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Tsujimoto SI, Sakamoto K, Nakano Y, Mizuno T, Shindo T, Watanabe J, Sato-Otsubo A, Osumi T, Matsumoto K, Tomizawa D, Kato M. Myelodysplastic syndrome in a patient with Barth syndrome (3-methylglutaconic aciduria type II). Pediatr Blood Cancer 2023; 70:e30033. [PMID: 36184828 DOI: 10.1002/pbc.30033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 09/01/2022] [Indexed: 01/25/2023]
Affiliation(s)
- Shin-Ichi Tsujimoto
- Children's Cancer Center, National Center for Child Health and Development, Tokyo, Japan.,Department of Pediatrics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Kenichi Sakamoto
- Children's Cancer Center, National Center for Child Health and Development, Tokyo, Japan.,Department of Pediatrics, Shiga University of Medical Science, Otsu, Japan
| | - Yoshiko Nakano
- Department of Pediatrics, The University of Tokyo Hospital, Tokyo, Japan
| | - Takanori Mizuno
- Children's Cancer Center, National Center for Child Health and Development, Tokyo, Japan.,Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Takahiro Shindo
- Division of Cardiology, National Center for Child Health and Development, Tokyo, Japan
| | - Junichi Watanabe
- Department of Hematology, Saitama Medical Center, Saitama Medical University, Saitama, Japan
| | - Aiko Sato-Otsubo
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Tomoo Osumi
- Children's Cancer Center, National Center for Child Health and Development, Tokyo, Japan
| | - Kimikazu Matsumoto
- Children's Cancer Center, National Center for Child Health and Development, Tokyo, Japan
| | - Daisuke Tomizawa
- Children's Cancer Center, National Center for Child Health and Development, Tokyo, Japan
| | - Motohiro Kato
- Children's Cancer Center, National Center for Child Health and Development, Tokyo, Japan.,Department of Pediatrics, The University of Tokyo Hospital, Tokyo, Japan.,Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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2
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Genetics of mitochondrial diseases: Current approaches for the molecular diagnosis. HANDBOOK OF CLINICAL NEUROLOGY 2023; 194:141-165. [PMID: 36813310 DOI: 10.1016/b978-0-12-821751-1.00011-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Mitochondrial diseases are a genetically and phenotypically variable set of monogenic disorders. The main characteristic of mitochondrial diseases is a defective oxidative phosphorylation. Both nuclear and mitochondrial DNA encode the approximately 1500 mitochondrial proteins. Since identification of the first mitochondrial disease gene in 1988 a total of 425 genes have been associated with mitochondrial diseases. Mitochondrial dysfunctions can be caused both by pathogenic variants in the mitochondrial DNA or the nuclear DNA. Hence, besides maternal inheritance, mitochondrial diseases can follow all modes of Mendelian inheritance. The maternal inheritance and tissue specificity distinguish molecular diagnostics of mitochondrial disorders from other rare disorders. With the advances made in the next-generation sequencing technology, whole exome sequencing and even whole-genome sequencing are now the established methods of choice for molecular diagnostics of mitochondrial diseases. They reach a diagnostic rate of more than 50% in clinically suspected mitochondrial disease patients. Moreover, next-generation sequencing is delivering a constantly growing number of novel mitochondrial disease genes. This chapter reviews mitochondrial and nuclear causes of mitochondrial diseases, molecular diagnostic methodologies, and their current challenges and perspectives.
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3
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Schiller J, Laube E, Wittig I, Kühlbrandt W, Vonck J, Zickermann V. Insights into complex I assembly: Function of NDUFAF1 and a link with cardiolipin remodeling. SCIENCE ADVANCES 2022; 8:eadd3855. [PMID: 36383672 PMCID: PMC9668296 DOI: 10.1126/sciadv.add3855] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 10/14/2022] [Indexed: 06/02/2023]
Abstract
Respiratory complex I is a ~1-MDa proton pump in mitochondria. Its structure has been revealed in great detail, but the structural basis of its assembly, in humans involving at least 15 assembly factors, is essentially unknown. We determined cryo-electron microscopy structures of assembly intermediates associated with assembly factor NDUFAF1 in a yeast model system. Subunits ND2 and NDUFC2 together with assembly factors NDUFAF1 and CIA84 form the nucleation point of the NDUFAF1-dependent assembly pathway. Unexpectedly, the cardiolipin remodeling enzyme tafazzin is an integral component of this core complex. In a later intermediate, all 12 subunits of the proximal proton pump module have assembled. NDUFAF1 locks the central ND3 subunit in an assembly-competent conformation, and major rearrangements of central subunits are required for complex I maturation.
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Affiliation(s)
- Jonathan Schiller
- Institute of Biochemistry II, University Hospital, Goethe University, 60590 Frankfurt am Main, Germany
- Center for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, 60438 Frankfurt am Main, Germany
| | - Eike Laube
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Ilka Wittig
- Functional Proteomics, Institute for Cardiovascular Physiology, Goethe University, 60590 Frankfurt am Main, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Volker Zickermann
- Institute of Biochemistry II, University Hospital, Goethe University, 60590 Frankfurt am Main, Germany
- Center for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, 60438 Frankfurt am Main, Germany
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4
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Left Ventricular Noncompaction Is Associated with Valvular Regurgitation and a Variety of Arrhythmias. J Cardiovasc Dev Dis 2022; 9:jcdd9020049. [PMID: 35200702 PMCID: PMC8876824 DOI: 10.3390/jcdd9020049] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 01/29/2022] [Indexed: 02/05/2023] Open
Abstract
Left ventricular noncompaction (LVNC) is a type of cardiomyopathy characterized anatomically by prominent ventricular trabeculation and deep intertrabecular recesses. The mortality associated with LVNC ranges from 5% to 47%. The etiology of LVNC is yet to be fully understood, although decades have passed since its recognition as a clinical entity globally. Furthermore, critical questions, i.e., whether LVNC represents an acquired pathology or has a congenital origin and whether the reduced contractile function in LVNC patients is a cause or consequence of noncompaction, remain to be addressed. In this study, to answer some of these questions, we analyzed the clinical features of LVNC patients. Out of 9582 subjects screened for abnormal cardiac functions, 45 exhibit the characteristics of LVNC, and 1 presents right ventricular noncompaction (RVNC). We found that 40 patients show valvular regurgitation, 39 manifest reduced systolic contractions, and 46 out of the 46 present different forms of arrhythmias that are not restricted to be caused by the noncompact myocardium. This retrospective examination of LVNC patients reveals some novel findings: LVNC is associated with regurgitation in most patients and arrhythmias in all patients. The thickness ratio of the trabecular layer to compact layer negatively correlates with fractional shortening, and reduced contractility might result from LVNC. This study adds evidence to support a congenital origin of LVNC that might benefit the diagnosis and subsequent characterization of LVNC patients.
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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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Lin Y, Huang J, Zhu Z, Zhang Z, Xian J, Yang Z, Qin T, Chen L, Huang J, Huang Y, Wu Q, Hu Z, Lin X, Xu G. Overlap phenotypes of the left ventricular noncompaction and hypertrophic cardiomyopathy with complex arrhythmias and heart failure induced by the novel truncated DSC2 mutation. Orphanet J Rare Dis 2021; 16:496. [PMID: 34819141 PMCID: PMC8611834 DOI: 10.1186/s13023-021-02112-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 11/06/2021] [Indexed: 12/18/2022] Open
Abstract
Background The left ventricular noncompaction cardiomyopathy (LVNC) is a rare subtype of cardiomyopathy associated with a high risk of heart failure (HF), thromboembolism, arrhythmia, and sudden cardiac death. Methods The proband with overlap phenotypes of LVNC and hypertrophic cardiomyopathy (HCM) complicates atrial fibrillation (AF), ventricular tachycardia (VT), and HF due to the diffuse myocardial lesion, which were diagnosed by electrocardiogram, echocardiogram and cardiac magnetic resonance imaging. Peripheral blood was collected from the proband and his relatives. DNA was extracted from the peripheral blood of proband for high-throughput target capture sequencing. The Sanger sequence verified the variants. The protein was extracted from the skin of the proband and healthy volunteer. The expression difference of desmocollin2 was detected by Western blot. Results The novel heterozygous truncated mutation (p.K47Rfs*2) of the DSC2 gene encoding an important component of desmosomes was detected by targeted capture sequencing. The western blots showed that the expressing level of functional desmocollin2 protein (~ 94kd) was lower in the proband than that in the healthy volunteer, indicating that DSC2 p.K47Rfs*2 obviously reduced the functional desmocollin2 protein expression in the proband. Conclusion The heterozygous DSC2 p.K47Rfs*2 remarkably and abnormally reduced the functional desmocollin2 expression, which may potentially induce the overlap phenotypes of LVNC and HCM, complicating AF, VT, and HF.
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Affiliation(s)
- Yubi Lin
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Jiana Huang
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China.,Reproductive Center, The Six Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510000, China
| | - Zhiling Zhu
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Zuoquan Zhang
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Jianzhong Xian
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Zhe Yang
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Tingfeng Qin
- Department of Physiology, The School of Medicine of Jinan University, Guangzhou, 510000, China
| | - Linxi Chen
- Department of Physiology, The School of Medicine of Jinan University, Guangzhou, 510000, China
| | - Jingmin Huang
- Department of Physiology, The School of Medicine of Jinan University, Guangzhou, 510000, China
| | - Yin Huang
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Qiaoyun Wu
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Zhenyu Hu
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China.,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore
| | - Xiufang Lin
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China.
| | - Geyang Xu
- Department of Physiology, The School of Medicine of Jinan University, Guangzhou, 510000, China.
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Le CH, Benage LG, Specht KS, Li Puma LC, Mulligan CM, Heuberger AL, Prenni JE, Claypool SM, Chatfield KC, Sparagna GC, Chicco AJ. Tafazzin deficiency impairs CoA-dependent oxidative metabolism in cardiac mitochondria. J Biol Chem 2020; 295:12485-12497. [PMID: 32665401 DOI: 10.1074/jbc.ra119.011229] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 07/07/2020] [Indexed: 12/20/2022] Open
Abstract
Barth syndrome is a mitochondrial myopathy resulting from mutations in the tafazzin (TAZ) gene encoding a phospholipid transacylase required for cardiolipin remodeling. Cardiolipin is a phospholipid of the inner mitochondrial membrane essential for the function of numerous mitochondrial proteins and processes. However, it is unclear how tafazzin deficiency impacts cardiac mitochondrial metabolism. To address this question while avoiding confounding effects of cardiomyopathy on mitochondrial phenotype, we utilized Taz-shRNA knockdown (TazKD ) mice, which exhibit defective cardiolipin remodeling and respiratory supercomplex instability characteristic of human Barth syndrome but normal cardiac function into adulthood. Consistent with previous reports from other models, mitochondrial H2O2 emission and oxidative damage were greater in TazKD than in wild-type (WT) hearts, but there were no differences in oxidative phosphorylation coupling efficiency or membrane potential. Fatty acid and pyruvate oxidation capacities were 40-60% lower in TazKD mitochondria, but an up-regulation of glutamate oxidation supported respiration rates approximating those with pyruvate and palmitoylcarnitine in WT. Deficiencies in mitochondrial CoA and shifts in the cardiac acyl-CoA profile paralleled changes in fatty acid oxidation enzymes and acyl-CoA thioesterases, suggesting limitations of CoA availability or "trapping" in TazKD mitochondrial metabolism. Incubation of TazKD mitochondria with exogenous CoA partially rescued pyruvate and palmitoylcarnitine oxidation capacities, implicating dysregulation of CoA-dependent intermediary metabolism rather than respiratory chain defects in the bioenergetic impacts of tafazzin deficiency. These findings support links among cardiolipin abnormalities, respiratory supercomplex instability, and mitochondrial oxidant production and shed new light on the distinct metabolic consequences of tafazzin deficiency in the mammalian heart.
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Affiliation(s)
- Catherine H Le
- Cell and Molecular Biology Program, Colorado State University, Fort Collins, Colorado, USA
| | - Lindsay G Benage
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Kalyn S Specht
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Lance C Li Puma
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Christopher M Mulligan
- Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Adam L Heuberger
- Department of Horticulture and Landscape Architecture, Colorado State University, Fort Collins, Colorado, USA
| | - Jessica E Prenni
- Department of Horticulture and Landscape Architecture, Colorado State University, Fort Collins, Colorado, USA
| | - Steven M Claypool
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Kathryn C Chatfield
- Department of Pediatrics, University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, Colorado, USA
| | - Genevieve C Sparagna
- Division of Cardiology, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Adam J Chicco
- Cell and Molecular Biology Program, Colorado State University, Fort Collins, Colorado, USA .,Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA.,Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, Colorado, USA
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8
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Garlid AO, Schaffer CT, Kim J, Bhatt H, Guevara-Gonzalez V, Ping P. TAZ encodes tafazzin, a transacylase essential for cardiolipin formation and central to the etiology of Barth syndrome. Gene 2019; 726:144148. [PMID: 31647997 DOI: 10.1016/j.gene.2019.144148] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 09/12/2019] [Accepted: 09/27/2019] [Indexed: 12/31/2022]
Abstract
Tafazzin, which is encoded by the TAZ gene, catalyzes transacylation to form mature cardiolipin and shows preference for the transfer of a linoleic acid (LA) group from phosphatidylcholine (PC) to monolysocardiolipin (MLCL) with influence from mitochondrial membrane curvature. The protein contains domains and motifs involved in targeting, anchoring, and an active site for transacylase activity. Tafazzin activity affects many aspects of mitochondrial structure and function, including that of the electron transport chain, fission-fusion, as well as apoptotic signaling. TAZ mutations are implicated in Barth syndrome, an underdiagnosed and devastating disease that primarily affects male pediatric patients with a broad spectrum of disease pathologies that impact the cardiovascular, neuromuscular, metabolic, and hematologic systems.
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Affiliation(s)
- Anders O Garlid
- Cardiovascular Data Science Training Program at UCLA, University of California at Los Angeles, CA 90095, USA; Department of Physiology, University of California at Los Angeles, CA 90095, USA.
| | - Calvin T Schaffer
- Cardiovascular Data Science Training Program at UCLA, University of California at Los Angeles, CA 90095, USA; Department of Physiology, University of California at Los Angeles, CA 90095, USA
| | - Jaewoo Kim
- Cardiovascular Data Science Training Program at UCLA, University of California at Los Angeles, CA 90095, USA; Department of Physiology, University of California at Los Angeles, CA 90095, USA
| | - Hirsh Bhatt
- Cardiovascular Data Science Training Program at UCLA, University of California at Los Angeles, CA 90095, USA; Department of Physiology, University of California at Los Angeles, CA 90095, USA
| | - Vladimir Guevara-Gonzalez
- Cardiovascular Data Science Training Program at UCLA, University of California at Los Angeles, CA 90095, USA; Department of Mathematics, University of California at Los Angeles, CA 90095, USA
| | - Peipei Ping
- Cardiovascular Data Science Training Program at UCLA, University of California at Los Angeles, CA 90095, USA; Department of Physiology, University of California at Los Angeles, CA 90095, USA; Department of Medicine/Cardiology, University of California at Los Angeles, CA 90095, USA; Department of Bioinformatics, University of California at Los Angeles, CA 90095, USA; Scalable Analytics Institute (ScAi), University of California at Los Angeles, CA 90095, USA.
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Finsterer J. Barth syndrome: mechanisms and management. APPLICATION OF CLINICAL GENETICS 2019; 12:95-106. [PMID: 31239752 PMCID: PMC6558240 DOI: 10.2147/tacg.s171481] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 05/04/2019] [Indexed: 12/21/2022]
Abstract
Objectives: Barth syndrome is an ultra-rare, infantile-onset, X-linked recessive mitochondrial disorder, primarily affecting males, due to variants in TAZ encoding for the cardiolipin transacylase tafazzin. This review aimed to summarize and discuss recent and earlier findings concerning the etiology, pathogenesis, clinical presentation, diagnosis, treatment, and outcome of Barth syndrome. Method: A literature review was undertaken through a MEDLINE search. Results: The phenotype of Barth syndrome is highly variable but most frequently patients present with hypertrophic/dilated/non-compaction cardiomyopathy, fibroelastosis, arrhythmias, neutropenia, mitochondrial myopathy, growth retardation, dysmorphism, cognitive impairment, and other, rarer features. Lactic acid and creatine kinase, and blood and urine organic acids, particularly 3-methylglutaconic acid and monolysocardiolipin, are often elevated. Cardiolipin is decreased. Biochemical investigations may show decreased activity of various respiratory chain complexes. The diagnosis is confirmed by documentation of a causative TAZ variant. Treatment is symptomatic and directed toward treating heart failure, arrhythmias, neutropenia, and mitochondrial myopathy. Conclusions: Although Barth syndrome is still an orphan disease, with fewer than 200 cases described so far, there is extensive ongoing research with regard to its pathomechanism and new therapeutic approaches. Although most of these approaches are still experimental, it can be expected that causative strategies will be developed in the near future.
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Affiliation(s)
- Josef Finsterer
- Krankenanstalt Rudolfstiftung, Messerli Institute, Vienna, Austria
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Lou W, Reynolds CA, Li Y, Liu J, Hüttemann M, Schlame M, Stevenson D, Strathdee D, Greenberg ML. Loss of tafazzin results in decreased myoblast differentiation in C2C12 cells: A myoblast model of Barth syndrome and cardiolipin deficiency. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1863:857-865. [PMID: 29694924 DOI: 10.1016/j.bbalip.2018.04.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/17/2018] [Accepted: 04/19/2018] [Indexed: 12/25/2022]
Abstract
Barth syndrome (BTHS) is an X-linked genetic disorder resulting from mutations in the tafazzin gene (TAZ), which encodes the transacylase that remodels the mitochondrial phospholipid cardiolipin (CL). While most BTHS patients exhibit pronounced skeletal myopathy, the mechanisms linking defective CL remodeling and skeletal myopathy have not been determined. In this study, we constructed a CRISPR-generated stable tafazzin knockout (TAZ-KO) C2C12 myoblast cell line. TAZ-KO cells exhibit mitochondrial deficits consistent with other models of BTHS, including accumulation of monolyso-CL (MLCL), decreased mitochondrial respiration, and increased mitochondrial ROS production. Additionally, tafazzin deficiency was associated with impairment of myocyte differentiation. Future studies should determine whether alterations in myogenic determination contribute to the skeletal myopathy observed in BTHS patients. The BTHS myoblast model will enable studies to elucidate mechanisms by which defective CL remodeling interferes with normal myocyte differentiation and skeletal muscle ontogenesis.
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Affiliation(s)
- Wenjia Lou
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | | | - Yiran Li
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Jenney Liu
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA
| | - Maik Hüttemann
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA
| | - Michael Schlame
- Department of Anesthesiology and Cell Biology, New York University School of Medicine, New York, NY, USA
| | - David Stevenson
- Transgenic Technology Laboratory, Cancer Research UK Beatson Institute, Garscube Estate, Glasgow, United Kingdom
| | - Douglas Strathdee
- Transgenic Technology Laboratory, Cancer Research UK Beatson Institute, Garscube Estate, Glasgow, United Kingdom
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA.
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12
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Wang J, Guo Y, Huang M, Zhang Z, Zhu J, Liu T, Shi L, Li F, Huang H, Fu L. Identification of TAZ mutations in pediatric patients with cardiomyopathy by targeted next-generation sequencing in a Chinese cohort. Orphanet J Rare Dis 2017; 12:26. [PMID: 28183324 PMCID: PMC5301434 DOI: 10.1186/s13023-016-0562-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 12/23/2016] [Indexed: 12/31/2022] Open
Abstract
Background Barth syndrome (BTHS) is a rare X-linked recessive disease characterized by cardiomyopathy, neutropenia, skeletal myopathy and growth delay. Early diagnosis and appropriate treatment may improve the prognosis of this disease. The purpose of this study is to determine the role of targeted next-generation sequencing (NGS) in the early diagnosis of BTHS in children with cardiomyopathy. Methods During the period between 2012 and 2015, a gene panel-based NGS approach was used to search for potentially disease-causing genetic variants in all patients referred to our institution with a clinical diagnosis of primary cardiomyopathy. NGS was performed using the Illumina sequencing system. Results A total of 180 Chinese pediatric patients (114 males and 66 females) diagnosed with primary cardiomyopathy were enrolled in this study. TAZ mutations were identified in four of the male index patients, including two novel mutations (c.527A > G, p.H176R and c.134_136delinsCC, p.H45PfsX38). All four probands and two additional affected male family members were born at full term with a median birth weight of 2350 g (range, 2000–2850 g). The median age at diagnosis of cardiomyopathy was 3.0 months (range, 1.0–20.0 months). The baseline echocardiography revealed prominent dilation and trabeculations of the left ventricle with impaired systolic function in the six patients, four of which fulfilled the diagnostic criteria of left ventricular noncompaction. Other aspects of their clinical presentations included hypotonia (6/6), growth delay (6/6), neutropenia (3/6) and 3-methylglutaconic aciduria (4/5). Five patients died at a median age of 7.5 months (range, 7.0–12.0 months). The cause of death was heart failure associated with infection in three patients and cardiac arrhythmia in two patients. The remaining one patient survived beyond infancy but had fallen into a persistent vegetative state after suffering from cardiac arrest. Conclusions This is the first report of systematic mutation screening of TAZ in a large cohort of pediatric patients with primary cardiomyopathy using the NGS approach. TAZ mutations were found in 4/114 (3.5%) male patients with primary cardiomyopathy. Our findings indicate that the inclusion of TAZ gene testing in cardiomyopathy genetic testing panels may contribute to the early diagnosis of BTHS.
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Affiliation(s)
- Jian Wang
- Research Division of Birth Defects, Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, People's Republic of China
| | - Ying Guo
- Department of Cardiology, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, 1678 Dongfang Road, Pudong, Shanghai, 200127, People's Republic of China
| | - Meirong Huang
- Department of Cardiology, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, 1678 Dongfang Road, Pudong, Shanghai, 200127, People's Republic of China
| | - Zhen Zhang
- Research Division of cardiovascular disease, Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, People's Republic of China
| | - Junxue Zhu
- Department of Cardiology, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, 1678 Dongfang Road, Pudong, Shanghai, 200127, People's Republic of China
| | - Tingliang Liu
- Department of Cardiology, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, 1678 Dongfang Road, Pudong, Shanghai, 200127, People's Republic of China
| | - Lin Shi
- Department of Cardiology, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, 1678 Dongfang Road, Pudong, Shanghai, 200127, People's Republic of China
| | - Fen Li
- Department of Cardiology, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, 1678 Dongfang Road, Pudong, Shanghai, 200127, People's Republic of China
| | - Huimin Huang
- Department of Cardiothoracic Surgery, Shanghai Children's Medical Center, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, People's Republic of China
| | - Lijun Fu
- Department of Cardiology, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, 1678 Dongfang Road, Pudong, Shanghai, 200127, People's Republic of China. .,Research Division of cardiovascular disease, Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, People's Republic of China.
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13
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Fukutin mutations in Fukuyama congenital muscular dystrophy do not cause noncompaction. Int J Cardiol 2016; 225:75-76. [DOI: 10.1016/j.ijcard.2016.09.093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 09/24/2016] [Indexed: 11/20/2022]
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14
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Hsu P, Liu X, Zhang J, Wang HG, Ye JM, Shi Y. Cardiolipin remodeling by TAZ/tafazzin is selectively required for the initiation of mitophagy. Autophagy 2016; 11:643-52. [PMID: 25919711 DOI: 10.1080/15548627.2015.1023984] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Tafazzin (TAZ) is a phospholipid transacylase that catalyzes the remodeling of cardiolipin, a mitochondrial phospholipid required for oxidative phosphorylation. Mutations of TAZ 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. Here we investigated the role of TAZ in regulating mitochondrial function and mitophagy. Using primary mouse embryonic fibroblasts (MEFs) with doxycycline-inducible knockdown of Taz, we showed that TAZ deficiency in MEFs caused defective mitophagosome biogenesis, but not other autophagic processes. Consistent with a key role of mitophagy in mitochondria quality control, TAZ deficiency in MEFs also led to impaired oxidative phosphorylation and severe oxidative stress. Together, these findings provide key insights on mitochondrial dysfunction in Barth syndrome, suggesting that pharmacological restoration of mitophagy may provide a novel treatment for this lethal condition.
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Key Words
- AdGFP-LC3, recombinant adenovirus expressing GFP tagged MAP1LC3B
- AdTAZ, recombinant adenovirus expressing Myc-tagged TAZ
- BTHS, Barth syndrome
- BafA1, bafilomycin A1
- Barth syndrome
- CCCP, carbonyl cyanide m-chlorophenylhydrazone
- CL, cardiolipin
- Dox, doxycycline
- FCCP, carbonyl cyanide p-triflouromethoxyphenylhydrazone
- LTG, LysoTracker Green
- MAP1LC3B/LC3B, microtubule-associated protein 1 light chain 3 beta
- MEF, mouse embryonic fibroblast
- MLCL, monolysocardiolipin
- MTR, MitoTracker Red
- PARK2, parkin RBR E3 ubiquitin protein ligase
- PINK1, PTEN-induced putative kinase 1
- SOD2, superoxide dismutase 2 mitochondrial
- TAZ, tafazzin
- TLCL, tetralinoleoyl-cardiolipin
- autophagy
- cardiolipin
- mitochondrial dysfunction
- mitophagosome
- mitophagy
- tafazzin
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Affiliation(s)
- Paul Hsu
- a Department of Cellular and Molecular Physiology ; Hershey , PA USA
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15
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Ting TW, Jamuar SS, Brett MS, Tan ES, Cham BWM, Lim JY, Law HY, Tan EC, Choo JTL, Lai AHM. Left Ventricular Non-compaction: Is It Genetic? Pediatr Cardiol 2015; 36:1565-72. [PMID: 26108892 DOI: 10.1007/s00246-015-1222-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 06/13/2015] [Indexed: 10/23/2022]
Abstract
Left ventricular non-compaction (LVNC) is reported to affect 0.14 % of the pediatric population. The etiology is heterogeneous and includes a wide number of genetic causes. As an illustration, we report two patients with LVNC who were diagnosed with a genetic syndrome. We then review the literature and suggest a diagnostic algorithm to evaluate individuals with LVNC. Case 1 is a 15-month-old girl who presented with hypotonia, global developmental delay, congenital heart defect (including LVNC) and facial dysmorphism. Case 2 is a 7-month-old girl with hypotonia, seizures, laryngomalacia and LVNC. We performed chromosomal microarray for both our patients and detected chromosome 1p36 microdeletion. We reviewed the literature for other genetic causes of LVNC and formulated a diagnostic algorithm, which includes assessment for syndromic disorders, inborn error of metabolism, copy number variants and non-syndromic monogenic disorder associated with LVNC. LVNC is a relatively newly recognized entity, with heterogeneity in underlying etiology. For a systematic approach of evaluating the underlying cause to improve clinical care of these patients, a diagnostic algorithm for genetic evaluation of patients with LVNC is proposed.
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Affiliation(s)
- Teck Wah Ting
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital, 100 Bukit Timah Road, Singapore, 229899, Singapore.,Singhealth Duke-NUS Paediatrics Academic Clinical Programme, Singapore, Singapore
| | - Saumya Shekhar Jamuar
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital, 100 Bukit Timah Road, Singapore, 229899, Singapore. .,Singhealth Duke-NUS Paediatrics Academic Clinical Programme, Singapore, Singapore.
| | | | - Ee Shien Tan
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital, 100 Bukit Timah Road, Singapore, 229899, Singapore.,Singhealth Duke-NUS Paediatrics Academic Clinical Programme, Singapore, Singapore
| | - Breana Wen Min Cham
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital, 100 Bukit Timah Road, Singapore, 229899, Singapore
| | - Jiin Ying Lim
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital, 100 Bukit Timah Road, Singapore, 229899, Singapore
| | - Hai Yang Law
- Singhealth Duke-NUS Paediatrics Academic Clinical Programme, Singapore, Singapore.,DNA Diagnostic and Research Laboratory, KK Women's and Children's Hospital, Singapore, Singapore
| | - Ene Choo Tan
- KK Research Centre, KK Women's and Children's Hospital, Singapore, Singapore
| | - Jonathan Tze Liang Choo
- Singhealth Duke-NUS Paediatrics Academic Clinical Programme, Singapore, Singapore.,Cardiology Service, Department of Paediatric Subspecialties, KK Women's and Children's Hospital, Singapore, Singapore
| | - Angeline Hwei Meeng Lai
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital, 100 Bukit Timah Road, Singapore, 229899, Singapore.,Singhealth Duke-NUS Paediatrics Academic Clinical Programme, Singapore, Singapore
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16
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Stacey RB, Caine AJ, Hundley WG. Evaluation and management of left ventricular noncompaction cardiomyopathy. Curr Heart Fail Rep 2015; 12:61-7. [PMID: 25399629 DOI: 10.1007/s11897-014-0237-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Left ventricular (LV) noncompaction cardiomyopathy (LVNC) is a form of cardiomyopathy in which trabeculations fail to "compact" with the left ventricular endocardium during fetal cardiac development and is classically associated with subsequent impairment of LV function, significant mortality, ventricular dysrhythmias, and embolic phenomena. As awareness and medical imaging quality have improved, it is becoming easier to identify trabeculations that traverse the LV cavity and serve as a distinguishing feature of this disorder. Differentiating true noncompaction from mild increases in trabeculations requires prudent imaging and clinical correlation. This review seeks to discuss the potential methods of evaluating left ventricular trabeculations, the role of increased trabeculations in cardiovascular disease, and how their presence may affect clinical management.
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Affiliation(s)
- R Brandon Stacey
- Department of Internal Medicine Section on Cardiology, Wake Forest University School of Medicine, Winston-Salem, NC, 27157, USA,
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17
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Reynolds S. Successful management of Barth syndrome: a systematic review highlighting the importance of a flexible and multidisciplinary approach. J Multidiscip Healthc 2015; 8:345-58. [PMID: 26251611 PMCID: PMC4524586 DOI: 10.2147/jmdh.s54802] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
This review describes and summarizes the available evidence related to the treatment and management of Barth syndrome. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards were used to identify articles published between December 2004 and January 2015. The Cochrane Population, Intervention, Control, Outcome, Study Design (PICOS) approach was used to guide the article selection and evaluation process. Of the 128 articles screened, 28 articles matched the systematic review inclusion criteria. The results of this review indicate the need for a flexible and multidisciplinary approach to manage the symptoms most commonly associated with Barth syndrome. It is recommended that a comprehensive care team should include individuals with Barth syndrome, their family members and caregivers, as well as medical, rehabilitative, nutritional, psychological, and educational professionals. The evidence for specific treatments, therapies, and techniques for individuals with Barth syndrome is currently lacking in both quality and quantity.
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Affiliation(s)
- Stacey Reynolds
- Department of Occupational Therapy, Virginia Commonwealth University, Richmond, VA, USA
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18
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Mayr JA, Haack TB, Freisinger P, Karall D, Makowski C, Koch J, Feichtinger RG, Zimmermann FA, Rolinski B, Ahting U, Meitinger T, Prokisch H, Sperl W. Spectrum of combined respiratory chain defects. J Inherit Metab Dis 2015; 38:629-40. [PMID: 25778941 PMCID: PMC4493854 DOI: 10.1007/s10545-015-9831-y] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 02/20/2015] [Accepted: 02/23/2015] [Indexed: 01/22/2023]
Abstract
Inherited disorders of mitochondrial energy metabolism form a large and heterogeneous group of metabolic diseases. More than 250 gene defects have been reported to date and this number continues to grow. Mitochondrial diseases can be grouped into (1) disorders of oxidative phosphorylation (OXPHOS) subunits and their assembly factors, (2) defects of mitochondrial DNA, RNA and protein synthesis, (3) defects in the substrate-generating upstream reactions of OXPHOS, (4) defects in relevant cofactors and (5) defects in mitochondrial homeostasis. Deficiency of more than one respiratory chain enzyme is a common finding. Combined defects are found in 49 % of the known disease-causing genes of mitochondrial energy metabolism and in 57 % of patients with OXPHOS defects identified in our diagnostic centre. Combined defects of complexes I, III, IV and V are typically due to deficiency of mitochondrial DNA replication, RNA metabolism or translation. Defects in cofactors can result in combined defects of various combinations, and defects of mitochondrial homeostasis can result in a generalised decrease of all OXPHOS enzymes. Noteworthy, identification of combined defects can be complicated by different degrees of severity of each affected enzyme. Furthermore, even defects of single respiratory chain enzymes can result in combined defects due to aberrant formation of respiratory chain supercomplexes. Combined OXPHOS defects have a great variety of clinical manifestations in terms of onset, course severity and tissue involvement. They can present as classical encephalomyopathy but also with hepatopathy, nephropathy, haematologic findings and Perrault syndrome in a subset of disorders.
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Affiliation(s)
- Johannes A Mayr
- Department of Paediatrics, Paracelsus Medical University, SALK Salzburg, Salzburg, 5020, Austria,
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Haghighi A, Haack TB, Atiq M, Mottaghi H, Haghighi-Kakhki H, Bashir RA, Ahting U, Feichtinger RG, Mayr JA, Rötig A, Lebre AS, Klopstock T, Dworschak A, Pulido N, Saeed MA, Saleh-Gohari N, Holzerova E, Chinnery PF, Taylor RW, Prokisch H. Sengers syndrome: six novel AGK mutations in seven new families and review of the phenotypic and mutational spectrum of 29 patients. Orphanet J Rare Dis 2014; 9:119. [PMID: 25208612 PMCID: PMC4167147 DOI: 10.1186/s13023-014-0119-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 07/17/2014] [Indexed: 01/28/2023] Open
Abstract
Background Sengers syndrome is an autosomal recessive condition characterized by congenital cataract, hypertrophic cardiomyopathy, skeletal myopathy and lactic acidosis. Mutations in the acylglycerol kinase (AGK) gene have been recently described as the cause of Sengers syndrome in nine families. Methods We investigated the clinical and molecular features of Sengers syndrome in seven new families; five families with the severe and two with the milder form. Results Sequence analysis of AGK revealed compound heterozygous or homozygous predicted loss-of-function mutations in all affected individuals. A total of eight different disease alleles were identified, of which six were novel, homozygous c.523_524delAT (p.Ile175Tyrfs*2), c.424-1G > A (splice site), c.409C > T (p.Arg137*) and c.877 + 3G > T (splice site), and compound heterozygous c.871C > T (p.Gln291*) and c.1035dup (p.Ile346Tyrfs*39). All patients displayed perinatal or early-onset cardiomyopathy and cataract, clinical features pathognomonic for Sengers syndrome. Other common findings included blood lactic acidosis and tachydyspnoea while nystagmus, eosinophilia and cervical meningocele were documented in only either one or two cases. Deficiency of the adenine nucleotide translocator was found in heart and skeletal muscle biopsies from two patients associated with respiratory chain complex I deficiency. In contrast to previous findings, mitochondrial DNA content was normal in both tissues. Conclusion We compare our findings to those in 21 previously reported AGK mutation-positive Sengers patients, confirming that Sengers syndrome is a clinically recognisable disorder of mitochondrial energy metabolism.
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Affiliation(s)
- Alireza Haghighi
- Department of Genetics, Harvard Medical School, 77 Ave Louis Pasteur, Boston 02115, MA, USA.
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20
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Mis-sesnse mutations in Tafazzin (TAZ) that escort to mild clinical symptoms of Barth syndrome is owed to the minimal inhibitory effect of the mutations on the enzyme function: In-silico evidence. Interdiscip Sci 2014; 7:21-35. [PMID: 25118650 DOI: 10.1007/s12539-013-0019-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 09/24/2013] [Accepted: 11/06/2013] [Indexed: 01/16/2023]
Abstract
Tafazzin (EC 2.3.1.23) is a Phospholipid Transacylase involved in Cardiolipin remodeling on mitochondrial membrane and coded by TAZ gene (Cytogenetic Location: Xq28) in human. Its mutations cause Barth syndrome (MIM ID: #302060)/3-Methyl Glutaconyl Aciduria Type II, an inborn error of metabolism often leading to foetal or infantile fatality. Nevertheless, some mis-sense mutations result in mild clinical symptoms. To evaluate the rationale of mild symptoms and for an insight of Tafazzin active site, sequence based and structure based ramifications of wild and mutant Tafazzins were compared in-silico. Sequence based domain predictions, surface accessibilities on substitution & conserved catalytic sites with statistical drifts, as well as thermal stability changes for the mutations and the interaction analysis of Tafazzin were performed. Crystal structure of Tafazzin is not yet resolved experimentally, therefore 3D coordinates of Tafazzin and its mutants were spawned through homology modeling. Energetically minimized and structurally validated models were used for comparative docking simulations. We analyzed active site geometry of the models in addition to calculating overall substrate binding efficiencies for each of the enzyme-ligand complex deduced from binding energies instead of comparing only the docking scores. Also, individual binding energies of catalytic residues on conserved HX4D motif of Acyltransferase superfamily present in Tafazzins were estimated. This work elucidates the basis of mild symptoms in patients with mis-sense mutations, identifies the most pathogenic mutant among others in the study and also divulges the critical role of HX4D domain towards successful transacylation by Taffazin. The in-silico observations are in complete agreement with clinical findings reported for the patients with mutations.
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