scholarly journals One NF1 Mutation may Conceal Another

Genes ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 633
Author(s):  
Laurence Pacot ◽  
Cyril Burin des Roziers ◽  
Ingrid Laurendeau ◽  
Audrey Briand-Suleau ◽  
Audrey Coustier ◽  
...  
Keyword(s):  
De Novo ◽  
Mapk Pathway ◽  
Neurofibromatosis Type ◽  
Negative Regulator ◽  
Loss Of Function ◽  
Complete Penetrance ◽  
Pathogenic Variants ◽  
Legius Syndrome ◽  
Nf1 Gene ◽  
Dominant Disease

Neurofibromatosis type 1 (NF1) is an autosomal dominant disease with complete penetrance but high variable expressivity. NF1 is caused by loss-of-function mutations in the NF1 gene, a negative regulator of the RAS-MAPK pathway. The NF1 gene has one of the highest mutation rates in human disorders, which may explain the outbreak of independent de novo variants in the same family. Here, we report the co-occurrence of pathogenic variants in the NF1 and SPRED1 genes in six families with NF1 and Legius syndrome, using next-generation sequencing. In five of these families, we observed the co-occurrence of two independent NF1 variants. All NF1 variants were classified as pathogenic, according to the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG-AMP) guidelines. In the sixth family, one sibling inherited a complete deletion of the NF1 gene from her mother and carried a variant of unknown significance in the SPRED1 gene. This variant was also present in her brother, who was diagnosed with Legius syndrome, a differential diagnosis of NF1. This work illustrates the complexity of molecular diagnosis in a not-so-rare genetic disease.

scholarly journals Genetic analyses of the NF1 gene in Turkish neurofibromatosis type I patients and definition of three novel variants

2017 ◽  
Vol 20 (1) ◽  
pp. 13-20 ◽  
Author(s):  
SD Ulusal ◽  
H Gürkan ◽  
E Atlı ◽  
SA Özal ◽  
M Çiftdemir ◽  
...  
Keyword(s):  
Next Generation Sequencing ◽  
Genetic Diagnosis ◽  
Neurofibromatosis Type ◽  
Type I ◽  
Neurofibromatosis Type I ◽  
Next Generation ◽  
Loss Of Function ◽  
Pathogenic Variants ◽  
Nf1 Gene ◽  
Generation Sequencing

Abstract Neurofibromatosis Type I (NF1) is a multi systemic autosomal dominant neurocutaneous disorder predisposing patients to have benign and/or malignant lesions predominantly of the skin, nervous system and bone. Loss of function mutations or deletions of the NF1 gene is responsible for NF1 disease. Involvement of various pathogenic variants, the size of the gene and presence of pseudogenes makes it difficult to analyze. We aimed to report the results of 2 years of multiplex ligation-dependent probe amplification (MLPA) and next generation sequencing (NGS) for genetic diagnosis of NF1 applied at our genetic diagnosis center. The MLPA, semiconductor sequencing and Sanger sequencing were performed in genomic DNA samples from 24 unrelated patients and their affected family members referred to our center suspected of having NF1. In total, three novel and 12 known pathogenic variants and a whole gene deletion were determined. We suggest that next generation sequencing is a practical tool for genetic analysis of NF1. Deletion/duplication analysis with MLPA may also be helpful for patients clinically diagnosed to carry NF1 but do not have a detectable mutation in NGS.

scholarly journals Challenges in the diagnosis of neurofibromatosis type 1 (NF1) in young children facilitated by means of revised diagnostic criteria including genetic testing for pathogenic NF1 gene variants

2021 ◽  
Author(s):  
Hildegard Kehrer-Sawatzki ◽  
David N. Cooper
Keyword(s):  
Young Children ◽  
Diagnostic Criteria ◽  
Neurofibromatosis Type 1 ◽  
Early Adulthood ◽  
Neurofibromatosis Type ◽  
Clinical Feature ◽  
Pathogenic Variants ◽  
Legius Syndrome ◽  
Nf1 Gene

AbstractNeurofibromatosis type 1 (NF1) is the most frequent disorder associated with multiple café-au-lait macules (CALM) which may either be present at birth or appear during the first year of life. Other NF1-associated features such as skin-fold freckling and Lisch nodules occur later during childhood whereas dermal neurofibromas are rare in young children and usually only arise during early adulthood. The NIH clinical diagnostic criteria for NF1, established in 1988, include the most common NF1-associated features. Since many of these features are age-dependent, arriving at a definitive diagnosis of NF1 by employing these criteria may not be possible in infancy if CALM are the only clinical feature evident. Indeed, approximately 46% of patients who are diagnosed with NF1 later in life do not meet the NIH diagnostic criteria by the age of 1 year. Further, the 1988 diagnostic criteria for NF1 are not specific enough to distinguish NF1 from other related disorders such as Legius syndrome. In this review, we outline the challenges faced in diagnosing NF1 in young children, and evaluate the utility of the recently revised (2021) diagnostic criteria for NF1, which include the presence of pathogenic variants in the NF1 gene and choroidal anomalies, for achieving an early and accurate diagnosis.

scholarly journals Simultaneous Detection of NF1, SPRED1, LZTR1, and NF2 Gene Mutations by Targeted NGS in an Italian Cohort of Suspected NF1 Patients

Genes ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 671
Author(s):  
Donatella Bianchessi ◽  
Maria Cristina Ibba ◽  
Veronica Saletti ◽  
Stefania Blasa ◽  
Tiziana Langella ◽  
...  
Keyword(s):  
Simultaneous Detection ◽  
Gene Mutations ◽  
Neurofibromatosis Type ◽  
Pathogenic Variant ◽  
Large Deletions ◽  
Pathogenic Variants ◽  
Legius Syndrome ◽  
Nf1 Gene ◽  
One Year ◽  
Next Generation Sequencing Ngs

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.

scholarly journals Hybrid Minigene Assay: An Efficient Tool to Characterize mRNA Splicing Profiles of NF1 Variants

Cancers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 999
Author(s):  
Valeria Morbidoni ◽  
Elisa Baschiera ◽  
Monica Forzan ◽  
Valentina Fumini ◽  
Dario Seif Ali ◽  
...  
Keyword(s):  
De Novo ◽  
Neurofibromatosis Type ◽  
Diagnostic Process ◽  
Fast Method ◽  
Loss Of Function ◽  
Clinical Criteria ◽  
Nf1 Gene ◽  
Set Up ◽  
Next Generation Sequencing Ngs ◽  
Minigene Assay

Neurofibromatosis type 1 (NF1) is caused by heterozygous loss of function mutations in the NF1 gene. Although patients are diagnosed according to clinical criteria and few genotype-phenotype correlations are known, molecular analysis remains important. NF1 displays allelic heterogeneity, with a high proportion of variants affecting splicing, including deep intronic alleles and changes outside the canonical splice sites, making validation problematic. Next Generation Sequencing (NGS) technologies integrated with multiplex ligation-dependent probe amplification (MLPA) have largely overcome RNA-based techniques but do not detect splicing defects. A rapid minigene-based system was set up to test the effects of NF1 variants on splicing. We investigated 29 intronic and exonic NF1 variants identified in patients during the diagnostic process. The minigene assay showed the coexistence of multiple mechanisms of splicing alterations for seven variants. A leaky effect on splicing was documented in one de novo substitution detected in a sporadic patient with a specific phenotype without neurofibromas. Our splicing assay proved to be a reliable and fast method to validate novel NF1 variants potentially affecting splicing and to detect hypomorphic effects that might have phenotypic consequences, avoiding the requirement of patient’s RNA.

scholarly journals NF1 regulates mesenchymal glioblastoma plasticity and aggressiveness through the AP-1 transcription factor FOSL1

2019 ◽  
Author(s):  
Carolina Marques ◽  
Thomas Unterkircher ◽  
Paula Kroon ◽  
Annalisa Izzo ◽  
Yuliia Dramaretska ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Stem Cell ◽  
Mapk Pathway ◽  
Neurofibromatosis Type ◽  
Gene Signature ◽  
Negative Regulator ◽  
Tumor Stem Cell ◽  
Stem Cell Lines ◽  
Mesenchymal Transformation

AbstractThe molecular basis underlying Glioblastoma (GBM) heterogeneity and plasticity are not fully understood. Using transcriptomic data of patient-derived brain tumor stem cell lines (BTSCs), classified based on GBM-intrinsic signatures, we identify the AP-1 transcription factor FOSL1 as a key regulator of the mesenchymal (MES) subtype. We provide a mechanistic basis to the role of the Neurofibromatosis type 1 gene (NF1), a negative regulator of the RAS/MAPK pathway, in GBM mesenchymal transformation through the modulation of FOSL1 expression. Depletion of FOSL1 in NF1-mutant human BTSCs and Kras-mutant mouse neural stem cells results in loss of the mesenchymal gene signature, reduction in stem cell properties and in vivo tumorigenic potential. Our data demonstrate that FOSL1 controls GBM plasticity and aggressiveness in response to NF1 alterations.

scholarly journals A comprehensive evaluation of pathogenic mutations in primary cutaneous melanomas, including the identification of novel loss-of-function variants

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ivana Ticha ◽  
Jan Hojny ◽  
Romana Michalkova ◽  
Ondrej Kodet ◽  
Eva Krkavcova ◽  
...  
Keyword(s):  
Cutaneous Melanoma ◽  
Comprehensive Evaluation ◽  
Mapk Pathway ◽  
Driver Mutations ◽  
Molecular Testing ◽  
Loss Of Function ◽  
Superficial Spreading ◽  
Pathogenic Variants ◽  
Frequent Mutations ◽  
Cycle Regulation

AbstractThe most common histological subtypes of cutaneous melanoma include superficial spreading and nodular melanoma. However, the spectrum of somatic mutations developed in those lesions and all potential druggable targets have not yet been fully elucidated. We present the results of a sequence capture NGS analysis of 114 primary nodular and superficial spreading melanomas identifying driver mutations using biostatistical, immunohistochemical and/or functional approach. The spectrum and frequency of pathogenic or likely pathogenic variants were identified across 54 evaluated genes, including 59 novel mutations, and the newly identified TP53 loss-of-function mutations p.(L194P) and p.(R280K). Frequently mutated genes most commonly affected the MAPK pathway, followed by chromatin remodeling, and cell cycle regulation. Frequent aberrations were also detected in the genes coding for proteins involved in DNA repair and the regulation and modification of cellular tight junctions. Furthermore, relatively frequent mutations were described in KDR and MET, which represent potential clinically important targets. Those results suggest that with the development of new therapeutic possibilities, not only BRAF testing, but complex molecular testing of cutaneous melanoma may become an integral part of the decision process concerning the treatment of patients with melanoma.

scholarly journals A large deletion in the COL2A1 gene expands the spectrum of pathogenic variants causing bulldog calf syndrome in cattle

2020 ◽  
Vol 62 (1) ◽  
Author(s):  
Joana Gonçalves Pontes Jacinto ◽  
Irene Monika Häfliger ◽  
Anna Letko ◽  
Cord Drögemüller ◽  
Jørgen Steen Agerholm
Keyword(s):  
De Novo ◽  
Genetic Disorders ◽  
Polymerase Chain Reaction Analysis ◽  
Large Deletion ◽  
Whole Genome Sequence ◽  
De Novo Mutation ◽  
Loss Of Function ◽  
Single Nucleotide Variants ◽  
Pathogenic Variants ◽  
Base Pair Deletion

Abstract Background Congenital bovine chondrodysplasia, also known as bulldog calf syndrome, is characterized by disproportionate growth of bones resulting in a shortened and compressed body, mainly due to reduced length of the spine and the long bones of the limbs. In addition, severe facial dysmorphisms including palatoschisis and shortening of the viscerocranium are present. Abnormalities in the gene collagen type II alpha 1 chain (COL2A1) have been associated with some cases of the bulldog calf syndrome. Until now, six pathogenic single-nucleotide variants have been found in COL2A1. Here we present a novel variant in COL2A1 of a Holstein calf and provide an overview of the phenotypic and allelic heterogeneity of the COL2A1-related bulldog calf syndrome in cattle. Case presentation The calf was aborted at gestation day 264 and showed generalized disproportionate dwarfism, with a shortened compressed body and limbs, and dysplasia of the viscerocranium; a phenotype resembling bulldog calf syndrome due to an abnormality in COL2A1. Whole-genome sequence (WGS) data was obtained and revealed a heterozygous 3513 base pair deletion encompassing 10 of the 54 coding exons of COL2A1. Polymerase chain reaction analysis and Sanger sequencing confirmed the breakpoints of the deletion and its absence in the genomes of both parents. Conclusions The pathological and genetic findings were consistent with a case of “bulldog calf syndrome”. The identified variant causing the syndrome was the result of a de novo mutation event that either occurred post-zygotically in the developing embryo or was inherited because of low-level mosaicism in one of the parents. The identified loss-of-function variant is pathogenic due to COL2A1 haploinsufficiency and represents the first structural variant causing bulldog calf syndrome in cattle. Furthermore, this case report highlights the utility of WGS-based precise diagnostics for understanding congenital disorders in cattle and the need for continued surveillance for genetic disorders in cattle.

scholarly journals A Cdo–Bnip-2–Cdc42 signaling pathway regulates p38α/β MAPK activity and myogenic differentiation

2008 ◽  
Vol 182 (3) ◽  
pp. 497-507 ◽  
Author(s):  
Jong-Sun Kang ◽  
Gyu-Un Bae ◽  
Min-Jeong Yi ◽  
Youn-Joo Yang ◽  
Ji-Eun Oh ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Cell Surface ◽  
Mapk Pathway ◽  
Myogenic Differentiation ◽  
Negative Regulator ◽  
Mitogen Activated Protein Kinase ◽  
Cell Surface Receptor ◽  
Myoblast Differentiation ◽  
Loss Of Function ◽  
Surface Receptor

The p38α/β mitogen-activated protein kinase (MAPK) pathway promotes skeletal myogenesis, but the mechanisms by which it is activated during this process are unclear. During myoblast differentiation, the promyogenic cell surface receptor Cdo binds to the p38α/β pathway scaffold protein JLP and, via JLP, p38α/β itself. We report that Cdo also interacts with Bnip-2, a protein that binds the small guanosine triphosphatase (GTPase) Cdc42 and a negative regulator of Cdc42, Cdc42 GTPase-activating protein (GAP). Moreover, Bnip-2 and JLP are brought together through mutual interaction with Cdo. Gain- and loss-of-function experiments with myoblasts indicate that the Cdo–Bnip-2 interaction stimulates Cdc42 activity, which in turn promotes p38α/β activity and cell differentiation. These results reveal a previously unknown linkage between a cell surface receptor and downstream modulation of Cdc42 activity. Furthermore, interaction with multiple scaffold-type proteins is a distinctive mode of cell surface receptor signaling and provides one mechanism for specificity of p38α/β activation during cell differentiation.

scholarly journals Retroviral Integration at the Epi1Locus Cooperates with Nf1 Gene Loss in the Progression to Acute Myeloid Leukemia

2001 ◽  
Vol 75 (19) ◽  
pp. 9427-9434 ◽  
Author(s):  
Susan M. Blaydes ◽  
Scott C. Kogan ◽  
Bao-Tran H. Truong ◽  
Debra J. Gilbert ◽  
Nancy A. Jenkins ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Neurofibromatosis Type ◽  
Juvenile Myelomonocytic Leukemia ◽  
Loss Of Function ◽  
Hematopoietic Stem ◽  
Retroviral Integration ◽  
Increased Risk ◽  
Nf1 Gene ◽  
Acute Myeloid

ABSTRACT Juvenile myelomonocytic leukemia (JMML) is a disease that occurs in young children and is associated with a high mortality rate. In most patients, JMML has a progressive course leading to death by virtue of infection, bleeding, or progression to acute myeloid leukemia (AML). As it is known that children with neurofibromatosis type 1 syndrome have a markedly increased risk of developing JMML, we have previously developed a mouse model of JMML through reconstitution of lethally irradiated mice with hematopoietic stem cells homozygous for a loss-of-function mutation in the Nf1 gene (D. L. Largaespada, C. I. Brannan, N. A. Jenkins, and N. G. Copeland, Nat. Genet. 12:137–143, 1996). In the course of these experiments, we found that all these genetically identical reconstituted mice developed a JMML-like disorder, but only a subset went on to develop more acute disease. This result strongly suggests that additional genetic lesions are responsible for disease progression to AML. Here, we describe the production of a unique tumor panel, created using the BXH-2 genetic background, for identification of these additional genetic lesions. Using this tumor panel, we have identified a locus, Epi1, which maps 30 to 40 kb downstream of theMyb gene and appears to be the most common site of somatic viral integration in BXH-2 mice. Our findings suggest that proviral integrations at Epi1 cooperate with loss of Nf1to cause AML.

scholarly journals Neuronal KGB-1 JNK MAPK signaling regulates the dauer developmental decision in response to environmental stress in C. elegans

2021 ◽  
Author(s):  
Deepshikha Dogra ◽  
Warakorn Kulalert ◽  
Frank Schroeder ◽  
Dennis H Kim
Keyword(s):  
Elevated Temperature ◽  
Signaling Pathways ◽  
Mapk Pathway ◽  
Negative Regulator ◽  
Loss Of Function ◽  
C Elegans ◽  
Metabolic Remodeling ◽  
Dauer Formation ◽  
Identification And Characterization

In response to stressful growth conditions of high population density, food scarcity and elevated temperature, young larvae of nematode Caenorhabditis elegans can enter a developmentally arrested stage called dauer that is characterized by dramatic anatomic and metabolic remodeling. Genetic analysis of dauer formation of C. elegans has served as an experimental paradigm for the identification and characterization of conserved neuroendocrine signaling pathways. Here, we report the identification and characterization of a conserved JNK-like mitogen-activated protein kinase (MAPK) pathway that is required for dauer formation in response to environmental stressors. We observed that loss-of-function mutations in the MLK-1-MEK-1-KGB-1 MAPK pathway suppress dauer entry. Loss-of-function mutation in the VHP-1 MAPK phosphatase, a known negative regulator of KGB-1 signaling, results in constitutive dauer formation which is dependent on the presence of dauer pheromone but independent of diminished food levels or elevated temperatures. Our data suggest that KGB-1 pathway acts in the sensory neurons, in parallel to established insulin and TGF-β signaling pathways, to transduce the dauer-inducing environmental cues of diminished food levels and elevated temperature.

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