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Morris AAM, Cuenoud B, Delerive P, Mundy H, Schwahn BC. Long-term use of investigational β-Hydroxybutyrate salts in children with multiple acyl-CoA dehydrogenase or pyruvate dehydrogenase deficiency. Mol Genet Metab Rep 2024; 40:101104. [PMID: 38983107 PMCID: PMC11231749 DOI: 10.1016/j.ymgmr.2024.101104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/30/2024] [Accepted: 06/04/2024] [Indexed: 07/11/2024] Open
Abstract
Several disorders of energy metabolism have been treated with exogenous ketone bodies. The benefit of this treatment is best documented in multiple acyl-CoA dehydrogenase deficiency (MADD) (MIM#231680). One might also expect ketone bodies to help in other disorders with impaired ketogenesis or in conditions that profit from a ketogenic diet. Here, we report the use of a novel preparation of dextro-β-hydroxybutyrate (D-βHB) salts in two cases of MADD and one case of pyruvate dehydrogenase (PDH) deficiency (MIM#312170). The two patients with MADD had previously been on a racemic mixture of D- and L‑sodium hydroxybutyrate. Patient #1 found D-βHB more palatable, and the change in formulation corrected hypernatraemia in patient #2. The patient with PDH deficiency was on a ketogenic diet but had not previously been given hydroxybutyrate. In this case, the addition of D-βHB improved ketosis. We conclude that NHS101 is a good candidate for further clinical studies in this group of diseases of inborn errors of metabolism.
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Affiliation(s)
| | - Bernard Cuenoud
- Nestlé Health Science, Avenue Nestlé 55., 1800 Vevy, Switzerland
| | | | - Helen Mundy
- Evelina London Children's Healthcare, Guy's and St Thomas' NHS Foundation Trust, London, UK
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Jacobsen JOB, Kelly C, Cipriani V, Research Consortium GE, Mungall CJ, Reese J, Danis D, Robinson PN, Smedley D. Phenotype-driven approaches to enhance variant prioritization and diagnosis of rare disease. Hum Mutat 2022; 43:1071-1081. [PMID: 35391505 PMCID: PMC9288531 DOI: 10.1002/humu.24380] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 01/25/2022] [Accepted: 04/03/2022] [Indexed: 11/20/2022]
Abstract
Rare disease diagnostics and disease gene discovery have been revolutionized by whole-exome and genome sequencing but identifying the causative variant(s) from the millions in each individual remains challenging. The use of deep phenotyping of patients and reference genotype-phenotype knowledge, alongside variant data such as allele frequency, segregation, and predicted pathogenicity, has proved an effective strategy to tackle this issue. Here we review the numerous tools that have been developed to automate this approach and demonstrate the power of such an approach on several thousand diagnosed cases from the 100,000 Genomes Project. Finally, we discuss the challenges that need to be overcome if we are going to improve detection rates and help the majority of patients that still remain without a molecular diagnosis after state-of-the-art genomic interpretation.
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Affiliation(s)
- Julius O. B. Jacobsen
- William Harvey Research Institute, Charterhouse Square, Barts and the London School of Medicine and Dentistry QueenQueen Mary University of LondonLondonUK
| | - Catherine Kelly
- William Harvey Research Institute, Charterhouse Square, Barts and the London School of Medicine and Dentistry QueenQueen Mary University of LondonLondonUK
| | - Valentina Cipriani
- William Harvey Research Institute, Charterhouse Square, Barts and the London School of Medicine and Dentistry QueenQueen Mary University of LondonLondonUK
| | | | - Christopher J. Mungall
- Environmental Genomics and Systems Biology, Lawrence Berkeley National LaboratoryBerkeleyCaliforniaUSA
| | - Justin Reese
- Environmental Genomics and Systems Biology, Lawrence Berkeley National LaboratoryBerkeleyCaliforniaUSA
| | - Daniel Danis
- The Jackson Laboratory for Genomic MedicineFarmingtonConnecticutUSA
| | | | - Damian Smedley
- William Harvey Research Institute, Charterhouse Square, Barts and the London School of Medicine and Dentistry QueenQueen Mary University of LondonLondonUK
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Sarkar A, Panati K, Narala VR. Code inside the codon: The role of synonymous mutations in regulating splicing machinery and its impact on disease. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2022; 790:108444. [PMID: 36307006 DOI: 10.1016/j.mrrev.2022.108444] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 10/10/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022]
Abstract
In eukaryotes, precise pre-mRNA processing, including alternative splicing, is essential to carry out the intricate protein translation process. Both point mutations (that alter the translated protein sequence) and synonymous mutations (that do not alter the translated protein sequence) are capable of affecting the splicing process. Synonymous mutations are known to affect gene expression via altering mRNA stability, mRNA secondary structure, splicing processes, and translational kinetics. In higher eukaryotes, precise splicing is regulated by three weakly conserved cis-elements, 5' and 3' splice sites and the branch site. Many other cis-acting elements (exonic/intronic splicing enhancers and silencers) and trans-acting splicing factors (serine and arginine-rich proteins and heterogeneous nuclear ribonucleoproteins) have also been found to enhance or suppress the splicing process. The appearance of synonymous mutations in cis-acting elements can alter the splicing process by changing the binding pattern of splicing factors to exonic splicing enhancers or silencer motifs. This results in exon skipping, intron retention, and various other forms of alternative splicing, eventually leading to the emergence of a wide range of diseases. The focus of this review is to elucidate the role of synonymous mutations and their impact on abnormal splicing mechanisms. Further, this study highlights the function of synonymous mutation in mediating abnormal splicing in cancer and development of X-linked, and autosomal inherited diseases.
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Affiliation(s)
- Avik Sarkar
- Department of Zoology, Vidyasagar University, Midnapore, West Bengal 721102, India
| | - Kalpana Panati
- Department of Biotechnology, Government College for Men, Kadapa 516004, India
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Simon MT, Eftekharian SS, Ferdinandusse S, Tang S, Naseri T, Reupena MS, McGarvey ST, Minster RL, Weeks DE, Nguyen DD, Lee S, Ellsworth KA, Vaz FM, Dimmock D, Pitt J, Abdenur JE. ECHS1 disease in two unrelated families of Samoan descent: Common variant - rare disorder. Am J Med Genet A 2021; 185:157-167. [PMID: 33112498 PMCID: PMC7746601 DOI: 10.1002/ajmg.a.61936] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/12/2020] [Accepted: 10/03/2020] [Indexed: 01/30/2023]
Abstract
Mutations in the short-chain enoyl-CoA hydratase (SCEH) gene, ECHS1, cause a rare autosomal recessive disorder of valine catabolism. Patients usually present with developmental delay, regression, dystonia, feeding difficulties, and abnormal MRI with bilateral basal ganglia involvement. We present clinical, biochemical, molecular, and functional data for four affected patients from two unrelated families of Samoan descent with identical novel compound heterozygous mutations. Family 1 has three affected boys while Family 2 has an affected daughter, all with clinical and MRI findings of Leigh syndrome and intermittent episodes of acidosis and ketosis. WES identified a single heterozygous variant in ECHS1 at position c.832G > A (p.Ala278Thr). However, western blot revealed significantly reduced ECHS1 protein for all affected family members. Decreased SCEH activity in fibroblasts and a mild increase in marker metabolites in urine further supported ECHS1 as the underlying gene defect. Additional investigations at the DNA (aCGH, WGS) and RNA (qPCR, RT-PCR, RNA-Seq, RNA-Array) level identified a silent, common variant at position c.489G > A (p.Pro163=) as the second mutation. This substitution, present at high frequency in the Samoan population, is associated with decreased levels of normally spliced mRNA. To our understanding, this is the first report of a novel, hypomorphic allele c.489G > A (p.Pro163=), associated with SCEH deficiency.
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Affiliation(s)
- Mariella T. Simon
- Division of Metabolic DisordersCHOC Children's HospitalOrangeCaliforniaUSA
- Department of Human GeneticsUniversity of CaliforniaLos AngelesCaliforniaUSA
| | - Shaya S. Eftekharian
- Division of Metabolic DisordersCHOC Children's HospitalOrangeCaliforniaUSA
- College of Osteopathic MedicineWestern University of Health SciencesPomonaCaliforniaUSA
| | - Sacha Ferdinandusse
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, Amsterdam UMCUniversity of Amsterdam, Amsterdam Gastroenterology and MetabolismAmsterdamThe Netherlands
| | - Sha Tang
- Department of Clinical GenomicsAmbry GeneticsCaliforniaUSA
| | | | | | - Stephen T. McGarvey
- Department of EpidemiologyInternational Health Institute, Brown University School of Public HealthProvidenceRhode IslandUSA
| | - Ryan L. Minster
- Department of Human GeneticsGraduate School of Public Health, University of PittsburghPittsburghPennsylvaniaUSA
| | - Daniel E. Weeks
- Department of Human GeneticsGraduate School of Public Health, University of PittsburghPittsburghPennsylvaniaUSA
- Department of BiostatisticsGraduate School of Public Health, University of PittsburghPittsburghPennsylvaniaUSA
| | | | - Daniel D. Nguyen
- Division of Metabolic DisordersCHOC Children's HospitalOrangeCaliforniaUSA
- Department of BiochemistryCalifornia State University Long BeachLong BeachCaliforniaUSA
| | - Sansan Lee
- Hawaii Community GeneticsHawai'i Pacific HealthHonoluluHawaiiUSA
| | | | - Frédéric M. Vaz
- Department of PaediatricsUniversity of Melbourne, Victorian Clinical Genetics Services, Murdoch Childrens Research InstituteMelbourneVictoriaAustralia
| | - David Dimmock
- Rady Children's Institute for Genomic MedicineSan DiegoCaliforniaUSA
| | - James Pitt
- Department of PaediatricsUniversity of Melbourne, Victorian Clinical Genetics Services, Murdoch Childrens Research InstituteMelbourneVictoriaAustralia
| | - Jose E. Abdenur
- Division of Metabolic DisordersCHOC Children's HospitalOrangeCaliforniaUSA
- Department of PediatricsUniversity of California IrvineOrangeCaliforniaUSA
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Oh J, Koo C, Kim KW, Lee JS. Potential role of stress-induced gluconeogenesis in disease aggravation and mortality in pyruvate dehydrogenase deficiency: A case-based hypothesis. Med Hypotheses 2020; 146:110432. [PMID: 33303308 DOI: 10.1016/j.mehy.2020.110432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/04/2020] [Accepted: 11/23/2020] [Indexed: 10/22/2022]
Abstract
Pyruvate dehydrogenase (PDH) deficiency is an inherited metabolic disorder caused by a defect in any subunit of the pyruvate dehydrogenase complex (PDHC), which has an essential role in glucose metabolism. The causes of disease progression in PDH deficiency are not fully understood yet. Based on repeated observations of a patient with PDH deficiency at our center, we hypothesized that stress-induced gluconeogenesis contributes to rapid exacerbation of the disease. This link has not been established previously.
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Affiliation(s)
- Jiyoung Oh
- Division of Clinical Genetics, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Chungmo Koo
- Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Kyung Won Kim
- Department of Pediatrics, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jin-Sung Lee
- Division of Clinical Genetics, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
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Winters L, Van Hoof E, De Catte L, Van Den Bogaert K, de Ravel T, De Waele L, Corveleyn A, Breckpot J. Massive parallel sequencing identifies RAPSN and PDHA1 mutations causing fetal akinesia deformation sequence. Eur J Paediatr Neurol 2017; 21:745-753. [PMID: 28495245 DOI: 10.1016/j.ejpn.2017.04.641] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 04/12/2017] [Accepted: 04/19/2017] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Fetal akinesia deformation sequence (FADS) or arthrogryposis multiplex congenita (AMC) is characterized by clinical ambiguity and genetic heterogeneity, hampering genetic diagnosis via traditional sequencing methods. Next generation sequencing (NGS) of all known disease-causing genes offers an elegant solution to identify the genetic etiology of AMC/FADS in a diagnostic setting. METHODS An in-house developed disease-associated gene panel was conducted in two unrelated fetuses with FADS. First, a de novo analysis was performed on the entire disease-associated gene panel. If no pathogenic mutation was identified, analysis of variants retained in a specific subpanel with arthrogryposis/fetal akinesia-causing genes was performed. RESULTS In the first family, FADS relates to a homozygous c.484G > A (p.Glu162Lys) mutation in the gene RAPSN. The second case concerns a sporadic patient with brain anomalies and arthrogryposis due to a de novo hemizygous c.498C > T splice-site mutation in the pyruvate dehydrogenase-alpha 1 (PDHA1) gene. DISCUSSION NGS facilitated genetic diagnosis, and hence genetic counseling, for both families with AMC/FADS. Biallelic RAPSN mutations typically result in congenital myasthenia syndrome, or occasionally in FADS. This is the first report attributing the RAPSN mutation c.484G > A, identified in a homozygous state in patient 1, to FADS. The second patient represents the first case of AMC due to a PDHA1 mutation, advocating that pyruvate dehydrogenase deficiency should be considered in the differential diagnosis of fetal akinesia. This study illustrates the relevance of a disease-associated-gene panel as a diagnostic tool in pregnancies complicated by this genetically heterogeneous condition.
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Affiliation(s)
- Lore Winters
- Department of Pediatrics, University Hospitals Leuven, Catholic University Leuven, Leuven, Belgium
| | - Evelien Van Hoof
- Center for Human Genetics, University Hospitals Leuven, Catholic University Leuven, Leuven, Belgium
| | - Luc De Catte
- Division of Woman and Child, Clinical Department of Obstetrics and Gynecology, Fetal Medicine Unit, University Hospitals Leuven, Leuven, Belgium
| | - Kris Van Den Bogaert
- Center for Human Genetics, University Hospitals Leuven, Catholic University Leuven, Leuven, Belgium
| | - Thomy de Ravel
- Center for Human Genetics, University Hospitals Leuven, Catholic University Leuven, Leuven, Belgium
| | - Liesbeth De Waele
- Department of Pediatric Neurology, University Hospitals Leuven, Leuven, Belgium
| | - Anniek Corveleyn
- Center for Human Genetics, University Hospitals Leuven, Catholic University Leuven, Leuven, Belgium
| | - Jeroen Breckpot
- Center for Human Genetics, University Hospitals Leuven, Catholic University Leuven, Leuven, Belgium.
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Soussi T, Taschner PEM, Samuels Y. Synonymous Somatic Variants in Human Cancer Are Not Infamous: A Plea for Full Disclosure in Databases and Publications. Hum Mutat 2017; 38:339-342. [PMID: 28026089 DOI: 10.1002/humu.23163] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 11/28/2016] [Accepted: 12/11/2016] [Indexed: 12/12/2022]
Abstract
Single-nucleotide variants (SNVs) are the most frequent genetic changes found in human cancer. Most driver alterations are missense and nonsense variants localized in the coding region of cancer genes. Unbiased cancer genome sequencing shows that synonymous SNVs (sSNVs) can be found clustered in the coding regions of several cancer oncogenes or tumor suppressor genes suggesting purifying selection. sSNVs are currently underestimated, as they are usually discarded during analysis. Furthermore, several public databases do not display sSNVs, which can lead to analytical bias and the false assumption that this mutational event is uncommon. Recent progress in our understanding of the deleterious consequences of these sSNVs for RNA stability and protein translation shows that they can act as strong drivers of cancer, as demonstrated for several cancer genes such as TP53 or BCL2L12. It is therefore essential that sSNVs be properly reported and analyzed in order to provide an accurate picture of the genetic landscape of the cancer genome.
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Affiliation(s)
- Thierry Soussi
- Sorbonne Université, UPMC Univ Paris 06, Paris, F-75005, France.,INSERM, U1138, Centre de Recherche des Cordeliers, Paris, France.,Department of Oncology-Pathology, Karolinska Institutet, Cancer Center Karolinska (CCK) R8:04, Stockholm, SE-171 76, Sweden
| | - Peter E M Taschner
- Generade Centre of Expertise Genomics and University of Applied Sciences Leiden, Leiden, 2333 CL, The Netherlands
| | - Yardena Samuels
- Molecular Cell Biology Department, Weizmann Institute of Science, Rehovot, 76100, Israel
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Decoding mechanisms by which silent codon changes influence protein biogenesis and function. Int J Biochem Cell Biol 2015; 64:58-74. [PMID: 25817479 DOI: 10.1016/j.biocel.2015.03.011] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 03/02/2015] [Accepted: 03/14/2015] [Indexed: 02/07/2023]
Abstract
SCOPE Synonymous codon usage has been a focus of investigation since the discovery of the genetic code and its redundancy. The occurrences of synonymous codons vary between species and within genes of the same genome, known as codon usage bias. Today, bioinformatics and experimental data allow us to compose a global view of the mechanisms by which the redundancy of the genetic code contributes to the complexity of biological systems from affecting survival in prokaryotes, to fine tuning the structure and function of proteins in higher eukaryotes. Studies analyzing the consequences of synonymous codon changes in different organisms have revealed that they impact nucleic acid stability, protein levels, structure and function without altering amino acid sequence. As such, synonymous mutations inevitably contribute to the pathogenesis of complex human diseases. Yet, fundamental questions remain unresolved regarding the impact of silent mutations in human disorders. In the present review we describe developments in this area concentrating on mechanisms by which synonymous mutations may affect protein function and human health. PURPOSE This synopsis illustrates the significance of synonymous mutations in disease pathogenesis. We review the different steps of gene expression affected by silent mutations, and assess the benefits and possible harmful effects of codon optimization applied in the development of therapeutic biologics. PHYSIOLOGICAL AND MEDICAL RELEVANCE Understanding mechanisms by which synonymous mutations contribute to complex diseases such as cancer, neurodegeneration and genetic disorders, including the limitations of codon-optimized biologics, provides insight concerning interpretation of silent variants and future molecular therapies.
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Deeb KK, Bedoyan JK, Wang R, Sremba L, Schroeder MC, Grahame GJ, Boyer M, McCandless SE, Kerr DS, Zhang S. Somatic mosaicism for a novel PDHA1 mutation in a male with severe pyruvate dehydrogenase complex deficiency. Mol Genet Metab Rep 2014; 1:362-367. [PMID: 27896109 PMCID: PMC5121365 DOI: 10.1016/j.ymgmr.2014.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 08/01/2014] [Accepted: 08/02/2014] [Indexed: 11/19/2022] Open
Abstract
Pyruvate dehydrogenase complex (PDC) deficiencies are mostly due to mutations in the X-linked PDHA1 gene. Males with hemizygous PDHA1 mutations are clinically more severely affected, while those with mosaic PDHA1 mutations may manifest milder phenotypes. We report a patient harboring a novel, mosaic missense PDHA1 mutation, c.523G > A (p.A175T), with a severe clinical presentation of congenital microcephaly, significant brain abnormalities, persistent seizures, profound developmental delay, and failure to thrive. We review published cases of PDHA1 mosaicism.
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Affiliation(s)
- Kristin K. Deeb
- Center for Human Genetics Laboratory University Hospitals Case Medical Center, Cleveland, OH, USA
| | - Jirair K. Bedoyan
- Center for Inherited Disorders of Energy Metabolism (CIDEM), University Hospitals Case Medical Center, Cleveland, OH, USA
| | - Raymond Wang
- Division of Metabolic Disorders, CHOC Children's Hospital, Orange, CA, USA
| | - Leighann Sremba
- Division of Metabolic Disorders, CHOC Children's Hospital, Orange, CA, USA
| | - Molly C. Schroeder
- Center for Human Genetics Laboratory University Hospitals Case Medical Center, Cleveland, OH, USA
| | - George J. Grahame
- Center for Inherited Disorders of Energy Metabolism (CIDEM), University Hospitals Case Medical Center, Cleveland, OH, USA
| | - Monica Boyer
- Division of Metabolic Disorders, CHOC Children's Hospital, Orange, CA, USA
| | - Shawn E. McCandless
- Center for Inherited Disorders of Energy Metabolism (CIDEM), University Hospitals Case Medical Center, Cleveland, OH, USA
| | - Douglas S. Kerr
- Center for Inherited Disorders of Energy Metabolism (CIDEM), University Hospitals Case Medical Center, Cleveland, OH, USA
| | - Shulin Zhang
- Center for Human Genetics Laboratory University Hospitals Case Medical Center, Cleveland, OH, USA
- Corresponding author at: Molecular Genetics Laboratory, Center for Human Genetics Laboratory, University Hospitals Case Medical Center, Department of Pathology, Case Western Reserve University, W.O. Walker Building, 6th floor, 10524 Euclid Avenue, Cleveland, OH 44106. Fax: + 1 216 9831144.
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Ferriero R, Boutron A, Brivet M, Kerr D, Morava E, Rodenburg RJ, Bonafé L, Baumgartner MR, Anikster Y, Braverman NE, Brunetti-Pierri N. Phenylbutyrate increases pyruvate dehydrogenase complex activity in cells harboring a variety of defects. Ann Clin Transl Neurol 2014; 1:462-70. [PMID: 25356417 PMCID: PMC4184775 DOI: 10.1002/acn3.73] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 05/20/2014] [Accepted: 05/20/2014] [Indexed: 11/30/2022] Open
Abstract
Objective Deficiency of pyruvate dehydrogenase complex (PDHC) is the most common genetic disorder leading to lactic acidosis. PDHC deficiency is genetically heterogenous and most patients have defects in the X-linked E1-α gene but defects in the other components of the complex encoded by PDHB, PDHX, DLAT, DLD genes or in the regulatory enzyme encoded by PDP1 have also been found. Phenylbutyrate enhances PDHC enzymatic activity in vitro and in vivo by increasing the proportion of unphosphorylated enzyme through inhibition of pyruvate dehydrogenase kinases and thus, has potential for therapy of patients with PDHC deficiency. In the present study, we investigated response to phenylbutyrate of multiple cell lines harboring all known gene defects resulting in PDHC deficiency. Methods Fibroblasts of patients with PDHC deficiency were studied for their enzyme activity at baseline and following phenylbutyrate incubation. Drug responses were correlated with genotypes and protein levels by Western blotting. Results Large deletions affecting PDHA1 that result in lack of detectable protein were unresponsive to phenylbutyrate, whereas increased PDHC activity was detected in most fibroblasts harboring PDHA1 missense mutations. Mutations affecting the R349-α residue were directed to proteasome degradation and were consistently unresponsive to short-time drug incubation but longer incubation resulted in increased levels of enzyme activity and protein that may be due to an additional effect of phenylbutyrate as a molecular chaperone. Interpretation PDHC enzyme activity was enhanced by phenylbutyrate in cells harboring missense mutations in PDHB, PDHX, DLAT, DLD, and PDP1 genes. In the prospect of a clinical trial, the results of this study may allow prediction of in vivo response in patients with PDHC deficiency harboring a wide spectrum of molecular defects.
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Affiliation(s)
- Rosa Ferriero
- Telethon Institute of Genetics and MedicineNaples, Italy
| | - Audrey Boutron
- Laboratoire de Biochimie, AP-HP Hôpital de BicêtreLe Kremlin Bicêtre, France
| | - Michele Brivet
- Laboratoire de Biochimie, AP-HP Hôpital de BicêtreLe Kremlin Bicêtre, France
| | - Douglas Kerr
- Center for Inherited Disorders of Energy Metabolism, Case Western Reserve UniversityCleveland, Ohio, USA
| | - Eva Morava
- Hayward Genetics Center, Tulane University Medical SchoolNew Orleans, Louisiana, USA
| | - Richard J Rodenburg
- Department of Pediatrics, Nijmegen Center for Mitochondrial Disorders, Radboud University Medical CenterNijmegen, The Netherlands
| | - Luisa Bonafé
- Center for Molecular Diseases, Lausanne University HospitalLausanne, Switzerland
| | - Matthias R Baumgartner
- Division for Metabolic Diseases and Children's Research Center, University Children's HospitalZürich, Switzerland
| | - Yair Anikster
- Metabolic Disease Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer and Sackler School of Medicine, Tel Aviv UniversityTel Aviv, Israel
| | - Nancy E Braverman
- Department of Human Genetics, McGill UniversityMontreal, Quebec, Canada
- Department of Pediatrics, Montreal Children's Hospital MontrealMontreal, Quebec, Canada
| | - Nicola Brunetti-Pierri
- Telethon Institute of Genetics and MedicineNaples, Italy
- Department of Translational Medicine, Federico II University of NaplesNaples, Italy
- Correspondence Nicola Brunetti-Pierri, Telethon Institute of Genetics and Medicine, Via P. Castellino, 111, 80131 Napoli, Italy. Tel: +39 081 6132361; Fax: +39 081 5609877; E-mail:
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Cauli: a mouse strain with an Ift140 mutation that results in a skeletal ciliopathy modelling Jeune syndrome. PLoS Genet 2013; 9:e1003746. [PMID: 24009529 PMCID: PMC3757063 DOI: 10.1371/journal.pgen.1003746] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 07/10/2013] [Indexed: 02/01/2023] Open
Abstract
Cilia are architecturally complex organelles that protrude from the cell membrane and have signalling, sensory and motility functions that are central to normal tissue development and homeostasis. There are two broad categories of cilia; motile and non-motile, or primary, cilia. The central role of primary cilia in health and disease has become prominent in the past decade with the recognition of a number of human syndromes that result from defects in the formation or function of primary cilia. This rapidly growing class of conditions, now known as ciliopathies, impact the development of a diverse range of tissues including the neural axis, craniofacial structures, skeleton, kidneys, eyes and lungs. The broad impact of cilia dysfunction on development reflects the pivotal position of the primary cilia within a signalling nexus involving a growing number of growth factor systems including Hedgehog, Pdgf, Fgf, Hippo, Notch and both canonical Wnt and planar cell polarity. We have identified a novel ENU mutant allele of Ift140, which causes a mid-gestation embryonic lethal phenotype in homozygous mutant mice. Mutant embryos exhibit a range of phenotypes including exencephaly and spina bifida, craniofacial dysmorphism, digit anomalies, cardiac anomalies and somite patterning defects. A number of these phenotypes can be attributed to alterations in Hedgehog signalling, although additional signalling systems are also likely to be involved. We also report the identification of a homozygous recessive mutation in IFT140 in a Jeune syndrome patient. This ENU-induced Jeune syndrome model will be useful in delineating the origins of dysmorphology in human ciliopathies. Skeletal ciliopathies are an emerging field of human disease in which skeletal birth defects arise due to abnormal communication between cells. This failure in communication arises following mutation in components of the primary cilia, a hair-like structure present on every cell. The skeletal ciliopathies are debilitating and in severe cases lead to death in early infancy. However, the mechanisms by which these malformations come about remains unclear. Mouse models are often used to delineate the causes of human birth defects and we have identified a model that mimics one of these conditions known as Jeune syndrome. It is the first mouse model with a mutation in the Ift140 gene, and these mice exhibit phenotypes that are often seen in this set of human syndromes. We have complimented this study with the discovery of a patient that presents with Jeune Syndrome resulting from mutation of human IFT140. This model will allow us to explore the role of IFT140 and the primary cilia in normal human development and provide insight into the field of human skeletal ciliopathies.
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Patel KP, O’Brien TW, Subramony SH, Shuster J, Stacpoole PW. The spectrum of pyruvate dehydrogenase complex deficiency: clinical, biochemical and genetic features in 371 patients. Mol Genet Metab 2012; 106:385-94. [PMID: 22896851 PMCID: PMC4003492 DOI: 10.1016/j.ymgme.2012.03.017] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
CONTEXT Pyruvate dehydrogenase complex (PDC) deficiency is a genetic mitochondrial disorder commonly associated with lactic acidosis, progressive neurological and neuromuscular degeneration and, usually, death during childhood. There has been no recent comprehensive analysis of the natural history and clinical course of this disease. OBJECTIVE We reviewed 371 cases of PDC deficiency, published between 1970 and 2010, that involved defects in subunits E1α and E1β and components E1, E2, E3 and the E3 binding protein of the complex. DATA SOURCES AND EXTRACTION English language peer-reviewed publications were identified, primarily by using PubMed and Google Scholar search engines. RESULTS Neurodevelopmental delay and hypotonia were the commonest clinical signs of PDC deficiency. Structural brain abnormalities frequently included ventriculomegaly, dysgenesis of the corpus callosum and neuroimaging findings typical of Leigh syndrome. Neither gender nor any clinical or neuroimaging feature differentiated the various biochemical etiologies of the disease. Patients who died were younger, presented clinically earlier and had higher blood lactate levels and lower residual enzyme activities than subjects who were still alive at the time of reporting. Survival bore no relationship to the underlying biochemical or genetic abnormality or to gender. CONCLUSIONS Although the clinical spectrum of PDC deficiency is broad, the dominant clinical phenotype includes presentation during the first year of life; neurological and neuromuscular degeneration; structural lesions revealed by neuroimaging; lactic acidosis and a blood lactate:pyruvate ratio ≤ 20.
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Affiliation(s)
- Kavi P. Patel
- Department of Medicine (Division of Endocrinology, Metabolism and
Diabetes), College of Medicine, University of Florida, Gainesville, FL 32611,
USA
| | - Thomas W. O’Brien
- Department of Biochemistry and Molecular Biology, College of
Medicine, University of Florida, Gainesville, FL 32611, USA
| | | | - Jonathan Shuster
- Department of Epidemiology and Health Policy Research, College of
Medicine, University of Florida, Gainesville, FL 32611, USA
| | - Peter W. Stacpoole
- Department of Medicine (Division of Endocrinology, Metabolism and
Diabetes), College of Medicine, University of Florida, Gainesville, FL 32611,
USA
- Department of Biochemistry and Molecular Biology, College of
Medicine, University of Florida, Gainesville, FL 32611, USA
- Corresponding author at: UF College of Medicine, 1600 SW
Archer Road M2-238, P.O. Box 100226, Gainesville, FL 32610, USA. Fax: +1
352 273 9013. (P.W. Stacpoole)
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Salahshourifar I, Wan Sulaiman WA, Halim AS, Zilfalil BA. Mutation screening of IRF6 among families with non-syndromic oral clefts and identification of two novel variants: Review of the literature. Eur J Med Genet 2012; 55:389-93. [PMID: 22440537 DOI: 10.1016/j.ejmg.2012.02.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2011] [Accepted: 02/13/2012] [Indexed: 12/17/2022]
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Fortugno P, Grosso F, Zambruno G, Pastore S, Faletra F, Castiglia D. A synonymous mutation in SPINK5 exon 11 causes Netherton syndrome by altering exonic splicing regulatory elements. J Hum Genet 2012; 57:311-5. [DOI: 10.1038/jhg.2012.22] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Patel KP, O'Brien TW, Subramony SH, Shuster J, Stacpoole PW. The spectrum of pyruvate dehydrogenase complex deficiency: clinical, biochemical and genetic features in 371 patients. Mol Genet Metab 2012; 105:34-43. [PMID: 22079328 PMCID: PMC3754811 DOI: 10.1016/j.ymgme.2011.09.032] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 09/27/2011] [Accepted: 09/27/2011] [Indexed: 01/01/2023]
Abstract
CONTEXT Pyruvate dehydrogenase complex (PDC) deficiency is a genetic mitochondrial disorder commonly associated with lactic acidosis, progressive neurological and neuromuscular degeneration and, usually, death during childhood. There has been no recent comprehensive analysis of the natural history and clinical course of this disease. OBJECTIVE We reviewed 371 cases of PDC deficiency, published between 1970 and 2010, that involved defects in subunits E1α and E1β and components E1, E2, E3 and the E3 binding protein of the complex. DATA SOURCES AND EXTRACTION English language peer-reviewed publications were identified, primarily by using PubMed and Google Scholar search engines. RESULTS Neurodevelopmental delay and hypotonia were the commonest clinical signs of PDC deficiency. Structural brain abnormalities frequently included ventriculomegaly, dysgenesis of the corpus callosum and neuroimaging findings typical of Leigh syndrome. Neither gender nor any clinical or neuroimaging feature differentiated the various biochemical etiologies of the disease. Patients who died were younger, presented clinically earlier and had higher blood lactate levels and lower residual enzyme activities than subjects who were still alive at the time of reporting. Survival bore no relationship to the underlying biochemical or genetic abnormality or to gender. CONCLUSIONS Although the clinical spectrum of PDC deficiency is broad, the dominant clinical phenotype includes presentation during the first year of life; neurological and neuromuscular degeneration; structural lesions revealed by neuroimaging; lactic acidosis and a blood lactate:pyruvate ratio ≤20.
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Affiliation(s)
- Kavi P. Patel
- Department of Medicine (Division of Endocrinology and Metabolism), College of Medicine, University of Florida, Gainesville, FL, 32611, USA
| | - Thomas W. O'Brien
- Department of Biochemistry and Molecular Biology College of Medicine, University of Florida, Gainesville, FL, 32611, USA
| | | | - Jonathan Shuster
- Epidemiology and Health Policy Research College of Medicine, University of Florida, Gainesville, FL, 32611, USA
| | - Peter W. Stacpoole
- Department of Medicine (Division of Endocrinology and Metabolism), College of Medicine, University of Florida, Gainesville, FL, 32611, USA
- Department of Biochemistry and Molecular Biology College of Medicine, University of Florida, Gainesville, FL, 32611, USA
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Imbard A, Boutron A, Vequaud C, Zater M, de Lonlay P, de Baulny HO, Barnerias C, Miné M, Marsac C, Saudubray JM, Brivet M. Molecular characterization of 82 patients with pyruvate dehydrogenase complex deficiency. Structural implications of novel amino acid substitutions in E1 protein. Mol Genet Metab 2011; 104:507-16. [PMID: 21914562 DOI: 10.1016/j.ymgme.2011.08.008] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2011] [Revised: 08/10/2011] [Accepted: 08/10/2011] [Indexed: 11/28/2022]
Abstract
BACKGROUND Pyruvate dehydrogenase complex (PDHc) deficiencies are an important cause of primary lactic acidosis. Most cases result from mutations in the X-linked gene for the pyruvate dehydrogenase E1α subunit (PDHA1) while a few cases result from mutations in genes for E1β (PDHB), E2 (DLAT), E3 (DLD) and E3BP (PDHX) subunits or PDH-phosphatase (PDP1). AIM To report molecular characterization of 82 PDHc-deficient patients and analyze structural effects of novel missense mutations in PDHA1. METHODS PDHA1 variations were investigated first, by exon sequencing using a long range PCR product, gene dosage assay and cDNA analysis. Mutation scanning in PDHX, PDHB, DLAT and DLD cDNAs was further performed in unsolved cases. Novel missense mutations in PDHA1 were located on the tridimensional model of human E1 protein to predict their possible functional consequences. RESULTS PDHA1 mutations were found in 30 girls and 35 boys. Three large rearrangements, including two contiguous gene deletion syndrome were identified. Novel missense, frameshift and splicing mutations were also delineated and a nonsense mutation in a mosaic male. Mutations p.Glu75Ala, p.Arg88Ser, p.Arg119Trp, p.Gly144Asp, p.Pro217Arg, p.Arg235Gly, p.Tyr243Cys, p.Tyr243Ser, p.Arg245Gly, p.Pro250Leu, p.Gly278Arg, p.Met282Val, p.Gly298Glu in PDHA1 were predicted to impair active site channel conformation or subunit interactions. Six out of the seven patients with PDHB mutations displayed the recurrent p.Met101Val mutation; 9 patients harbored PDHX mutations and one patient DLD mutations. CONCLUSION We provide an efficient stepwise strategy for mutation screening in PDHc genes and expand the growing list of PDHA1 mutations analyzed at the structural level.
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Affiliation(s)
- A Imbard
- Biochimie-Hôpital de Bicêtre, Hôpitaux Universitaires Paris-Sud, AP-HP, Paris, France
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Gargani M, Valentini A, Pariset L. A novel point mutation within the EDA gene causes an exon dropping in mature RNA in Holstein Friesian cattle breed affected by X-linked anhidrotic ectodermal dysplasia. BMC Vet Res 2011; 7:35. [PMID: 21740563 PMCID: PMC3224562 DOI: 10.1186/1746-6148-7-35] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 07/08/2011] [Indexed: 12/14/2022] Open
Abstract
Background X-linked anhidrotic ectodermal dysplasia is a disorder characterized by abnormal development of tissues and organs of ectodermal origin caused by mutations in the EDA gene. The bovine EDA gene encodes the ectodysplasin A, a membrane protein expressed in keratinocytes, hair follicles and sweat glands, which is involved in the interactions between cell and cell and/or cell and matrix. Four mutations causing ectodermal dysplasia in cattle have been described so far. Results We identified a new single nucleotide polymorphism (SNP) at the 9th base of exon 8 in the EDA gene in two calves of Holstein Friesian cattle breed affected by ectodermal dysplasia. This SNP is located in the exonic splicing enhancer (ESEs) recognized by SRp40 protein. As a consequence, the spliceosome machinery is no longer able to recognize the sequence as exonic and causes exon skipping. The mutation determines the deletion of the entire exon (131 bp) in the RNA processing, causing a severe alteration of the protein structure and thus the disease. Conclusion We identified a mutation, never described before, that changes the regulation of alternative splicing in the EDA gene and causes ectodermal dysplasia in cattle. The analysis of the SNP allows the identification of carriers that can transmit the disease to the offspring. This mutation can thus be exploited for a rational and efficient selection of unequivocally healthy cows for breeding.
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Affiliation(s)
- Maria Gargani
- Department for Innovation in Biological, Agro-Food and Forest systems (DIBAF), University of Tuscia, Viterbo, Italy.
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Mew NA, Loewenstein JB, Kadom N, Lichter-Konecki U, Gropman AL, Martin JM, Vanderver A. MRI features of 4 female patients with pyruvate dehydrogenase E1 alpha deficiency. Pediatr Neurol 2011; 45:57-9. [PMID: 21723463 PMCID: PMC3129538 DOI: 10.1016/j.pediatrneurol.2011.02.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 11/24/2010] [Accepted: 02/10/2011] [Indexed: 10/18/2022]
Abstract
Pyruvate dehydrogenase complex is a key intramitochondrial multienzyme complex required for the conversion of pyruvate to acetyl-CoA. Most patients with pyruvate dehydrogenase deficiency have a defect in the E1 alpha subunit, associated with mutations in the PDHA1 gene. In this report, we submit detailed magnetic resonance images in 4 affected female patients with PDHA1 mutations who had with severe cortical atrophy, dilated ventricles, and an incomplete corpus callosum. In one of these patients, the magnetic resonance imaging pattern prompted molecular diagnostic testing when enzymatic testing was normal. We underscore that this constellation of features, which may be misdiagnosed as periventricular leukomalacia, illustrates a pattern highly suggestive of a deficiency of pyruvate dehydrogenase E1 alpha in female patients and should trigger appropriate diagnostic investigations.
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Affiliation(s)
- Nicholas Ah Mew
- Division of Genetics and Metabolism, Children’s National Medical Center, Washington, DC
| | | | - Nadja Kadom
- Department of Diagnostic Imaging and Radiology, Children’s National Medical Center, Washington, DC
| | - Uta Lichter-Konecki
- Division of Genetics and Metabolism, Children’s National Medical Center, Washington, DC
| | - Andrea L. Gropman
- Department of Neurology, Children’s National Medical Center, Washington, DC
| | - Jodie M. Martin
- Department of Neurology, Children’s National Medical Center, Washington, DC
| | - Adeline Vanderver
- Department of Neurology, Children’s National Medical Center, Washington, DC
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Fukao T, Horikawa R, Naiki Y, Tanaka T, Takayanagi M, Yamaguchi S, Kondo N. A novel mutation (c.951C>T) in an exonic splicing enhancer results in exon 10 skipping in the human mitochondrial acetoacetyl-CoA thiolase gene. Mol Genet Metab 2010; 100:339-44. [PMID: 20488739 DOI: 10.1016/j.ymgme.2010.03.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/16/2010] [Accepted: 03/16/2010] [Indexed: 12/25/2022]
Abstract
Mitochondrial acetoacetyl-CoA thiolase (T2) deficiency is an inherited disorder affecting isoleucine catabolism and ketone body metabolism. A Japanese female developed a severe ketoacidotic attack at the age of 7 months. Urinary organic acid analysis showed elevated excretion of 2-methyl-3-hydroxybutyrate but not tiglylglycine. She was diagnosed as having T2 deficiency by enzyme assay using fibroblasts. Mutation analysis revealed a compound heterozygote of c.556G>T(D186Y) and c.951C>T(D317D). Since c.951C>T does not cause amino acid change, we performed cDNA analysis and found that exon 10 skipping had occurred in the c.951C>T allele. A computer search using an ESE finder showed that an exonic splicing enhancer sequence, SF2/ASF, was located in CTGA(951)CGC. We hypothesized that the exonic splicing enhancer is necessary for accurate splicing since the first nucleotide of exon 10 is C, which weakens the splice acceptor site of intron 9. We made a mini gene construct including exon 9-truncated intron 9-exon 10-truncated intron 10-exon 11 for a splicing experiment. We also made three mutant constructs which alter the SF2/ASF site (947C>T, 951C>T, 952G>A). An min-gene splicing experiment clearly showed that exon 10 skipping was induced in all three mutant constructs. Moreover, additional substitution of G for C at the first nucleotide of exon 10 resulted in normal splicing in these three mutants. These results confirmed that c.951C>T diminished the effect of the exonic splicing enhancer and caused exon 10 skipping.
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Affiliation(s)
- Toshiyuki Fukao
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501-1194, Japan.
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Quintana E, Gort L, Busquets C, Navarro-Sastre A, Lissens W, Moliner S, Lluch M, Vilaseca MA, De Meirleir L, Ribes A, Briones P. Mutational study in thePDHA1gene of 40 patients suspected of pyruvate dehydrogenase complex deficiency. Clin Genet 2010; 77:474-82. [DOI: 10.1111/j.1399-0004.2009.01313.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Abstract
OBJECTIVE We have assessed whether CFTR gene has a major impact on chronic pancreatitis (CP) pathogenesis than that provided by the CFTR mutations. For this aim, we have evaluated clinical parameters, CFTR mutations, and 3 potential regulatory CFTR variants (coding single-nucleotide polymorphisms): c.1540A>G, c.2694T>G, and c.4521G>A. METHODS CFTR gene analysis was performed in a cohort of 136 CP patients and 93 controls from Spanish population using current scanning techniques (single-strand conformation polymorphism/heteroduplex, denaturing gradient gel electrophoresis, and denaturing high-performance liquid chromatography) and direct sequencing. RESULTS A higher frequency of CFTR mutations were observed in patients (39%) than in controls (15%; P < or = 0.001), differences being mostly attributable to the prevalence of the cystic fibrosis (CF)-causing mutations (P = 0.009). The analysis of variants has shown statistically significant differences between patients and controls for c.4521G>A (Pcorrected = 0.036). Furthermore, the multi-marker analysis revealed that the 1540A;2694G;4521A (AGA) haplotype was more prevalent in CP than controls (Pcorrected = 0.042). Remarkably, this association was unrelated to CF-causing mutations (P = 0.006). CONCLUSIONS Our results corroborate the higher susceptibility of CF carriers to CP and, furthermore, suggest that the AGA haplotype could contribute to an increased risk in the development of CP irrespective of other CF-causing mutations.
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Woolfe A, Mullikin JC, Elnitski L. Genomic features defining exonic variants that modulate splicing. Genome Biol 2010; 11:R20. [PMID: 20158892 PMCID: PMC2872880 DOI: 10.1186/gb-2010-11-2-r20] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 02/03/2010] [Accepted: 02/16/2010] [Indexed: 12/21/2022] Open
Abstract
A comparative analysis of SNPs and their exonic and intronic environments identifies the features predictive of splice affecting variants. Background Single point mutations at both synonymous and non-synonymous positions within exons can have severe effects on gene function through disruption of splicing. Predicting these mutations in silico purely from the genomic sequence is difficult due to an incomplete understanding of the multiple factors that may be responsible. In addition, little is known about which computational prediction approaches, such as those involving exonic splicing enhancers and exonic splicing silencers, are most informative. Results We assessed the features of single-nucleotide genomic variants verified to cause exon skipping and compared them to a large set of coding SNPs common in the human population, which are likely to have no effect on splicing. Our findings implicate a number of features important for their ability to discriminate splice-affecting variants, including the naturally occurring density of exonic splicing enhancers and exonic splicing silencers of the exon and intronic environment, extensive changes in the number of predicted exonic splicing enhancers and exonic splicing silencers, proximity to the splice junctions and evolutionary constraint of the region surrounding the variant. By extending this approach to additional datasets, we also identified relevant features of variants that cause increased exon inclusion and ectopic splice site activation. Conclusions We identified a number of features that have statistically significant representation among exonic variants that modulate splicing. These analyses highlight putative mechanisms responsible for splicing outcome and emphasize the role of features important for exon definition. We developed a web-tool, Skippy, to score coding variants for these relevant splice-modulating features.
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Affiliation(s)
- Adam Woolfe
- Genomic Functional Analysis Section, National Human Genome Research Institute, National Institutes of Health, Rockville, Maryland 20892, USA.
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Raponi M, Baralle D. Alternative splicing: good and bad effects of translationally silent substitutions. FEBS J 2010; 277:836-40. [DOI: 10.1111/j.1742-4658.2009.07519.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Yik WY, Steinberg SJ, Moser AB, Moser HW, Hacia JG. Identification of novel mutations and sequence variation in the Zellweger syndrome spectrum of peroxisome biogenesis disorders. Hum Mutat 2009; 30:E467-80. [PMID: 19105186 DOI: 10.1002/humu.20932] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Peroxisome biogenesis disorders (PBD) are a heterogeneous group of autosomal recessive neurodegenerative disorders that affect multiple organ systems. Approximately 80% of PBD patients are classified in the Zellweger syndrome spectrum (PBD-ZSS). Mutations in the PEX1, PEX6, PEX10, PEX12, or PEX26 genes are found in approximately 90% of PBD-ZSS patients. Here, we sequenced the coding regions and splice junctions of these five genes in 58 PBD-ZSS cases previously subjected to targeted sequencing of a limited number of PEX gene exons. In our cohort, 71 unique sequence variants were identified, including 18 novel mutations predicted to disrupt protein function and 2 novel silent variants. We identified 4 patients who had two deleterious mutations in one PEX gene and a third deleterious mutation in a second PEX gene. For two such patients, we conducted cell fusion complementation analyses to identify the defective gene responsible for aberrant peroxisome assembly. Overall, we provide empirical data to estimate the relative fraction of disease-causing alleles that occur in the coding and splice junction sequences of these five PEX genes and the frequency of cases where mutations occur in multiple PEX genes. This information is beneficial for efforts aimed at establishing rapid and sensitive clinical diagnostics for PBD-ZSS patients and interpreting the results from these genetic tests.
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Affiliation(s)
- Wing Yan Yik
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, California, USA
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Abstract
The mammalian target of rapamycin (mTOR) plays an essential role in the regulation of cell growth, proliferation and apoptosis. Raptor, the regulatory associated protein of mTOR, is an important member in this signaling pathway. In the present report,we identified and characterized a novel splicing variant of this gene, RAPTOR v2, in which exons 14-17, 474 bp in total, are omitted from the mRNA. This deletion does not change the open reading frame, but causes a nearly complete absence of HEAT repeats, which were shown to be involved in the binding of mTOR substrates. Real time PCR performed on 48 different human tissues demonstrated the ubiquitous presence of this splice variant. Quantification of mRNA levels in lymphoblastoid cell lines (LCL) from 56 unrelated HapMap individuals revealed that the expression of this splicing form is quite variable. One synonymous SNP, rs2289759 in exon 14, was predicted by ESEfinder to cause a significant gain/loss of SRp55 and/or SF2/ASF binding sites, and thus potentially influence splicing. This prediction was confirmed by linear regression analysis between the ratio of RAPTOR v2 to total RAPTOR mRNA levels and the SNP genotype in the above 56 individuals (r=0.281 and P=0.036). Moreover, the functional evaluation indicated that this splicing isoform is expected to retain the ability to bind mTOR, but is unlikely to bind mTOR substrates, hence affecting signal transduction and further cell proliferation.
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Affiliation(s)
- Chang Sun
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA.
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Mowrer KR, Wolfe MS. Identification of acis-acting element involved in the regulation of BACE1 mRNA alternative splicing. J Neurochem 2009; 109:1008-16. [DOI: 10.1111/j.1471-4159.2009.06026.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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28
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Somatic mosaicism for a PDHA1 mutation in a female with pyruvate dehydrogenase deficiency. Hum Genet 2008; 124:187-93. [DOI: 10.1007/s00439-008-0538-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 08/01/2008] [Accepted: 08/04/2008] [Indexed: 02/04/2023]
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