1
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Tomczewski MV, Chan JZ, Al-Majmaie DM, Liu MR, Cocco AD, Stark KD, Strathdee D, Duncan RE. Phenotypic Characterization of Female Carrier Mice Heterozygous for Tafazzin Deletion. BIOLOGY 2023; 12:1238. [PMID: 37759637 PMCID: PMC10525480 DOI: 10.3390/biology12091238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/02/2023] [Accepted: 09/08/2023] [Indexed: 09/29/2023]
Abstract
Barth syndrome (BTHS) is caused by mutations in tafazzin resulting in deficits in cardiolipin remodeling that alter major metabolic processes. The tafazzin gene is encoded on the X chromosome, and therefore BTHS primarily affects males. Female carriers are typically considered asymptomatic, but age-related changes have been reported in female carriers of other X-linked disorders. Therefore, we examined the phenotype of female mice heterozygous for deletion of the tafazzin gene (Taz-HET) at 3 and 12 months of age. Food intakes, body masses, lean tissue and adipose depot weights, daily activity levels, metabolic measures, and exercise capacity were assessed. Age-related changes in mice resulted in small but significant genotype-specific differences in Taz-HET mice compared with their female Wt littermates. By 12 months, Taz-HET mice weighed less than Wt controls and had smaller gonadal, retroperitoneal, and brown adipose depots and liver and brain masses, despite similar food consumption. Daily movement, respiratory exchange ratio, and total energy expenditure did not vary significantly between the age-matched genotypes. Taz-HET mice displayed improved glucose tolerance and insulin sensitivity at 12 months compared with their Wt littermates but had evidence of slightly reduced exercise capacity. Tafazzin mRNA levels were significantly reduced in the cardiac muscle of 12-month-old Taz-HET mice, which was associated with minor but significant alterations in the heart cardiolipin profile. This work is the first to report the characterization of a model of female carriers of heterozygous tafazzin deficiency and suggests that additional study, particularly with advancing age, is warranted.
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Affiliation(s)
- Michelle V. Tomczewski
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, 200 University Ave W., BMH1044, Waterloo, ON N2L 3G1, Canada; (M.V.T.); (J.Z.C.); (D.M.A.-M.); (M.R.L.); (K.D.S.)
| | - John Z. Chan
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, 200 University Ave W., BMH1044, Waterloo, ON N2L 3G1, Canada; (M.V.T.); (J.Z.C.); (D.M.A.-M.); (M.R.L.); (K.D.S.)
| | - Duaa M. Al-Majmaie
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, 200 University Ave W., BMH1044, Waterloo, ON N2L 3G1, Canada; (M.V.T.); (J.Z.C.); (D.M.A.-M.); (M.R.L.); (K.D.S.)
| | - Ming Rong Liu
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, 200 University Ave W., BMH1044, Waterloo, ON N2L 3G1, Canada; (M.V.T.); (J.Z.C.); (D.M.A.-M.); (M.R.L.); (K.D.S.)
| | - Alex D. Cocco
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, 200 University Ave W., BMH1044, Waterloo, ON N2L 3G1, Canada; (M.V.T.); (J.Z.C.); (D.M.A.-M.); (M.R.L.); (K.D.S.)
| | - Ken D. Stark
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, 200 University Ave W., BMH1044, Waterloo, ON N2L 3G1, Canada; (M.V.T.); (J.Z.C.); (D.M.A.-M.); (M.R.L.); (K.D.S.)
| | - Douglas Strathdee
- Transgenic Technology Laboratory, Cancer Research UK Beatson Institute, Switchback Road, Glasgow G61 1BD, Scotland, UK;
| | - Robin E. Duncan
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, 200 University Ave W., BMH1044, Waterloo, ON N2L 3G1, Canada; (M.V.T.); (J.Z.C.); (D.M.A.-M.); (M.R.L.); (K.D.S.)
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2
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Płatek T, Sordyl M, Polus A, Olszanecka A, Kroczka S, Solnica B. Analysis of tafazzin and deoxyribonuclease 1 like 1 transcripts and X chromosome sequencing in the evaluation of the effect of mosaicism in the TAZ gene on phenotypes in a family affected by Barth syndrome. Mutat Res 2022; 826:111812. [PMID: 36628843 DOI: 10.1016/j.mrfmmm.2022.111812] [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: 07/15/2022] [Revised: 11/11/2022] [Accepted: 12/23/2022] [Indexed: 12/31/2022]
Abstract
Barth syndrome is a rare disease affecting mitochondria structure and function in males. In our previous study, we have shown a new mutation (c.83T>A, p.Val28Glu) in the TAZ gene in two affected patients with congenital cardiomyopathy. Furthermore, women in this family had no mutations in their blood cells, whereas they only had mutations in the oral epithelial cells. The objective of the project was to evaluate the effect of intertissue mosaicisms on the Barth syndrome phenotypes, searching for another disease-related loci on chromosome X and finally to assess the consequences of the mutation. We conducted the advanced genetic study including cytogenetic research (constitutional karyotyping in blood and fibroblasts), NGS sequencing (with custom chromosome X sequencing together with the evaluation of loss of heterozygosity (LOH) and aberrations (CNV) in the whole genome) in four different tissues and sequencing of tafazzin and deoxyribonuclease 1 like 1 transcripts. The presence of deletions within the 5'untranslated region of the TAZ gene and/or the noncoding regions of the DNASE1L1 gene were detected in several tissues. Whereas, there is no intertissue mosaicism regarding point mutation in TAZ gene in all investigated tissues in female carriers. Only the male patient presented biochemical markers and neurological symptoms of Barth syndrome. All the female carriers are healthy and have normal tafazzin and deoxyribonuclease 1 like 1 transcripts in 2 analyzed tissues. The conclusion of this study is that we cannot rule out or confirm mosaicism in the noncoding regions of TAZ or DNASE1L1 genes, but this is not clinically relevant in female carriers because they are healthy. Finally, it has been proven that mutation (c.83T>A, p.Val28Glu) is responsible for disease in males in this family.
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Affiliation(s)
- Teresa Płatek
- Department of Clinical Biochemistry, Jagiellonian University Medical College, Kraków, Poland.
| | - Maria Sordyl
- Department of Clinical Biochemistry, Jagiellonian University Medical College, Kraków, Poland
| | - Anna Polus
- Department of Clinical Biochemistry, Jagiellonian University Medical College, Kraków, Poland
| | - Agnieszka Olszanecka
- 1st Department of Cardiology, Interventional Electrocardiology and Hypertension, Faculty of Medicine, Jagiellonian University Medical College, Krakow, Poland
| | - Sławomir Kroczka
- Department of Child and Adolescent Neurology, Jagiellonian University Medical College, Krakow, Poland; Department of Child Neurology, University Children's Hospital, Krakow, Poland
| | - Bogdan Solnica
- Department of Clinical Biochemistry, Jagiellonian University Medical College, Kraków, Poland
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3
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Dudek J, Maack C. Mechano-energetic aspects of Barth syndrome. J Inherit Metab Dis 2022; 45:82-98. [PMID: 34423473 DOI: 10.1002/jimd.12427] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/28/2021] [Accepted: 08/19/2021] [Indexed: 12/22/2022]
Abstract
Energy-demanding organs like the heart are strongly dependent on oxidative phosphorylation in mitochondria. Oxidative phosphorylation is governed by the respiratory chain located in the inner mitochondrial membrane. The inner mitochondrial membrane is the only cellular membrane with significant amounts of the phospholipid cardiolipin, and cardiolipin was found to directly interact with a number of essential protein complexes, including respiratory chain complexes I to V. An inherited defect in the biogenesis of cardiolipin causes Barth syndrome, which is associated with cardiomyopathy, skeletal myopathy, neutropenia and growth retardation. Energy conversion is dependent on reducing equivalents, which are replenished by oxidative metabolism in the Krebs cycle. Cardiolipin deficiency in Barth syndrome also affects Krebs cycle activity, metabolite transport and mitochondrial morphology. During excitation-contraction coupling, calcium (Ca2+ ) released from the sarcoplasmic reticulum drives sarcomeric contraction. At the same time, Ca2+ influx into mitochondria drives the activation of Krebs cycle dehydrogenases and the regeneration of reducing equivalents. Reducing equivalents are essential not only for energy conversion, but also for maintaining a redox buffer, which is required to detoxify reactive oxygen species (ROS). Defects in CL may also affect Ca2+ uptake into mitochondria and thereby hamper energy supply and demand matching, but also detoxification of ROS. Here, we review the impact of cardiolipin deficiency on mitochondrial function in Barth syndrome and discuss potential therapeutic strategies.
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Affiliation(s)
- Jan Dudek
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
| | - Christoph Maack
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
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4
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Pu WT. Experimental models of Barth syndrome. J Inherit Metab Dis 2022; 45:72-81. [PMID: 34370877 PMCID: PMC8814986 DOI: 10.1002/jimd.12423] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 08/01/2021] [Accepted: 08/05/2021] [Indexed: 01/03/2023]
Abstract
Mutation of the gene Tafazzin (TAZ) causes Barth syndrome, an X-linked disorder characterized by cardiomyopathy, skeletal muscle weakness, and neutropenia. TAZ is an acyltransferase that catalyzes the remodeling of cardiolipin, the signature phospholipid of the inner mitochondrial membrane. Here, we review the major model systems that have been established to study the role of cardiolipin remodeling in mitochondrial function and the pathogenesis of Barth syndrome. We summarize key features of each model and provide examples of how each has contributed to advance our understanding of TAZ function and Barth syndrome pathophysiology.
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Affiliation(s)
- William T. Pu
- Department of Cardiology, Boston Children’s Hospital, 300 Longwood Ave., Boston, MA 02115
- Harvard Stem Cell Institute, Harvard University, 7 Divinity Ave, Cambridge, MA 02138
- correspondence:
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5
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Ji J, Greenberg ML. Cardiolipin function in the yeast S. cerevisiae and the lessons learned for Barth syndrome. J Inherit Metab Dis 2022; 45:60-71. [PMID: 34626131 PMCID: PMC8755574 DOI: 10.1002/jimd.12447] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 09/21/2021] [Accepted: 10/06/2021] [Indexed: 01/03/2023]
Abstract
Cardiolipin (CL) is the signature phospholipid (PL) of mitochondria and plays a pivotal role in mitochondrial and cellular function. Disruption of the CL remodeling gene tafazzin (TAZ) causes the severe genetic disorder Barth syndrome (BTHS). Our current understanding of the function of CL and the mechanism underlying the disease has greatly benefited from studies utilizing the powerful yeast model Saccharomyces cerevisiae. In this review, we discuss important findings on the function of CL and its remodeling from yeast studies and the implications of these findings for BTHS, highlighting the potential physiological modifiers that may contribute to the disparities in clinical presentation among BTHS patients.
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Affiliation(s)
- Jiajia Ji
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
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6
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Petit PX, Ardilla-Osorio H, Penalvia L, Nathan E. R. Tafazzin Mutation Affecting Cardiolipin Leads to Increased Mitochondrial Superoxide Anions and Mitophagy Inhibition in Barth Syndrome. Cells 2020; 9:cells9102333. [PMID: 33096711 PMCID: PMC7589545 DOI: 10.3390/cells9102333] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/19/2020] [Accepted: 10/20/2020] [Indexed: 01/01/2023] Open
Abstract
Tafazzin is a phospholipid transacylase that catalyzes the remodeling of cardiolipin, a mitochondrial phospholipid required for oxidative phosphorylation. Mutations of the tafazzin gene cause Barth syndrome, which is characterized by mitochondrial dysfunction and dilated cardiomyopathy, leading to premature death. However, the molecular mechanisms underlying the cause of mitochondrial dysfunction in Barth syndrome remain poorly understood. We again highlight the fact that the tafazzin deficiency is also linked to defective oxidative phosphorylation associated with oxidative stress. All the mitochondrial events are positioned in a context where mitophagy is a key element in mitochondrial quality control. Here, we investigated the role of tafazzin in mitochondrial homeostasis dysregulation and mitophagy alteration. Using a HeLa cell model of tafazzin deficiency, we show that dysregulation of tafazzin in HeLa cells induces alteration of mitophagy. Our findings provide some additional insights into mitochondrial dysfunction associated with Barth syndrome, but also show that mitophagy inhibition is concomitant with apoptosis dysfunction through the inability of abnormal mitochondrial cardiolipin to assume its role in cytoplasmic signal transduction. Our work raises hope that pharmacological manipulation of the mitophagic pathway together with mitochondrially targeted antioxidants may provide new insights leading to promising treatment for these highly lethal conditions.
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Affiliation(s)
- Patrice X. Petit
- SSPIN Saints-Pères Paris Institut de Neurosciences, CNRS UMR 8003, “Mitochondria, Apoptosis and Autophagy Signalling” Université de Paris—Campus Saint-Germain, 45 rue des Saints-Pères, 75006 Paris, France; (L.P.); (R.N.E.)
- Correspondence: or ; Tel.: +33(0)6-78-24-80-87
| | - Hector Ardilla-Osorio
- Laboratoire Cellules Souches et Prions, INSERM-S 1124, Université de Paris—Campus Saint-Germain, 45 rue des Saints Pères, 75006 Paris, France;
| | - Lucile Penalvia
- SSPIN Saints-Pères Paris Institut de Neurosciences, CNRS UMR 8003, “Mitochondria, Apoptosis and Autophagy Signalling” Université de Paris—Campus Saint-Germain, 45 rue des Saints-Pères, 75006 Paris, France; (L.P.); (R.N.E.)
| | - Rainey Nathan E.
- SSPIN Saints-Pères Paris Institut de Neurosciences, CNRS UMR 8003, “Mitochondria, Apoptosis and Autophagy Signalling” Université de Paris—Campus Saint-Germain, 45 rue des Saints-Pères, 75006 Paris, France; (L.P.); (R.N.E.)
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7
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Bertero E, Kutschka I, Maack C, Dudek J. Cardiolipin remodeling in Barth syndrome and other hereditary cardiomyopathies. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165803. [PMID: 32348916 DOI: 10.1016/j.bbadis.2020.165803] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/19/2019] [Accepted: 04/13/2020] [Indexed: 12/18/2022]
Abstract
Mitochondria play a prominent role in cardiac energy metabolism, and their function is critically dependent on the integrity of mitochondrial membranes. Disorders characterized by mitochondrial dysfunction are commonly associated with cardiac disease. The mitochondrial phospholipid cardiolipin directly interacts with a number of essential protein complexes in the mitochondrial membranes including the respiratory chain, mitochondrial metabolite carriers, and proteins critical for mitochondrial morphology. Barth syndrome is an X-linked disorder caused by an inherited defect in the biogenesis of the mitochondrial phospholipid cardiolipin. How cardiolipin deficiency impacts on mitochondrial function and how mitochondrial dysfunction causes cardiomyopathy has been intensively studied in cellular and animal models of Barth syndrome. These findings may also have implications for the molecular mechanisms underlying other inherited disorders associated with defects in cardiolipin, such as Sengers syndrome and dilated cardiomyopathy with ataxia (DCMA).
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Affiliation(s)
- Edoardo Bertero
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, 97078 Würzburg, Germany
| | - Ilona Kutschka
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, 97078 Würzburg, Germany
| | - Christoph Maack
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, 97078 Würzburg, Germany
| | - Jan Dudek
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, 97078 Würzburg, Germany.
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8
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Loss of the mitochondrial lipid cardiolipin leads to decreased glutathione synthesis. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1865:158542. [PMID: 31672571 DOI: 10.1016/j.bbalip.2019.158542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 09/18/2019] [Accepted: 09/23/2019] [Indexed: 12/30/2022]
Abstract
Previous studies demonstrated that loss of CL in the yeast mutant crd1Δ leads to perturbation of mitochondrial iron‑sulfur (FeS) cluster biogenesis, resulting in decreased activity of mitochondrial and cytosolic Fe-S-requiring enzymes, including aconitase and sulfite reductase. In the current study, we show that crd1Δ cells exhibit decreased levels of glutamate and cysteine and are deficient in the essential antioxidant, glutathione, a tripeptide of glutamate, cysteine, and glycine. Glutathione is the most abundant non-protein thiol essential for maintaining intracellular redox potential in almost all eukaryotes, including yeast. Consistent with glutathione deficiency, the growth defect of crd1Δ cells at elevated temperature was rescued by supplementation of glutathione or glutamate and cysteine. Sensitivity to the oxidants iron (FeSO4) and hydrogen peroxide (H2O2), was rescued by supplementation of glutathione. The decreased intracellular glutathione concentration in crd1Δ was restored by supplementation of glutamate and cysteine, but not by overexpressing YAP1, an activator of expression of glutathione biosynthetic enzymes. These findings show for the first time that CL plays a critical role in regulating intracellular glutathione metabolism.
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9
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Li Y, Lou W, Raja V, Denis S, Yu W, Schmidtke MW, Reynolds CA, Schlame M, Houtkooper RH, Greenberg ML. Cardiolipin-induced activation of pyruvate dehydrogenase links mitochondrial lipid biosynthesis to TCA cycle function. J Biol Chem 2019; 294:11568-11578. [PMID: 31186346 DOI: 10.1074/jbc.ra119.009037] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 05/22/2019] [Indexed: 12/17/2022] Open
Abstract
Cardiolipin (CL) is the signature phospholipid of mitochondrial membranes. Although it has long been known that CL plays an important role in mitochondrial bioenergetics, recent evidence in the yeast model indicates that CL is also essential for intermediary metabolism. To gain insight into the function of CL in energy metabolism in mammalian cells, here we analyzed the metabolic flux of [U-13C]glucose in a mouse C2C12 myoblast cell line, TAZ-KO, which is CL-deficient because of CRISPR/Cas9-mediated knockout of the CL-remodeling enzyme tafazzin (TAZ). TAZ-KO cells exhibited decreased flux of [U-13C]glucose to [13C]acetyl-CoA and M2 and M4 isotopomers of tricarboxylic acid (TCA) cycle intermediates. The activity of pyruvate carboxylase, the predominant enzyme for anaplerotic replenishing of the TCA cycle, was elevated in TAZ-KO cells, which also exhibited increased sensitivity to the pyruvate carboxylase inhibitor phenylacetate. We attributed a decreased carbon flux from glucose to acetyl-CoA in the TAZ-KO cells to a ∼50% decrease in pyruvate dehydrogenase (PDH) activity, which was observed in both TAZ-KO cells and cardiac tissue from TAZ-KO mice. Protein-lipid overlay experiments revealed that PDH binds to CL, and supplementing digitonin-solubilized TAZ-KO mitochondria with CL restored PDH activity to WT levels. Mitochondria from TAZ-KO cells exhibited an increase in phosphorylated PDH, levels of which were reduced in the presence of supplemented CL. These findings indicate that CL is required for optimal PDH activation, generation of acetyl-CoA, and TCA cycle function, findings that link the key mitochondrial lipid CL to TCA cycle function and energy metabolism.
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Affiliation(s)
- Yiran Li
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
| | - Wenjia Lou
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
| | - Vaishnavi Raja
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
| | - Simone Denis
- Laboratory of Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Amsterdam Gastroenterology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Wenxi Yu
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
| | - Michael W Schmidtke
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
| | - Christian A Reynolds
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
| | - Michael Schlame
- Department of Anesthesiology, New York University School of Medicine, New York 10016, New York.,Department of Cell Biology, New York University School of Medicine, New York 10016, New York
| | - Riekelt H Houtkooper
- Laboratory of Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Amsterdam Gastroenterology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
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10
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Ghosh S, Iadarola DM, Ball WB, Gohil VM. Mitochondrial dysfunctions in barth syndrome. IUBMB Life 2019; 71:791-801. [PMID: 30746873 DOI: 10.1002/iub.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/14/2019] [Accepted: 01/15/2019] [Indexed: 12/18/2022]
Abstract
Barth syndrome (BTHS) is a rare multisystemic genetic disorder caused by mutations in the TAZ gene. TAZ encodes a mitochondrial enzyme that remodels the acyl chain composition of newly synthesized cardiolipin, a phospholipid unique to mitochondrial membranes. The clinical abnormalities observed in BTHS patients are caused by perturbations in various mitochondrial functions that rely on remodeled cardiolipin. However, the contribution of different cardiolipin-dependent mitochondrial functions to the pathology of BTHS is not fully understood. In this review, we will discuss recent findings from different genetic models of BTHS, including the yeast model of cardiolipin deficiency that has uncovered the specific in vivo roles of cardiolipin in mitochondrial respiratory chain biogenesis, bioenergetics, intermediary metabolism, mitochondrial dynamics, and quality control. We will also describe findings from higher eukaryotic models of BTHS that highlight a link between cardiolipin-dependent mitochondrial function and its impact on tissue and organ function. © 2019 IUBMB Life, 9999(9999):1-11, 2019.
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Affiliation(s)
- Sagnika Ghosh
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Donna M Iadarola
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Writoban Basu Ball
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
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11
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Raja V, Salsaa M, Joshi AS, Li Y, van Roermund CWT, Saadat N, Lazcano P, Schmidtke M, Hüttemann M, Gupta SV, Wanders RJA, Greenberg ML. Cardiolipin-deficient cells depend on anaplerotic pathways to ameliorate defective TCA cycle function. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:654-661. [PMID: 30731133 DOI: 10.1016/j.bbalip.2019.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 10/22/2018] [Accepted: 02/02/2019] [Indexed: 01/01/2023]
Abstract
Previous studies have shown that the cardiolipin (CL)-deficient yeast mutant, crd1Δ, has decreased levels of acetyl-CoA and decreased activities of the TCA cycle enzymes aconitase and succinate dehydrogenase. These biochemical phenotypes are expected to lead to defective TCA cycle function. In this study, we report that signaling and anaplerotic metabolic pathways that supplement defects in the TCA cycle are essential in crd1Δ mutant cells. The crd1Δ mutant is synthetically lethal with mutants in the TCA cycle, retrograde (RTG) pathway, glyoxylate cycle, and pyruvate carboxylase 1. Glutamate levels were decreased, and the mutant exhibited glutamate auxotrophy. Glyoxylate cycle genes were up-regulated, and the levels of glyoxylate metabolites succinate and citrate were increased in crd1Δ. Import of acetyl-CoA from the cytosol into mitochondria is essential in crd1Δ, as deletion of the carnitine-acetylcarnitine translocase led to lethality in the CL mutant. β-oxidation was functional in the mutant, and oleate supplementation rescued growth defects. These findings suggest that TCA cycle deficiency caused by the absence of CL necessitates activation of anaplerotic pathways to replenish acetyl-CoA and TCA cycle intermediates. Implications for Barth syndrome, a genetic disorder of CL metabolism, are discussed.
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Affiliation(s)
- Vaishnavi Raja
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, United States of America
| | - Michael Salsaa
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, United States of America
| | - Amit S Joshi
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, United States of America
| | - Yiran Li
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, United States of America
| | - Carlo W T van Roermund
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, Amsterdam, the Netherlands
| | - Nadia Saadat
- Department of Nutrition and Food Science, Wayne State University, Detroit, MI 48202, United States of America
| | - Pablo Lazcano
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, United States of America
| | - Michael Schmidtke
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, United States of America
| | - Maik Hüttemann
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201
| | - Smiti V Gupta
- Department of Nutrition and Food Science, Wayne State University, Detroit, MI 48202, United States of America
| | - Ronald J A Wanders
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, Amsterdam, the Netherlands
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, United States of America.
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12
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Hirono K, Hata Y, Nakazawa M, Momoi N, Tsuji T, Matsuoka T, Ayusawa M, Abe Y, Hayashi T, Tsujii N, Abe T, Sakaguchi H, Wang C, Takasaki A, Takarada S, Okabe M, Miyao N, Nakaoka H, Ibuki K, Saito K, Ozawa S, Nishida N, Bowles NE, Ichida F. Clinical and Echocardiographic Impact of Tafazzin Variants on Dilated Cardiomyopathy Phenotype in Left Ventricular Non-Compaction Patients in Early Infancy. Circ J 2018; 82:2609-2618. [DOI: 10.1253/circj.cj-18-0470] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Keiichi Hirono
- Department of Pediatrics, Graduate School of Medicine, University of Toyama
| | - Yukiko Hata
- Legal Medicine, Graduate School of Medicine, University of Toyama
| | - Makoto Nakazawa
- Department of Pediatric and Lifelong Congenital Cardiology Institute, Southern Tohoku Research Institute for Neuroscience, Southern Tohoku General Hospital
| | - Nobuo Momoi
- Department of Pediatrics, Fukushima Medical University
| | - Tohru Tsuji
- Department of Pediatrics, Fukushima Medical University
| | - Taro Matsuoka
- Department of Pediatrics, Toyonaka Municipal Hospital
| | - Mamoru Ayusawa
- Department of Pediatrics and Child Health, Nihon University School of Medicine
| | - Yuriko Abe
- Department of Pediatrics and Child Health, Nihon University School of Medicine
| | | | | | - Tadaaki Abe
- Department of Pediatrics, Niigata City General Hospital
| | - Heima Sakaguchi
- Department of Pediatric Cardiology, National Cerebral and Cardiovascular Center
| | - Ce Wang
- Department of Pediatrics, Graduate School of Medicine, University of Toyama
| | - Asami Takasaki
- Department of Pediatrics, Graduate School of Medicine, University of Toyama
| | - Shinya Takarada
- Department of Pediatrics, Graduate School of Medicine, University of Toyama
| | - Mako Okabe
- Department of Pediatrics, Graduate School of Medicine, University of Toyama
| | - Nariaki Miyao
- Department of Pediatrics, Graduate School of Medicine, University of Toyama
| | - Hideyuki Nakaoka
- Department of Pediatrics, Graduate School of Medicine, University of Toyama
| | - Keijiro Ibuki
- Department of Pediatrics, Graduate School of Medicine, University of Toyama
| | - Kazuyoshi Saito
- Department of Pediatrics, Graduate School of Medicine, University of Toyama
| | - Sayaka Ozawa
- Department of Pediatrics, Graduate School of Medicine, University of Toyama
| | - Naoki Nishida
- Legal Medicine, Graduate School of Medicine, University of Toyama
| | - Neil E. Bowles
- Department of Occupational and Environmental Health and Safety, University of Utah
| | - Fukiko Ichida
- Department of Pediatrics, Graduate School of Medicine, University of Toyama
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13
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Barth syndrome cells display widespread remodeling of mitochondrial complexes without affecting metabolic flux distribution. Biochim Biophys Acta Mol Basis Dis 2018; 1864:3650-3658. [PMID: 30251684 DOI: 10.1016/j.bbadis.2018.08.041] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 07/25/2018] [Accepted: 08/30/2018] [Indexed: 12/31/2022]
Abstract
Barth syndrome (BTHS) is a rare X-linked disorder that is characterized by cardiac and skeletal myopathy, neutropenia and growth abnormalities. The disease is caused by mutations in the tafazzin (TAZ) gene encoding an enzyme involved in the acyl chain remodeling of the mitochondrial phospholipid cardiolipin (CL). Biochemically, this leads to decreased levels of mature CL and accumulation of the intermediate monolysocardiolipin (MLCL). At a cellular level, this causes mitochondrial fragmentation and reduced stability of the respiratory chain supercomplexes. However, the exact mechanism through which tafazzin deficiency leads to disease development remains unclear. We therefore aimed to elucidate the pathways affected in BTHS cells by employing proteomic and metabolic profiling assays. Complexome profiling of patient skin fibroblasts revealed significant effects for about 200 different mitochondrial proteins. Prominently, we found a specific destabilization of higher order oxidative phosphorylation (OXPHOS) supercomplexes, as well as changes in complexes involved in cristae organization and CL trafficking. Moreover, the key metabolic complexes 2-oxoglutarate dehydrogenase (OGDH) and branched-chain ketoacid dehydrogenase (BCKD) were profoundly destabilized in BTHS patient samples. Surprisingly, metabolic flux distribution assays using stable isotope tracer-based metabolomics did not show reduced flux through the TCA cycle. Overall, insights from analyzing the impact of TAZ mutations on the mitochondrial complexome provided a better understanding of the resulting functional and structural consequences and thus the pathological mechanisms leading to Barth syndrome.
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14
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Bondue A, Arbustini E, Bianco A, Ciccarelli M, Dawson D, De Rosa M, Hamdani N, Hilfiker-Kleiner D, Meder B, Leite-Moreira AF, Thum T, Tocchetti CG, Varricchi G, Van der Velden J, Walsh R, Heymans S. Complex roads from genotype to phenotype in dilated cardiomyopathy: scientific update from the Working Group of Myocardial Function of the European Society of Cardiology. Cardiovasc Res 2018; 114:1287-1303. [PMID: 29800419 PMCID: PMC6054212 DOI: 10.1093/cvr/cvy122] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 05/05/2018] [Accepted: 05/16/2018] [Indexed: 12/14/2022] Open
Abstract
Dilated cardiomyopathy (DCM) frequently affects relatively young, economically, and socially active adults, and is an important cause of heart failure and transplantation. DCM is a complex disease and its pathological architecture encounters many genetic determinants interacting with environmental factors. The old perspective that every pathogenic gene mutation would lead to a diseased heart, is now being replaced by the novel observation that the phenotype depends not only on the penetrance-malignancy of the mutated gene-but also on epigenetics, age, toxic factors, pregnancy, and a diversity of acquired diseases. This review discusses how gene mutations will result in mutation-specific molecular alterations in the heart including increased mitochondrial oxidation (sarcomeric gene e.g. TTN), decreased calcium sensitivity (sarcomeric genes), fibrosis (e.g. LMNA and TTN), or inflammation. Therefore, getting a complete picture of the DCM patient will include genomic data, molecular assessment by preference from cardiac samples, stratification according to co-morbidities, and phenotypic description. Those data will help to better guide the heart failure and anti-arrhythmic treatment, predict response to therapy, develop novel siRNA-based gene silencing for malignant gene mutations, or intervene with mutation-specific altered gene pathways in the heart.This article is part of the Mini Review Series from the Varenna 2017 meeting of the Working Group of Myocardial Function of the European Society of Cardiology.
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Affiliation(s)
- Antoine Bondue
- Department of Cardiology, CUB Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Eloisa Arbustini
- Centre for Inherited Cardiovascular Diseases, IRCCS Foundation, University Hospital Policlinico San Matteo, Pavia, Italy
| | - Anna Bianco
- Department of Translational Medical Sciences, Federico II University, Naples, Italy
- Department of Cardiology, Maastricht University Medical Center & CARIM, Maastricht University, Maastricht, The Netherlands
| | - Michele Ciccarelli
- School of Medicine, Surgery and Dentistry, University of Salerno, Salerno, Italy
| | - Dana Dawson
- School of Medicine and Dentistry, University of Aberdeen, Aberdeen, UK
| | - Matteo De Rosa
- School of Medicine, Surgery and Dentistry, University of Salerno, Salerno, Italy
| | - Nazha Hamdani
- Department of Systems Physiology, Ruhr University Bochum, Bochum, Germany
| | - Denise Hilfiker-Kleiner
- Molecular Cardiology, Department of Cardiology and Angiology, Hannover Medical School, Hannover, Germany
| | - Benjamin Meder
- Department of Cardiology, Heidelberg University, Heidelberg, Germany
- Department of Genetics, Stanford University School of Medicine, Genome Technology Center, Palo Alto, CA, USA
| | - Adelino F Leite-Moreira
- Cardiovascular R&D Unit, Department of Surgery and Physiology, Faculty of Medicine, University of Porto, Porto, Portugal
- Department of Cardiothoracic Surgery, Hospital of S. João, Porto, Portugal
| | - Thomas Thum
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Hannover, Germany
| | - Carlo G Tocchetti
- Department of Translational Medical Sciences, Federico II University, Naples, Italy
| | - Gilda Varricchi
- Department of Translational Medical Sciences, Federico II University, Naples, Italy
| | - Jolanda Van der Velden
- Department of Physiology, VU University Medical Centre, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
- Netherlands Heart Institute, Utrecht, The Netherlands
| | - Roddy Walsh
- Cardiovascular Research Center, Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, London, UK
| | - Stephane Heymans
- Department of Cardiology, Maastricht University Medical Center & CARIM, Maastricht University, Maastricht, The Netherlands
- Netherlands Heart Institute, Utrecht, The Netherlands
- Department of Cardiovascular Sciences, Leuven University, Leuven, Belgium
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15
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Johnson JM, Ferrara PJ, Verkerke ARP, Coleman CB, Wentzler EJ, Neufer PD, Kew KA, de Castro Brás LE, Funai K. Targeted overexpression of catalase to mitochondria does not prevent cardioskeletal myopathy in Barth syndrome. J Mol Cell Cardiol 2018; 121:94-102. [PMID: 30008435 DOI: 10.1016/j.yjmcc.2018.07.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 06/20/2018] [Accepted: 07/01/2018] [Indexed: 12/25/2022]
Abstract
Barth Syndrome (BTHS) is an X-linked recessive disorder characterized by cardiomyopathy and muscle weakness. The underlying cause of BTHS is a mutation in the tafazzin (TAZ) gene, a key enzyme of cardiolipin biosynthesis. The lack of CL arising from loss of TAZ function results in destabilization of the electron transport system, promoting oxidative stress that is thought to contribute to development of cardioskeletal myopathy. Indeed, in vitro studies demonstrate that mitochondria-targeted antioxidants improve contractile capacity in TAZ-deficient cardiomyocytes. The purpose of the present study was to determine if resolving mitochondrial oxidative stress would be sufficient to prevent cardiomyopathy and skeletal myopathy in vivo using a mouse model of BTHS. To this end we crossed mice that overexpress catalase in the mitochondria (MCAT mice) with TAZ-deficient mice (TAZKD) to produce TAZKD mice that selectively overexpress catalase in the mitochondria (TAZKD+MCAT mice). TAZKD+MCAT mice exhibited decreased mitochondrial H2O2 emission and lipid peroxidation compared to TAZKD littermates, indicating decreased oxidative stress. Despite the improvements in oxidative stress, TAZKD+MCAT mice developed cardiomyopathy and mild muscle weakness similar to TAZKD littermates. These findings indicate that resolving oxidative stress is not sufficient to suppress cardioskeletal myopathy associated with BTHS.
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Affiliation(s)
- Jordan M Johnson
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA; Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA; Department of Physical Therapy & Athletic Training, University of Utah, Salt Lake City, UT, USA; East Carolina Diabetes & Obesity Institute, East Carolina University, Greenville, NC, USA; Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - Patrick J Ferrara
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA; Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA; Department of Physical Therapy & Athletic Training, University of Utah, Salt Lake City, UT, USA; East Carolina Diabetes & Obesity Institute, East Carolina University, Greenville, NC, USA; Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - Anthony R P Verkerke
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA; Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA; Department of Physical Therapy & Athletic Training, University of Utah, Salt Lake City, UT, USA; East Carolina Diabetes & Obesity Institute, East Carolina University, Greenville, NC, USA; Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - Chanel B Coleman
- East Carolina Diabetes & Obesity Institute, East Carolina University, Greenville, NC, USA; Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - Edward J Wentzler
- East Carolina Diabetes & Obesity Institute, East Carolina University, Greenville, NC, USA; Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - P Darrell Neufer
- East Carolina Diabetes & Obesity Institute, East Carolina University, Greenville, NC, USA; Department of Kinesiology, East Carolina University, Greenville, NC, USA; Department of Physiology, East Carolina University, Greenville, NC, USA
| | - Kimberly A Kew
- Department of Chemistry, East Carolina University, Greenville, NC, USA
| | | | - Katsuhiko Funai
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA; Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA; Department of Physical Therapy & Athletic Training, University of Utah, Salt Lake City, UT, USA; East Carolina Diabetes & Obesity Institute, East Carolina University, Greenville, NC, USA; Department of Kinesiology, East Carolina University, Greenville, NC, USA; Department of Physiology, East Carolina University, Greenville, NC, USA; Program in Molecular Medicine, University of Utah, Salt Lake City, UT, USA.
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16
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Imai-Okazaki A, Kishita Y, Kohda M, Yatsuka Y, Hirata T, Mizuno Y, Harashima H, Hirono K, Ichida F, Noguchi A, Yoshida M, Tokorodani C, Nishiuchi R, Takeda A, Nakaya A, Sakata Y, Murayama K, Ohtake A, Okazaki Y. Barth Syndrome: Different Approaches to Diagnosis. J Pediatr 2018; 193:256-260. [PMID: 29249525 DOI: 10.1016/j.jpeds.2017.09.075] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/18/2017] [Accepted: 09/27/2017] [Indexed: 12/28/2022]
Abstract
The diagnosis of Barth syndrome is challenging owing to the wide phenotypic spectrum with allelic heterogeneity. Here we report 3 cases of Barth syndrome with phenotypic and allelic heterogeneity that were diagnosed by different approaches, including whole exome sequencing and final confirmation by reverse-transcription polymease chain reaction.
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Affiliation(s)
- Atsuko Imai-Okazaki
- Department of Genome Informatics, Graduate School of Medicine, Osaka University, Osaka, Japan; Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Osaka, Japan; Division of Genomic Medicine Research, Medical Genomics Center, National Center for Global Health and Medicine, Tokyo, Japan
| | - Yoshihito Kishita
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
| | - Masakazu Kohda
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
| | - Yukiko Yatsuka
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
| | - Tomoko Hirata
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
| | - Yosuke Mizuno
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
| | - Hiroko Harashima
- Department of Pediatrics, Saitama Medical University, Saitama, Japan
| | - Keiichi Hirono
- Department of Pediatrics, Graduate School of Medicine, University of Toyama, Toyama, Japan
| | - Fukiko Ichida
- Department of Pediatrics, Graduate School of Medicine, University of Toyama, Toyama, Japan
| | - Atsuko Noguchi
- Department of Pediatrics, Graduate School of Medicine, Akita University, Akita, Japan
| | - Masayuki Yoshida
- Department of Molecular Pathology and Tumor Pathology, Graduate School of Medicine, Akita University, Akita, Japan
| | - Chiho Tokorodani
- Department of Pediatrics, Kochi Health Sciences Center, Kochi, Japan
| | - Ritsuo Nishiuchi
- Department of Pediatrics, Kochi Health Sciences Center, Kochi, Japan
| | - Atsuhito Takeda
- Department of Pediatrics, Graduate School of Medicine, Hokkaido University, Hokkaido, Japan
| | - Akihiro Nakaya
- Department of Genome Informatics, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Yasushi Sakata
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Akira Ohtake
- Department of Pediatrics, Saitama Medical University, Saitama, Japan; Center for Intractable Diseases, Saitama Medical University Hospital, Saitama, Japan
| | - Yasushi Okazaki
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan; Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan.
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17
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Moore AA, Sawyers C, Adkins DE, Docherty AR. Opportunities for an enhanced integration of neuroscience and genomics. Brain Imaging Behav 2017; 12:1211-1219. [PMID: 29063506 DOI: 10.1007/s11682-017-9780-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Neuroimaging and genetics are two rapidly expanding fields of research. Thoughtful integration of these areas is critical for ongoing large-scale research into the genetic mechanisms underlying brain structure, function, and development. Neuroimaging genetics has been slow to evolve relative to psychiatric genetics research, and some may be unaware that new statistical methods allow for the genomic analysis of more modestly-sized imaging samples. We present a broad overview of the extant imaging genetics literature, provide an interpretation of the major problems surrounding the integration of neuroimaging and genetics, discuss the influence and impact of genetics consortia, and suggest statistical genetic analyses that expand the repertoire of imaging researchers amassing rich behavioral data in modestly-sized samples. Specific attention is paid to the creative use of polygenic risk scoring in imaging genetic analyses, with primers on the most current risk scoring applications.
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Affiliation(s)
- Ashlee A Moore
- Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23220, USA.,Center for Clinical and Translational Research, Virginia Commonwealth University, Richmond, VA, 23220, USA
| | - Chelsea Sawyers
- Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23220, USA.,Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA, 23220, USA
| | - Daniel E Adkins
- Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23220, USA.,University Neuropsychiatric Institute, University of Utah School of Medicine, 501 Chipeta Way, Salt Lake City, UT, 84110, USA.,Department of Psychiatry, University of Utah School of Medicine, Salt Lake City, UT, 84110, USA.,Department of Sociology, University of Utah, Salt Lake City, UT, 84110, USA
| | - Anna R Docherty
- Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23220, USA. .,University Neuropsychiatric Institute, University of Utah School of Medicine, 501 Chipeta Way, Salt Lake City, UT, 84110, USA. .,Department of Psychiatry, University of Utah School of Medicine, Salt Lake City, UT, 84110, USA.
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18
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Kang SL, Tometzki A, Taliotis D, Martin R. Stent Therapy for Aortic Coarctation in Children <30 kg: Use of the Low Profile Valeo Stent. Pediatr Cardiol 2017; 38:1441-1449. [PMID: 28780709 DOI: 10.1007/s00246-017-1682-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 07/06/2017] [Indexed: 01/23/2023]
Abstract
To report our experience of coarctation stent therapy in small children weighing less than 30 kg, with the low profile dilatable Valeo stent and review the literature on coarctation stent therapy in this patient population. Coarctation stent implantation was undertaken in 14 consecutive children using the Bard Valeo Stent. Demographic, angiographic, echocardiographic and clinical data were reviewed retrospectively. The median age at the time of procedure was 5.1 (2.6-7.5) years and median weight was 20.8 (14.7-27) kg. There was improvement in median coarctation diameter from 4 (1.3-5.2) to 9.5 (5.8-12.7) mm, p < 0.001; and a reduction in the median peak pressure gradient across the coarctation from 35 (20-49) to 9 (0-15) mmHg, p < 0.001. Median stent recoil was 7.9 (0-20)%. There was one case of access related complication that resolved without sequelae. Follow-up was a median of 15 (3.0-57.2) months. CT angiogram performed at a median time of 3.3 (2.6-10.2) months post procedure showed no aortic wall injury and preserved stent integrity in all cases. Two children underwent re-intervention for stent dilation and further stent implantation due to in-stent stenosis and somatic growth after 3 years. Six of fourteen children remained on a single antihypertensive agent post-intervention at last follow-up. Implantation of the dilatable Valeo stent is a feasible treatment strategy in native or recurrent coarctation in small children, accepting that additional stent implantation may be necessary with somatic growth. Further study is required to determine longer-term stent efficacy and clinical outcome.
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Affiliation(s)
- Sok-Leng Kang
- Bristol Royal Hospital for Children, University Hospitals Bristol NHS Foundation Trust, Paul O'Gorman Building, Upper Maudlin Street, Bristol, BS2 8BJ, UK
| | - Andrew Tometzki
- Bristol Royal Hospital for Children, University Hospitals Bristol NHS Foundation Trust, Paul O'Gorman Building, Upper Maudlin Street, Bristol, BS2 8BJ, UK
| | - Demetris Taliotis
- Bristol Royal Hospital for Children, University Hospitals Bristol NHS Foundation Trust, Paul O'Gorman Building, Upper Maudlin Street, Bristol, BS2 8BJ, UK
| | - Robin Martin
- Bristol Royal Hospital for Children, University Hospitals Bristol NHS Foundation Trust, Paul O'Gorman Building, Upper Maudlin Street, Bristol, BS2 8BJ, UK.
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19
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Raja V, Reynolds CA, Greenberg ML. Barth syndrome: A life-threatening disorder caused by abnormal cardiolipin remodeling. ACTA ACUST UNITED AC 2017; 2:58-62. [PMID: 31032491 PMCID: PMC6482962 DOI: 10.29245/2572-9411/2017/2.1087] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Barth syndrome (BTHS) is a rare X-linked genetic disorder characterized by cardiomyopathy, skeletal myopathy, neutropenia, and organic aciduria. The presence and severity of clinical manifestations are highly variable in BTHS, even among patients with identical gene mutations. Currently, less than 200 patients are diagnosed worldwide, but it is estimated that the disorder may be substantially under-diagnosed due to the variable spectrum of clinical manifestations. BTHS is caused by mutations in the gene tafazzin (TAZ), resulting in defective remodeling of cardiolipin (CL), the signature phospholipid of the mitochondrial membranes. Many of the clinical sequela associated with BTHS can be directly attributed to mitochondria defects. In 2008, a definitive biochemical test was described based on detection of the abnormal CL profile characteristic of BTHS. This mini-review provides an overview of the etiology of BTHS, as well as a description of common clinical phenotypes associated with the disorder.
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Affiliation(s)
- Vaishnavi Raja
- Department of Biological Sciences, Wayne State University, USA
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20
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Dudek J, Maack C. Barth syndrome cardiomyopathy. Cardiovasc Res 2017; 113:399-410. [PMID: 28158532 DOI: 10.1093/cvr/cvx014] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/19/2016] [Accepted: 01/04/2017] [Indexed: 02/02/2023] Open
Abstract
Barth syndrome (BTHS) is an inherited form of cardiomyopathy, caused by a mutation within the gene encoding the mitochondrial transacylase tafazzin. Tafazzin is involved in the biosynthesis of the unique phospholipid cardiolipin (CL), which is almost exclusively found in mitochondrial membranes. CL directly interacts with a number of essential protein complexes in the mitochondrial membranes including the respiratory chain, mitochondrial metabolite carriers, and proteins, involved in shaping mitochondrial morphology. Here we describe, how in BTHS CL deficiency causes changes in the morphology of mitochondria, structural changes in the respiratory chain, decreased respiration, and increased generation of reactive oxygen species. A large number of cellular and animal models for BTHS have been established to elucidate how mitochondrial dysfunction induces sarcomere disorganization and reduced contractility, resulting in dilated cardiomyopathy in vivo.
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Affiliation(s)
- Jan Dudek
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Christoph Maack
- Klinik für Innere Medizin III, Universitätsklinikum des Saarlandes, 66421 Homburg/Saar, Germany
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21
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Borna NN, Kishita Y, Ishikawa K, Nakada K, Hayashi JI, Tokuzawa Y, Kohda M, Nyuzuki H, Yamashita-Sugahara Y, Nasu T, Takeda A, Murayama K, Ohtake A, Okazaki Y. A novel mutation in TAZ causes mitochondrial respiratory chain disorder without cardiomyopathy. J Hum Genet 2017; 62:539-547. [PMID: 28123175 DOI: 10.1038/jhg.2016.165] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 11/17/2016] [Accepted: 12/08/2016] [Indexed: 12/15/2022]
Abstract
Tafazzin, encoded by the TAZ gene, is a mitochondrial membrane-associated protein that remodels cardiolipin (CL), an important mitochondrial phospholipid. TAZ mutations are associated with Barth syndrome (BTHS). BTHS is an X-linked multisystemic disorder affecting usually male patients. Through sequence analysis of TAZ, we found one novel mutation c.39_60del p.(Pro14Alafs*19) by whole-exome sequencing and a reported missense mutation c.280C>T p.(Arg94Cys) by Sanger sequencing in two male patients (Pt1 and Pt2). Patient with c.280C>T mutation had dilated cardiomyopathy, while another patient with c.39_60del mutation had no feature of cardiomyopathy. A reported m.1555A>G homoplasmic variant was also identified in the patient having mutation c.39_60del by whole mitochondrial DNA sequencing method. This variant was not considered to be the main cause of mitochondrial dysfunction based on a cytoplasmic hybrid (cybrid) assay. Tafazzin expression was absent in both patient-derived fibroblast cells. Complementation of TAZ expression in fibroblasts from the patient with the novel mutation c.39_60del restored mitochondrial respiratory complex assembly. High-performance liquid chromatography-tandem mass spectrometry-based metabolic analysis revealed the decline of CL and the accumulation of monolysocardiolipin, indicating the loss of tafazzin activity. Owing to phenotypic variability, it is difficult to diagnose BTHS based on clinical features only. We conclude that genetic analysis should be performed to avoid underdiagnosis of this potentially life-threatening inborn error of metabolism.
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Affiliation(s)
- Nurun N Borna
- Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
| | - Yoshihito Kishita
- Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
| | - Kaori Ishikawa
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Kazuto Nakada
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Jun-Ichi Hayashi
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Yoshimi Tokuzawa
- Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
| | - Masakazu Kohda
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
| | - Hiromi Nyuzuki
- Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
| | - Yzumi Yamashita-Sugahara
- Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
| | - Takashi Nasu
- Department of Pediatrics, Obihiro Kosei General Hospital, Obihiro, Japan
| | - Atsuhito Takeda
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Hokkaido, Japan
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Akira Ohtake
- Department of Pediatrics, Saitama Medical University, Saitama, Japan
| | - Yasushi Okazaki
- Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan.,Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
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22
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Raja V, Joshi AS, Li G, Maddipati KR, Greenberg ML. Loss of Cardiolipin Leads to Perturbation of Acetyl-CoA Synthesis. J Biol Chem 2016; 292:1092-1102. [PMID: 27941023 DOI: 10.1074/jbc.m116.753624] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 12/08/2016] [Indexed: 11/06/2022] Open
Abstract
Cardiolipin (CL), the signature phospholipid of mitochondrial membranes, plays an important role in mitochondrial processes and bioenergetics. CL is synthesized de novo and undergoes remodeling in the mitochondrial membranes. Perturbation of CL remodeling leads to the rare X-linked genetic disorder Barth syndrome, which shows disparities in clinical presentation. To uncover biochemical modifiers that exacerbate CL deficiency, we carried out a synthetic genetic array screen to identify synthetic lethal interactions with the yeast CL synthase mutant crd1Δ. The results indicated that crd1Δ is synthetically lethal with mutants in pyruvate dehydrogenase (PDH), which catalyzes the conversion of pyruvate to acetyl-CoA. Acetyl-CoA levels were decreased in the mutant. The synthesis of acetyl-CoA depends primarily on the PDH-catalyzed conversion of pyruvate in the mitochondria and on the PDH bypass in the cytosol, which synthesizes acetyl-CoA from acetate. Consistent with perturbation of the PDH bypass, crd1Δ cells grown on acetate as the sole carbon source exhibited decreased growth, decreased acetyl-CoA, and increased intracellular acetate levels resulting from decreased acetyl-CoA synthetase activity. PDH mRNA and protein levels were up-regulated in crd1Δ cells, but PDH enzyme activity was not increased, indicating that PDH up-regulation did not compensate for defects in the PDH bypass. These findings demonstrate for the first time that CL is required for acetyl-CoA synthesis, which is decreased in CL-deficient cells as a result of a defective PDH bypass pathway.
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Affiliation(s)
- Vaishnavi Raja
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and
| | - Amit S Joshi
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and
| | - Guiling Li
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and
| | - Krishna Rao Maddipati
- the Department of Pathology, Bioactive Lipids Research Program, Wayne State University School of Medicine, Karmanos Cancer Institute, Detroit, Michigan 48202
| | - Miriam L Greenberg
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and
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23
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Mondal A, Jin JP. Protein Structure-Function Relationship at Work: Learning from Myopathy Mutations of the Slow Skeletal Muscle Isoform of Troponin T. Front Physiol 2016; 7:449. [PMID: 27790152 PMCID: PMC5062619 DOI: 10.3389/fphys.2016.00449] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 09/20/2016] [Indexed: 12/03/2022] Open
Abstract
Troponin T (TnT) is the sarcomeric thin filament anchoring subunit of the troponin complex in striated muscles. A nonsense mutation in exon 11 of the slow skeletal muscle isoform of TnT (ssTnT) gene (TNNT1) was found in the Amish populations in Pennsylvania and Ohio. This single nucleotide substitution causes a truncation of the ssTnT protein at Glu180 and the loss of the C-terminal tropomyosin (Tm)-binding site 2. As a consequence, it abolishes the myofilament integration of ssTnT and the loss of function causes an autosomal recessive nemaline myopathy (NM). More TNNT1 mutations have recently been reported in non-Amish ethnic groups with similar recessive NM phenotypes. A nonsense mutation in exon 9 truncates ssTnT at Ser108, deleting Tm-binding site 2 and a part of the middle region Tm-binding site 1. Two splicing site mutations result in truncation of ssTnT at Leu203 or deletion of the exon 14-encoded C-terminal end segment. Another splicing mutation causes an internal deletion of the 39 amino acids encoded by exon 8, partially damaging Tm-binding site 1. The three splicing mutations of TNNT1 all preserve the high affinity Tm-binding site 2 but still present recessive NM phenotypes. The molecular mechanisms for these mutations to cause myopathy provide interesting models to study and understand the structure-function relationship of TnT. This focused review summarizes the current knowledge of TnT isoform regulation, structure-function relationship of TnT and how various ssTnT mutations cause recessive NM, in order to promote in depth studies for further understanding the pathogenesis and pathophysiology of TNNT1 myopathies toward the development of effective treatments.
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Affiliation(s)
- Anupom Mondal
- Department of Physiology, Wayne State University School of Medicine Detroit, MI, USA
| | - J-P Jin
- Department of Physiology, Wayne State University School of Medicine Detroit, MI, USA
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24
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Brión M, de Castro López MJ, Santori M, Pérez Muñuzuri A, López Abel B, Baña Souto AM, Martínez Soto MI, Couce ML. Prospective and Retrospective Diagnosis of Barth Syndrome Aided by Next-Generation Sequencing. Am J Clin Pathol 2016; 145:507-13. [PMID: 27124939 DOI: 10.1093/ajcp/aqw025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES To establish a genetic and clinical diagnosis in a newborn with fetal-onset dilated cardiomyopathy using next-generation sequencing technologies. METHODS We have conducted the clinical evaluation of the proband and the molecular characterization of his disease by means of whole-exome sequencing. In addition, the clinical evaluation and subsequent genetic screening of five relatives has been performed. This comprises two males with features of left ventricular noncompaction cardiomyopathy, two females suspected of being carriers, and one pregnant female at risk of being a carrier and thereby transmitting the disease to her child. RESULTS We have discovered a novel variant in the TAZ gene by means of whole-exome sequencing. This, together with the performance of further clinical analyses, led to an early diagnosis of Barth syndrome in the proband. The genetic screening of the subject's familial group revealed full cosegregation of the variant with another two affected males and identified several female carriers. CONCLUSIONS The investigation for Barth syndrome must be considered in male babies and young boys with dilated cardiomyopathy and left ventricular noncompaction. Next-generation sequencing technologies provide an accurate and rapid diagnostic tool in prospectively and retrospectively identifying individuals with this Mendelian syndrome.
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Affiliation(s)
- María Brión
- From the Grupo de Xenética de Enfermidades Cardiovasculares, Instituto de Investigación Sanitaria de Santiago, Red de Investigación Cardiovascular, Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain
| | | | - Montserrat Santori
- From the Grupo de Xenética de Enfermidades Cardiovasculares, Instituto de Investigación Sanitaria de Santiago, Red de Investigación Cardiovascular, Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain
| | | | - Bernardo López Abel
- Pediatric Cardiac Unit, Department of Pediatrics, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain
| | | | - María Isabel Martínez Soto
- Pediatric Cardiac Unit, Department of Pediatrics, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain
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25
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Thompson WR, DeCroes B, McClellan R, Rubens J, Vaz FM, Kristaponis K, Avramopoulos D, Vernon HJ. New targets for monitoring and therapy in Barth syndrome. Genet Med 2016; 18:1001-10. [PMID: 26845103 DOI: 10.1038/gim.2015.204] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 12/07/2015] [Indexed: 01/20/2023] Open
Abstract
PURPOSE Barth syndrome (BTHS), an X-linked disorder caused by defects in TAZ, is the only known single-gene disorder of cardiolipin remodeling. We hypothesized that through analysis of affected individuals, we would gain a better understanding of the range of clinical features and identify targets for monitoring and therapy. METHODS We conducted a multidisciplinary investigation involving 42 patients with BTHS, including echocardiograms, muscle strength testing, functional exercise capacity testing, physical activity assessments, cardiolipin analysis, 3-methylglutaconic acid analysis, and review of genotype data. We analyzed data points to provide a quantitative spectrum of disease characteristics and to identify relationships among phenotype, genotype, and relevant metabolites. RESULTS Echocardiography revealed considerable variability in cardiac features. By contrast, almost all patients had significantly reduced functional exercise capacity. Multivariate analysis revealed significant relationships between cardiolipin ratio and left ventricular mass and between cardiolipin ratio and functional exercise capacity. We additionally identified genotypes associated with a less severe metabolic and clinical profile. CONCLUSION We defined previously unrecognized metabolite/phenotype/genotype relationships, established targets for therapeutic monitoring, and validated avenues for clinical assessment. In addition to providing insight into BTHS, these studies also provide insight into the myriad of multifactorial disorders that converge on the cardiolipin pathway.Genet Med 18 10, 1001-1010.
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Affiliation(s)
- W Reid Thompson
- Division of Pediatric Cardiology, Department of Pediatrics, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Brittany DeCroes
- Department of Physical Therapy, Kennedy Krieger Institute, Baltimore, Maryland
| | - Rebecca McClellan
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland
| | - Jessica Rubens
- Department of Pediatrics, Johns Hopkins University, Baltimore, Maryland
| | - Frédéric M Vaz
- Department of Clinical Chemistry and Pediatrics, Academic Medical Center, Amsterdam, The Netherlands
| | - Kara Kristaponis
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland
| | - Dimitrios Avramopoulos
- McKusick-Nathans Institute of Genetic Medicine, Department of Pediatrics, Johns Hopkins University, Baltimore, Maryland
| | - Hilary J Vernon
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland.,McKusick-Nathans Institute of Genetic Medicine, Department of Pediatrics, Johns Hopkins University, Baltimore, Maryland
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26
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Saric A, Andreau K, Armand AS, Møller IM, Petit PX. Barth Syndrome: From Mitochondrial Dysfunctions Associated with Aberrant Production of Reactive Oxygen Species to Pluripotent Stem Cell Studies. Front Genet 2016; 6:359. [PMID: 26834781 PMCID: PMC4719219 DOI: 10.3389/fgene.2015.00359] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 12/15/2015] [Indexed: 12/22/2022] Open
Abstract
Mutations in the gene encoding the enzyme tafazzin, TAZ, cause Barth syndrome (BTHS). Individuals with this X-linked multisystem disorder present cardiomyopathy (CM) (often dilated), skeletal muscle weakness, neutropenia, growth retardation, and 3-methylglutaconic aciduria. Biopsies of the heart, liver and skeletal muscle of patients have revealed mitochondrial malformations and dysfunctions. It is the purpose of this review to summarize recent results of studies on various animal or cell models of Barth syndrome, which have characterized biochemically the strong cellular defects associated with TAZ mutations. Tafazzin is a mitochondrial phospholipidlysophospholipid transacylase that shuttles acyl groups between phospholipids and regulates the remodeling of cardiolipin (CL), a unique inner mitochondrial membrane phospholipid dimer consisting of two phosphatidyl residues linked by a glycerol bridge. After their biosynthesis, the acyl chains of CLs may be modified in remodeling processes involving up to three different enzymes. Their characteristic acyl chain composition depends on the function of tafazzin, although the enzyme itself surprisingly lacks acyl specificity. CLs are crucial for correct mitochondrial structure and function. In addition to their function in the basic mitochondrial function of ATP production, CLs play essential roles in cardiac function, apoptosis, autophagy, cell cycle regulation and Fe-S cluster biosynthesis. Recent developments in tafazzin research have provided strong insights into the link between mitochondrial dysfunction and the production of reactive oxygen species (ROS). An important tool has been the generation of BTHS-specific induced pluripotent stem cells (iPSCs) from BTHS patients. In a complementary approach, disease-specific mutations have been introduced into wild-type iPSC lines enabling direct comparison with isogenic controls. iPSC-derived cardiomyocytes were then characterized using biochemical and classical bioenergetic approaches. The cells are tested in a "heart-on-chip" assay to model the pathophysiology in vitro, to characterize the underlying mechanism of BTHS deriving from TAZ mutations, mitochondrial deficiencies and ROS production and leading to tissue defects, and to evaluate potential therapies with the use of mitochondrially targeted antioxidants.
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Affiliation(s)
- Ana Saric
- INSERM U 1124 "Toxicologie, Pharmacologie et Signalisation Cellulaire" and "FR 3567" CNRS Chimie, Toxicologie, Signalisation Cellulaire et Cibles Thérapeutiques, Université Paris Descartes - Centre Universitaire des Saints-PèresParis, France; Division of Molecular Medicine, Ruđer Bošković InstituteZagreb, Croatia
| | - Karine Andreau
- INSERM U 1124 "Toxicologie, Pharmacologie et Signalisation Cellulaire" and "FR 3567" CNRS Chimie, Toxicologie, Signalisation Cellulaire et Cibles Thérapeutiques, Université Paris Descartes - Centre Universitaire des Saints-Pères Paris, France
| | - Anne-Sophie Armand
- INSERM U 1124 "Toxicologie, Pharmacologie et Signalisation Cellulaire" and "FR 3567" CNRS Chimie, Toxicologie, Signalisation Cellulaire et Cibles Thérapeutiques, Université Paris Descartes - Centre Universitaire des Saints-Pères Paris, France
| | - Ian M Møller
- Department of Molecular Biology and Genetics, Aarhus University Slagelse, Denmark
| | - Patrice X Petit
- INSERM U 1124 "Toxicologie, Pharmacologie et Signalisation Cellulaire" and "FR 3567" CNRS Chimie, Toxicologie, Signalisation Cellulaire et Cibles Thérapeutiques, Université Paris Descartes - Centre Universitaire des Saints-Pères Paris, France
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27
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Kang SL, Forsey J, Dudley D, Steward CG, Tsai-Goodman B. Clinical Characteristics and Outcomes of Cardiomyopathy in Barth Syndrome: The UK Experience. Pediatr Cardiol 2016; 37:167-76. [PMID: 26337810 DOI: 10.1007/s00246-015-1260-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 08/27/2015] [Indexed: 10/23/2022]
Abstract
Barth syndrome (BTHS) is an X-linked disorder characterised by cardiomyopathy, neutropenia, skeletal myopathy and growth delay. This study describes the UK national clinical experience and outcome of cardiomyopathy in BTHS. The clinical course and echocardiographic changes of all patients with BTHS in the UK were reviewed from 2004 to 2014. In addition, strain analysis using 2D speckle tracking echocardiography was performed to further assess left ventricular function in the most recent follow-up. At last follow-up, 22 of 27 patients were alive with a median age of 12.6 (2.0-23.8) years; seven underwent cardiac transplantation at a median age of 2 (0.33-3.6) years, and five died (18.5%) at a median age of 1.8 (0.02-4.22) years. All deaths were related to cardiomyopathy or its management. Left ventricular diastolic dimension and systolic function measured by fractional shortening tended to normalise and stabilise after the first 3 years of life in the majority of patients. However, patients with BTHS (n = 16) had statistically significant reduction in global longitudinal and circumferential strain compared to controls (n = 18), (p < 0.001), despite apparent normal conventional measures of function. There was also reduced or reversed apical rotation and reduced left ventricular twist. Sustained ventricular arrhythmia was not seen at follow-up. Cardiac phenotype in BTHS is variable; however, longer-term outcome in our cohort suggests good prognosis after the first 5 years of life. Most patients appeared to have recovered near normal cardiac function by conventional echocardiographic measures, but strain analysis showed abnormal myocardial deformation and rotational mechanics.
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Affiliation(s)
- Sok-Leng Kang
- Department of Paediatric Cardiology, Bristol Royal Hospital for Children, Paul O'Gorman Building, Upper Maudlin Street, Bristol, BS2 8BJ, UK.
| | | | - Declan Dudley
- Department of Paediatric Cardiology, Bristol Royal Hospital for Children, Paul O'Gorman Building, Upper Maudlin Street, Bristol, BS2 8BJ, UK
| | - Colin G Steward
- NHS Specialised Services Barth Syndrome Service, Bristol Royal Hospital for Children, Bristol, UK
| | - Beverly Tsai-Goodman
- Department of Paediatric Cardiology, Bristol Royal Hospital for Children, Paul O'Gorman Building, Upper Maudlin Street, Bristol, BS2 8BJ, UK
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28
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Zapała B, Płatek T, Wybrańska I. A novel TAZ gene mutation and mosaicism in a Polish family with Barth syndrome. Ann Hum Genet 2015; 79:218-24. [PMID: 25776009 PMCID: PMC4654251 DOI: 10.1111/ahg.12108] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 01/22/2015] [Indexed: 11/29/2022]
Abstract
Barth syndrome (BTHS) is an X-linked recessive disease primarily affecting males. Clinically, the disease is characterized by hypertrophic or dilated cardiomyopathy, skeletal myopathy, chronic/cyclic neutropenia, 3-methylglutaconic aciduria, growth retardation and respiratory chain dysfunction. It is caused by mutations in the TAZ gene coding for the tafazzin protein which is responsible for cardiolipin remodeling. In this work, we present a novel pathogenic TAZ mutation c.83T>A, p.Val28Glu, found in mosaic form in almost all female members of a Polish family. Sanger sequencing of DNA from peripheral blood and from epithelial cells showed female mosaicism in three generations. This appears to be a new mechanism of inheritance and further research is required in order to understand the mechanism of this mosaicism. We conclude that BTHS genetic testing should include two or more tissues for women that appear to be noncarriers when blood DNA is initially tested. The results of our study should not only be applicable to BTHS families, but also to families with other X-linked diseases.
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Affiliation(s)
- Barbara Zapała
- Department of Clinical Biochemistry, Jagiellonian University, Kraków, Poland
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29
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Borkar M, Bijarnia-Mahay S, Kohli S, Juneja M, Srivastava Y, Saxena R, Verma IC. Identification of a Novel TAZ Gene Mutation in a Family With X-Linked Dilated Cardiomyopathy Barth Syndrome. JOURNAL OF INBORN ERRORS OF METABOLISM AND SCREENING 2015. [DOI: 10.1177/2326409814567131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Minal Borkar
- Center of Medical Genetics, Sir Ganga Ram Hospital, New Delhi, India
- Present Address: Faculty of Medicine, University of Calgary, Calgary, Canada
| | - Sunita Bijarnia-Mahay
- Center of Medical Genetics, Sir Ganga Ram Hospital, New Delhi, India
- Ganga Ram Institute for Post graduate Medical Education and Research (GRIPMER), Sir Ganga Ram Hospital, New Delhi, India
| | - Sudha Kohli
- Center of Medical Genetics, Sir Ganga Ram Hospital, New Delhi, India
- Ganga Ram Institute for Post graduate Medical Education and Research (GRIPMER), Sir Ganga Ram Hospital, New Delhi, India
| | - Monica Juneja
- Department of Pediatrics, Maulana Azad Medical College and Associated Lok Nayak Hospital, New Delhi, India
| | - Yogesh Srivastava
- Division of Molecular Oncology, Institute of Cytology and Preventive Oncology, Noida, India
- Department of Reproductive Biology, All India Institute of Medical Sciences, New Delhi, India
| | - Renu Saxena
- Center of Medical Genetics, Sir Ganga Ram Hospital, New Delhi, India
- Ganga Ram Institute for Post graduate Medical Education and Research (GRIPMER), Sir Ganga Ram Hospital, New Delhi, India
| | - Ishwar C. Verma
- Center of Medical Genetics, Sir Ganga Ram Hospital, New Delhi, India
- Ganga Ram Institute for Post graduate Medical Education and Research (GRIPMER), Sir Ganga Ram Hospital, New Delhi, India
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30
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Gaspard GJ, McMaster CR. The mitochondrial quality control protein Yme1 is necessary to prevent defective mitophagy in a yeast model of Barth syndrome. J Biol Chem 2015; 290:9284-98. [PMID: 25688091 DOI: 10.1074/jbc.m115.641878] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Indexed: 11/06/2022] Open
Abstract
The Saccharomyces cerevisiae TAZ1 gene is an orthologue of human TAZ; both encode the protein tafazzin. Tafazzin is a transacylase that transfers acyl chains with unsaturated fatty acids from phospholipids to monolysocardiolipin to generate cardiolipin with unsaturated fatty acids. Mutations in human TAZ cause Barth syndrome, a fatal childhood cardiomyopathy biochemically characterized by reduced cardiolipin mass and increased monolysocardiolipin levels. To uncover cellular processes that require tafazzin to maintain cell health, we performed a synthetic genetic array screen using taz1Δ yeast cells to identify genes whose deletion aggravated its fitness. The synthetic genetic array screen uncovered several mitochondrial cellular processes that require tafazzin. Focusing on the i-AAA protease Yme1, a mitochondrial quality control protein that degrades misfolded proteins, we determined that in cells lacking both Yme1 and Taz1 function, there were substantive mitochondrial ultrastructural defects, ineffective superoxide scavenging, and a severe defect in mitophagy. We identify an important role for the mitochondrial protease Yme1 in the ability of cells that lack tafazzin function to maintain mitochondrial structural integrity and mitochondrial quality control and to undergo mitophagy.
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Affiliation(s)
| | - Christopher R McMaster
- From the Departments of Biochemistry and Molecular Biology and Pharmacology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
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31
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Saunders C, Smith L, Wibrand F, Ravn K, Bross P, Thiffault I, Christensen M, Atherton A, Farrow E, Miller N, Kingsmore SF, Ostergaard E. CLPB variants associated with autosomal-recessive mitochondrial disorder with cataract, neutropenia, epilepsy, and methylglutaconic aciduria. Am J Hum Genet 2015; 96:258-65. [PMID: 25597511 DOI: 10.1016/j.ajhg.2014.12.020] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 12/19/2014] [Indexed: 11/29/2022] Open
Abstract
3-methylglutaconic aciduria (3-MGA-uria) is a nonspecific finding associated with mitochondrial dysfunction, including defects of oxidative phosphorylation. 3-MGA-uria is classified into five groups, of which one, type IV, is genetically heterogeneous. Here we report five children with a form of type IV 3-MGA-uria characterized by cataracts, severe psychomotor regression during febrile episodes, epilepsy, neutropenia with frequent infections, and death in early childhood. Four of the individuals were of Greenlandic descent, and one was North American, of Northern European and Asian descent. Through a combination of homozygosity mapping in the Greenlandic individuals and exome sequencing in the North American, we identified biallelic variants in the caseinolytic peptidase B homolog (CLPB). The causative variants included one missense variant, c.803C>T (p.Thr268Met), and two nonsense variants, c.961A>T (p.Lys321*) and c.1249C>T (p.Arg417*). The level of CLPB protein was markedly decreased in fibroblasts and liver of affected individuals. CLPB is proposed to function as a mitochondrial chaperone involved in disaggregation of misfolded proteins, resulting from stress such as heat denaturation.
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MESH Headings
- Abnormalities, Multiple/genetics
- Abnormalities, Multiple/pathology
- Atrophy/genetics
- Atrophy/pathology
- Base Sequence
- Brain/pathology
- Cataract/genetics
- Cataract/pathology
- Child, Preschool
- Codon, Nonsense/genetics
- Endopeptidase Clp/genetics
- Endopeptidase Clp/metabolism
- Epilepsy/genetics
- Epilepsy/pathology
- Exome/genetics
- Fatal Outcome
- Female
- Fibroblasts/metabolism
- Genes, Recessive/genetics
- Greenland
- Humans
- Infant
- Infant, Newborn
- Liver/metabolism
- Male
- Metabolism, Inborn Errors/genetics
- Metabolism, Inborn Errors/pathology
- Mitochondrial Diseases/genetics
- Mitochondrial Diseases/pathology
- Molecular Sequence Data
- Movement Disorders/genetics
- Movement Disorders/pathology
- Mutation, Missense/genetics
- Neutropenia/genetics
- Neutropenia/pathology
- Sequence Analysis, DNA
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Affiliation(s)
- Carol Saunders
- Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, MO 64108, USA; Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO 64108, USA.
| | - Laurie Smith
- Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, MO 64108, USA; Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108, USA
| | - Flemming Wibrand
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark
| | - Kirstine Ravn
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark
| | - Peter Bross
- Research Unit for Molecular Medicine, Aarhus University and Aarhus University Hospital, 8200 Aarhus, Denmark
| | - Isabelle Thiffault
- Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, MO 64108, USA
| | - Mette Christensen
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark
| | - Andrea Atherton
- Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108, USA
| | - Emily Farrow
- Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, MO 64108, USA; Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108, USA
| | - Neil Miller
- Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, MO 64108, USA
| | - Stephen F Kingsmore
- Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, MO 64108, USA; Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO 64108, USA; Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108, USA
| | - Elsebet Ostergaard
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark.
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32
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Vaz-Drago R, Pinheiro MT, Martins S, Enguita FJ, Carmo-Fonseca M, Custódio N. Transcription-coupled RNA surveillance in human genetic diseases caused by splice site mutations. Hum Mol Genet 2015; 24:2784-95. [PMID: 25652404 DOI: 10.1093/hmg/ddv039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 01/31/2015] [Indexed: 12/15/2022] Open
Abstract
Current estimates indicate that approximately one-third of all disease-causing mutations are expected to disrupt splicing. Abnormal splicing often leads to disruption of the reading frame with introduction of a premature termination codon (PTC) that targets the mRNA for degradation in the cytoplasm by nonsense mediated decay (NMD). In addition to NMD there are RNA surveillance mechanisms that act in the nucleus while transcripts are still associated with the chromatin template. However, the significance of nuclear RNA quality control in the context of human genetic diseases is unknown. Here we used patient-derived lymphoblastoid cell lines as disease models to address how biogenesis of mRNAs is affected by splice site mutations. We observed that most of the mutations analyzed introduce PTCs and trigger mRNA degradation in the cytoplasm. However, for some mutant transcripts, RNA levels associated with chromatin were found down-regulated. Quantification of nascent transcripts further revealed that a subset of genes containing splicing mutations (SM) have reduced transcriptional activity. Following treatment with the translation inhibitor cycloheximide the cytoplasmic levels of mutant RNAs increased, while the levels of chromatin-associated transcripts remained unaltered. These results suggest that transcription-coupled surveillance mechanisms operate independently from NMD to reduce cellular levels of abnormal RNAs caused by SM.
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Affiliation(s)
- Rita Vaz-Drago
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa 1649-028, Portugal
| | - Marco T Pinheiro
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa 1649-028, Portugal
| | - Sandra Martins
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa 1649-028, Portugal
| | - Francisco J Enguita
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa 1649-028, Portugal
| | - Maria Carmo-Fonseca
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa 1649-028, Portugal
| | - Noélia Custódio
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa 1649-028, Portugal
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33
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Lu YW, Claypool SM. Disorders of phospholipid metabolism: an emerging class of mitochondrial disease due to defects in nuclear genes. Front Genet 2015; 6:3. [PMID: 25691889 PMCID: PMC4315098 DOI: 10.3389/fgene.2015.00003] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 01/06/2015] [Indexed: 01/14/2023] Open
Abstract
The human nuclear and mitochondrial genomes co-exist within each cell. While the mitochondrial genome encodes for a limited number of proteins, transfer RNAs, and ribosomal RNAs, the vast majority of mitochondrial proteins are encoded in the nuclear genome. Of the multitude of mitochondrial disorders known to date, only a fifth are maternally inherited. The recent characterization of the mitochondrial proteome therefore serves as an important step toward delineating the nosology of a large spectrum of phenotypically heterogeneous diseases. Following the identification of the first nuclear gene defect to underlie a mitochondrial disorder, a plenitude of genetic variants that provoke mitochondrial pathophysiology have been molecularly elucidated and classified into six categories that impact: (1) oxidative phosphorylation (subunits and assembly factors); (2) mitochondrial DNA maintenance and expression; (3) mitochondrial protein import and assembly; (4) mitochondrial quality control (chaperones and proteases); (5) iron–sulfur cluster homeostasis; and (6) mitochondrial dynamics (fission and fusion). Here, we propose that an additional class of genetic variant be included in the classification schema to acknowledge the role of genetic defects in phospholipid biosynthesis, remodeling, and metabolism in mitochondrial pathophysiology. This seventh class includes a small but notable group of nuclear-encoded proteins whose dysfunction impacts normal mitochondrial phospholipid metabolism. The resulting human disorders present with a diverse array of pathologic consequences that reflect the variety of functions that phospholipids have in mitochondria and highlight the important role of proper membrane homeostasis in mitochondrial biology.
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Affiliation(s)
- Ya-Wen Lu
- Department of Physiology, School of Medicine, Johns Hopkins University Baltimore, MD, USA
| | - Steven M Claypool
- Department of Physiology, School of Medicine, Johns Hopkins University Baltimore, MD, USA
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Abstract
Beyond their contribution to basic metabolism, the major cellular organelles, in particular mitochondria, can determine whether cells respond to stress in an adaptive or suicidal manner. Thus, mitochondria can continuously adapt their shape to changing bioenergetic demands as they are subjected to quality control by autophagy, or they can undergo a lethal permeabilization process that initiates apoptosis. Along similar lines, multiple proteins involved in metabolic circuitries, including oxidative phosphorylation and transport of metabolites across membranes, may participate in the regulated or catastrophic dismantling of organelles. Many factors that were initially characterized as cell death regulators are now known to physically or functionally interact with metabolic enzymes. Thus, several metabolic cues regulate the propensity of cells to activate self-destructive programs, in part by acting on nutrient sensors. This suggests the existence of "metabolic checkpoints" that dictate cell fate in response to metabolic fluctuations. Here, we discuss recent insights into the intersection between metabolism and cell death regulation that have major implications for the comprehension and manipulation of unwarranted cell loss.
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Affiliation(s)
- Douglas R Green
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - Lorenzo Galluzzi
- Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, F-75006 Paris, France. Université Paris Descartes/Paris V; Sorbonne Paris Cité; F-75005 Paris, France. INSERM, U1138, F-94805 Villejuif, France
| | - Guido Kroemer
- Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, F-75006 Paris, France. Université Paris Descartes/Paris V; Sorbonne Paris Cité; F-75005 Paris, France. INSERM, U1138, F-94805 Villejuif, France. Metabolomics and Cell Biology Platforms, Gustave Roussy, F-94805 Villejuif, France. Pôle de Biologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, F-75015 Paris, France.
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Mazurová S, Tesařová M, Magner M, Houšťková H, Hansíková H, Augustínová J, Tomek V, Vondráčková A, Zeman J, Honzík T. Novel mutations in the TAZ gene in patients with Barth syndrome. Prague Med Rep 2014; 114:139-53. [PMID: 24093814 DOI: 10.14712/23362936.2014.16] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Barth syndrome is an X-linked recessive disorder that is caused by mutations in Taffazin gene (TAZ), leading to severe cardiolipin deficiency which results in respiratory chain dysfunction. Barth syndrome is characterized by cardiomyopathy, neutropenia, skeletal myopathy, growth deficiency and 3-methylglutaconic aciduria. In this paper, we present clinical, biochemical and molecular data of the first four Czech patients from four unrelated families diagnosed with this rare disease. The mean age of onset was 5.5 ± 3.8 months. One child suffered from sudden cardiac death at the age of 2 years, the age of living patients is between 3 and 13 years. Muscle hypotonia was present in all four patients; cardiomyopathy and growth retardation in three and neutropenia in two of them. Two patients manifested a dilated and one patient a hypertrophic cardiomyopathy. A characteristic laboratory abnormality was the intermittently increased excretion of 3-methylglutaconic acid. Three novel hemizygous mutations in the TAZ gene were found (c.584G>T; c.109+6T>C; c.86G>A). We conclude that Barth syndrome should be included in differential diagnosis of cardiomyopathy in childhood, especially in the cooccurrence of dilated cardiomyopathy and 3-methylglutaconic aciduria.
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Affiliation(s)
- S Mazurová
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
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Wei B, Lu Y, Jin JP. Deficiency of slow skeletal muscle troponin T causes atrophy of type I slow fibres and decreases tolerance to fatigue. J Physiol 2014; 592:1367-80. [PMID: 24445317 DOI: 10.1113/jphysiol.2013.268177] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The total loss of slow skeletal muscle troponin T (ssTnT encoded by TNNT1 gene) due to a nonsense mutation in codon Glu(180) causes a lethal form of recessively inherited nemaline myopathy (Amish nemaline myopathy, ANM). To investigate the pathogenesis and muscle pathophysiology of ANM, we studied the phenotypes of partial and total loss of ssTnT in Tnnt1 gene targeted mice. An insertion of neomycin resistance cassette in intron 10 of Tnnt1 gene caused an approximately 60% decrease in ssTnT protein expression whereas cre-loxP-mediated deletion of exons 11-13 resulted in total loss of ssTnT, as seen in ANM muscles. In diaphragm and soleus muscles of the knockdown and knockout mouse models, we demonstrated that ssTnT deficiency resulted in significantly decreased levels of other slow fibre-specific myofilament proteins whereas fast fibre-specific myofilament proteins were increased correspondingly. Immunohistochemical studies revealed that ssTnT deficiency produced significantly smaller type I slow fibres and compensatory growth of type II fast fibres. Along with the slow fibre atrophy and the changes in myofilament protein isoform contents, ssTnT deficiency significantly reduced the tolerance to fatigue in soleus muscle. ssTnT-deficient soleus muscle also contains significant numbers of small-sized central nuclei type I fibres, indicating active regeneration. The data provide strong support for the essential role of ssTnT in skeletal muscle function and the causal effect of its loss in the pathology of ANM. This observation further supports the hypothesis that the function of slow fibres can be restored in ANM patients if a therapeutic supplement of ssTnT is achieved.
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Affiliation(s)
- Bin Wei
- Department of Physiology, Wayne State University School of Medicine, Detroit MI 48201, USA.
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Raja V, Greenberg ML. The functions of cardiolipin in cellular metabolism-potential modifiers of the Barth syndrome phenotype. Chem Phys Lipids 2014; 179:49-56. [PMID: 24445246 DOI: 10.1016/j.chemphyslip.2013.12.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 12/20/2013] [Accepted: 12/20/2013] [Indexed: 12/30/2022]
Abstract
The phospholipid cardiolipin (CL) plays a role in many cellular functions and signaling pathways both inside and outside of mitochondria. This review focuses on the role of CL in energy metabolism. Many reactions of electron transport and oxidative phosphorylation, the transport of metabolites required for these processes, and the stabilization of electron transport chain supercomplexes require CL. Recent studies indicate that CL is required for the synthesis of iron-sulfur (Fe-S) co-factors, which are essential for numerous metabolic pathways. Activation of carnitine shuttle enzymes that are required for fatty acid metabolism is CL dependent. The presence of substantial amounts of CL in the peroxisomal membrane suggests that CL may be required for peroxisomal functions. Understanding the role of CL in energy metabolism may identify physiological modifiers that exacerbate the loss of CL and underlie the variation in symptoms observed in Barth syndrome, a genetic disorder of CL metabolism.
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Affiliation(s)
- Vaishnavi Raja
- Department of Biological Sciences, Wayne State University, Detroit, United States
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, United States.
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Karkucinska-Wieckowska A, Trubicka J, Werner B, Kokoszynska K, Pajdowska M, Pronicki M, Czarnowska E, Lebiedzinska M, Sykut-Cegielska J, Ziolkowska L, Jaron W, Dobrzanska A, Ciara E, Wieckowski MR, Pronicka E. Left ventricular noncompaction (LVNC) and low mitochondrial membrane potential are specific for Barth syndrome. J Inherit Metab Dis 2013; 36:929-37. [PMID: 23361305 PMCID: PMC3825551 DOI: 10.1007/s10545-013-9584-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 12/28/2012] [Accepted: 01/02/2013] [Indexed: 11/17/2022]
Abstract
Barth syndrome (BTHS) is an X-linked mitochondrial defect characterised by dilated cardiomyopathy, neutropaenia and 3-methylglutaconic aciduria (3-MGCA). We report on two affected brothers with c.646G > A (p.G216R) TAZ gene mutations. The pathogenicity of the mutation, as indicated by the structure-based functional analyses, was further confirmed by abnormal monolysocardiolipin/cardiolipin ratio in dry blood spots of the patients as well as the occurrence of this mutation in another reported BTHS proband. In both brothers, 2D-echocardiography revealed some features of left ventricular noncompaction (LVNC) despite marked differences in the course of the disease; the eldest child presented with isolated cardiomyopathy from late infancy, whereas the youngest showed severe lactic acidosis without 3-MGCA during the neonatal period. An examination of the patients' fibroblast cultures revealed that extremely low mitochondrial membrane potentials (mtΔΨ about 50 % of the control value) dominated other unspecific mitochondrial changes detected (respiratory chain dysfunction, abnormal ROS production and depressed antioxidant defense). 1) Our studies confirm generalised mitochondrial dysfunction in the skeletal muscle and the fibroblasts of BTHS patients, especially a severe impairment in the mtΔΨ and the inhibition of complex V activity. It can be hypothesised that impaired mtΔΨ and mitochondrial ATP synthase activity may contribute to episodes of cardiac arrhythmia that occurred unexpectedly in BTHS patients. 2) Severe lactic acidosis without 3-methylglutaconic aciduria in male neonates as well as an asymptomatic mild left ventricular noncompaction may characterise the ranges of natural history of Barth syndrome.
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Affiliation(s)
| | - Joanna Trubicka
- Department of Medical Genetics, The Children’s Memorial Health Institute, Warsaw, Poland
| | - Bozena Werner
- Department of Pediatric Cardiology and General Pediatrics, Medical University of Warsaw, Warsaw, Poland
| | - Katarzyna Kokoszynska
- Laboratory of Bioinformatics and Biostatistics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Roentgena 5, 02-781 Warsaw, Poland
| | - Magdalena Pajdowska
- Department of Biochemistry and Experimental Medicine, Children’s Memorial Health Institute, Warsaw, Poland
| | - Maciej Pronicki
- Department of Pathology, The Children’s Memorial Health Institute, Warsaw, Poland
| | - Elzbieta Czarnowska
- Department of Pathology, The Children’s Memorial Health Institute, Warsaw, Poland
| | | | - Jolanta Sykut-Cegielska
- Department of Metabolic Diseases, The Children’s Memorial Health Institute, Aleja Dzieci Polskich 20, 04-730 Warsaw, Poland
| | - Lidia Ziolkowska
- Department of Cardiology, The Children’s Memorial Health Institute, Warsaw, Poland
| | - Weronika Jaron
- Department of Surgery and Transplantation, The Children’s Memorial Health Institute, Warsaw, Poland
| | - Anna Dobrzanska
- Department of Neonatology, Pathology and Intensive Care, The Children’s Memorial Health Institute, Warsaw, Poland
| | - Elzbieta Ciara
- Department of Medical Genetics, The Children’s Memorial Health Institute, Warsaw, Poland
| | | | - Ewa Pronicka
- Department of Metabolic Diseases, The Children’s Memorial Health Institute, Aleja Dzieci Polskich 20, 04-730 Warsaw, Poland
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Sarig O, Goldsher D, Nousbeck J, Fuchs-Telem D, Cohen-Katsenelson K, Iancu TC, Manov I, Saada A, Sprecher E, Mandel H. Infantile mitochondrial hepatopathy is a cardinal feature of MEGDEL syndrome (3-methylglutaconic aciduria type IV with sensorineural deafness, encephalopathy and Leigh-like syndrome) caused by novel mutations in SERAC1. Am J Med Genet A 2013; 161A:2204-15. [PMID: 23918762 DOI: 10.1002/ajmg.a.36059] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 04/19/2013] [Indexed: 12/17/2022]
Abstract
3-Methylglutaconic aciduria (3-MGCA) type IV is defined as a heterogeneous group of inborn errors featuring in common 3-MGCA and associated with primary mitochondrial dysfunction leading to a spectrum of multisystem conditions. We studied four patients who presented at birth with a clinical picture simulating a primary mitochondrial hepatic disorder consistent with the MEGDEL syndrome including 3-MGCA, sensorineural deafness, encephalopathy and a brain magnetic resonance imaging with signs of Leigh disease. All affected children displayed biochemical features consistent with mitochondrial OXPHOS dysfunction including hepatic mitochondrial DNA depletion in one patient. Homozygosity mapping identified a candidate locus on 6q25.2-6q26. Using whole exome sequencing, we identified two novel homozygous mutations in SERAC1 recently reported to harbor mutations in MEGDEL syndrome. Both mutations were found to lead to decreased or absent expression of SERAC1. The present findings indicate that infantile hepatopathy is a cardinal feature of MEGDEL syndrome. We thus propose to rename the disease MEGDHEL syndrome.
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Affiliation(s)
- Ofer Sarig
- Department of Dermatology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
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Affiliation(s)
- Boon Yew Tan
- Johns Hopkins University, Division of Cardiology, Center for Inherited Heart Disease, Baltimore, MD, USA
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Jefferies JL. Barth syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS. PART C, SEMINARS IN MEDICAL GENETICS 2013; 163C:198-205. [PMID: 23843353 PMCID: PMC3892174 DOI: 10.1002/ajmg.c.31372] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Indexed: 01/06/2023]
Abstract
Barth syndrome (BTHS) is an X-linked recessive disorder that is typically characterized by cardiomyopathy (CMP), skeletal myopathy, growth retardation, neutropenia, and increased urinary levels of 3-methylglutaconic acid (3-MGCA). There may be a wide variability of phenotypes amongst BTHS patients with some exhibiting some or all of these findings. BTHS was first described as a disease of the mitochondria resulting in neutropenia as well as skeletal and cardiac myopathies. Over the past few years, a greater understanding of BTHS has developed related to the underlying genetic mechanisms responsible for the disease. Mutations in the TAZ gene on chromosome Xq28, also known as G4.5, are responsible for the BTHS phenotype resulting in a loss-of-function in the protein product tafazzin. Clinical management of BTHS has also seen improvement. Patients with neutropenia are susceptible to life-threatening bacterial infections with sepsis being a significant concern for possible morbidity and mortality. Increasingly, BTHS patients are suffering from heart failure secondary to their CMP. Left ventricular noncompaction (LVNC) and dilated CMP are the most common cardiac phenotypes reported and can lead to symptoms of heart failure as well as ventricular arrhythmias. Expanded treatment options for end-stage myocardial dysfunction now offer an opportunity to change the natural history for these patients. Herein, we will provide a current review of the genetic and molecular basis of BTHS, the clinical features and management of BTHS, and potential future directions for therapeutic strategies.
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Affiliation(s)
- John L Jefferies
- Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
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Rigaud C, Lebre AS, Touraine R, Beaupain B, Ottolenghi C, Chabli A, Ansquer H, Ozsahin H, Di Filippo S, De Lonlay P, Borm B, Rivier F, Vaillant MC, Mathieu-Dramard M, Goldenberg A, Viot G, Charron P, Rio M, Bonnet D, Donadieu J. Natural history of Barth syndrome: a national cohort study of 22 patients. Orphanet J Rare Dis 2013; 8:70. [PMID: 23656970 PMCID: PMC3656783 DOI: 10.1186/1750-1172-8-70] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 04/28/2013] [Indexed: 12/16/2022] Open
Abstract
Background This study describes the natural history of Barth syndrome (BTHS). Methods The medical records of all patients with BTHS living in France were identified in multiple sources and reviewed. Results We identified 16 BTHS pedigrees that included 22 patients. TAZ mutations were observed in 15 pedigrees. The estimated incidence of BTHS was 1.5 cases per million births (95%CI: 0.2–2.3). The median age at presentation was 3.1 weeks (range, 0–1.4 years), and the median age at last follow-up was 4.75 years (range, 3–15 years). Eleven patients died at a median age of 5.1 months; 9 deaths were related to cardiomyopathy and 2 to sepsis. The 5-year survival rate was 51%, and no deaths were observed in patients ≥3 years. Fourteen patients presented with cardiomyopathy, and cardiomyopathy was documented in 20 during follow-up. Left ventricular systolic function was very poor during the first year of life and tended to normalize over time. Nineteen patients had neutropenia. Metabolic investigations revealed inconstant moderate 3-methylglutaconic aciduria and plasma arginine levels that were reduced or in the low-normal range. Survival correlated with two prognostic factors: severe neutropenia at diagnosis (<0.5 × 109/L) and birth year. Specifically, the survival rate was 70% for patients born after 2000 and 20% for those born before 2000. Conclusions This survey found that BTHS outcome was affected by cardiac events and by a risk of infection that was related to neutropenia. Modern management of heart failure and prevention of infection in infancy may improve the survival of patients with BTHS without the need for heart transplantation.
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Affiliation(s)
- Charlotte Rigaud
- AP-HP, Registre français des neutropénies chroniques sévères, Centre de référence des déficits Immunitaires Héréditaires, Service d'Hémato-oncologie Pédiatrique Hôpital Trousseau, Paris, France.
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Lamari F, Mochel F, Sedel F, Saudubray JM. Disorders of phospholipids, sphingolipids and fatty acids biosynthesis: toward a new category of inherited metabolic diseases. J Inherit Metab Dis 2013; 36:411-25. [PMID: 22814679 DOI: 10.1007/s10545-012-9509-7] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 05/29/2012] [Accepted: 06/12/2012] [Indexed: 12/29/2022]
Abstract
We wish to delineate a novel, and rapidly expanding, group of inborn errors of metabolism with neurological/muscular presentations: the defects in phospholipids, sphingolipids and long chain fatty acids biosynthesis. At least 14 disorders have been described so far. Clinical presentations are diverse but can be divided into (1) diseases of the central nervous system; (2) peripheral neuropathies; and (3) muscular/cardiac presentations. (1) Leukodystrophy and/or iron deposits in basal ganglia is a common feature of phospholipase A2 deficiency, fatty acid hydroxylase deficiency, and pantothenate kinase-associated neurodegeneration. Infantile epilepsy has been reported in GM3 synthetase deficiency. Spastic quadriplegia with ichthyosis and intellectual disability are the presenting signs of the elongase 4 deficiency and the Sjogren-Larsson syndrome caused by fatty aldehyde dehydrogenase deficiency. Spastic paraplegia and muscle wasting are also seen in patients with mutations in the neuropathy target esterase gene. (2) Peripheral neuropathy is a prominent feature in PHARC syndrome due to α/β-hydrolase 12 deficiency, and in hereditary sensory autonomic neuropathy type I due to serine palmitoyl-CoA transferase deficiency. (3) Muscular/cardiac presentations include recurrent myoglobinuria in phosphatidate phosphatase 1 (Lipin1) deficiency; cardiomyopathy and multivisceral involvement in Barth syndrome secondary to tafazzin mutations; congenital muscular dystrophy due to choline kinase deficiency, Sengers syndrome due to acylglycerol kinase deficiency and Chanarin Dorfman syndrome due to α/β- hydrolase 5 deficiency. These synthesis defects of complex lipid molecules stand at the frontier between classical inborn errors of metabolism and other genetic diseases involving the metabolism of structural proteins.
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Affiliation(s)
- F Lamari
- Neurometabolic Unit, Pitié-Salpêtrière Hospital, AP-HP & University Pierre and Marie Curie, Paris, France
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Abstract
OBJECTIVE Barth syndrome is an X-linked recessive disorder characterized by dilated cardiomyopathy, neutropenia, 3-methylglutaconic aciduria, abnormal mitochondria, variably expressed skeletal myopathy, and growth delay. The disorder is caused by mutations in the tafazzin (TAZ/G4.5) gene located on Xq28. We report a novel exonic splicing mutation in the TAZ gene in a patient with atypical Barth syndrome. PATIENT & METHODS The 4-month-old proband presented with respiratory distress, neutropenia, and dilated cardiomyopathy with reduced ejection fraction of 10%. No 3-methylglutaconic aciduria was detected on repeated urine organic acid analyses. Family history indicated that his maternal uncle died of endocardial fibroelastosis and dilated cardiomyopathy at 26 months. TAZ DNA sequencing, mRNA analysis, and cardiolipin analysis were performed. RESULTS A novel nucleotide substitution c.553A>G in exon 7 of the TAZ gene was identified in the proband, predicting an amino acid substitution p.Met185Val. However, this mutation created a new splice donor signal within exon 7 causing mis-splicing of the message, producing two messages that only differ in the presence/absence of exon 5; these retain intron 6 and have only 11 bases of exon 7. Cardiolipin analysis confirmed the loss of tafazzin activity. The proband's mother, maternal aunt, and grandmother carry the same mutation. CONCLUSIONS The identification of a TAZ gene mutation, mRNA analysis, and monolysocardiolipin/cardiolipin ratio determination were important for the diagnosis and genetic counseling in this family with atypical Barth syndrome that was not found to be associated with 3-methylglutaconic aciduria.
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Gonzalvez F, D'Aurelio M, Boutant M, Moustapha A, Puech JP, Landes T, Arnauné-Pelloquin L, Vial G, Taleux N, Slomianny C, Wanders RJ, Houtkooper RH, Bellenguer P, Møller IM, Gottlieb E, Vaz FM, Manfredi G, Petit PX. Barth syndrome: cellular compensation of mitochondrial dysfunction and apoptosis inhibition due to changes in cardiolipin remodeling linked to tafazzin (TAZ) gene mutation. Biochim Biophys Acta Mol Basis Dis 2013; 1832:1194-206. [PMID: 23523468 DOI: 10.1016/j.bbadis.2013.03.005] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 02/27/2013] [Accepted: 03/08/2013] [Indexed: 01/21/2023]
Abstract
Cardiolipin is a mitochondrion-specific phospholipid that stabilizes the assembly of respiratory chain complexes, favoring full-yield operation. It also mediates key steps in apoptosis. In Barth syndrome, an X chromosome-linked cardiomyopathy caused by tafazzin mutations, cardiolipins display acyl chain modifications and are present at abnormally low concentrations, whereas monolysocardiolipin accumulates. Using immortalized lymphoblasts from Barth syndrome patients, we showed that the production of abnormal cardiolipin led to mitochondrial alterations. Indeed, the lack of normal cardiolipin led to changes in electron transport chain stability, resulting in cellular defects. We found a destabilization of the supercomplex (respirasome) I+III2+IVn but also decreased amounts of individual complexes I and IV and supercomplexes I+III and III+IV. No changes were observed in the amounts of individual complex III and complex II. We also found decreased levels of complex V. This complex is not part of the supercomplex suggesting that cardiolipin is required not only for the association/stabilization of the complexes into supercomplexes but also for the modulation of the amount of individual respiratory chain complexes. However, these alterations were compensated by an increase in mitochondrial mass, as demonstrated by electron microscopy and measurements of citrate synthase activity. We suggest that this compensatory increase in mitochondrial content prevents a decrease in mitochondrial respiration and ATP synthesis in the cells. We also show, by extensive flow cytometry analysis, that the type II apoptosis pathway was blocked at the mitochondrial level and that the mitochondria of patients with Barth syndrome cannot bind active caspase-8. Signal transduction is thus blocked before any mitochondrial event can occur. Remarkably, basal levels of superoxide anion production were slightly higher in patients' cells than in control cells as previously evidenced via an increased protein carbonylation in the taz1Δ mutant in the yeast. This may be deleterious to cells in the long term. The consequences of mitochondrial dysfunction and alterations to apoptosis signal transduction are considered in light of the potential for the development of future treatments.
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Affiliation(s)
- François Gonzalvez
- INSERM U-747 et Université Paris V-Descartes, Centre de Recherche des Saint-Pères, 45 Rue des Saint-Pères, 75006 Paris, France
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Affiliation(s)
| | - Zaza Khuchua
- Division of Molecular and Cardiovascular Biology; Cincinnati Children's Research Foundation; Cincinnati; OH; USA
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Ronvelia D, Greenwood J, Platt J, Hakim S, Zaragoza MV. Intrafamilial variability for novel TAZ gene mutation: Barth syndrome with dilated cardiomyopathy and heart failure in an infant and left ventricular noncompaction in his great-uncle. Mol Genet Metab 2012; 107:428-32. [PMID: 23031367 PMCID: PMC3483384 DOI: 10.1016/j.ymgme.2012.09.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 09/11/2012] [Indexed: 11/30/2022]
Abstract
BACKGROUND The tafazzin gene (TAZ) is located at Xq28 and encodes a protein involved in the transacylation of cardiolipin, an essential mitochondrial phospholipid. Mutations in TAZ are associated with Barth syndrome (BTHS), the X-linked recessive condition with dilated cardiomyopathy, skeletal myopathy, growth retardation, neutropenia and organic aciduria. TAZ mutations also contribute to left ventricular noncompaction (LVNC), a cardiomyopathy characterized by loose, trabeculated myocardium. CASE REPORT We report a family with a novel TAZ mutation and the clinical spectrum from severe BTHS in an infant to skeletal myopathy with LVNC in an adult, the oldest individual with BTHS reported. The proband is a 51-year-old male with muscle weakness since early childhood. He remained stable until the age of 43. His initial evaluations found LVNC and borderline neutropenia with no elevation of urine 3-methylglutaconic acid. The proband's great nephew is a 3-year-old who presented at birth with poor feeding, hypotonia, lactic acidosis and hypoglycemia. At three months he was admitted with failure to thrive, lethargy and respiratory distress due to heart failure. Cardiac studies revealed dilated cardiomyopathy with a spongiform trabeculated pattern of the left ventricle. Laboratory studies showed cyclic neutropenia and elevated urine 3-methylglutaconic and 3-methylglutaric acids. At age 11months the patient had a heart transplant. We conducted sequence analysis of the TAZ gene for two affected individuals, the proband first and then his great-nephew. A novel, hemizygous nonsense mutation in TAZ exon 7 (c.583G>T, p.Gly195X) was detected. CONCLUSION At his current age of 51years-old, the proband is the oldest surviving individual reported with a confirmed molecular diagnosis and features of Barth syndrome. Further studies will be conducted to identify the genetic modifying factor(s) associated with the wide phenotypic range seen in this family.
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Affiliation(s)
- Diti Ronvelia
- UC Irvine Cardiogenomics Program, Dept of Pediatrics, Division of Genetics & Metabolism and Dept of Biological Sciences, University of California, Irvine, School of Medicine, Irvine, CA
| | - Jaclyn Greenwood
- UC Irvine Cardiogenomics Program, Dept of Pediatrics, Division of Genetics & Metabolism and Dept of Biological Sciences, University of California, Irvine, School of Medicine, Irvine, CA
| | - Julia Platt
- UC Irvine Cardiogenomics Program, Dept of Pediatrics, Division of Genetics & Metabolism and Dept of Biological Sciences, University of California, Irvine, School of Medicine, Irvine, CA
| | - Simin Hakim
- UC Irvine Cardiogenomics Program, Dept of Pediatrics, Division of Genetics & Metabolism and Dept of Biological Sciences, University of California, Irvine, School of Medicine, Irvine, CA
| | - Michael V. Zaragoza
- UC Irvine Cardiogenomics Program, Dept of Pediatrics, Division of Genetics & Metabolism and Dept of Biological Sciences, University of California, Irvine, School of Medicine, Irvine, CA
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48
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Roberts AE, Nixon C, Steward CG, Gauvreau K, Maisenbacher M, Fletcher M, Geva J, Byrne BJ, Spencer CT. The Barth Syndrome Registry: distinguishing disease characteristics and growth data from a longitudinal study. Am J Med Genet A 2012; 158A:2726-32. [PMID: 23045169 DOI: 10.1002/ajmg.a.35609] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 07/17/2012] [Indexed: 11/07/2022]
Abstract
Barth syndrome (BTHS); MIM accession # 302060) is a rare X-linked recessive cardioskeletal mitochondrial myopathy with features of cardiomyopathy, neutropenia, and growth abnormalities. The objectives of this study were to further elucidate the natural history, clinical disease presentation, and course, and describe growth characteristics for males with BTHS. Patients with a confirmed genetic diagnosis of BTHS are referred to the BTHS Registry through the Barth Syndrome Foundation, self-referral, or physician referral. This study is based on data obtained from 73 subjects alive at the time of enrollment that provided self-reported and/or medical record abstracted data. The mean age at diagnosis of BTHS was 4.04 ± 5.45 years. While the vast majority of subjects reported a history of cardiac dysfunction, nearly 6% denied any history of cardiomyopathy. Although most subjects had only mildly abnormal cardiac function by echocardiography reports, 70% were recognized as having cardiomyopathy in the first year of life and 12% have required cardiac transplantation. Of the 73 enrolled subjects, there have been five deaths. Growth curves were generated demonstrating a shift down for weight, length, and height versus the normative population with late catch up in height for a significant percentage of cases. This data also confirms a significant number of patients with low birth weight, complications in the newborn period, failure to thrive, neutropenia, developmental delay of motor milestones, and mild learning difficulties. However, it is apparent that the disease manifestations are variable, both over time for an individual patient and across the BTHS population.
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Affiliation(s)
- Amy E Roberts
- Department of Cardiology, Boston Children's Hospital, Boston, Massachusetts, USA
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Carlsson G, Fasth A, Berglöf E, Lagerstedt-Robinson K, Nordenskjöld M, Palmblad J, Henter JI, Fadeel B. Incidence of severe congenital neutropenia in Sweden and risk of evolution to myelodysplastic syndrome/leukaemia. Br J Haematol 2012; 158:363-9. [PMID: 22624626 DOI: 10.1111/j.1365-2141.2012.09171.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 04/11/2012] [Indexed: 11/30/2022]
Abstract
Severe congenital neutropenia (SCN) is characterized by low blood neutrophil counts, early bacterial infections, and risk of leukaemia development. As yet, no population-based incidence estimates of SCN have been reported. Children less than 16 years of age with SCN were sought in Sweden during the 20-year period 1987-2006 by a questionnaire to all Swedish Departments of Paediatrics and by reviewing the Swedish Health and Welfare Statistical Databases. Thirty-two patients were diagnosed with congenital neutropenia during this period. All received treatment with recombinant granulocyte-colony stimulating factor (G-CSF). Twenty-one patients were diagnosed as SCN or probable SCN, corresponding to 1·0 per 100,000 live births. Nine (43%) had ELANE mutations, four (19%) HAX1 mutations and eight (38%) were children with disease of unknown genetic aetiology. Four out of 21 patients (19%) developed myelodysplastic syndrome/leukaemia and three (14%) died, all with leukaemia. The cumulative incidence of myelodysplastic syndrome/leukaemia was 31%. The observed incidence of SCN in this population-based study was higher than previously estimated, possibly because genetic testing now can identify SCN cases previously thought to be idiopathic or benign neutropenia. The risk of developing myelodysplastic syndrome/leukaemia is considerable. ELANE mutations are the most commonly identified genetic defects.
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Affiliation(s)
- Göran Carlsson
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden.
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50
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Cosson L, Toutain A, Simard G, Kulik W, Matyas G, Guichet A, Blasco H, Maakaroun-Vermesse Z, Vaillant MC, Le Caignec C, Chantepie A, Labarthe F. Barth syndrome in a female patient. Mol Genet Metab 2012; 106:115-20. [PMID: 22410210 DOI: 10.1016/j.ymgme.2012.01.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 01/17/2012] [Accepted: 01/17/2012] [Indexed: 10/14/2022]
Abstract
BACKGROUND Barth syndrome (BTHS) is an X-linked recessive disorder characterized by cardiomyopathy, skeletal myopathy and cyclic neutropenia in male patients. It is caused by mutations in the TAZ gene coding for the tafazzin, a protein involved in the remodeling of cardiolipin. Loss of cardiolipin in the inner mitochondrial membrane results in respiratory chain dysfunction. No specific symptom has been identified in female carriers. CASE REPORT We report the first case of BTHS confirmed by TAZ gene analysis in a female patient. This girl experienced severe heart failure at 1-month of age. Echocardiography diagnosed dilated-hypokinetic and hypertrophic cardiomyopathy with noncompaction of the left ventricle. Initial metabolic screening was normal, except for a cyclic neutropenia. Respiratory chain analysis performed on skin fibroblasts revealed a decreased activity of complexes I, III and IV. Screening on a bloodspot showed abnormal monolysocardiolipin:cardiolipin ratio, later confirmed on cultured fibroblasts, indicative of BTHS. Genetic analyses finally confirmed the diagnosis of BTHS, by showing a large intragenic deletion of exons 1 through 5 in the TAZ gene. Cytogenetic analysis showed mosaicism for monosomy X and for a ring X chromosome with a large deletion of the long arm including the Xq28 region. The girl presented recurrent episodes of severe acute heart failure, progressive muscle weakness, and had a fatal septic shock at 3 years. CONCLUSION This case highlights that the diagnosis of BTHS should also be suspected in female patients presenting a phenotype similar to affected boys. In these cases, analysis of the monolysocardiolipin:cardiolipin ratio in bloodspots is a rapid and sensitive screening tool for BTHS. However clinical expression in a carrier female requires hemizygosity for the mutated allele of the TAZ gene, which supposes a rearrangement of the TAZ gene region on the other X chromosome.
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Affiliation(s)
- Laure Cosson
- Service de Médecine Pédiatrique, CHRU de Tours, Université François Rabelais, Tours, France
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