  
Keyword(s):  
Neurofibromatosis Type 1 ◽  
Clinical Symptoms ◽  
Genetic Disorder ◽  
Gene Mutations ◽  
Neurofibromatosis Type ◽  
Genetic Modifiers ◽  
Complete Penetrance ◽  
Nf1 Gene ◽  
Underlying Mechanisms

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.

scholarly journals Application of Combined Long Amplicon Sequencing (CoLAS) for Genetic Analysis of Neurofibromatosis Type 1: A Pilot Study

2021 ◽  
Vol 43 (2) ◽  
pp. 782-801
Author(s):  
Sumihito Togi ◽  
Hiroki Ura ◽  
Yo Niida
Keyword(s):  
Genetic Analysis ◽  
Neurofibromatosis Type 1 ◽  
Gene Mutations ◽  
Neurofibromatosis Type ◽  
Amplicon Sequencing ◽  
Causative Mutation ◽  
Coding Region ◽  
Causative Gene ◽  
Nf1 Gene

Elaborate analyses of the status of gene mutations in neurofibromatosis type 1 (NF1) are still difficult nowadays due to the large gene sizes, broad mutation spectrum, and the various effects of mutations on mRNA splicing. These problems cannot be solved simply by sequencing the entire coding region using next-generation sequencing (NGS). We recently developed a new strategy, named combined long amplicon sequencing (CoLAS), which is a method for simultaneously analysing the whole genomic DNA region and, also, the full-length cDNA of the disease-causative gene with long-range PCR-based NGS. In this study, CoLAS was specifically arranged for NF1 genetic analysis, then applied to 20 patients (five previously reported and 15 newly recruited patients, including suspicious cases) for optimising the method and to verify its efficacy and benefits. Among new cases, CoLAS detected not only 10 mutations, including three unreported mutations and one mosaic mutation, but also various splicing abnormalities and allelic expression ratios quantitatively. In addition, heterozygous mapping by polymorphisms, including introns, showed copy number monitoring of the entire NF1 gene region was possible in the majority of patients tested. Moreover, it was shown that, when a chromosomal level microdeletion was suspected from heterozygous mapping, it could be detected directly by breakpoint-specific long PCR. In conclusion, CoLAS not simply detect the causative mutation but accurately elucidated the entire structure of the NF1 gene, its mRNA expression, and also the splicing status, which reinforces its high usefulness in the gene analysis of NF1.

scholarly journals Non-Oncological Neuroradiological Manifestations in NF1 and Their Clinical Implications

Cancers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1831
Author(s):  
Camilla Russo ◽  
Carmela Russo ◽  
Daniele Cascone ◽  
Federica Mazio ◽  
Claudia Santoro ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Structural Organization ◽  
Neurofibromatosis Type ◽  
Review Article ◽  
Tumor Suppressor Protein ◽  
Clinical Implications ◽  
Nf1 Gene ◽  
The Central Nervous System

Neurofibromatosis type 1 (NF1), the most frequent phakomatosis and one of the most common inherited tumor predisposition syndromes, is characterized by several manifestations that pervasively involve central and peripheral nervous system structures. The disorder is due to mutations in the NF1 gene, which encodes for the ubiquitous tumor suppressor protein neurofibromin; neurofibromin is highly expressed in neural crest derived tissues, where it plays a crucial role in regulating cell proliferation, differentiation, and structural organization. This review article aims to provide an overview on NF1 non-neoplastic manifestations of neuroradiological interest, involving both the central nervous system and spine. We also briefly review the most recent MRI functional findings in NF1.

A highly informative CA/GT repeat polymorphism in intron 38 of the human neurofibromatosis type 1 (NF1) gene

1993 ◽  
Vol 92 (4) ◽  
pp. 429-430 ◽  
Author(s):  
Conxi L�zaro ◽  
Antonia Gaona ◽  
Ganfeng Xu ◽  
Robert Weiss ◽  
Xavier Estivill
Keyword(s):  
Neurofibromatosis Type 1 ◽  
Neurofibromatosis Type ◽  
Repeat Polymorphism ◽  
Nf1 Gene
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