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Martínez-Pizarro A, Álvarez M, Dembic M, Lindegaard CA, Castro M, Richard E, Andresen BS, Desviat LR. Splice-Switching Antisense Oligonucleotides Correct Phenylalanine Hydroxylase Exon 11 Skipping Defects and Rescue Enzyme Activity in Phenylketonuria. Nucleic Acid Ther 2024. [PMID: 38591802 DOI: 10.1089/nat.2024.0014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024] Open
Abstract
The PAH gene encodes the hepatic enzyme phenylalanine hydroxylase (PAH), and its deficiency, known as phenylketonuria (PKU), leads to neurotoxic high levels of phenylalanine. PAH exon 11 is weakly defined, and several missense and intronic variants identified in patients affect the splicing process. Recently, we identified a novel intron 11 splicing regulatory element where U1snRNP binds, participating in exon 11 definition. In this work, we describe the implementation of an antisense strategy targeting intron 11 sequences to correct the effect of PAH mis-splicing variants. We used an in vitro assay with minigenes and identified splice-switching antisense oligonucleotides (SSOs) that correct the exon skipping defect of PAH variants c.1199+17G>A, c.1199+20G>C, c.1144T>C, and c.1066-3C>T. To examine the functional rescue induced by the SSOs, we generated a hepatoma cell model with variant c.1199+17G>A using CRISPR/Cas9. The edited cell line reproduces the exon 11 skipping pattern observed from minigenes, leading to reduced PAH protein levels and activity. SSO transfection results in an increase in exon 11 inclusion and corrects PAH deficiency. Our results provide proof of concept of the potential therapeutic use of a single SSO for different exonic and intronic splicing variants causing PAH exon 11 skipping in PKU.
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Affiliation(s)
- Ainhoa Martínez-Pizarro
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, IUBM, CIBERER, IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
| | - Mar Álvarez
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, IUBM, CIBERER, IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
| | - Maja Dembic
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Caroline A Lindegaard
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Margarita Castro
- Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), CIBERER, IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
| | - Eva Richard
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, IUBM, CIBERER, IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Lourdes R Desviat
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, IUBM, CIBERER, IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
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2
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Larsen TV, Maansson CT, Daugaard TF, Andresen BS, Sorensen BS, Nielsen AL. Trans-Regulation of Alternative PD-L1 mRNA Processing by CDK12 in Non-Small-Cell Lung Cancer Cells. Cells 2023; 12:2844. [PMID: 38132164 PMCID: PMC10741404 DOI: 10.3390/cells12242844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/10/2023] [Accepted: 12/13/2023] [Indexed: 12/23/2023] Open
Abstract
Immunotherapy using checkpoint inhibitors targeting the interaction between PD-1 on T cells and PD-L1 on cancer cells has shown significant results in non-small-cell lung cancer (NSCLC). Not all patients respond to the therapy, and PD-L1 expression heterogeneity is proposed to be one determinant for this. The alternative processing of PD-L1 RNA, which depends on an alternative poly-A site in intron 4, generates a shorter mRNA variant (PD-L1v4) encoding soluble PD-L1 (sPD-L1), relative to the canonical PD-L1v1 mRNA encoding membrane-associated PD-L1 (mPD-L1). This study aimed to identify factors influencing the ratio between these two PD-L1 mRNAs in NSCLC cells. First, we verified the existence of the alternative PD-L1 RNA processing in NSCLC cells, and from in silico analyses, we identified a candidate list of regulatory factors. Examining selected candidates showed that CRISPR/Cas9-generated loss-of-function mutations in CDK12 increased the PD-L1v4/PD-L1v1 mRNA ratio and, accordingly, the sPD-L1/mPD-L1 balance. The CDK12/13 inhibitor THZ531 could also increase the PD-L1v4/PD-L1v1 mRNA ratio and impact the PD-L1 transcriptional response to IFN-γ stimulation. The fact that CDK12 regulates PD-L1 transcript variant formation in NSCLC cells is consistent with CDK12's role in promoting transcriptional elongation over intron-located poly-A sites. This study lays the groundwork for clinical investigations to delineate the implications of the CDK12-mediated balancing of sPD-L1 relative to mPD-L1 for immunotherapeutic responses in NSCLC.
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Affiliation(s)
- Trine V. Larsen
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark; (T.V.L.); (C.T.M.); (T.F.D.)
| | - Christoffer T. Maansson
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark; (T.V.L.); (C.T.M.); (T.F.D.)
- Department of Clinical Medicine, Aarhus University, 8200 Aarhus, Denmark;
- Department of Clinical Biochemistry, Aarhus University Hospital, 8200 Aarhus, Denmark
| | - Tina F. Daugaard
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark; (T.V.L.); (C.T.M.); (T.F.D.)
| | - Brage S. Andresen
- Department of Biology and Molecular Biology, Southern University of Denmark, 5230 Odense, Denmark;
| | - Boe S. Sorensen
- Department of Clinical Medicine, Aarhus University, 8200 Aarhus, Denmark;
- Department of Clinical Biochemistry, Aarhus University Hospital, 8200 Aarhus, Denmark
| | - Anders L. Nielsen
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark; (T.V.L.); (C.T.M.); (T.F.D.)
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3
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Thomassen M, Mesman RLS, Hansen TVO, Menendez M, Rossing M, Esteban‐Sánchez A, Tudini E, Törngren T, Parsons MT, Pedersen IS, Teo SH, Kruse TA, Møller P, Borg Å, Jensen UB, Christensen LL, Singer CF, Muhr D, Santamarina M, Brandao R, Andresen BS, Feng B, Canson D, Richardson ME, Karam R, Pesaran T, LaDuca H, Conner BR, Abualkheir N, Hoang L, Calléja FMGR, Andrews L, James PA, Bunyan D, Hamblett A, Radice P, Goldgar DE, Walker LC, Engel C, Claes KBM, Macháčková E, Baralle D, Viel A, Wappenschmidt B, Lazaro C, Vega A, Vreeswijk MPG, de la Hoya M, Spurdle AB. Clinical, splicing, and functional analysis to classify BRCA2 exon 3 variants: Application of a points-based ACMG/AMP approach. Hum Mutat 2022; 43:1921-1944. [PMID: 35979650 PMCID: PMC10946542 DOI: 10.1002/humu.24449] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 08/05/2022] [Accepted: 08/09/2022] [Indexed: 01/25/2023]
Abstract
Skipping of BRCA2 exon 3 (∆E3) is a naturally occurring splicing event, complicating clinical classification of variants that may alter ∆E3 expression. This study used multiple evidence types to assess pathogenicity of 85 variants in/near BRCA2 exon 3. Bioinformatically predicted spliceogenic variants underwent mRNA splicing analysis using minigenes and/or patient samples. ∆E3 was measured using quantitative analysis. A mouse embryonic stem cell (mESC) based assay was used to determine the impact of 18 variants on mRNA splicing and protein function. For each variant, population frequency, bioinformatic predictions, clinical data, and existing mRNA splicing and functional results were collated. Variant class was assigned using a gene-specific adaptation of ACMG/AMP guidelines, following a recently proposed points-based system. mRNA and mESC analysis combined identified six variants with transcript and/or functional profiles interpreted as loss of function. Cryptic splice site use for acceptor site variants generated a transcript encoding a shorter protein that retains activity. Overall, 69/85 (81%) variants were classified using the points-based approach. Our analysis shows the value of applying gene-specific ACMG/AMP guidelines using a points-based approach and highlights the consideration of cryptic splice site usage to appropriately assign PVS1 code strength.
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Affiliation(s)
- Mads Thomassen
- Department of Clinical GeneticsOdense University HospitalOdence CDenmark
| | - Romy L. S. Mesman
- Department of Human GeneticsLeiden University Medical CenterLeidenthe Netherlands
| | - Thomas V. O. Hansen
- Department of Clinical Genetics, RigshospitaletCopenhagen University HospitalCopenhagenDenmark
| | - Mireia Menendez
- Hereditary Cancer ProgramCatalan Institute of Oncology, ONCOBELL‐IDIBELL‐IDTP, CIBERONCHospitalet de LlobregatSpain
| | - Maria Rossing
- Center for Genomic Medicine, RigshospitaletCopenhagen University HospitalCopenhagenDenmark
| | - Ada Esteban‐Sánchez
- Molecular Oncology Laboratory, CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Emma Tudini
- Department of Genetics and Computational BiologyQIMR Berghofer Medical Research InstituteBrisbaneQueenslandAustralia
| | - Therese Törngren
- Division of Oncology, Department of Clinical Sciences LundLund UniversityLundSweden
| | - Michael T. Parsons
- Department of Genetics and Computational BiologyQIMR Berghofer Medical Research InstituteBrisbaneQueenslandAustralia
| | - Inge S. Pedersen
- Molecular Diagnostics, Aalborg University HospitalAalborgDenmark
- Clinical Cancer Research CenterAalborg University HospitalAalborgDenmark
- Department of Clinical MedicineAalborg UniversityAalborgDenmark
| | - Soo H. Teo
- Breast Cancer Research ProgrammeCancer Research MalaysiaSubang JayaSelangorMalaysia
- Department of Surgery, Faculty of MedicineUniversity of MalayaKuala LumpurMalaysia
| | - Torben A. Kruse
- Department of Clinical GeneticsOdense University HospitalOdence CDenmark
| | - Pål Møller
- Department of Tumour BiologyThe Norwegian Radium Hospital, Oslo University HospitalOsloNorway
| | - Åke Borg
- Division of Oncology, Department of Clinical Sciences LundLund UniversityLundSweden
| | - Uffe B. Jensen
- Department of Clinical GeneticsAarhus University HospitalAarhus NDenmark
| | | | - Christian F. Singer
- Department of OB/GYN and Comprehensive Cancer CenterMedical University of ViennaViennaAustria
| | - Daniela Muhr
- Department of OB/GYN and Comprehensive Cancer CenterMedical University of ViennaViennaAustria
| | - Marta Santamarina
- Fundación Pública Galega de Medicina XenómicaSantiago de CompostelaSpain
- Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), Complejo Hospitalario Universitario de Santiago, SERGASSantiago de CompostelaSpain
- Centro de Investigación en Red de Enfermedades Raras (CIBERER)MadridSpain
| | - Rita Brandao
- Department of Clinical GeneticsMaastricht University Medical CenterMaastrichtthe Netherlands
| | - Brage S. Andresen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical SciencesUniversity of Southern DenmarkOdenseDenmark
| | - Bing‐Jian Feng
- Department of DermatologyHuntsman Cancer Institute, University of Utah School of MedicineSalt Lake CityUtahUSA
| | - Daffodil Canson
- Department of Genetics and Computational BiologyQIMR Berghofer Medical Research InstituteBrisbaneQueenslandAustralia
| | | | | | | | | | | | | | | | | | - Lesley Andrews
- Hereditary Cancer Clinic, Nelune Comprehensive Cancer Care CentreSydneyNew South WalesAustralia
| | - Paul A. James
- Parkville Familial Cancer Centre, Peter MacCallum Cancer CenterMelbourneVictoriaAustralia
- Sir Peter MacCallum Department of OncologyThe University of MelbourneMelbourneVictoriaAustralia
| | - Dave Bunyan
- Human Development and Health, Faculty of MedicineUniversity of SouthamptonSouthamptonUK
| | - Amanda Hamblett
- Middlesex Health Shoreline Cancer CenterWestbrookConnecticutUSA
| | - Paolo Radice
- Unit of Molecular Bases of Genetic Risk and Genetic Testing, Department of ResearchFondazione IRCCS Istituto Nazionale dei Tumori (INT)MilanItaly
| | - David E. Goldgar
- Department of DermatologyHuntsman Cancer Institute, University of Utah School of MedicineSalt Lake CityUtahUSA
| | - Logan C. Walker
- Department of Pathology and Biomedical ScienceUniversity of OtagoChristchurchNew Zealand
| | - Christoph Engel
- Institute for Medical Informatics, Statistics and EpidemiologyUniversity of LeipzigLeipzigGermany
| | | | - Eva Macháčková
- Department of Cancer Epidemiology and GeneticsMasaryk Memorial Cancer InstituteBrnoCzech Republic
| | - Diana Baralle
- Human Development and Health, Faculty of MedicineUniversity of SouthamptonSouthamptonUK
| | - Alessandra Viel
- Division of Functional Onco‐genomics and GeneticsCentro di Riferimento Oncologico di Aviano (CRO), IRCCSAvianoItaly
| | - Barbara Wappenschmidt
- Center for Familial Breast and Ovarian Cancer, Faculty of Medicine and University Hospital CologneUniversity of CologneCologneGermany
- Center for Integrated Oncology (CIO), Faculty of Medicine and University Hospital CologneUniversity of CologneCologneGermany
| | - Conxi Lazaro
- Hereditary Cancer ProgramCatalan Institute of Oncology, ONCOBELL‐IDIBELL‐IDTP, CIBERONCHospitalet de LlobregatSpain
| | - Ana Vega
- Fundación Pública Galega de Medicina XenómicaSantiago de CompostelaSpain
- Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), Complejo Hospitalario Universitario de Santiago, SERGASSantiago de CompostelaSpain
- Centro de Investigación en Red de Enfermedades Raras (CIBERER)MadridSpain
| | - ENIGMA Consortium
- Department of Genetics and Computational BiologyQIMR Berghofer Medical Research InstituteBrisbaneQueenslandAustralia
| | | | - Miguel de la Hoya
- Molecular Oncology Laboratory, CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Amanda B. Spurdle
- Department of Genetics and Computational BiologyQIMR Berghofer Medical Research InstituteBrisbaneQueenslandAustralia
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4
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Varzari A, Deyneko IV, Bruun GH, Dembic M, Hofmann W, Cebotari VM, Ginda SS, Andresen BS, Illig T. Candidate genes and sequence variants for susceptibility to mycobacterial infection identified by whole-exome sequencing. Front Genet 2022; 13:969895. [PMID: 36338958 PMCID: PMC9632272 DOI: 10.3389/fgene.2022.969895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 10/04/2022] [Indexed: 11/13/2022] Open
Abstract
Inborn errors of immunity are known to influence susceptibility to mycobacterial infections. The aim of this study was to characterize the genetic profile of nine patients with mycobacterial infections (eight with BCGitis and one with disseminated tuberculosis) from the Republic of Moldova using whole-exome sequencing. In total, 12 variants in eight genes known to be associated with Mendelian Susceptibility to Mycobacterial Disease (MSMD) were detected in six out of nine patients examined. In particular, a novel splice site mutation c.373–2A>C in STAT1 gene was found and functionally confirmed in a patient with disseminated tuberculosis. Trio analysis was possible for seven out of nine patients, and resulted in 23 candidate variants in 15 novel genes. Four of these genes - GBP2, HEATR3, PPP1R9B and KDM6A were further prioritized, considering their elevated expression in immune-related tissues. Compound heterozygosity was found in GBP2 in a single patient, comprising a maternally inherited missense variant c.412G>A/p.(Ala138Thr) predicted to be deleterious and a paternally inherited intronic mutation c.1149+14T>C. Functional studies demonstrated that the intronic mutation affects splicing and the level of transcript. Finally, we analyzed pathogenicity of variant combinations in gene pairs and identified five patients with putative oligogenic inheritance. In summary, our study expands the spectrum of genetic variation contributing to susceptibility to mycobacterial infections in children and provides insight into the complex/oligogenic disease-causing mode.
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Affiliation(s)
- Alexander Varzari
- Laboratory of Human Genetics, Chiril Draganiuc Institute of Phthisiopneumology, Kishinev, Moldova
- Hannover Unified Biobank, Hannover Medical School, Hannover, Germany
- *Correspondence: Alexander Varzari,
| | - Igor V. Deyneko
- Laboratory of Functional Genomics, Timiryazev Institute of Plant Physiology Russian Academy of Sciences, Moscow, Russia
| | - Gitte Hoffmann Bruun
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
- The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Maja Dembic
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
- The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
- Department of Clinical Genetics, Odense University Hospital, Odense, Denmark
- Department of Mathematics and Computer Science, University of Southern Denmark, Odense, Denmark
| | - Winfried Hofmann
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
| | - Victor M. Cebotari
- Municipal Hospital of Phthisiopneumology, Department of Pediatrics, Kishinev, Moldova
| | - Sergei S. Ginda
- Laboratory of Immunology and Allergology, Chiril Draganiuc Institute of Phthisiopneumology, Kishinev, Moldova
| | - Brage S. Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
- The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Thomas Illig
- Hannover Unified Biobank, Hannover Medical School, Hannover, Germany
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5
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Martínez-Pizarro A, Leal F, Holm LL, Doktor TK, Petersen USS, Bueno M, Thöny B, Pérez B, Andresen BS, Desviat LR. Antisense Oligonucleotide Rescue of Deep-Intronic Variants Activating Pseudoexons in the 6-Pyruvoyl-Tetrahydropterin Synthase Gene. Nucleic Acid Ther 2022; 32:378-390. [PMID: 35833796 PMCID: PMC9595628 DOI: 10.1089/nat.2021.0066] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We report two new 6-pyruvoyl-tetrahydropterin synthase splicing variants identified through genomic sequencing and transcript analysis in a patient with tetrahydrobiopterin deficiency, presenting with hyperphenylalaninemia and monoamine neurotransmitter deficiency. Variant c.243 + 3A>G causes exon 4 skipping. The deep-intronic c.164-672C>T variant creates a potential 5' splice site that leads to the inclusion of four overlapping pseudoexons, corresponding to exonizations of an antisense short interspersed nuclear element AluSq repeat sequence. Two of the identified pseudoexons have been reported previously, activated by different deep-intronic variants, and were also detected at residual levels in control cells. Interestingly, the predominant pseudoexon is nearly identical to a disease causing activated pseudoexon in the F8 gene, with the same 3' and 5' splice sites. Splice switching antisense oligonucleotides (SSOs) were designed to hybridize with splice sites and/or predicted binding sites for regulatory splice factors. Different SSOs corrected the aberrant pseudoexon inclusion, both in minigenes and in fibroblasts from patients carrying the new variant c.164-672C>T or the previously described c.164-716A>T. With SSO treatment PTPS protein was recovered, illustrating the therapeutic potential of the approach, for patients with different pseudoexon activating variants in the region. In addition, the natural presence of pseudoexons in the wild type context suggests the possibility of applying the antisense strategy in patients with hypomorphic PTS variants with the purpose of upregulating their expression to increase overall protein and activity.
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Affiliation(s)
- Ainhoa Martínez-Pizarro
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), CIBERER, IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
| | - Fátima Leal
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), CIBERER, IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
| | - Lise Lolle Holm
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Ulrika S S Petersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - María Bueno
- Congenital Metabolic Diseases Unit, Hospital Virgen del Rocio, Sevilla, Spain
| | - Beat Thöny
- Division of Metabolism, University Children's Hospital Zürich, Zürich, Switzerland
| | - Belén Pérez
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), CIBERER, IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Lourdes R Desviat
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), CIBERER, IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
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6
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Guerra B, Doktor TK, Frederiksen SB, Somyajit K, Andresen BS. Essential role of CK2α for the interaction and stability of replication fork factors during DNA synthesis and activation of the S-phase checkpoint. Cell Mol Life Sci 2022; 79:339. [PMID: 35661926 PMCID: PMC9166893 DOI: 10.1007/s00018-022-04374-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 05/09/2022] [Accepted: 05/12/2022] [Indexed: 11/25/2022]
Abstract
The ataxia telangiectasia mutated and Rad3-related (ATR)-CHK1 pathway is the major signalling cascade activated in response to DNA replication stress. This pathway is associated with the core of the DNA replication machinery comprising CDC45, the replicative MCM2-7 hexamer, GINS (altogether forming the CMG complex), primase-polymerase (POLε, -α, and -δ) complex, and additional fork protection factors such as AND-1, CLASPIN (CLSPN), and TIMELESS/TIPIN. In this study, we report that functional protein kinase CK2α is critical for preserving replisome integrity and for mounting S-phase checkpoint signalling. We find that CDC45, CLSPN and MCM7 are novel CK2α interacting partners and these interactions are particularly important for maintenance of stable MCM7-CDC45, ATRIP-ATR-MCM7, and ATR-CLSPN protein complexes. Consistently, cells depleted of CK2α and treated with hydroxyurea display compromised replisome integrity, reduced chromatin binding of checkpoint mediator CLSPN, attenuated ATR-mediated S-phase checkpoint and delayed recovery of stalled forks. In further support of this, differential gene expression analysis by RNA-sequencing revealed that down-regulation of CK2α accompanies global shutdown of genes that are implicated in the S-phase checkpoint. These findings add to our understanding of the molecular mechanisms involved in DNA replication by showing that the protein kinase CK2α is essential for maintaining the stability of the replisome machinery and for optimizing ATR-CHK1 signalling activation upon replication stress.
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Affiliation(s)
- Barbara Guerra
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark.
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Sabrina B Frederiksen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Kumar Somyajit
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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7
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Holm LL, Doktor TK, Hansen MB, Petersen USS, Andresen BS. Vulnerable exons, like ACADM exon 5, are highly dependent on maintaining a correct balance between splicing enhancers and silencers. Hum Mutat 2021; 43:253-265. [PMID: 34923709 DOI: 10.1002/humu.24321] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 11/08/2021] [Accepted: 12/15/2021] [Indexed: 12/22/2022]
Abstract
It is now widely accepted that aberrant splicing of constitutive exons is often caused by mutations affecting cis-acting splicing regulatory elements, but there is a misconception that all exons have an equal dependency on splicing regulatory elements and thus a similar susceptibility to aberrant splicing. We investigated exonic mutations in ACADM exon 5 to experimentally examine their effect on splicing and found that 7 out of 11 tested mutations affected exon inclusion, demonstrating that this constitutive exon is particularly vulnerable to exonic splicing mutations. Employing ACADM exon 5 and 6 as models, we demonstrate that the balance between splicing enhancers and silencers, flanking intron length, and flanking splice site strength are important factors that determine exon definition and splicing efficiency of the exon in question. Our study shows that two constitutive exons in ACADM have different inherent vulnerabilities to exonic splicing mutations. This suggests that in silico prediction of potential pathogenic effects on splicing from exonic mutations may be improved by also considering the inherent vulnerability of the exon. Moreover, we show that single nucleotide polymorphism that affect either of two different exonic splicing silencers, located far apart in exon 5, all protect against both immediately flanking and more distant exonic splicing mutations.
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Affiliation(s)
- Lise L Holm
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M., Denmark.,Department of Molecular Biology and Biochemistry, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M., Denmark.,Department of Molecular Biology and Biochemistry, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Michael B Hansen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M., Denmark.,Department of Molecular Biology and Biochemistry, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Ulrika S S Petersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M., Denmark.,Department of Molecular Biology and Biochemistry, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M., Denmark.,Department of Molecular Biology and Biochemistry, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
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8
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Petersen USS, Doktor TK, Andresen BS. Pseudoexon activation in disease by non-splice site deep intronic sequence variation - wild type pseudoexons constitute high-risk sites in the human genome. Hum Mutat 2021; 43:103-127. [PMID: 34837434 DOI: 10.1002/humu.24306] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 11/02/2021] [Accepted: 11/06/2021] [Indexed: 12/27/2022]
Abstract
Accuracy of pre-messenger RNA (pre-mRNA) splicing is crucial for normal gene expression. Complex regulation supports the spliceosomal distinction between authentic exons and the many seemingly functional splice sites delimiting pseudoexons. Pseudoexons are nonfunctional intronic sequences that can be activated for aberrant inclusion in mRNA, which may cause disease. Pseudoexon activation is very challenging to predict, in particular when activation occurs by sequence variants that alter the splicing regulatory environment without directly affecting splice sites. As pseudoexon inclusion often evades detection due to activation of nonsense-mediated mRNA decay, and because conventional diagnostic procedures miss deep intronic sequence variation, pseudoexon activation is a heavily underreported disease mechanism. Pseudoexon characteristics have mainly been studied based on in silico predicted sequences. Moreover, because recognition of sequence variants that create or strengthen splice sites is possible by comparison with well-established consensus sequences, this type of pseudoexon activation is by far the most frequently reported. Here we review all known human disease-associated pseudoexons that carry functional splice sites and are activated by deep intronic sequence variants located outside splice site sequences. We delineate common characteristics that make this type of wild type pseudoexons distinct high-risk sites in the human genome.
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Affiliation(s)
- Ulrika S S Petersen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
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9
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Guerra B, Dembic M, Siddiqui MA, Dominguez I, Ceppi P, Andresen BS. Down-Regulation of CK2α Leads toUp-Regulation of the Cyclin-Dependent Kinase Inhibitor p27 KIP1 in Conditions Unfavorable for the Growth of Myoblast Cells. Cell Physiol Biochem 2021; 54:1177-1198. [PMID: 33216476 DOI: 10.33594/000000308] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2020] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND/AIMS Compelling evidence indicates that CK2α, which is one of the two catalytic isoforms of protein kinase CK2, is required for cell viability and plays an important role in cell proliferation and differentiation. While much is known on CK2 in the context of disease states, particularly cancer, its critical role in non-cancerous cell growth has not been extensively investigated. METHODS In the present study, we have employed a cell line derived from rat heart with inducible down-regulation of CK2α and CK2α-knockout mouse tissue to identify CK2-mediated molecular mechanisms regulating cell growth. For this, we have performed Incucyte® live-cell analysis and applied flow cytometry, western blot, immunoprecipitation, immunohistochemistry, RT-qPCR and luciferase-based methods. RESULTS Here, we show that lack of CK2α results in significantly delayed cell cycle progression through G1, inhibition of cyclin E-CDK2 complex, decreased phosphorylation of Rb protein at S795, and inactivation of E2F transcription factor. These events are accompanied by nuclear accumulation and up-regulation of the cyclin-dependent kinase inhibitor p27KIP1 in cells and CK2α-knockout mouse tissues. We found that increased levels of p27KIP1 are mainly attributable to post-translational modifications, namely phosphorylation at S10 and T197 amino acid residues catalyzed by Dyrk1B and AMPK, respectively, as silencing of FoxO3A transcription factor, which activates CDKN1B the gene coding for p27KIP1, does not result in markedly decreased expression levels of the corresponding protein. Interestingly, simultaneous silencing of CK2α and p27KIP1 significantly impairs cell cycle progression without increasing cell death. CONCLUSION Taken together, our study sheds light on the molecular mechanisms controlling cell cycle progression through G1 phase when myoblasts proliferation potential is impaired by CK2α depletion. Our results suggest that elevated levels of p27KIP1, which follows CK2α depletion, contribute to delay the G1-to-S phase transition. Effects seen when p27KIP1 is down-regulated are independent of CK2α and reflect the protective role exerted by p27KIP1 under unfavorable cell growth conditions.
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Affiliation(s)
- Barbara Guerra
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark,
| | - Maja Dembic
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Mohammad A Siddiqui
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Isabel Dominguez
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Paolo Ceppi
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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10
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Frederiksen SB, Holm LL, Larsen MR, Doktor TK, Andersen HS, Hastings ML, Hua Y, Krainer AR, Andresen BS. Identification of SRSF10 as a regulator of SMN2 ISS-N1. Hum Mutat 2020; 42:246-260. [PMID: 33300159 DOI: 10.1002/humu.24149] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 10/22/2020] [Accepted: 12/06/2020] [Indexed: 01/02/2023]
Abstract
Understanding the splicing code can be challenging as several splicing factors bind to many splicing-regulatory elements. The SMN1 and SMN2 silencer element ISS-N1 is the target of the antisense oligonucleotide drug, Spinraza, which is the treatment against spinal muscular atrophy. However, limited knowledge about the nature of the splicing factors that bind to ISS-N1 and inhibit splicing exists. It is likely that the effect of Spinraza comes from blocking binding of these factors, but so far, an unbiased characterization has not been performed and only members of the hnRNP A1/A2 family have been identified by Western blot analysis and nuclear magnetic resonance to bind to this silencer. Employing an MS/MS-based approach and surface plasmon resonance imaging, we show for the first time that splicing factor SRSF10 binds to ISS-N1. Furthermore, using splice-switching oligonucleotides we modulated the splicing of the SRSF10 isoforms generating either the long or the short protein isoform of SRSF10 to regulate endogenous SMN2 exon 7 inclusion. We demonstrate that the isoforms of SRSF10 regulate SMN1 and SMN2 splicing with different strength correlating with the length of their RS domain. Our results suggest that the ratio between the SRSF10 isoforms is important for splicing regulation.
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Affiliation(s)
- Sabrina B Frederiksen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Lise L Holm
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Martin R Larsen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Henriette S Andersen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Michelle L Hastings
- Department of Cell Biology and Anatomy, Center for Genetic Diseases, Chicago Medical School and School of Graduate and Postdoctoral Studies, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, USA
| | - Yimin Hua
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA
| | - Adrian R Krainer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
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11
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Bruun GH, Bang JMV, Christensen LL, Brøner S, Petersen USS, Guerra B, Grønning AGB, Doktor TK, Andresen BS. Blocking of an intronic splicing silencer completely rescues IKBKAP exon 20 splicing in familial dysautonomia patient cells. Nucleic Acids Res 2019; 46:7938-7952. [PMID: 29762696 PMCID: PMC6125618 DOI: 10.1093/nar/gky395] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 04/30/2018] [Indexed: 12/22/2022] Open
Abstract
Familial dysautonomia (FD) is a severe genetic disorder causing sensory and autonomic dysfunction. It is predominantly caused by a c.2204+6T>C mutation in the IKBKAP gene. This mutation decreases the 5′ splice site strength of IKBKAP exon 20 leading to exon 20 skipping and decreased amounts of full-length IKAP protein. We identified a binding site for the splicing regulatory protein hnRNP A1 downstream of the IKBKAP exon 20 5′-splice site. We show that hnRNP A1 binds to this splicing regulatory element (SRE) and that two previously described inhibitory SREs inside IKBKAP exon 20 are also bound by hnRNP A1. Knockdown of hnRNP A1 in FD patient fibroblasts increases IKBKAP exon 20 inclusion demonstrating that hnRNP A1 is a negative regulator of IKBKAP exon 20 splicing. Furthermore, by mutating the SREs in an IKBKAP minigene we show that all three SREs cause hnRNP A1-mediated exon repression. We designed splice switching oligonucleotides (SSO) that blocks the intronic hnRNP A1 binding site, and demonstrate that this completely rescues splicing of IKBKAP exon 20 in FD patient fibroblasts and increases the amounts of IKAP protein. We propose that this may be developed into a potential new specific treatment of FD.
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Affiliation(s)
- Gitte H Bruun
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Jeanne M V Bang
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Lise L Christensen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Sabrina Brøner
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Ulrika S S Petersen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Barbara Guerra
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Alexander G B Grønning
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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12
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Dembic M, Andersen HS, Bastin J, Doktor TK, Corydon TJ, Sass JO, Lopes Costa A, Djouadi F, Andresen BS. Next generation sequencing of RNA reveals novel targets of resveratrol with possible implications for Canavan disease. Mol Genet Metab 2019; 126:64-76. [PMID: 30446350 DOI: 10.1016/j.ymgme.2018.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 10/17/2018] [Accepted: 10/19/2018] [Indexed: 12/21/2022]
Abstract
Resveratrol (RSV) is a small compound first identified as an activator of sirtuin 1 (SIRT1), a key factor in mediating the effects of caloric restriction. Since then, RSV received great attention for its widespread beneficial effects on health and in connection to many diseases. RSV improves the metabolism and the mitochondrial function, and more recently it was shown to restore fatty acid β-oxidation (FAO) capacities in patient fibroblasts harboring mutations with residual enzyme activity. Many of RSV's beneficial effects are mediated by the transcriptional coactivator PGC-1α, a direct target of SIRT1 and a master regulator of the mitochondrial fatty acid oxidation. Despite numerous studies RSV's mechanism of action is still not completely elucidated. Our aim was to investigate the effects of RSV on gene regulation on a wide scale, possibly to detect novel genes whose up-regulation by RSV may be of interest with respect to disease treatment. We performed Next Generation Sequencing of RNA on normal fibroblasts treated with RSV. To investigate whether the effects of RSV are mediated through SIRT1 we expanded the analysis to include SIRT1-knockdown fibroblasts. We identified the aspartoacylase (ASPA) gene, mutated in Canavan disease, to be strongly up-regulated by RSV in several cell lines, including Canavan disease fibroblasts. We further link RSV to the up-regulation of other genes involved in myelination including the glial specific transcription factors POU3F1, POU3F2, and myelin basic protein (MBP). We also observe a strong up-regulation by RSV of the riboflavin transporter gene SLC52a1. Mutations in SLC52a1 cause transient multiple acyl-CoA dehydrogenase deficiency (MADD). Our analysis of alternative splicing identified novel metabolically important genes affected by RSV, among which is particularly interesting the α subunit of the stimulatory G protein (Gsα), which regulates the cellular levels of cAMP through adenylyl cyclase. We conclude that in fibroblasts RSV stimulates the PGC-1α and p53 pathways, and up-regulates genes affecting the glucose metabolism, mitochondrial β-oxidation, and mitochondrial biogenesis. We further confirm that RSV might be a relevant treatment in the correction of FAO deficiencies and we suggest that treatment in other metabolic disorders including Canavan disease and MADD might be also beneficial.
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Affiliation(s)
- Maja Dembic
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
| | - Henriette S Andersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
| | - Jean Bastin
- INSERM UMR-S 1124, Université Paris Descartes, UFR Biomédicale des Saints-Pères, 45, rue des Saints-Pères, 75270 Paris, cedex 06, France
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
| | - Thomas J Corydon
- Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark; Department of Ophthalmology, Aarhus University Hospital, 8000 Aarhus C, Denmark.
| | - Jörn Oliver Sass
- Research Group Inborn Errors of Metabolism, Department of Natural Sciences & IFGA, University of Applied Sciences, Rheinbach, Germany.
| | - Alexandra Lopes Costa
- INSERM UMR-S 1124, Université Paris Descartes, UFR Biomédicale des Saints-Pères, 45, rue des Saints-Pères, 75270 Paris, cedex 06, France
| | - Fatima Djouadi
- INSERM UMR-S 1124, Université Paris Descartes, UFR Biomédicale des Saints-Pères, 45, rue des Saints-Pères, 75270 Paris, cedex 06, France
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark.
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13
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Rauen KA, Schoyer L, Schill L, Stronach B, Albeck J, Andresen BS, Cavé H, Ellis M, Fruchtman SM, Gelb BD, Gibson CC, Gripp K, Hefner E, Huang WYC, Itkin M, Kerr B, Linardic CM, McMahon M, Oberlander B, Perlstein E, Ratner N, Rogers L, Schenck A, Shankar S, Shvartsman S, Stevenson DA, Stites EC, Stork PJS, Sun C, Therrien M, Ullian EM, Widemann BC, Yeh E, Zampino G, Zenker M, Timmer W, McCormick F. Proceedings of the fifth international RASopathies symposium: When development and cancer intersect. Am J Med Genet A 2018; 176:2924-2929. [PMID: 30302932 DOI: 10.1002/ajmg.a.40632] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 08/02/2018] [Indexed: 11/07/2022]
Abstract
This report summarizes and highlights the fifth International RASopathies Symposium: When Development and Cancer Intersect, held in Orlando, Florida in July 2017. The RASopathies comprise a recognizable pattern of malformation syndromes that are caused by germ line mutations in genes that encode components of the RAS/mitogen-activated protein kinase (MAPK) pathway. Because of their common underlying pathogenetic etiology, there is significant overlap in their phenotypic features, which includes craniofacial dysmorphology, cardiac, cutaneous, musculoskeletal, gastrointestinal and ocular abnormalities, neurological and neurocognitive issues, and a predisposition to cancer. The RAS pathway is a well-known oncogenic pathway that is commonly found to be activated in somatic malignancies. As in somatic cancers, the RASopathies can be caused by various pathogenetic mechanisms that ultimately impact or alter the normal function and regulation of the MAPK pathway. As such, the RASopathies represent an excellent model of study to explore the intersection of the effects of dysregulation and its consequence in both development and oncogenesis.
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Affiliation(s)
- Katherine A Rauen
- Department of Pediatrics, University of California Davis, MIND Institute, Sacramento, California
| | | | | | | | - John Albeck
- Department of Pediatrics, University of California Davis, Davis, California
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Hélène Cavé
- Genetics Department, Hôpitaux de Paris, Hôpital Robert Debré, Paris-Diderot University, Paris, France
| | | | | | - Bruce D Gelb
- Departments of Pediatrics and Genetics and Genomic Sciences, Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | | | - Karen Gripp
- Departments of Division of Medical Genetics, AI duPont Hospital for Children, Wilmington, Delaware
| | - Erin Hefner
- Costello Syndrome Family Network, Creve Coeur, Illinois
| | - William Y C Huang
- Department of Chemistry, University of California Berkeley, Berkeley, California
| | - Maxim Itkin
- Department of Radiology, Penn Medicine, Philadelphia, Pennsylvania
| | - Bronwyn Kerr
- Department of Genetic Medicine, Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - Corinne M Linardic
- Department of Pediatrics, Duke University School of Medicine, Durham, North Carolina
| | - Martin McMahon
- Departments of McMahon, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
| | | | | | - Nancy Ratner
- Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | | | - Annette Schenck
- Departments of Ratner, Radboud University Medical Center, Nijmegen, Netherlands
| | - Suma Shankar
- Department of Pediatrics, University of California Davis, Davis, California
| | - Stanislav Shvartsman
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey
| | - David A Stevenson
- Department of Pediatrics, Stanford University, Palo Alto, California
| | - Edward C Stites
- Departments of Integrative Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California
| | - Philip J S Stork
- Departments of Stork, Oregon Health & Sciences University, Portland, Oregon
| | - Cheng Sun
- Department of Stem Cell and Regenrative Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Marc Therrien
- Department of Pathology and Cell Biology, University of Montreal, Montreal, Quebec, Canada
| | - Erik M Ullian
- Department of Ophthalmology, Neuroscience Program, University of California, San Francisco, San Francisco, California
| | - Brigitte C Widemann
- Departments of Peiatric Oncology Branch, National Cancer Institute, Center for Cancer Research, Pediatric Oncology Branch, Bethesda, Maryland
| | - Erika Yeh
- Department of Ophthalmology, Neuroscience Program, University of California, San Francisco, San Francisco, California
| | - Giuseppe Zampino
- Departments of Department of Medicine and Surgery, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Martin Zenker
- Departments of Institute of Human Genetics, University Hospital Magdeburg, Magdeburg, Germany
| | - William Timmer
- Departments of Cancer Therapy Evaluation Program, National Cancer Institute, Cancer Therapy Evaluation Program (CTEP), Bethesda, Maryland
| | - Frank McCormick
- Department of Ophthalmology, Neuroscience Program, University of California, San Francisco, San Francisco, California
- Departments of McCormick, RAS Initiative, Frederick National Lab, Frederick, Maryland
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14
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Martínez-Pizarro A, Dembic M, Pérez B, Andresen BS, Desviat LR. Intronic PAH gene mutations cause a splicing defect by a novel mechanism involving U1snRNP binding downstream of the 5' splice site. PLoS Genet 2018; 14:e1007360. [PMID: 29684050 PMCID: PMC5933811 DOI: 10.1371/journal.pgen.1007360] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 05/03/2018] [Accepted: 04/11/2018] [Indexed: 11/18/2022] Open
Abstract
Phenylketonuria (PKU), one of the most common inherited diseases of amino acid metabolism, is caused by mutations in the phenylalanine hydroxylase (PAH) gene. Recently, PAH exon 11 was identified as a vulnerable exon due to a weak 3’ splice site, with different exonic mutations affecting exon 11 splicing through disruption of exonic splicing regulatory elements. In this study, we report a novel intron 11 regulatory element, which is involved in exon 11 splicing, as revealed by the investigated pathogenic effect of variants c.1199+17G>A and c.1199+20G>C, identified in PKU patients. Both mutations cause exon 11 skipping in a minigene system. RNA binding assays indicate that binding of U1snRNP70 to this intronic region is disrupted, concomitant with a slightly increased binding of inhibitors hnRNPA1/2. We have investigated the effect of deletions and point mutations, as well as overexpression of adapted U1snRNA to show that this splicing regulatory motif is important for regulation of correct splicing at the natural 5’ splice site. The results indicate that U1snRNP binding downstream of the natural 5’ splice site determines efficient exon 11 splicing, thus providing a basis for development of therapeutic strategies to correct PAH exon 11 splicing mutations. In this work, we expand the functional effects of non-canonical intronic U1 snRNP binding by showing that it may enhance exon definition and that, consequently, intronic mutations may cause exon skipping by a novel mechanism, where they disrupt stimulatory U1 snRNP binding close to the 5’ splice site. Notably, our results provide further understanding of the reported therapeutic effect of exon specific U1 snRNA for splicing mutations in disease. Splicing defects constitute a major cause of human disease. Mutations affecting conserved splicing sequences at exon-intron junctions are easily recognized as possibly pathogenic, whereas variants in exonic or intronic regions are difficult to classify without functional evidence provided by transcript analysis or in vitro analysis using minigenes. In this work, we sought out to study the pathogenicity of two novel intronic PAH variants identified in phenylketonuria patients. Both mutations resulted in exon skipping in minigenes. We demonstrate that U1snRNP70 binds to the intronic region and that this binding is abolished in the mutant sequences. Correction of the splicing defect was achieved using modified U1 snRNA perfectly complementary to each of the mutant sequences. The results extend the repertoire of natural U1 snRNP cellular functions by including its role as splicing enhancer via binding downstream of the natural 5’ splice site. In addition, our results correlate with the described therapeutic effect of modified U1snRNP for splicing mutations in different genes, thus having a significant impact in the development of specific therapies for splicing defects.
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Affiliation(s)
- Ainhoa Martínez-Pizarro
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, CEDEM, CIBERER, IdiPaz, Universidad Autónoma, Madrid, Spain
| | - Maja Dembic
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Belén Pérez
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, CEDEM, CIBERER, IdiPaz, Universidad Autónoma, Madrid, Spain
| | - Brage S. Andresen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
- * E-mail: (BSA); (LRD)
| | - Lourdes R. Desviat
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, CEDEM, CIBERER, IdiPaz, Universidad Autónoma, Madrid, Spain
- * E-mail: (BSA); (LRD)
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15
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Mosegaard S, Bruun GH, Flyvbjerg KF, Bliksrud YT, Gregersen N, Dembic M, Annexstad E, Tangeraas T, Olsen RKJ, Andresen BS. An intronic variation in SLC52A1 causes exon skipping and transient riboflavin-responsive multiple acyl-CoA dehydrogenation deficiency. Mol Genet Metab 2017; 122:182-188. [PMID: 29122468 DOI: 10.1016/j.ymgme.2017.10.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 10/31/2017] [Accepted: 10/31/2017] [Indexed: 11/23/2022]
Abstract
Vitamin B2, riboflavin is essential for cellular function, as it participates in a diversity of redox reactions central to human metabolism, through its role as precursor for the cofactors flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are electron carriers. The electron transfer flavoprotein (ETF) and its dehydrogenase (ETFDH), uses FAD as cofactor. The ETF and ETFDH are forming the electron transport pathway for many mitochondrial flavoprotein dehydrogenases involved in fatty acid, amino acid and choline metabolism. A variation in either ETF or ETFDH causes multiple acyl-CoA dehydrogenation deficiency (MADD), but genetic variations in the riboflavin metabolism or transportation of riboflavin can also cause MADD. The most common variations are located in the riboflavin transporter 2 (RFVT2) and 3 (RFVT3), that are highly expressed in brain and intestinal tissues, respectively. Deficiency of riboflavin transporter 1 (RFVT1), encoded by the SLC52A1 gene, highly expressed in the placenta, has only been reported once. We here report a case of transient MADD, caused by a heterozygous intronic variation, c.1134+11G>A, in the SLC52A1 gene encoding RFVT1. This variation creates a binding site for the splice inhibitory hnRNP A1 protein and causes exon 4 skipping. Riboflavin deficiency and maternal malnutrition during pregnancy might have been the determining factor in the outcome of this case.
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Affiliation(s)
- Signe Mosegaard
- Research Unit for Molecular Medicine, Department of Clinical Medicine, Aarhus University and University Hospital, 8200 Aarhus N, Denmark
| | - Gitte Hoffmann Bruun
- Department of Biochemistry and Molecular Biology, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Karen Freund Flyvbjerg
- Department of Biochemistry and Molecular Biology, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | | | - Niels Gregersen
- Research Unit for Molecular Medicine, Department of Clinical Medicine, Aarhus University and University Hospital, 8200 Aarhus N, Denmark
| | - Maja Dembic
- Department of Biochemistry and Molecular Biology, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Ellen Annexstad
- Ostfold Hospital Trust, Women's and Children's Department, Norway
| | - Trine Tangeraas
- Department of Pediatrics, Oslo University Hospital, Oslo, Norway
| | - Rikke Katrine Jentoft Olsen
- Research Unit for Molecular Medicine, Department of Clinical Medicine, Aarhus University and University Hospital, 8200 Aarhus N, Denmark
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark.
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Heintz C, Doktor TK, Lanjuin A, Escoubas CC, Zhang Y, Weir HJ, Dutta S, Silva-García CG, Bruun GH, Morantte I, Hoxhaj G, Manning BD, Andresen BS, Mair WB. Corrigendum: Splicing factor 1 modulates dietary restriction and TORC1 pathway longevity in C. elegans. Nature 2017; 547:476. [PMID: 28700577 DOI: 10.1038/nature23313] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This corrects the article DOI: 10.1038/nature20789.
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Santra S, Macdonald A, Preece MA, Olsen RK, Andresen BS. Long-term outcome of isobutyryl-CoA dehydrogenase deficiency diagnosed following an episode of ketotic hypoglycaemia. Mol Genet Metab Rep 2016; 10:28-30. [PMID: 28053874 PMCID: PMC5198737 DOI: 10.1016/j.ymgmr.2016.11.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 11/23/2016] [Accepted: 11/23/2016] [Indexed: 11/17/2022] Open
Abstract
Isobutyryl-CoA Dehydrogenase Deficiency (IBDD) is an inherited disorder of valine metabolism caused by mutations in ACAD8. Most reported patients have been diagnosed through newborn screening programmes due to elevated C4-carnitine levels and appear clinically asymptomatic. One reported non-screened patient had dilated cardiomyopathy and anaemia at the age of two years. We report a 13 month old girl diagnosed with IBDD after developing hypoglycaemic encephalopathy (blood glucose 1.9 mmol/l) during an episode of rotavirus-induced gastroenteritis. Metabolic investigations demonstrated an appropriate ketotic response (free fatty acids 2594 μmol/l, 3-hydroxybutyrate 3415 μmol/l), mildly elevated plasma lactate (3.4 mmol/l), increased C4-carnitine on blood spot and plasma acylcarnitine analysis and other metabolic abnormalities secondary to ketosis. After recovery, C4-carnitine remained increased and isobutyrylglycine was detected on urine organic acid analysis. Free carnitine was normal in all acylcarnitine samples. IBDD was confirmed by finding a homozygous c.845C > T substitution in ACAD8. The patient was given, but has not used, a glucose polymer emergency regimen and after ten years' follow-up has had no further episodes of hypoglycaemia nor has she developed cardiomyopathy or anaemia. Psychomotor development has been normal to date. Though we suspect IBDD did not contribute to hypoglycaemia in this patient, patients should be followed-up carefully and glucose polymer emergency regimens may be indicated if recurrent episodes of hypoglycaemia occur.
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Affiliation(s)
- S Santra
- Department of Clinical Inherited Metabolic Disorders, Birmingham Children's Hospital, Steelhouse Lane, Birmingham B4 6NH, United Kingdom
| | - A Macdonald
- Department of Dietetics, Birmingham Children's Hospital, Steelhouse Lane, Birmingham B4 6NH, United Kingdom
| | - M A Preece
- Department of Newborn Screening and Biochemical Genetics, Birmingham Children's Hospital, Steelhouse Lane, Birmingham B4 6NH, United Kingdom
| | - R K Olsen
- Research Unit for Molecular Medicine, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Aarhus, Denmark
| | - B S Andresen
- Research Unit for Molecular Medicine, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Aarhus, Denmark; The Villum Center for Bioanalytical Sciences and Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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Evans M, Andresen BS, Nation J, Boneh A. VLCAD deficiency: Follow-up and outcome of patients diagnosed through newborn screening in Victoria. Mol Genet Metab 2016; 118:282-7. [PMID: 27246109 DOI: 10.1016/j.ymgme.2016.05.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 05/15/2016] [Accepted: 05/15/2016] [Indexed: 12/31/2022]
Abstract
Very long chain acyl-CoA dehydrogenase (VLCAD) deficiency is an inherited metabolic disorder of fatty acid oxidation. Treatment practices of the disorder have changed over the past 10-15years since this disorder was included in newborn screening programs and patients were diagnosed pre-symptomatically. A genotype-phenotype correlation has been suggested but the discovery of novel mutations make this knowledge limited. Herein, we describe our experience in treating patients (n=22) diagnosed through newborn screening and mutational confirmation and followed up over a median period of 104months. We report five novel mutations. In 2013 we formalised our treatment protocol, which essentially follows a European consensus paper from 2009 and our own experience. The prescribed low natural fat diet is relaxed for patients who are asymptomatic when reaching age 5years but medium-chain triglyceride oil is recommended before and after physical activity regardless of age. Metabolic stability, growth, development and cardiac function are satisfactory in all patients. There were no episodes of encephalopathy or hypoglycaemia but three patients had episodes of muscle pain with our without rhabdomyolysis. Body composition studies showed a negative association between dietary protein intake and percent body fat. Larger patient cohort and longer follow up time are required for further elucidation of genotype-phenotype correlations and for establishing the role of dietary protein in metabolic stability and long-term healthier body composition in patients with VLCAD deficiency.
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Affiliation(s)
- Maureen Evans
- Department of Metabolic Medicine, Royal Children's Hospital Melbourne, Australia
| | - Brage S Andresen
- Research Unit for Molecular Medicine, Skejby Sygehus, Aarhus, Denmark; The Villum Center for Bioanalytical Sciences, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Judy Nation
- Department of Metabolic Medicine, Royal Children's Hospital Melbourne, Australia
| | - Avihu Boneh
- Department of Metabolic Medicine, Royal Children's Hospital Melbourne, Australia; Department of Paediatrics, University of Melbourne, Australia; Metabolic research, Murdoch Childrens Research Institute, Australia.
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Bruun GH, Doktor TK, Borch-Jensen J, Masuda A, Krainer AR, Ohno K, Andresen BS. Global identification of hnRNP A1 binding sites for SSO-based splicing modulation. BMC Biol 2016; 14:54. [PMID: 27380775 PMCID: PMC4932749 DOI: 10.1186/s12915-016-0279-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 06/23/2016] [Indexed: 01/14/2023] Open
Abstract
Background Many pathogenic genetic variants have been shown to disrupt mRNA splicing. Besides splice mutations in the well-conserved splice sites, mutations in splicing regulatory elements (SREs) may deregulate splicing and cause disease. A promising therapeutic approach is to compensate for this deregulation by blocking other SREs with splice-switching oligonucleotides (SSOs). However, the location and sequence of most SREs are not well known. Results Here, we used individual-nucleotide resolution crosslinking immunoprecipitation (iCLIP) to establish an in vivo binding map for the key splicing regulatory factor hnRNP A1 and to generate an hnRNP A1 consensus binding motif. We find that hnRNP A1 binding in proximal introns may be important for repressing exons. We show that inclusion of the alternative cassette exon 3 in SKA2 can be significantly increased by SSO-based treatment which blocks an iCLIP-identified hnRNP A1 binding site immediately downstream of the 5’ splice site. Because pseudoexons are well suited as models for constitutive exons which have been inactivated by pathogenic mutations in SREs, we used a pseudoexon in MTRR as a model and showed that an iCLIP-identified hnRNP A1 binding site downstream of the 5′ splice site can be blocked by SSOs to activate the exon. Conclusions The hnRNP A1 binding map can be used to identify potential targets for SSO-based therapy. Moreover, together with the hnRNP A1 consensus binding motif, the binding map may be used to predict whether disease-associated mutations and SNPs affect hnRNP A1 binding and eventually mRNA splicing. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0279-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gitte H Bruun
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark
| | - Jonas Borch-Jensen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark
| | - Akio Masuda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Adrian R Krainer
- Cold Spring Harbor Laboratory, PO Box 100, Cold Spring Harbor, NY, 11724, USA
| | - Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark.
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20
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Hartung AM, Swensen J, Uriz IE, Lapin M, Kristjansdottir K, Petersen USS, Bang JMV, Guerra B, Andersen HS, Dobrowolski SF, Carey JC, Yu P, Vaughn C, Calhoun A, Larsen MR, Dyrskjøt L, Stevenson DA, Andresen BS. The Splicing Efficiency of Activating HRAS Mutations Can Determine Costello Syndrome Phenotype and Frequency in Cancer. PLoS Genet 2016; 12:e1006039. [PMID: 27195699 PMCID: PMC4873146 DOI: 10.1371/journal.pgen.1006039] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 04/18/2016] [Indexed: 12/25/2022] Open
Abstract
Costello syndrome (CS) may be caused by activating mutations in codon 12/13 of the HRAS proto-oncogene. HRAS p.Gly12Val mutations have the highest transforming activity, are very frequent in cancers, but very rare in CS, where they are reported to cause a severe, early lethal, phenotype. We identified an unusual, new germline p.Gly12Val mutation, c.35_36GC>TG, in a 12-year-old boy with attenuated CS. Analysis of his HRAS cDNA showed high levels of exon 2 skipping. Using wild type and mutant HRAS minigenes, we confirmed that c.35_36GC>TG results in exon 2 skipping by simultaneously disrupting the function of a critical Exonic Splicing Enhancer (ESE) and creation of an Exonic Splicing Silencer (ESS). We show that this vulnerability of HRAS exon 2 is caused by a weak 3' splice site, which makes exon 2 inclusion dependent on binding of splicing stimulatory proteins, like SRSF2, to the critical ESE. Because the majority of cancer- and CS- causing mutations are located here, they affect splicing differently. Therefore, our results also demonstrate that the phenotype in CS and somatic cancers is not only determined by the different transforming potentials of mutant HRAS proteins, but also by the efficiency of exon 2 inclusion resulting from the different HRAS mutations. Finally, we show that a splice switching oligonucleotide (SSO) that blocks access to the critical ESE causes exon 2 skipping and halts proliferation of cancer cells. This unravels a potential for development of new anti-cancer therapies based on SSO-mediated HRAS exon 2 skipping.
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Affiliation(s)
- Anne-Mette Hartung
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Jeff Swensen
- Caris Life Sciences, Phoenix, Arizona, United States of America
- Department of Pathology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- ARUP Laboratories, Salt Lake City, Utah, United States of America
| | - Inaki E. Uriz
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Morten Lapin
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Karen Kristjansdottir
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Ulrika S. S. Petersen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Jeanne Mari V. Bang
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Barbara Guerra
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Henriette Skovgaard Andersen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Steven F. Dobrowolski
- Department of Pathology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - John C. Carey
- Department of Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
| | - Ping Yu
- ARUP Laboratories, Salt Lake City, Utah, United States of America
| | - Cecily Vaughn
- ARUP Laboratories, Salt Lake City, Utah, United States of America
| | - Amy Calhoun
- Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Martin R. Larsen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Lars Dyrskjøt
- Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - David A. Stevenson
- Division of Medical Genetics, Stanford University, Stanford, California, United States of America
| | - Brage S. Andresen
- Department of Biochemistry and Molecular Biology and The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
- * E-mail:
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21
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Stevenson DA, Schill L, Schoyer L, Andresen BS, Bakker A, Bayrak-Toydemir P, Burkitt-Wright E, Chatfield K, Elefteriou F, Elgersma Y, Fisher MJ, Franz D, Gelb BD, Goriely A, Gripp KW, Hardan AY, Keppler-Noreuil KM, Kerr B, Korf B, Leoni C, McCormick F, Plotkin SR, Rauen KA, Reilly K, Roberts A, Sandler A, Siegel D, Walsh K, Widemann BC. The Fourth International Symposium on Genetic Disorders of the Ras/MAPK pathway. Am J Med Genet A 2016; 170:1959-66. [PMID: 27155140 DOI: 10.1002/ajmg.a.37723] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 04/23/2016] [Indexed: 12/14/2022]
Abstract
The RASopathies are a group of disorders due to variations of genes associated with the Ras/MAPK pathway. Some of the RASopathies include neurofibromatosis type 1 (NF1), Noonan syndrome, Noonan syndrome with multiple lentigines, cardiofaciocutaneous (CFC) syndrome, Costello syndrome, Legius syndrome, and capillary malformation-arteriovenous malformation (CM-AVM) syndrome. In combination, the RASopathies are a frequent group of genetic disorders. This report summarizes the proceedings of the 4th International Symposium on Genetic Disorders of the Ras/MAPK pathway and highlights gaps in the field. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Ype Elgersma
- Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Michael J Fisher
- Children's Hospital of Philadelphia, The Perelman School of Medicine at the University of Pennsylvania, University of Pennsylvania, Philadelphia, Pennsylvania
| | | | - Bruce D Gelb
- Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | | | - Karen W Gripp
- Division of Medical Genetics, A. I. duPont Hospital for Children, Wilmington, Delaware
| | | | | | | | - Bruce Korf
- University of Alabama-Birmingham, Alabama
| | - Chiara Leoni
- Fondazione Policlinico Universitario A. Gemelli, Rome, Italy
| | | | | | - Katherine A Rauen
- Division of Genomic Medicine, Department of Pediatrics, UC Davis, Sacramento, California
| | | | - Amy Roberts
- Boston Children's Hospital, Boston, Massachusetts
| | - Abby Sandler
- National Cancer Institute, NIH, Bethesda, Maryland
| | - Dawn Siegel
- Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Karin Walsh
- George Washington University Medical School, Washington, District of Columbia
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Djouadi F, Habarou F, Le Bachelier C, Ferdinandusse S, Schlemmer D, Benoist JF, Boutron A, Andresen BS, Visser G, de Lonlay P, Olpin S, Fukao T, Yamaguchi S, Strauss AW, Wanders RJA, Bastin J. Mitochondrial trifunctional protein deficiency in human cultured fibroblasts: effects of bezafibrate. J Inherit Metab Dis 2016; 39:47-58. [PMID: 26109258 DOI: 10.1007/s10545-015-9871-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 05/26/2015] [Indexed: 12/31/2022]
Abstract
Mitochondrial trifunctional protein (MTP) deficiency caused by HADHA or HADHB gene mutations exhibits substantial molecular, biochemical, and clinical heterogeneity and ranks among the more severe fatty acid oxidation (FAO) disorders, without pharmacological treatment. Since bezafibrate has been shown to potentially correct other FAO disorders in patient cells, we analyzed its effects in 26 MTP-deficient patient fibroblasts representing 16 genotypes. Overall, the patient cell lines exhibited variable, complex, biochemical profiles and pharmacological responses. HADHA-deficient fibroblasts showed markedly reduced alpha subunit protein levels together with decreased beta-subunit abundance, exhibited a -86 to -96% defect in LCHAD activity, and produced large amounts of C14 and C16 hydroxyacylcarnitines. In control fibroblasts, exposure to bezafibrate (400 μM for 48 h) increased the abundance of HADHA and HADHB mRNAs, immune-detectable alpha and beta subunit proteins, activities of LCHAD and LCKAT, and stimulated FAO capacities, clearly indicating that MTP is pharmacologically up-regulated by bezafibrate in human fibroblasts. In MTP-deficient patient fibroblasts, which were found markedly FAO-deficient, bezafibrate improved FAO capacities in six of 26 (23%) cases, including three cell lines heterozygous for the common c1528G > C mutation. Altogether, our results strongly suggest that, due to variable effects of HADHA and HADHB mutations on MTP abundance and residual activity, improvement of MTP deficiency in response to bezafibrate was achieved in a subset of responsive genotypes.
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Affiliation(s)
- Fatima Djouadi
- INSERM UMR-1124, Université Paris Descartes, Centre Universitaire des Saints Pères, 45 rue des Saints Pères, 75006, Paris, France
| | - Florence Habarou
- INSERM UMR-1124, Université Paris Descartes, Centre Universitaire des Saints Pères, 45 rue des Saints Pères, 75006, Paris, France
| | - Carole Le Bachelier
- INSERM UMR-1124, Université Paris Descartes, Centre Universitaire des Saints Pères, 45 rue des Saints Pères, 75006, Paris, France
| | - Sacha Ferdinandusse
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry and Pediatrics, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Dimitri Schlemmer
- Centre de Référence des Maladies Héréditaires du Métabolisme, Service de Biochimie-Hormonologie, Hôpital Robert Debré, 48 bd Sérurier, 75019, Paris, France
| | - Jean François Benoist
- Centre de Référence des Maladies Héréditaires du Métabolisme, Service de Biochimie-Hormonologie, Hôpital Robert Debré, 48 bd Sérurier, 75019, Paris, France
| | - Audrey Boutron
- Service de Biochimie, Hôpital Bicêtre, 78 rue du Général Leclerc, 94270, Le Kremlin Bicêtre, France
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark
| | - Gepke Visser
- Wilhelmina Children's Hospital, University Medical Centre Utrecht, Lundlaan 6, 3584 EA, Utrecht, The Netherlands
| | - Pascale de Lonlay
- INSERM U781, Institut Imagine des Maladies Génétiques, Université Paris Descartes et Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Necker, 149 rue de Sèvres, 75015, Paris, France
| | - Simon Olpin
- Department of Clinical Chemistry, Sheffield Children's Hospital, Western Bank, Sheffield, South Yorkshire, S10 2TH, UK
| | - Toshiyuki Fukao
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Yanagido 1-1, Gifu, 501-1194, Japan
| | - Seiji Yamaguchi
- Department of Pediatrics, Shimane University School of Medicine, 89-1 Enya-Cho, Izumo, 693-8501, Japan
| | - Arnold W Strauss
- Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA
| | - Ronald J A Wanders
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry and Pediatrics, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Jean Bastin
- INSERM UMR-1124, Université Paris Descartes, Centre Universitaire des Saints Pères, 45 rue des Saints Pères, 75006, Paris, France.
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Aksglaede L, Christensen M, Olesen JH, Duno M, Olsen RKJ, Andresen BS, Hougaard DM, Lund AM. Abnormal Newborn Screening in a Healthy Infant of a Mother with Undiagnosed Medium-Chain Acyl-CoA Dehydrogenase Deficiency. JIMD Rep 2015; 23:67-70. [PMID: 25763512 DOI: 10.1007/8904_2015_428] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 02/05/2015] [Accepted: 02/18/2015] [Indexed: 05/08/2023] Open
Abstract
A neonate with low blood free carnitine level on newborn tandem mass spectrometry screening was evaluated for possible carnitine transporter defect (CTD). The plasma concentration of free carnitine was marginally reduced, and the concentrations of acylcarnitines (including C6, C8, and C10:1) were normal on confirmatory tests. Organic acids in urine were normal. In addition, none of the frequent Faroese SLC22A5 mutations (p.N32S, c.825-52G>A) which are common in the Danish population were identified. Evaluation of the mother showed low-normal free carnitine, but highly elevated medium-chain acylcarnitines (C6, C8, and C10:1) consistent with medium-chain acyl-CoA dehydrogenase deficiency (MCADD). The diagnosis was confirmed by the finding of homozygous presence of the c.985A>G mutation in ACADM.
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Affiliation(s)
- Lise Aksglaede
- Centre for Inherited Metabolic Diseases, Department of Clinical Genetics, Copenhagen University Hospital, Copenhagen, Denmark,
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Brown A, Crowe L, Andresen BS, Anderson V, Boneh A. Neurodevelopmental profiles of children with very long chain acyl-CoA dehydrogenase deficiency diagnosed by newborn screening. Mol Genet Metab 2014; 113:278-82. [PMID: 25456746 DOI: 10.1016/j.ymgme.2014.10.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/03/2014] [Accepted: 10/03/2014] [Indexed: 11/19/2022]
Abstract
BACKGROUND Very long chain acyl-CoA dehydrogenase (VLCAD) deficiency is a disorder of fatty acid oxidation with an estimated incidence of between 1:31,500 and 1:125,000. There is limited information regarding neurodevelopmental outcomes, probably because the disorder is perceived as affecting the skeletal and heart muscles, and many children are deemed asymptomatic. The aim of this study was to utilise a comprehensive neuropsychological assessment battery that assessed IQ, language, attention, memory, executive functioning, motor skills, behaviour, and social skills in children 4 to 10 years old diagnosed with VLCAD deficiency through newborn screening. METHOD Seven children completed neuropsychological assessment and one child was only involved in part of the study (2 female, 6 male). Parents completed questionnaires regarding executive functioning, behaviour and social skills. RESULTS IQ scores ranged from average to the superior range. No deficits were found in fine or gross motor skills. One patient had a mild language deficit, and two patients had previously required speech therapy. Verbal memory, attention and executive functioning skills were generally average or above. Visual memory scores were mostly above average. Parents' questionnaires identified one child as having social skills deficits, and two as having behavioural problems such as hyperactivity. One child rated high on an autism spectrum subscale; another was formally diagnosed with autism spectrum disorder-both children were symptomatic at birth. CONCLUSIONS VLCAD deficiency does not have a significant impact on cognitive or motor skills. Some children may be vulnerable to speech, social and behavioural issues.
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Affiliation(s)
- Amy Brown
- Australian Centre for Child Neuropsychological Studies, Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Australia; Department of Paediatrics, The University of Melbourne, Melbourne, Australia.
| | - Louise Crowe
- Australian Centre for Child Neuropsychological Studies, Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Australia
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology, University of Southern, Denmark
| | - Vicki Anderson
- Australian Centre for Child Neuropsychological Studies, Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Australia; Department of Paediatrics, The University of Melbourne, Melbourne, Australia; Department of Psychology, Royal Children's Hospital, Melbourne, Australia
| | - Avihu Boneh
- Department of Paediatrics, The University of Melbourne, Melbourne, Australia; Metabolic Research, Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Australia
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25
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Olsen RKJ, Brøner S, Sabaratnam R, Doktor TK, Andersen HS, Bruun GH, Gahrn B, Stenbroen V, Olpin SE, Dobbie A, Gregersen N, Andresen BS. TheETFDHc.158A>G Variation Disrupts the Balanced Interplay of ESE- and ESS-Binding Proteins thereby Causing Missplicing and Multiple Acyl-CoA Dehydrogenation Deficiency. Hum Mutat 2013; 35:86-95. [DOI: 10.1002/humu.22455] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 09/25/2013] [Indexed: 12/19/2022]
Affiliation(s)
- Rikke K. J. Olsen
- Research Unit for Molecular Medicine; Aarhus University Hospital and Department of Clinical Medicine, Aarhus University; Aarhus Denmark
| | - Sabrina Brøner
- Department of Biochemistry and Molecular Biology; University of Southern Denmark; Odense Denmark
| | - Rugivan Sabaratnam
- Department of Biochemistry and Molecular Biology; University of Southern Denmark; Odense Denmark
| | - Thomas K. Doktor
- Department of Biochemistry and Molecular Biology; University of Southern Denmark; Odense Denmark
| | - Henriette S. Andersen
- Department of Biochemistry and Molecular Biology; University of Southern Denmark; Odense Denmark
| | - Gitte H. Bruun
- Department of Biochemistry and Molecular Biology; University of Southern Denmark; Odense Denmark
| | - Birthe Gahrn
- Research Unit for Molecular Medicine; Aarhus University Hospital and Department of Clinical Medicine, Aarhus University; Aarhus Denmark
| | - Vibeke Stenbroen
- Research Unit for Molecular Medicine; Aarhus University Hospital and Department of Clinical Medicine, Aarhus University; Aarhus Denmark
| | - Simon E. Olpin
- Department of Clinical Chemistry; The Children's Hospital; Sheffield United Kingdom
| | - Angus Dobbie
- Department of Clinical Genetics; St James's University Hospital; Leeds United Kingdom
| | - Niels Gregersen
- Research Unit for Molecular Medicine; Aarhus University Hospital and Department of Clinical Medicine, Aarhus University; Aarhus Denmark
| | - Brage S. Andresen
- Department of Biochemistry and Molecular Biology; University of Southern Denmark; Odense Denmark
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Oerton J, Khalid JM, Besley G, Dalton RN, Downing M, Green A, Henderson M, Krywawych S, Leonard J, Andresen BS, Dezateux C. Newborn screening for medium chain acyl-CoA dehydrogenase deficiency in England: prevalence, predictive value and test validity based on 1.5 million screened babies. J Med Screen 2011; 18:173-81. [PMID: 22166308 PMCID: PMC3243649 DOI: 10.1258/jms.2011.011086] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Medium chain acyl-CoA dehydrogenase deficiency (MCADD) is a rare, life-threatening condition. Early diagnosis by screening asymptomatic newborns may improve outcome, but the benefit to newborns identified with variants not encountered clinically is uncertain. OBJECTIVE To estimate, overall and by ethnic group: screen-positive prevalence and predictive value (PPV); MCADD prevalence; proportion MCADD variants detected of predicted definite or uncertain clinical importance. SETTING All births in areas of high ethnic minority prevalence in England. METHODS Prospective multicentre pilot screening service; testing at age five to eight days; standardized screening, diagnostic and management protocols; independent expert review of screen-positive cases to assign MCADD diagnosis and predicted clinical importance (definite or uncertain). RESULTS Approximately 1.5 million babies (79% white; 10% Asian) were screened. MCADD was confirmed in 147 of 190 babies with a positive screening result (screen-positive prevalence: 1.20 per 10,000; MCADD prevalence: 0.94 per 10,000; PPV 77% [95% CI 71-83]), comprising 103 (70%) with MCADD variants of definite clinical importance (95 white [95%]; 2 Asian [2%]) and 44 (30%) with variants of uncertain clinical importance (29 white [67%]; 12 Asian [28%]). CONCLUSION One baby in every 10,000 born in England is diagnosed with MCADD by newborn screening; around 60 babies each year. While the majority of MCADD variants detected are predicted to be of definite clinical importance, this varies according to ethnic group, with variants of uncertain importance most commonly found in Asian babies. These findings provide support for MCADD screening but highlight the need to take account of the ethnic diversity of the population tested at implementation.
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Affiliation(s)
- Juliet Oerton
- MRC Centre of Epidemiology for Child Health, Institute of Child Health, University College London, 30 Guilford Street, London, WC1N 1EH, United Kingdom
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Sykut-Cegielska J, Gradowska W, Piekutowska-Abramczuk D, Andresen BS, Olsen RKJ, Ołtarzewski M, Pronicki M, Pajdowska M, Bogdańska A, Jabłońska E, Radomyska B, Kuśmierska K, Krajewska-Walasek M, Gregersen N, Pronicka E. Urgent metabolic service improves survival in long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency detected by symptomatic identification and pilot newborn screening. J Inherit Metab Dis 2011; 34:185-95. [PMID: 21103935 DOI: 10.1007/s10545-010-9244-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 08/04/2010] [Accepted: 10/29/2010] [Indexed: 10/18/2022]
Abstract
UNLABELLED Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is a fatty acid oxidation disorder with especially high mortality and uncertain long-term outcome. The aim of the study was to analyze the influence of diagnostic approach on survival in 59 affected children. Referral to a metabolic center was replaced over time by urine/blood testing in centralized metabolic laboratory (selective screening) and by pilot tandem mass spectrometry newborn screening (NBS). Molecular analysis revealed the prevalent mutation in the HADHA gene in all 58 examined cases. Twenty patients died. The number of detections and number of deaths were respectively 9 and 4 (44%) in the patients recognized by differential diagnosis, 28 and 9 (32%) - by selective screening, and 11 and 1 (9%) - by NBS. In 80% of cases the death occurred before or within 3 weeks from the identification. Urgent and active metabolic service remarkably influenced the surviving. The current age of 39 survivors is 0.5 to 23 yrs (mean 7.2 yrs). The disease frequency estimated on the patients number was 1: 115 450, whereas in the pilot NBS - 1: 109 750 (658 492 neonates tested). Interestingly, the phenylalanine level in asymptomatic neonates frequently exceeded the cut-off values. CONCLUSIONS 1) Urgent metabolic intervention decreases mortality of LCHAD-deficient patients, but the prognosis is still uncertain. 2) Emergent metabolic reporting and service are crucial also for the survival of neonates detected by NBS. 3) The nationwide selective screening appeared efficient in LCHADD detection in the country. 4) Transient mild hyperphenylalaninaemia may occur in LCHAD-deficient newborns.
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Affiliation(s)
- Jolanta Sykut-Cegielska
- Department of Metabolic Diseases, Endocrinology and Diabetology, Children's Memorial Health Institute, Warsaw, Poland
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Piekutowska-Abramczuk D, Olsen RKJ, Wierzba J, Popowska E, Jurkiewicz D, Ciara E, Ołtarzewski M, Gradowska W, Sykut-Cegielska J, Krajewska-Walasek M, Andresen BS, Gregersen N, Pronicka E. A comprehensive HADHA c.1528G>C frequency study reveals high prevalence of long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency in Poland. J Inherit Metab Dis 2010; 33 Suppl 3:S373-7. [PMID: 20814823 DOI: 10.1007/s10545-010-9190-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 08/03/2010] [Accepted: 08/09/2010] [Indexed: 11/29/2022]
Abstract
Isolated long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is associated with c.1528G>C substitution in the HADHA gene, since most patients have the prevalent mutation on at least one allele. As it is known that the disease is relatively frequent in Europe, especially around the Baltic Sea, and that the majority of Polish LCHADD patients originate from the coastal Pomeranian province, partly inhabited by an ancient ethnic group, the Kashubians, we aimed to determine the carrier frequency of the prevalent HADHA mutation in various districts of Poland with special focus on the Kashubian district. A total of 6,854 neonatal dried blood samples from the entire country, including 2,976 Pomeranian neonates of Kashubian origin, were c.1528G>C genotyped. Fifty-nine heterozygous carriers for the prevalent c.1528G>C substitution (41 Pomeranian children) were detected in the studied group. Our data reveal a geographically skewed distribution of the c.1528C allele in the Polish population; in the northern Pomeranian province the carrier frequency is 1:73, which is the highest frequency ever reported, whereas in the remaining regions it is 1:217. Hence, the incidence of LCHADD in Poland is predicted to be 1:118,336 versus 1:16,900 in the Pomeranian district. Despite the relative rarity of the disease, screening for LCHADD in neonates born in the northern part of Poland, especially those of Kashubian origin, is justified. Our data allow us to suggest a probable Kashubian origin of the prevalent c.1528G>C mutation.
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Affiliation(s)
- Dorota Piekutowska-Abramczuk
- Department of Medical Genetics, Children's Memorial Health Institute, Al. Dzieci Polskich 20, 04-730 Warsaw, Poland.
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29
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Dessein AF, Fontaine M, Andresen BS, Gregersen N, Brivet M, Rabier D, Napuri-Gouel S, Dobbelaere D, Mention-Mulliez K, Martin-Ponthieu A, Briand G, Millington DS, Vianey-Saban C, Wanders RJA, Vamecq J. A novel mutation of the ACADM gene (c.145C>G) associated with the common c.985A>G mutation on the other ACADM allele causes mild MCAD deficiency: a case report. Orphanet J Rare Dis 2010; 5:26. [PMID: 20923556 PMCID: PMC2967532 DOI: 10.1186/1750-1172-5-26] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Accepted: 10/05/2010] [Indexed: 12/31/2022] Open
Abstract
A female patient, with normal familial history, developed at the age of 30 months an episode of diarrhoea, vomiting and lethargy which resolved spontaneously. At the age of 3 years, the patient re-iterated vomiting, was sub-febrile and hypoglycemic, fell into coma, developed seizures and sequels involving right hemi-body. Urinary excretion of hexanoylglycine and suberylglycine was low during this metabolic decompensation. A study of pre- and post-prandial blood glucose and ketones over a period of 24 hours showed a normal glycaemic cycle but a failure to form ketones after 12 hours fasting, suggesting a mitochondrial β-oxidation defect. Total blood carnitine was lowered with unesterified carnitine being half of the lowest control value. A diagnosis of mild MCAD deficiency (MCADD) was based on rates of 1-14C-octanoate and 9, 10-3H-myristate oxidation and of octanoyl-CoA dehydrogenase being reduced to 25% of control values. Other mitochondrial fatty acid oxidation proteins were functionally normal. De novo acylcarnitine synthesis in whole blood samples incubated with deuterated palmitate was also typical of MCADD. Genetic studies showed that the patient was compound heterozygous with a sequence variation in both of the two ACADM alleles; one had the common c.985A>G mutation and the other had a novel c.145C>G mutation. This is the first report for the ACADM gene c.145C>G mutation: it is located in exon 3 and causes a replacement of glutamine to glutamate at position 24 of the mature protein (Q24E). Associated with heterozygosity for c.985A>G mutation, this mutation is responsible for a mild MCADD phenotype along with a clinical story corroborating the emerging literature view that patients with genotypes representing mild MCADD (high residual enzyme activity and low urinary levels of glycine conjugates), similar to some of the mild MCADDs detected by MS/MS newborn screening, may be at risk for disease presentation.
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Affiliation(s)
- Anne-Frédérique Dessein
- Department of Biochemistry and Molecular Biology, Laboratory of Hormonology, Metabolism-Nutrition & Oncology, Center of Biology and Pathology Pierre-Marie Degand, CHRU Lille, 59037 Lille, France
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Dobrowolski SF, Andersen HS, Doktor TK, Andresen BS. The phenylalanine hydroxylase c.30C>G synonymous variation (p.G10G) creates a common exonic splicing silencer. Mol Genet Metab 2010; 100:316-23. [PMID: 20457534 DOI: 10.1016/j.ymgme.2010.04.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 04/07/2010] [Indexed: 11/30/2022]
Abstract
PKU is caused by mutations in PAH. A c.30C>G synonymous variation in exon 1, previously reported as neutral, was observed in two patients. The variation creates a GGG triplet, which is part of several exonic splicing silencer (ESS) motifs. Because the 5'-splice site of PAH exon 1 is intrinsically weak and therefore could be responsive to a new flanking ESS, we hypothesized that c.30C>G could cause aberrant mRNA splicing. We demonstrate that c.30C>G causes aberrant mRNA splicing in two different reporter minigenes, and that this is abolished if a preexisting flanking GGG triplet is disrupted. GGG triplets are part of the consensus motif bound by splicing-inhibitory hnRNPH proteins and we observed a dramatic increase in hnRNPH binding to c.30C>G PAH RNA. We conclude that c.30C>G creates a hnRNPH-binding ESS, which can disrupt mRNA splicing. A disease-causing mutation in HEXB, which has previously been associated with exon skipping in patients also creates a GGG triplet. We show that the mutant HEXB motif causes exon skipping of a reporter minigene and that this is also influenced by a flanking GGG triplet. We suggest that aberrant splicing caused by creation/abolishment of GGG triplets located together with a preexisting flanking GGG triplet, may be an underreported cause of human disease. It is important to recognize that exonic sequence changes may disrupt mRNA splicing. This is particularly important in PAH, since PKU patients harboring such mutations are unlikely to respond to therapy with 6R-tetrahydrobiopterin (BH(4)), despite the fact that the genetic code indicates otherwise.
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Affiliation(s)
- Steven F Dobrowolski
- Department of Pathology, School of Medicine, University of Utah, Salt Lake City, UT, USA
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31
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Homolova K, Zavadakova P, Doktor TK, Schroeder LD, Kozich V, Andresen BS. The deep intronic c.903+469T>C mutation in the MTRR gene creates an SF2/ASF binding exonic splicing enhancer, which leads to pseudoexon activation and causes the cblE type of homocystinuria. Hum Mutat 2010; 31:437-44. [PMID: 20120036 PMCID: PMC3429857 DOI: 10.1002/humu.21206] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Deep intronic mutations are often ignored as possible causes of human diseases. A deep intronic mutation in the MTRR gene, c.903+469T>C, is the most frequent mutation causing the cblE type of homocystinuria. It is well known to be associated with pre-mRNA mis-splicing, resulting in pseudoexon inclusion; however, the pathological mechanism remains unknown. We used minigenes to demonstrate that this mutation is the direct cause of MTRR pseudoexon inclusion, and that the pseudoexon is normally not recognized due to a suboptimal 5' splice site. Within the pseudoexon we identified an exonic splicing enhancer (ESE), which is activated by the mutation. Cotransfection and siRNA experiments showed that pseudoexon inclusion depends on the cellular amounts of SF2/ASF and in vitro RNA-binding assays showed dramatically increased SF2/ASF binding to the mutant MTRR ESE. The mutant MTRR ESE sequence is identical to an ESE of the alternatively spliced MST1R proto-oncogene, which suggests that this ESE could be frequently involved in splicing regulation. Our study conclusively demonstrates that an intronic single nucleotide change is sufficient to cause pseudoexon activation via creation of a functional ESE, which binds a specific splicing factor. We suggest that this mechanism may cause genetic disease much more frequently than previously reported.
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Affiliation(s)
- Katerina Homolova
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague 2, Czech Republic
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32
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Khalid JM, Oerton J, Cortina-Borja M, Andresen BS, Besley G, Dalton RN, Downing M, Green A, Henderson M, Leonard J, Dezateux C. Ethnicity of children with homozygous c.985A>G medium-chain acyl-CoA dehydrogenase deficiency: findings from screening approximately 1.1 million newborn infants. J Med Screen 2009; 15:112-7. [PMID: 18927092 DOI: 10.1258/jms.2008.008043] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVES It has been suggested that homozygous c.985A>G medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is a disease of White ethnic origin but little is known regarding its ethnic distribution. We estimated ethnic-specific homozygous c.985A>G MCADD birth prevalence from a large-scale UK newborn screening study. METHODS Homozygous c.985A>G MCADD cases were ascertained in six English newborn screening centres between 1 March 2004 and 28 February 2007 by screening approximately 1.1 million newborns using tandem mass spectrometry analysis of underivatised blood spot samples to quantitate octanoylcarnitine (C8). Follow-up biochemistry and mutation analyses for cases (mean triplicate C8 value >/=0.5 micromol/L) were reviewed to confirm diagnosis. Ethnicity was ascertained from clinician report and denominators from 2001 UK Census estimates of ethnic group of children less than one year. RESULTS Sixty-four infants were c.985A>G MCADD homozygotes (overall prevalence 5.8 per 100,000 live births; 95% CI 4.4-7.2). Sixty (93%) were White, two (3%) were mixed/other and two were of unknown ethnic origin. No Asian or Black homozygotes were identified. Proportions of White, mixed/other, Asian and Black births in screening regions were estimated, yielding homozygous c.985A>G MCADD birth prevalence of 6.9 per 100,000 (95% CI 5.2-8.8) in White, and 95% CI estimates of 0-2.7 per 100,000 in Asian and 0-5.8 in Black populations. The c.985A>G carrier frequency in the White group was estimated at one in 65 (95% CI 1/74, 1/61) under Hardy-Weinberg conditions. CONCLUSION c.985A>G homozygous MCADD is not found in Black and Asian ethnic groups that have been screened at birth in England. This is consistent with the earlier published observations suggesting that MCADD due to the c.985A>G mutation is a disease of White ethnic origin.
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Affiliation(s)
- J M Khalid
- UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
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Horvath GA, Davidson AGF, Stockler-Ipsiroglu SG, Lillquist YP, Waters PJ, Olpin S, Andresen BS, Palaty J, Nelson J, Vallance H. Newborn screening for MCAD deficiency: experience of the first three years in British Columbia, Canada. Can J Public Health 2008. [PMID: 18767270 DOI: 10.1007/bf03403754] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
BACKGROUND Medium Chain Acyl-CoA Dehydrogenase (MCAD) Deficiency is an autosomal recessive disorder of fatty acid oxidation, with potential fatal outcome. MCAD deficiency is diagnosed by acylcarnitine analysis on newborn screening blood spot cards by tandem mass spectrometry. Early diagnosis of MCAD and presymptomatic treatment can potentially reduce morbidity and mortality. OBJECTIVES To evaluate incidence, clinical outcome, biochemical and molecular phenotype of MCAD cases detected in the first three years of newborn screening in British Columbia (BC). METHODS AND RESULTS Medium chain length acylcarnitines, octanoylcarnitine (C8) and decanoylcarnitine (C10), were measured on newborn screening blood spot cards. Out of 121,000 live births, 17 newborns had C8 values above the screening cut-off of 0.38 umol/L. Ten newborns had elevated C8 on repeat cards and were investigated further. Both C8 and C8/C10 ratios remained abnormal in all confirmed MCAD cases. Positive predictive value of screening was 58% with no false negative results. Seven patients were homozygous for the common c.985A > G MCAD mutation and three others were compound heterozygous for the c.985A > G and a second mutation. Two novel mutations were identified (c.260T > C and c.382T > A). The estimated incidence of MCAD was approximately 1:12,000 live births. Upon frequent feeding and carnitine supplementation, none of the patients had metabolic crises or adverse outcomes. CONCLUSION Frequency of MCAD in BC is comparable to reports from other newborn screening programs. Persistence of elevated C8 levels and C8/C10 ratios in confirmed MCAD cases suggest that these are sensitive markers for newborn screening. Early detection and treatment have successfully prevented adverse health outcomes in patients with MCAD.
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Affiliation(s)
- Gabriella A Horvath
- Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, BC
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Gregersen N, Andresen BS, Pedersen CB, Olsen RKJ, Corydon TJ, Bross P. Mitochondrial fatty acid oxidation defects--remaining challenges. J Inherit Metab Dis 2008; 31:643-57. [PMID: 18836889 DOI: 10.1007/s10545-008-0990-y] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 08/13/2008] [Accepted: 08/14/2008] [Indexed: 02/04/2023]
Abstract
Mitochondrial fatty acid oxidation defects have been recognized since the early 1970s. The discovery rate has been rather constant, with 3-4 'new' disorders identified every decade and with the most recent example, ACAD9 deficiency, reported in 2007. In this presentation we will focus on three of the 'old' defects: medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, riboflavin responsive multiple acyl-CoA dehydrogenation (RR-MAD) deficiency, and short-chain acyl-CoA dehydrogenase (SCAD) deficiency. These disorders have been discussed in many publications and at countless conference presentations, and many questions relating to them have been answered. However, continuing clinical and pathophysiological research has raised many further questions, and new ideas and methodologies may be required to answer these. We will discuss these challenges. For MCAD deficiency the key question is why 80% of symptomatic patients are homozygous for the prevalent ACADM gene variation c.985A > G whereas this is found in only approximately 50% of newborns with a positive screen. For RR-MAD deficiency, the challenge is to find the connection between variations in the ETFDH gene and the observed deficiency of a number of different mitochondrial dehydrogenases as well as deficiency of FAD and coenzyme Q(10). With SCAD deficiency, the challenge is to elucidate whether ACADS gene variations are disease-associated, especially when combined with other genetic/cellular/environmental factors, which may act synergistically.
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Affiliation(s)
- Niels Gregersen
- Research Unit for Molecular Medicine, Institute of Clinical Medicine, The Faculty of Health Sciences, Aarhus University, Aarhus N, Denmark.
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35
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Pedersen CB, Kølvraa S, Kølvraa A, Stenbroen V, Kjeldsen M, Ensenauer R, Tein I, Matern D, Rinaldo P, Vianey-Saban C, Ribes A, Lehnert W, Christensen E, Corydon TJ, Andresen BS, Vang S, Bolund L, Vockley J, Bross P, Gregersen N. The ACADS gene variation spectrum in 114 patients with short-chain acyl-CoA dehydrogenase (SCAD) deficiency is dominated by missense variations leading to protein misfolding at the cellular level. Hum Genet 2008; 124:43-56. [PMID: 18523805 DOI: 10.1007/s00439-008-0521-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Accepted: 05/23/2008] [Indexed: 11/26/2022]
Abstract
Short-chain acyl-CoA dehydrogenase (SCAD) deficiency is an inherited disorder of mitochondrial fatty acid oxidation associated with variations in the ACADS gene and variable clinical symptoms. In addition to rare ACADS inactivating variations, two common variations, c.511C > T (p.Arg171Trp) and c.625G > A (p.Gly209Ser), have been identified in patients, but these are also present in up to 14% of normal populations leading to questions of their clinical relevance. The common variant alleles encode proteins with nearly normal enzymatic activity at physiological conditions in vitro. SCAD enzyme function, however, is impaired at increased temperature and the tendency to misfold increases under conditions of cellular stress. The present study examines misfolding of variant SCAD proteins identified in patients with SCAD deficiency. Analysis of the ACADS gene in 114 patients revealed 29 variations, 26 missense, one start codon, and two stop codon variations. In vitro import studies of variant SCAD proteins in isolated mitochondria from SCAD deficient (SCAD-/-) mice demonstrated an increased tendency of the abnormal proteins to misfold and aggregate compared to the wild-type, a phenomenon that often leads to gain-of-function cellular phenotypes. However, no correlation was found between the clinical phenotype and the degree of SCAD dysfunction. We propose that SCAD deficiency should be considered as a disorder of protein folding that can lead to clinical disease in combination with other genetic and environmental factors.
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Affiliation(s)
- Christina B Pedersen
- Research Unit for Molecular Medicine, Skejby and Faculty of Health Sciences, Aarhus University Hospital, Brendstrupgaardsvej 100, 8200, Aarhus, Denmark.
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Gobin-Limballe S, Djouadi F, Aubey F, Olpin S, Andresen BS, Yamaguchi S, Mandel H, Fukao T, Ruiter JPN, Wanders RJA, McAndrew R, Kim JJ, Bastin J. Genetic basis for correction of very-long-chain acyl-coenzyme A dehydrogenase deficiency by bezafibrate in patient fibroblasts: toward a genotype-based therapy. Am J Hum Genet 2007; 81:1133-43. [PMID: 17999356 DOI: 10.1086/522375] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Accepted: 08/01/2007] [Indexed: 12/30/2022] Open
Abstract
Very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency is an inborn mitochondrial fatty-acid beta-oxidation (FAO) defect associated with a broad mutational spectrum, with phenotypes ranging from fatal cardiopathy in infancy to adolescent-onset myopathy, and for which there is no established treatment. Recent data suggest that bezafibrate could improve the FAO capacities in beta-oxidation-deficient cells, by enhancing the residual level of mutant enzyme activity via gene-expression stimulation. Since VLCAD-deficient patients frequently harbor missense mutations with unpredictable effects on enzyme activity, we investigated the response to bezafibrate as a function of genotype in 33 VLCAD-deficient fibroblasts representing 45 different mutations. Treatment with bezafibrate (400 microM for 48 h) resulted in a marked increase in FAO capacities, often leading to restoration of normal values, for 21 genotypes that mainly corresponded to patients with the myopathic phenotype. In contrast, bezafibrate induced no changes in FAO for 11 genotypes corresponding to severe neonatal or infantile phenotypes. This pattern of response was not due to differential inductions of VLCAD messenger RNA, as shown by quantitative real-time polymerase chain reaction, but reflected variable increases in measured VLCAD residual enzyme activity in response to bezafibrate. Genotype cross-analysis allowed the identification of alleles carrying missense mutations, which could account for these different pharmacological profiles and, on this basis, led to the characterization of 9 mild and 11 severe missense mutations. Altogether, the responses to bezafibrate reflected the severity of the metabolic blockage in various genotypes, which appeared to be correlated with the phenotype, thus providing a new approach for analysis of genetic heterogeneity. Finally, this study emphasizes the potential of bezafibrate, a widely prescribed hypolipidemic drug, for the correction of VLCAD deficiency and exemplifies the integration of molecular information in a therapeutic strategy.
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Affiliation(s)
- S Gobin-Limballe
- Université Paris-Descartes, Centre National de la Recherche Scientifique Biotram, Paris, France
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Roca X, Olson AJ, Rao AR, Enerly E, Kristensen VN, Børresen-Dale AL, Andresen BS, Krainer AR, Sachidanandam R. Features of 5'-splice-site efficiency derived from disease-causing mutations and comparative genomics. Genome Res 2007; 18:77-87. [PMID: 18032726 DOI: 10.1101/gr.6859308] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Many human diseases, including Fanconi anemia, hemophilia B, neurofibromatosis, and phenylketonuria, can be caused by 5'-splice-site (5'ss) mutations that are not predicted to disrupt splicing, according to position weight matrices. By using comparative genomics, we identify pairwise dependencies between 5'ss nucleotides as a conserved feature of the entire set of 5'ss. These dependencies are also conserved in human-mouse pairs of orthologous 5'ss. Many disease-associated 5'ss mutations disrupt these dependencies, as can some human SNPs that appear to alter splicing. The consistency of the evidence signifies the relevance of this approach and suggests that 5'ss SNPs play a role in complex diseases.
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Affiliation(s)
- Xavier Roca
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
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38
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Kanavin OJ, Woldseth B, Jellum E, Tvedt B, Andresen BS, Stromme P. 2-methylbutyryl-CoA dehydrogenase deficiency associated with autism and mental retardation: a case report. J Med Case Rep 2007; 1:98. [PMID: 17883863 PMCID: PMC2045671 DOI: 10.1186/1752-1947-1-98] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Accepted: 09/20/2007] [Indexed: 11/18/2022] Open
Abstract
Background 2-methylbutyryl-CoA dehydrogenase deficiency or short/branched chain acyl-CoA dehydrogenase deficiency (SBCADD) is caused by a defect in the degradation pathway of the amino acid L-isoleucine. Methods We report a four-year-old mentally retarded Somali boy with autism and a history of seizures, who was found to excrete increased amounts of 2-methylbutyryl glycine in the urine. The SBCAD gene was examined with sequence analysis. His development was assessed with psychometric testing before and after a trial with low protein diet. Results We found homozygosity for A > G changing the +3 position of intron 3 (c.303+3A > G) in the SBCAD gene. Psychometric testing showed moderate mental retardation and behavioral scores within the autistic spectrum. No beneficial effect was detected after 5 months with a low protein diet. Conclusion This mutation was also found in two previously reported cases with SBCADD, both originating from Somalia and Eritrea, indicating that it is relatively prevalent in this population. Autism has not previously been described with mutations in this gene, thus expanding the clinical spectrum of SBCADD.
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Affiliation(s)
- Oivind J Kanavin
- Department of Pediatrics, Ullevål University Hospital, Oslo, Norway
| | - Berit Woldseth
- Department of Clinical Chemistry, Rikshospitalet-Radiumhospitalet Medical Center, Oslo, Norway
| | - Egil Jellum
- Department of Clinical Chemistry, Rikshospitalet-Radiumhospitalet Medical Center, Oslo, Norway
| | - Bjorn Tvedt
- Department of Pediatrics, Ullevål University Hospital, Oslo, Norway
| | - Brage S Andresen
- Research Unit for Molecular Medicine, Skejby Sygehus, DK 8200, Århus N, Denmark
- Institute of Human Genetics, Aarhus University, Aarhus, Denmark
| | - Petter Stromme
- Department of Pediatrics, Ullevål University Hospital, Oslo, Norway
- Faculty of Medicine, University of Oslo, Norway
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Olsen RKJ, Olpin SE, Andresen BS, Miedzybrodzka ZH, Pourfarzam M, Merinero B, Frerman FE, Beresford MW, Dean JCS, Cornelius N, Andersen O, Oldfors A, Holme E, Gregersen N, Turnbull DM, Morris AAM. ETFDH mutations as a major cause of riboflavin-responsive multiple acyl-CoA dehydrogenation deficiency. Brain 2007; 130:2045-54. [PMID: 17584774 DOI: 10.1093/brain/awm135] [Citation(s) in RCA: 217] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Multiple acyl-CoA dehydrogenation deficiency (MADD) is a disorder of fatty acid, amino acid and choline metabolism that can result from defects in two flavoproteins, electron transfer flavoprotein (ETF) or ETF: ubiquinone oxidoreductase (ETF:QO). Some patients respond to pharmacological doses of riboflavin. It is unknown whether these patients have defects in the flavoproteins themselves or defects in the formation of the cofactor, FAD, from riboflavin. We report 15 patients from 11 pedigrees. All the index cases presented with encephalopathy or muscle weakness or a combination of these symptoms; several had previously suffered cyclical vomiting. Urine organic acid and plasma acyl-carnitine profiles indicated MADD. Clinical and biochemical parameters were either totally or partly corrected after riboflavin treatment. All patients had mutations in the gene for ETF:QO. In one patient, we show that the ETF:QO mutations are associated with a riboflavin-sensitive impairment of ETF:QO activity. This patient also had partial deficiencies of flavin-dependent acyl-CoA dehydrogenases and respiratory chain complexes, most of which were restored to control levels after riboflavin treatment. Low activities of mitochondrial flavoproteins or respiratory chain complexes have been reported previously in two of our patients with ETF:QO mutations. We postulate that riboflavin-responsive MADD may result from defects of ETF:QO combined with general mitochondrial dysfunction. This is the largest collection of riboflavin-responsive MADD patients ever reported, and the first demonstration of the molecular genetic basis for the disorder.
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Affiliation(s)
- Rikke K J Olsen
- The Research Unit for Molecular Medicine, Aarhus University Hospital and Faculty of Health Sciences, Skejby Sygehus, Aarhus, Denmark.
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Maydan G, Andresen BS, Madsen PP, Zeigler M, Raas-Rothschild A, Zlotogorski A, Gutman A, Korman SH. TAT gene mutation analysis in three Palestinian kindreds with oculocutaneous tyrosinaemia type II; characterization of a silent exonic transversion that causes complete missplicing by exon 11 skipping. J Inherit Metab Dis 2006; 29:620-6. [PMID: 16917729 DOI: 10.1007/s10545-006-0407-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2006] [Revised: 07/21/2006] [Accepted: 08/01/2006] [Indexed: 10/24/2022]
Abstract
Deficiency of the hepatic cytosolic enzyme tyrosine aminotransferase (TAT) causes marked hypertyrosinaemia leading to painful palmoplantar hyperkeratoses, pseudodendritic keratitis and variable mental retardation (oculocutaneous tyrosinaemia type II or Richner-Hanhart syndrome). Parents may therefore seek prenatal diagnosis, but this is not possible by biochemical assays as tyrosine does not accumulate in amniotic fluid and TAT is not expressed in chorionic villi or amniocytes. Molecular analysis is therefore the only possible approach for prenatal diagnosis and carrier detection. To this end, we sought TAT gene mutations in 9 tyrosinaemia II patients from three consanguineous Palestinian kindreds. In two kindreds (7 patients), the only potential abnormality identified after sequencing all 12 exons and exon-intron boundaries was homozygosity for a silent, single-nucleotide transversion c.1224G > T (p.T408T) at the last base of exon 11. This was predicted to disrupt the 5' donor splice site of exon 11 and result in missplicing. However, as TAT is expressed exclusively in liver, patient mRNA could not be obtained for splicing analysis. A minigene approach was therefore used to assess the effect of c.1224G > T on exon 11 splicing. Transfection experiments with wild-type and c.1224G > T mutant minigene constructs demonstrated that c.1224G > T results in complete exon 11 skipping, illustrating the utility of this approach for confirming a putative splicing defect when cDNA is unavailable. Homozygosity for a c.1249C > T (R417X) exon 12 nonsense mutation (previously reported in a French patient) was identified in both patients from the third kindred, enabling successful prenatal diagnosis of an unaffected fetus using chorionic villous tissue.
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Affiliation(s)
- G Maydan
- Department of Clinical Biochemistry, Hadassah--Hebrew University Medical Center, Jerusalem, Israel
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41
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Pedersen CB, Bischoff C, Christensen E, Simonsen H, Lund AM, Young SP, Koeberl DD, Millington DS, Roe CR, Roe DS, Wanders RJA, Ruiter JPN, Keppen LD, Stein Q, Knudsen I, Gregersen N, Andresen BS. Variations in IBD (ACAD8) in children with elevated C4-carnitine detected by tandem mass spectrometry newborn screening. Pediatr Res 2006; 60:315-20. [PMID: 16857760 DOI: 10.1203/01.pdr.0000233085.72522.04] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The isobutyryl-CoA dehydrogenase (IBD) enzyme is involved in the degradation of valine. IBD deficiency was first reported in 1998 and subsequent genetic investigations identified acyl-CoA dehydrogenase (ACAD) 8, now IBD, as the gene responsible for IBD deficiency. Only three individuals homozygous or compound heterozygous for variations in the IBD gene have been reported. We present IBD deficiency in an additional four newborns with elevated C(4)-carnitine identified by tandem mass spectrometry (MS/MS) screening in Denmark and the United States. Three showed urinary excretions of isobutyryl-glycine, and in vitro probe analysis of fibroblasts from two newborns indicated enzymatic IBD defect. Molecular genetic analysis revealed seven new rare variations in the IBD gene (c.348C>A, c.400G>T, c.409G>A, c.455T>C, c.958G>A, c.1000C>T and c.1154G>A). Furthermore, sequence analysis of the short-chain acyl-CoA dehydrogenase (SCAD) gene revealed heterozygosity for the prevalent c.625G>A susceptibility variation in all newborns and in the first reported IBD patient. Functional studies in isolated mitochondria demonstrated that the IBD variations present in the Danish newborn (c.409G>A and c.958G>A) together with a previously published IBD variation (c.905G>A) disturbed protein folding and reduced the levels of correctly folded IBD tetramers. Accordingly, low/no IBD residual enzyme activity was detectable when the variant IBD proteins were overexpressed in Chang cells.
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Affiliation(s)
- Christina B Pedersen
- Research Unit for Molecular Medicine, Aarhus University Hospital, Skejby Sygehus, 8200 Aarhus N, Denmark
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Boneh A, Andresen BS, Gregersen N, Ibrahim M, Tzanakos N, Peters H, Yaplito-Lee J, Pitt JJ. VLCAD deficiency: pitfalls in newborn screening and confirmation of diagnosis by mutation analysis. Mol Genet Metab 2006; 88:166-70. [PMID: 16488171 DOI: 10.1016/j.ymgme.2005.12.012] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2005] [Revised: 12/21/2005] [Accepted: 12/21/2005] [Indexed: 11/15/2022]
Abstract
We diagnosed six newborn babies with very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) through newborn screening in three years in Victoria (prevalence rate: 1:31,500). We identified seven known and two new mutations in our patients (2/6 homozygotes; 4/6 compound heterozygotes). Blood samples taken at age 48-72 h were diagnostic whereas repeat samples at an older age were normal in 4/6 babies. Urine analysis was normal in 5/5. We conclude that the timing of blood sampling for newborn screening is important and that it is important to perform mutation analysis to avoid false-negative diagnoses of VLCADD in asymptomatic newborn babies. In view of the emerging genotype-phenotype correlation in this disorder, the information derived from mutational analysis can be helpful in designing the appropriate follow-up and therapeutic regime for these patients.
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Affiliation(s)
- A Boneh
- Metabolic Service and Newborn Screening Laboratory, Genetic Health Services Victoria, Melbourne, Australia.
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43
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Waddell L, Wiley V, Carpenter K, Bennetts B, Angel L, Andresen BS, Wilcken B. Medium-chain acyl-CoA dehydrogenase deficiency: genotype-biochemical phenotype correlations. Mol Genet Metab 2006; 87:32-9. [PMID: 16291504 DOI: 10.1016/j.ymgme.2005.09.020] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2005] [Revised: 09/27/2005] [Accepted: 09/27/2005] [Indexed: 11/18/2022]
Abstract
The fatty acid oxidation disorder most commonly identified by tandem mass spectrometry newborn screening is the potentially fatal medium-chain acyl-CoA dehydrogenase deficiency (MCAD). In clinically presenting cases, 80% are homozygous for the common mutation, c.985A > G and 18% heterozygous. We screened 592,785 babies and identified 34 with MCAD, 17 homozygous for c.985A > G, 14 with one copy, and 3 with no copy. We sequenced the exons of 19 patients, the 17 carrying one or no copy of c.985A > G, and two with marginal findings, and examined correlations between groups of mutations and biochemical markers. We found two known or putative pathogenic mutations in 18 of the 19 patients. Two mutations appeared more than once: c.199T > C, not recorded in clinically presenting cases (n = 4), and c.583G > A (n = 2). Patients homozygous for c.985A > G had the highest levels of neonatal octanoylcarnitine, plasma octanoylcarnitine when asymptomatic, and urinary acylglycines. Compound heterozygotes of c.985A > G and other mutations had intermediate levels, and those without c.985A > G, or heterozygous for that and c.199T > C had the lowest levels of these analytes. There was overlap in all values. The c.985A > G and c.583G > A mutations appear to have functional effects towards the severe end of the spectrum, and the c.199T > C mutation a smaller effect, as has been previously postulated. If these results are confirmed and extended, this could influence the advice given to parents of babies with MCAD detected by newborn screening, and make management more specific. In the meantime, all MCAD patients identified by newborn screening have, by definition, a functional defect and require careful clinical management.
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Affiliation(s)
- Leigh Waddell
- The NSW Newborn Screening Programme, Children's Hospital at Westmead, Sydney, Australia
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44
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O'Reilly LP, Andresen BS, Engel PC. Two novel variants of human medium chain acyl-CoA dehydrogenase (MCAD). K364R, a folding mutation, and R256T, a catalytic-site mutation resulting in a well-folded but totally inactive protein. FEBS J 2005; 272:4549-57. [PMID: 16128823 DOI: 10.1111/j.1742-4658.2005.04878.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two novel rare mutations, MCAD approximately 842G-->C (R256T) and MCAD approximately 1166A-->G (K364R), have been investigated to assess how far the biochemical properties of the mutant proteins correlate with the clinical phenotype of medium chain acyl-CoA dehydrogenase (MCAD) deficiency. When the gene for K364R was overexpressed in Escherichia coli, the synthesized mutant protein only exhibited activity when the gene for chaperonin GroELS was co-overexpressed. Levels of activity correlated with the amounts of native MCAD protein visible in western blots. The R256T mutant, by contrast, displayed no activity either with or without chaperonin, but in this case a strong MCAD protein band was seen in the western blots throughout. The proteins were also purified, and the enzyme function and thermostability investigated. The K364R protein showed only moderate kinetic impairment, whereas the R256T protein was again totally inactive. Neither mutant showed marked depletion of FAD. The pure K364R protein was considerably less thermostable than wild-type MCAD. Western blots indicated that, although the R256T mutant protein is less thermostable than normal MCAD, it is much more stable than K364R. Though clinically asymptomatic thus far, both mutations have a severe impact on the biochemical phenotype of the protein. K364R, like several previously described MCAD mutant proteins, appears to be defective in folding. R256T, by contrast, is a well-folded protein that is nevertheless devoid of catalytic activity. How the mutations specifically affect the catalytic activity and the folding is further discussed.
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Affiliation(s)
- Linda P O'Reilly
- Department of Biochemistry and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin, Ireland
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45
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Olsen RKJ, Andresen BS, Christensen E, Mandel H, Skovby F, Nielsen JP, Knudsen I, Vianey-Saban C, Simonsen H, Gregersen N. DNA-based prenatal diagnosis for severe and variant forms of multiple acyl-CoA dehydrogenation deficiency. Prenat Diagn 2005; 25:60-4. [PMID: 15662686 DOI: 10.1002/pd.983] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVES Multiple acyl-CoA dehydrogenation deficiency (MADD) is a clinically heterogeneous disorder of mitochondrial fatty acid, amino acid, and choline oxidation due to mutations in the genes encoding electron transfer flavoprotein (ETF) or ETF ubiquinone oxidoreductase (ETFQO). So far, prenatal diagnosis of MADD has relied mostly on second-trimester biochemical analyses of amniotic fluid or cultured amniocytes. We report here on an alternative DNA-based approach for prenatal diagnosis in pregnancies at risk of MADD. METHODS We used our knowledge of the mutational status in three unrelated families with a history of MADD to perform direct sequencing for the familial mutations using genomic DNA isolated from chorionic villus samples (CVS) at gestational week 10 to 11. RESULTS Within two days, we were able to carry out accurate DNA-based prenatal testing in one pregnancy at risk of severe MADD, and in two pregnancies at risk of variant forms of MADD. CONCLUSION This is the first report of DNA-based prenatal diagnosis of MADD. Our molecular approach is suitable for fast and reliable first-trimester prenatal diagnosis in pregnancies at risk of severe and variant forms of MADD.
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Affiliation(s)
- Rikke K J Olsen
- Research Unit for Molecular Medicine, Aarhus University Hospital and Faculty of Health Sciences, Skejby Sygehus, Aarhus, Denmark.
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Olpin SE, Clark S, Andresen BS, Bischoff C, Olsen RKJ, Gregersen N, Chakrapani A, Downing M, Manning NJ, Sharrard M, Bonham JR, Muntoni F, Turnbull DN, Pourfarzam M. Biochemical, clinical and molecular findings in LCHAD and general mitochondrial trifunctional protein deficiency. J Inherit Metab Dis 2005; 28:533-44. [PMID: 15902556 DOI: 10.1007/s10545-005-0533-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2004] [Accepted: 01/10/2005] [Indexed: 10/25/2022]
Abstract
General mitochondrial trifunctional protein (TFP) deficiency leads to a wide clinical spectrum of disease ranging from severe neonatal/infantile cardiomyopathy and early death to mild chronic progressive sensorimotor poly-neuropathy with episodic rhabdomyolysis. Isolated long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency resulting from the common Glu510Gln mutation usually gives rise to a moderately severe phenotype with multiorgan involvement with high morbidity and mortality. However, isolated LCHAD deficiency can also be consistent with long-term survival in patients identified and treated from an early age. We present biochemical, clinical and mutation data in 9 patients spanning the full spectrum of disease. Fibroblast acylcarnitine profiling shows good correlation with clinical phenotype using the ratio C18(OH)/(C14(OH)+C12(OH)). This ratio shows a gradation of values, from high in four patients with severe neonatal disease (2.5+/-0.8), to low in two neuromyopathic patients (0.35, 0.2). Fibroblast fatty acid oxidation flux assays also show correlation with the patient phenotype, when expressed either as percentage residual activity with palmitate or as a ratio of percentage activity of myristate/oleate (M/O ratio). Fibroblasts from four patients with severe neonatal disease gave an M/O ratio of 4.0+/-0.6 compared to 1.97 and 1.62 in two neuromyopathic patients. Specific enzyme assay of LCHAD and long-chain 3-ketothiolase activity in patient cells shows lack of correlation with phenotype. These results show that measurements in intact cells, which allow all determinative and modifying cellular factors to be present, better reflect patient phenotype. Mutation analysis reveals a number of alpha- and beta-subunit mutations. Peripheral sensorimotor polyneuropathy, often as the initial major presenting feature but usually later accompanied by episodic rhabdomyolysis, is a manifestation of mild TFP protein deficiency. The mild clinical presentation and relative difficulty in diagnosis suggest that this form of TFP is probably underdiagnosed.
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Affiliation(s)
- S E Olpin
- Department of Clinical Chemistry, Sheffield Children's Hospital, Sheffield, UK.
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Korman SH, Andresen BS, Zeharia A, Gutman A, Boneh A, Pitt JJ. 2-ethylhydracrylic aciduria in short/branched-chain acyl-CoA dehydrogenase deficiency: application to diagnosis and implications for the R-pathway of isoleucine oxidation. Clin Chem 2004; 51:610-7. [PMID: 15615815 DOI: 10.1373/clinchem.2004.043265] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND Isolated excretion of 2-methylbutyrylglycine (2-MBG) is the hallmark of short/branched-chain acyl-CoA dehydrogenase deficiency (SBCADD), a recently identified defect in the proximal pathway of L-isoleucine oxidation. SBCADD might be underdiagnosed because detection and recognition of urine acylglycines is problematic. Excretion of 2-ethylhydracrylic acid (2-EHA), an intermediate formed in the normally minor R-pathway of L-isoleucine oxidation, has not previously been described in SBCADD. METHODS Samples from four patients with 2-MBG excretion were analyzed by gas chromatography-mass spectrometry for urine organic acids, quantification of 2-MBG, and chiral determination of 2-methylbutyric acid. Blood-spot acylcarnitines were measured by electrospray-tandem mass spectrometry. Mutations in the ACADSB gene encoding SBCAD were identified by direct sequencing. RESULTS SBCADD was confirmed in each patient by demonstration of different ACADSB gene mutations. In multiple urine samples, organic acid analysis revealed a prominent 2-EHA peak usually exceeding the size of the 2-MBG peak. Approximately 40-46% of total 2-methylbutyric acid conjugates were in the form of the R-isomer, indicating significant metabolism via the R-pathway. CONCLUSIONS If, as generally believed, SBCAD is responsible for R-2-MBG dehydrogenation in the R-pathway, 2-EHA would not be produced in SBCADD. Our observation of 2-ethylhydracrylic aciduria in SBCADD implies that a different or alternative enzyme serves this function. Increased flux through the R-pathway may act as a safety valve for overflow of accumulating S-pathway metabolites and thereby mitigate the severity of SBCADD. Awareness of 2-ethylhydracrylic aciduria as a diagnostic marker could lead to increased detection of SBCADD and improved definition of its clinical phenotype.
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Affiliation(s)
- Stanley H Korman
- Department of Clinical Biochemistry, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
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Korman SH, Gutman A, Brooks R, Sinnathamby T, Gregersen N, Andresen BS. Homozygosity for a severe novel medium-chain acyl-CoA dehydrogenase (MCAD) mutation IVS3-1G > C that leads to introduction of a premature termination codon by complete missplicing of the MCAD mRNA and is associated with phenotypic diversity ranging from sudden neonatal death to asymptomatic status. Mol Genet Metab 2004; 82:121-9. [PMID: 15171999 DOI: 10.1016/j.ymgme.2004.03.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Revised: 03/07/2004] [Accepted: 03/12/2004] [Indexed: 10/26/2022]
Abstract
Virtually all patients with medium-chain acyl-CoA dehydrogenase deficiency (MCADD) are homozygous or compound heterozygous for the 985A > G mutation, which limits the study of a possible genotype/phenotype correlation. A newborn Palestinian infant died suddenly on the second day of life. A previous sibling had also died in similar circumstances aged 3 weeks. Urine organic acid and bloodspot acylcarnitine analysis were consistent with MCADD. He was homozygous for a novel MCAD splice mutation, IVS3-1G > C. This mutation leads to deletion of 7 bp and introduction of a premature termination codon as a result of complete missplicing of MCAD mRNA. This misspliced MCAD mRNA encodes a non-functional protein and is furthermore reduced in amounts due to nonsense-mediated decay, resulting in total lack of functional MCAD enzyme. This is the first molecular identification of MCADD in an Arab patient and the first reported splice mutation in the MCAD gene that has been functionally characterized. The association of homozygosity for a null mutation with lethal neonatal presentation in the index patient and presumably the previous infant suggested a genotype/phenotype correlation. However, a 6-year-old completely asymptomatic sibling also had the characteristic MCADD biochemical phenotype and was homozygous for the same IVS3-1G > C mutation. As a first candidate to modify the disease presentation, by modulating the overlapping enzyme activity, we tested the entire family for the prevalent SCAD gene 625G > A susceptibility variant. Interestingly, all family members were 625G > A homozygous. Additional genetic and/or environmental factors must play a major role in determining the phenotypic diversity of MCADD.
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Affiliation(s)
- Stanley H Korman
- Department of Clinical Biochemistry, Hadassah--Hebrew University Medical Center, Jerusalem 91120, Israel.
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Gregersen N, Bross P, Andresen BS. Genetic defects in fatty acid beta-oxidation and acyl-CoA dehydrogenases. Molecular pathogenesis and genotype-phenotype relationships. ACTA ACUST UNITED AC 2004; 271:470-82. [PMID: 14728674 DOI: 10.1046/j.1432-1033.2003.03949.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mitochondrial fatty acid oxidation deficiencies are due to genetic defects in enzymes of fatty acid beta-oxidation and transport proteins. Genetic defects have been identified in most of the genes where nearly all types of sequence variations (mutation types) have been associated with disease. In this paper, we will discuss the effects of the various types of sequence variations encountered and review current knowledge regarding the genotype-phenotype relationship, especially in patients with acyl-CoA dehydrogenase deficiencies where sufficient material exists for a meaningful discussion. Because mis-sense sequence variations are prevalent in these diseases, we will discuss the implications of these types of sequence variations on the processing and folding of mis-sense variant proteins. As the prevalent mis-sense variant K304E MCAD protein has been studied intensively, the investigations on biogenesis, stability and kinetic properties for this variant enzyme will be discussed in detail and used as a paradigm for the study of other mis-sense variant proteins. We conclude that the total effect of mis-sense sequence variations may comprise an invariable--sequence variation specific--effect on the catalytic parameters and a conditional effect, which is dependent on cellular, physiological and genetic factors other than the sequence variation itself.
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Affiliation(s)
- Niels Gregersen
- Research Unit for Molecular Medicine, Aarhus University Hospital and Faculty of Health Sciences, Aarhus University, Aarhus, Denmark.
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Schaefer J, Jackson S, Reichmann H, Andresen BS. Rezidivierende menstruationsabhängige Rhabdomyolysen und demyelinisierende Polyneuropathie - ein neues Krankheitsbild? Akt Neurol 2004. [DOI: 10.1055/s-2004-833182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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