scholarly journals A de novo synonymous variant in EFTUD2 disrupts normal splicing and causes mandibulofacial dysostosis with microcephaly: case report

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Arthur Jacob ◽  
Jennifer Pasquier ◽  
Raphael Carapito ◽  
Frédéric Auradé ◽  
Anne Molitor ◽  
...  
Keyword(s):  
Splice Site ◽  
De Novo ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Genetic Alterations ◽  
Donor Splice Site ◽  
Donor Splice ◽  
First Case ◽  
Synonymous Variant ◽  
Mandibulofacial Dysostosis

Abstract Background Mandibulofacial dysostosis with microcephaly (MFDM) is a rare autosomal dominant genetic disease characterized by intellectual and growth retardations, as well as major microcephaly, induced by missense and splice site variants or microdeletions in the EFTUD2 gene. Case presentation Here, we investigate the case of a young girl with symptoms of MFDM and a normal karyotype. Whole-exome sequencing of the family was performed to identify genetic alterations responsible for this phenotype. We identified a de novo synonymous variant in the EFTUD2 gene. We demonstrated that this synonymous variant disrupts the donor splice-site in intron 9 resulting in the skipping of exon 9 and a frameshift that leads to a premature stop codon. Conclusions We present the first case of MFDM caused by a synonymous variant disrupting the donor splice site, leading to exon skipping.

scholarly journals A Deep Intronic Variant Activates a Pseudoexon in the MTM1Gene in a Family with X-Linked Myotubular Myopathy

2020 ◽  
Vol 11 (5-6) ◽  
pp. 264-270
Author(s):  
Jamie Fitzgerald ◽  
Cori Feist ◽  
Paula Dietz ◽  
Stephen Moore ◽  
Donald Basel
Keyword(s):  
Splice Site ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Nonsense Mediated Decay ◽  
Intronic Sequence ◽  
Myotubular Myopathy ◽  
Donor Splice ◽  
Genomic Screening ◽  
Low Levels ◽  
Translational Inhibitor

We report a novel intronic variant in the <i>MTM1</i> gene in 4 males in a family with severe X-linked myotubular myopathy. The A&#x3e;G variant in deep intronic space activates a cryptic 5′ donor splice site resulting in the inclusion of a 48-bp pseudoexon into the mature <i>MTM1</i> mRNA. The variant is present in all affected males, absent in unaffected males, and heterozygous in the mother of the affected males. The included intronic sequence contains a premature stop codon, and experiments using a translational inhibitor indicate that the mutant mRNAs undergo nonsense-mediated decay. We conclude that affected males produce no, or low, levels of <i>MTM1</i> mRNA likely leading to a significant reduction of myotubularin-1 protein resulting in the severe neonatal myopathy present in this family. The study highlights the need to consider noncoding variants in genomic screening in families with X-linked myotubular myopathy.

Ectopic Transcript Analysis Indicates that Allelic Exclusion is an Important Cause of Type I Protein C Deficiency in Patients with Nonsense and Frameshift Mutations in the PROC Gene

1996 ◽  
Vol 75 (06) ◽  
pp. 870-876 ◽  
Author(s):  
José Manuel Soria ◽  
Lutz-Peter Berg ◽  
Jordi Fontcuberta ◽  
Vijay V Kakkar ◽  
Xavier Estivill ◽  
...  
Keyword(s):  
Splice Site ◽  
Protein C ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Allelic Exclusion ◽  
Polymorphism Analysis ◽  
Type I ◽  
Protein C Deficiency ◽  
Nonsense Mutations ◽  
Stop Codons

SummaryNonsense mutations, deletions and splice site mutations are a common cause of type I protein C deficiency. Either directly or indirectly by altering the reading frame, these' lesions generate or may generate premature stop codons and could therefore be expected to result in premature termination of translation. In this study, the possibility that such mutations could instead exert their pathological effects at an earlier stage in the expression pathway, through “allelic exclusion” at the RNA level, was investigated. Protein C (PROC) mRNA was analysed in seven Spanish type I protein C deficient patients heterozygous for two nonsense mutations, a 7bp deletion, a 2bp insertion and three splice site mutations. Ectopic RNA transcripts from patient and control lymphocytes were analysed by RT-PCR and direct sequencing of amplified PROC cDNA fragments. The nonsense mutations and the deletion were absent from the cDNAs indicating that only mRNA derived from the normal allele had been expressed. Similarly for the splice site mutations, only normal PROC cDNAs were obtained. In one case, exclusion of the mutated allele could be confirmed by polymorphism analysis. In contrast to these six mutations, the 2 bp insertion was not associated with loss of mRNA from the mutated allele. In this case, cDNA analysis revealed the absence of 19 bases from the PROC mRNA consistent with the generation and utilization of a cryptic splice site 3’ to the site of mutation, which would result in a frameshift and a premature stop codon. It is concluded that allelic exclusion is a common causative mechanism in those cases of type I protein C deficiency which result from mutations that introduce premature stop codons

Severe Homozygous Protein C Deficiency: Identification of a Splice Site Missense Mutation (184, Q → H) in Exon 7 of the Protein C Gene

1994 ◽  
Vol 72 (01) ◽  
pp. 065-069 ◽  
Author(s):  
J M Soria ◽  
D Brito ◽  
J Barceló ◽  
J Fontcuberta ◽  
L Botero ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Gene Product ◽  
Splice Site ◽  
Protein C ◽  
Purpura Fulminans ◽  
Single Strand Conformation Polymorphism ◽  
Donor Splice Site ◽  
Protein C Deficiency ◽  
Donor Splice ◽  
Newborn Child

SummarySingle strand conformation polymorphism (SSCP) analysis of exon 7 of the protein C gene has identified a novel splice site missense mutation (184, Q → H), in a newborn child with purpura fulminans and undetectable protein C levels. The mutation, seen in the homozygous state in the child and in the heterozygous state in her mother, was characterized and found to be a G to C nucleotide substitution at the -1 position of the donor splice site of intron 7 of the protein C gene, which changes histidine 184 for glutamine (184, Q → H). According to analysis of the normal and mutated sequences, this mutation should also abolish the function of the donor splice site of intron 7 of the protein C gene. Since such a mutation is compatible with the absence of gene product in plasma and since DNA sequencing of all protein C gene exons in this patient did not reveal any other mutation, we postulate that mutation 184, Q → H results in the absence of protein C gene product in plasma, which could be the cause of the severe phenotype observed in this patient.

scholarly journals A rare large duplication of MLH1 identified in Lynch syndrome

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Abhishek Kumar ◽  
Nagarajan Paramasivam ◽  
Obul Reddy Bandapalli ◽  
Matthias Schlesner ◽  
Tianhui Chen ◽  
...  
Keyword(s):  
Amino Acid ◽  
Lynch Syndrome ◽  
Splice Site ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Splice Donor Site ◽  
Laboratory Diagnostics ◽  
Mmr Genes ◽  
Base Pair Deletion ◽  
Splice Site Variant

Abstract Background The most frequently identified strong cancer predisposition mutations for colorectal cancer (CRC) are those in the mismatch repair (MMR) genes in Lynch syndrome. Laboratory diagnostics include testing tumors for immunohistochemical staining (IHC) of the Lynch syndrome-associated DNA MMR proteins and/or for microsatellite instability (MSI) followed by sequencing or other techniques, such as denaturing high performance liquid chromatography (DHPLC), to identify the mutation. Methods In an ongoing project focusing on finding Mendelian cancer syndromes we applied whole-exome/whole-genome sequencing (WES/WGS) to 19 CRC families. Results Three families were identified with a pathogenic/likely pathogenic germline variant in a MMR gene that had previously tested negative in DHPLC gene variant screening. All families had a history of CRC in several family members across multiple generations. Tumor analysis showed loss of the MMR protein IHC staining corresponding to the mutated genes, as well as MSI. In family A, a structural variant, a duplication of exons 4 to 13, was identified in MLH1. The duplication was predicted to lead to a frameshift at amino acid 520 and a premature stop codon at amino acid 539. In family B, a 1 base pair deletion was found in MLH1, resulting in a frameshift and a stop codon at amino acid 491. In family C, we identified a splice site variant in MSH2, which was predicted to lead loss of a splice donor site. Conclusions We identified altogether three pathogenic/likely pathogenic variants in the MMR genes in three of the 19 sequenced families. The MLH1 variants, a duplication of exons 4 to 13 and a frameshift variant, were novel, based on the InSiGHT and ClinVar databases; the MSH2 splice site variant was reported by a single submitter in ClinVar. As a variant class, duplications have rarely been reported in the MMR gene literature, particularly those covering several exons.

Construction of a helper cell line for avian reticuloendotheliosis virus cloning vectors

1983 ◽  
Vol 3 (12) ◽  
pp. 2241-2249
Author(s):  
S Watanabe ◽  
H M Temin
Keyword(s):  
Cell Line ◽  
Thymidine Kinase ◽  
Splice Site ◽  
Virus Production ◽  
Helper Virus ◽  
Donor Splice Site ◽  
Reticuloendotheliosis Virus ◽  
Donor Splice ◽  
Proviral Dna ◽  
Viral Dnas

We wished to construct cell lines that supply the gene products of gag, pol, and env for the growth of replication-defective reticuloendotheliosis retrovirus vectors without production of the helper virus. To do this, first we located by S1 mapping the donor and acceptor splice sites of reticuloendotheliosis virus strain A. The donor splice site is ca. 850 base pairs from the 5' end of proviral DNA. It is close to or overlaps the encapsidation sequences for viral RNA. The splice acceptor site is ca. 5.6 kilobase pairs from the 5' end of proviral DNA. Therefore, the encapsidation sequences and the donor splice site were removed from viral DNA to give expression of the gag and pol genes without virus production. The promoter in the long terminal repeat was fused to a site near the first ATG codon of the env gene, thereby deleting the encapsidation sequences and the gag and pol genes to give expression of the env gene without virus production. The permissive canine cell line D17 was transfected with the two modified viral DNAs. Two cell clones that contain both modified viral DNAs support the production of replication-defective spleen necrosis virus-thymidine kinase recombinant retrovirus vectors without the production of helper virus. To prevent recombination, the vector contains deletions that overlap with deletions in the integrated helper virus DNAs. This helper cell-vector system will be useful to derive infectious recombinant virus stocks of high titer (over 10(5) thymidine kinase transforming units per ml) which are able to infect avian, rat, and dog cells without the aid of helper virus.

Molecular Mechanisms of FVII Deficiency: Expression of Mutations Clustered in the IVS7 Donor Splice Site of Factor VII Gene

Blood ◽  
1998 ◽  
Vol 92 (5) ◽  
pp. 1646-1651 ◽  
Author(s):  
M. Pinotti ◽  
R. Toso ◽  
R. Redaelli ◽  
M. Berrettini ◽  
G. Marchetti ◽  
...  
Keyword(s):  
Splice Site ◽  
Molecular Mechanisms ◽  
Catalytic Domain ◽  
Point Mutations ◽  
Factor Vii ◽  
Donor Splice Site ◽  
Donor Splice ◽  
Expression Studies ◽  
Fvii Deficiency ◽  
American Society

Abstract In three Italian patients, two point mutations and a short deletion were found in the intron 7 of factor VII gene, clustered in the donor splice site and located in the first of several repeats. The mutation 9726+5G→A, the most frequent cause of symptomatic factor VII deficiency in Italy, as well as the deletion (9729del4) gave rise in expression studies to abnormally spliced transcripts, which were exclusively produced from the cryptic site in the second repeat. The insertion in the mature mRNA of the first intronic repeat caused (9726+5G→A) a reading frameshift, abolishing most of the factor VII catalytic domain, or produced (9729del4), an altered factor with 11 additional residues, the activity of which was not detectable in the cell medium after mutagenesis and expression studies. Studies of factor VII ectopic mRNA from leukocytes and expression studies indicated that the deleted gene produced 30% of normally spliced transcript. Differently, the 9726+5G→A mutation permitted a very low level (0.2% to 1%) of correct splicing to occur, which could be of great importance to prevent the onset, in the homozygous patients, of most of the life-threatening bleeding symptoms. The 9726+7A→G mutation was found to be a rare and functionally silent polymorphism. These findings, which provide further evidence of the interplay of sequence and position in the 5′ splice site selection, throw light on the heterogeneous molecular bases and clinical phenotypes of FVII deficiency. © 1998 by The American Society of Hematology.

Molecular and Cellular Characterization of a New α-Thalassemia Mutation (HBA2:c.94A>C) Generating an Alternative Splice Site and a Premature Stop Codon

Hemoglobin ◽  
2012 ◽  
Vol 36 (3) ◽  
pp. 244-252 ◽  
Author(s):  
Talal Qadah ◽  
Jill Finlayson ◽  
Christopher Newbound ◽  
Nicole Pell ◽  
Michelle Pascoe ◽  
...  
Keyword(s):  
Alternative Splice ◽  
Splice Site ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Alternative Splice Site ◽  
Thalassemia Mutation
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