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Tucci S. An Altered Sphingolipid Profile as a Risk Factor for Progressive Neurodegeneration in Long-Chain 3-Hydroxyacyl-CoA Deficiency (LCHADD). Int J Mol Sci 2022; 23:ijms23137144. [PMID: 35806149 PMCID: PMC9266703 DOI: 10.3390/ijms23137144] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/23/2022] [Accepted: 06/25/2022] [Indexed: 12/03/2022] Open
Abstract
Long-chain 3-hydroxyacyl-CoA deficiency (LCHADD) and mitochondrial trifunctional protein (MTPD) belong to a group of inherited metabolic diseases affecting the degradation of long-chain chain fatty acids. During metabolic decompensation the incomplete degradation of fatty acids results in life-threatening episodes, coma and death. Despite fast identification at neonatal screening, LCHADD/MTPD present with progressive neurodegenerative symptoms originally attributed to the accumulation of toxic hydroxyl acylcarnitines and energy deficiency. Recently, it has been shown that LCHADD human fibroblasts display a disease-specific alteration of complex lipids. Accumulating fatty acids, due to defective β-oxidation, contribute to a remodeling of several lipid classes including mitochondrial cardiolipins and sphingolipids. In the last years the face of LCHADD/MTPD has changed. The reported dysregulation of complex lipids other than the simple acylcarnitines represents a novel aspect of disease development. Indeed, aberrant lipid profiles have already been associated with other neurodegenerative diseases such as Parkinson’s Disease, Alzheimer’s Disease, amyotrophic lateral sclerosis and retinopathy. Today, the physiopathology that underlies the development of the progressive neuropathic symptoms in LCHADD/MTPD is not fully understood. Here, we hypothesize an alternative disease-causing mechanism that contemplates the interaction of several factors that acting in concert contribute to the heterogeneous clinical phenotype.
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Affiliation(s)
- Sara Tucci
- Pharmacy, Medical Center, University of Freiburg, 79106 Freiburg, Germany;
- Department of General Pediatrics, Adolescent Medicine and Neonatology, Faculty of Medicine, Medical Centre-University of Freiburg, 79106 Freiburg, Germany
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Ørstavik K, Arntzen KA, Mathisen P, Backe PH, Tangeraas T, Rasmussen M, Kristensen E, Van Ghelue M, Jonsrud C, Bliksrud YT. Novel mutations in the HADHB gene causing a mild phenotype of mitochondrial trifunctional protein (MTP) deficiency. JIMD Rep 2022; 63:193-198. [PMID: 35433169 PMCID: PMC8995838 DOI: 10.1002/jmd2.12276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 02/08/2022] [Accepted: 02/11/2022] [Indexed: 11/11/2022] Open
Abstract
Mitochondrial trifunctional protein (MTP) deficiency is an ultrarare hereditary recessive disorder causing a broad spectrum of phenotypes with lethal infantile cardiomyopathy at the most severe end. Attenuated forms with polyneuropathy have been reported combined with myoglobinuria or rhabdomyolysis as key features. We here report three young adults (two siblings) in which three variants in the HADHB-gene were identified. All three cases had a similar mild phenotype with axonal neuropathy and frequent intermittent weakness episodes but without myoglobinuria. Special dietary precautions were recommended to minimize complications especially during infections and other catabolic states. MTP deficiency is therefore an important differential diagnosis in patients with milder fluctuating neuromuscular symptoms. Take‐home message Axonal neuropathy and recurrent muscular weakness without concomitant rhabdomyolysis may be due to MTP deficiency.
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Affiliation(s)
- Kristin Ørstavik
- Department of Neurology, Section for Rare Neuromuscular disorders and EMANOslo University Hospital, RikshospitaletOsloNorway
| | - Kjell Arne Arntzen
- National Neuromuscular Centre Norway and Department of NeurologyUniversity Hospital of North NorwayTromsøNorway
| | - Per Mathisen
- Department of CardiologyOslo University Hospital, RikshospitaletOsloNorway
| | - Paul Hoff Backe
- Department of MicrobiologyOslo University Hospital, Rikshospitalet and University of OsloOsloNorway
- Department of Medical BiochemistryInstitute for Clinical Medicine, University of OsloOsloNorway
| | - Trine Tangeraas
- Norwegian National Unit for Newborn Screening, Division of Pediatric and Adolescent MedicineOslo University HospitalOsloNorway
| | - Magnhild Rasmussen
- Department of Neurology, Section for Rare Neuromuscular disorders and EMANOslo University Hospital, RikshospitaletOsloNorway
- Department of Clinical Neurosciences for ChildrenOslo University Hospital, RikshospitaletOsloNorway
| | - Erle Kristensen
- Department of Medical BiochemistryOslo University Hospital, RikshospitaletOsloNorway
| | - Marijke Van Ghelue
- Department of Medical Genetics, Division of Child and Adolescent HealthUniversity Hospital of North NorwayTromsøNorway
| | - Christoffer Jonsrud
- Department of Medical Genetics, Division of Child and Adolescent HealthUniversity Hospital of North NorwayTromsøNorway
| | - Yngve Thomas Bliksrud
- Department of Medical BiochemistryOslo University Hospital, RikshospitaletOsloNorway
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Yang J, Yuan D, Tan X, Zeng Y, Tang N, Chen D, Tan J, Cai R, Huang J, Yan T. Analysis of a family with mitochondrial trifunctional protein deficiency caused by HADHA gene mutations. Mol Med Rep 2021; 25:47. [PMID: 34878152 PMCID: PMC8674702 DOI: 10.3892/mmr.2021.12563] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 11/22/2021] [Indexed: 11/21/2022] Open
Abstract
Mitochondrial trifunctional protein (MTP) deficiency (MTPD; MIM 609015) is a metabolic disease of fatty acid oxidation. MTPD is an autosomal recessive disorder caused by mutations in the HADHA gene, encoding the α-subunit of a trifunctional protease, or in the HADHB gene, encoding the β-subunit of a trifunctional protease. To the best of our knowledge, only two cases of families with MTPD due to HADHB gene mutations have been reported in China, and the HADHA gene mutation has not been reported in a Chinese family with MTPD. The present study reported the clinical characteristics and compound heterozygous HADHA gene mutations of two patients with MTPD in the Chinese population. The medical history, routine examination data, blood acyl-carnitine analysis results, results of pathological examination after autopsy and family pedigree map were collected for patients with MTPD. The HADHA gene was analyzed by Sanger sequencing or high-throughput sequencing, the pathogenicity of the newly discovered variant was interpreted by bioinformatics analysis, and the function of the mutated protein was modeled and analyzed according to 3D structure. The two patients with MTPD experienced metabolic crises and died following an infectious disease. Lactate dehydrogenase, creatine kinase (CK), CK-MB and liver enzyme abnormalities were observed in routine examinations. Tandem mass spectrometry revealed that long-chain acyl-carnitine was markedly elevated in blood samples from the patients with MTPD. The autopsy results for one child revealed fat accumulation in the liver and heart. Next-generation sequencing detected compound heterozygous c.703C>T (p.R235W) and c.2107G>A (p.G703R) mutations in the HADHA gene. The mother did not have acute fatty liver during pregnancy with the two patients. Using amniotic fluid prenatal diagnostic testing, the unborn child was confirmed to carry only c.2107G>A (p.G703R). Molecular mechanistic analysis indicated that the two variants affected the conformation of the α-subunit of the MTP enzyme complex, and consequently affected the stability and function of the enzyme complex. The present study comprehensively analyzed the cases, including exome sequencing and protein structure analysis and, to the best of our knowledge, describes the first observation of compound heterozygous mutations in the HADHA gene underlying this disorder in China. The clinical phenotypes of the two heterozygous variants of the HADHA gene are non-lethal. The present study may improve understanding of the HADHA gene mutation spectrum and clinical phenotype in the Chinese population.
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Affiliation(s)
- Jinling Yang
- Newborn Screening Center, Department of Medical Genetics, Key Laboratory of Prevention and Control of Birth Defects, Liuzhou Maternity and Child Health Care Hospital, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, Guangxi 545000, P.R. China
| | - Dejian Yuan
- Newborn Screening Center, Department of Medical Genetics, Key Laboratory of Prevention and Control of Birth Defects, Liuzhou Maternity and Child Health Care Hospital, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, Guangxi 545000, P.R. China
| | - Xiaohui Tan
- School of Forensic Medicine, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China
| | - Yexi Zeng
- Newborn Screening Center, Huizhou Second Maternity and Child Health Care Hospital, Huizhou, Guangdong 516001, P.R. China
| | - Ning Tang
- Newborn Screening Center, Department of Medical Genetics, Key Laboratory of Prevention and Control of Birth Defects, Liuzhou Maternity and Child Health Care Hospital, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, Guangxi 545000, P.R. China
| | - Dayu Chen
- Newborn Screening Center, Department of Medical Genetics, Key Laboratory of Prevention and Control of Birth Defects, Liuzhou Maternity and Child Health Care Hospital, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, Guangxi 545000, P.R. China
| | - Jianqiang Tan
- Newborn Screening Center, Department of Medical Genetics, Key Laboratory of Prevention and Control of Birth Defects, Liuzhou Maternity and Child Health Care Hospital, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, Guangxi 545000, P.R. China
| | - Ren Cai
- Newborn Screening Center, Department of Medical Genetics, Key Laboratory of Prevention and Control of Birth Defects, Liuzhou Maternity and Child Health Care Hospital, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, Guangxi 545000, P.R. China
| | - Jun Huang
- Newborn Screening Center, Department of Medical Genetics, Key Laboratory of Prevention and Control of Birth Defects, Liuzhou Maternity and Child Health Care Hospital, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, Guangxi 545000, P.R. China
| | - Tizhen Yan
- Newborn Screening Center, Department of Medical Genetics, Key Laboratory of Prevention and Control of Birth Defects, Liuzhou Maternity and Child Health Care Hospital, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, Guangxi 545000, P.R. China
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Phospholipids: Identification and Implication in Muscle Pathophysiology. Int J Mol Sci 2021; 22:ijms22158176. [PMID: 34360941 PMCID: PMC8347011 DOI: 10.3390/ijms22158176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 07/24/2021] [Accepted: 07/26/2021] [Indexed: 12/29/2022] Open
Abstract
Phospholipids (PLs) are amphiphilic molecules that were essential for life to become cellular. PLs have not only a key role in compartmentation as they are the main components of membrane, but they are also involved in cell signaling, cell metabolism, and even cell pathophysiology. Considered for a long time to simply be structural elements of membranes, phospholipids are increasingly being viewed as sensors of their environment and regulators of many metabolic processes. After presenting their main characteristics, we expose the increasing methods of PL detection and identification that help to understand their key role in life processes. Interest and importance of PL homeostasis is growing as pathogenic variants in genes involved in PL biosynthesis and/or remodeling are linked to human diseases. We here review diseases that involve deregulation of PL homeostasis and present a predominantly muscular phenotype.
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Grünert SC, Eckenweiler M, Haas D, Lindner M, Tsiakas K, Santer R, Tucci S, Spiekerkoetter U. The spectrum of peripheral neuropathy in disorders of the mitochondrial trifunctional protein. J Inherit Metab Dis 2021; 44:893-902. [PMID: 33638202 DOI: 10.1002/jimd.12372] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/25/2021] [Accepted: 02/25/2021] [Indexed: 12/28/2022]
Abstract
Peripheral neuropathy is a known irreversible long-term complication of long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) and mitochondrial trifunctional protein deficiency (MTPD), two inherited disorders of mitochondrial long-chain fatty acid oxidation. The underlying pathophysiology of neuropathy is still not fully understood. We report electrophysiological studies and neurological findings in a series of 8 LCHAD-deficient and 11 MTP-deficient patients. The median age at time of the study was 8.0 years (0.5-25 years). The overall prevalence of neuropathy was 58% with neuropathic symptoms being slightly more common in MTPD compared to LCHADD (70% vs 50%, respectively). Onset of neuropathy was significantly earlier in MTPD patients compared to LCHADD patients (median age at onset 4.7 vs 15.3 years, respectively, P = .047). In four patients, isolated peripheral neuropathy was the first and only presenting symptom, and in all four the diagnosis was missed by newborn screening. About half of the patients (45.5%) had a sensorimotor neuropathy, while 27.3% showed a pure motor form and another 27.3% an isolated sensory form. Despite early diagnosis by newborn screening and early initiation of therapy, peripheral neuropathy cannot be prevented in all patients with LCHADD/MTPD and has severe impact on the life of affected patients. Electrophysiology classifies LCHADD/MTPD neuropathy as axonal with secondary demyelination. A novel observation is that in patients with acute, fulminant onset of neuropathy, symptoms can be partly reversible. Further studies are needed to elucidate the underlying pathophysiology of axonal damage and possible therapeutic targets.
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Affiliation(s)
- Sarah C Grünert
- Department of General Pediatrics, Adolescent Medicine and Neonatology, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | - Matthias Eckenweiler
- Department of Neuropediatrics and Muscle Disorders, University Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Dorothea Haas
- Department of Neuropediatrics and Pediatric Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Martin Lindner
- Department of Pediatric Neurology, University Children's Hospital, Frankfurt/Main, Germany
| | | | - René Santer
- Department of Pediatrics, University Medical Center Eppendorf, Hamburg, Germany
| | - Sara Tucci
- Department of General Pediatrics, Adolescent Medicine and Neonatology, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | - Ute Spiekerkoetter
- Department of General Pediatrics, Adolescent Medicine and Neonatology, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg, Germany
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Abstract
The mitochondrial trifunctional protein (TFP) catalyzes three reactions in the fatty acid β-oxidation process. Mutations in the two TFP subunits cause mitochondrial trifunctional protein deficiency and acute fatty liver of pregnancy that can lead to death. Here we report a 4.2-Å cryo-electron microscopy α2β2 tetrameric structure of the human TFP. The tetramer has a V-shaped architecture that displays a distinct assembly compared with the bacterial TFPs. A concave surface of the TFP tetramer interacts with the detergent molecules in the structure, suggesting that this region is involved in associating with the membrane. Deletion of a helical hairpin in TFPβ decreases its binding to the liposomes in vitro and reduces its membrane targeting in cells. Our results provide the structural basis for TFP function and have important implications for fatty acid oxidation related diseases.
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El-Gharbawy A, Vockley J. Inborn Errors of Metabolism with Myopathy: Defects of Fatty Acid Oxidation and the Carnitine Shuttle System. Pediatr Clin North Am 2018; 65:317-335. [PMID: 29502916 PMCID: PMC6566095 DOI: 10.1016/j.pcl.2017.11.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Fatty acid oxidation disorders (FAODs) and carnitine shuttling defects are inborn errors of energy metabolism with associated mortality and morbidity due to cardiomyopathy, exercise intolerance, rhabdomyolysis, and liver disease with physiologic stress. Hypoglycemia is characteristically hypoketotic. Lactic acidemia and hyperammonemia may occur during decompensation. Recurrent rhabdomyolysis is debilitating. Expanded newborn screening can detect most of these disorders, allowing early, presymptomatic treatment. Treatment includes avoiding fasting and sustained extraneous exercise and providing high-calorie hydration during illness to prevent lipolysis, and medium-chain triglyceride oil supplementation in long-chain FAODs. Carnitine supplementation may be helpful. However, conventional treatment does not prevent all symptoms.
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Affiliation(s)
- Areeg El-Gharbawy
- Department of Pediatrics, Division of Medical Genetics, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA 15224, USA; Cairo University, Kasr Al-Aini, Cairo, Egypt
| | - Jerry Vockley
- Department of Pediatrics, Division of Medical Genetics, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
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El-Gharbawy A, Goldstein A. Mitochondrial Fatty Acid Oxidation Disorders Associated with Cardiac Disease. CURRENT PATHOBIOLOGY REPORTS 2017. [DOI: 10.1007/s40139-017-0148-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Fletcher AL, Pennesi ME, Harding CO, Weleber RG, Gillingham MB. Observations regarding retinopathy in mitochondrial trifunctional protein deficiencies. Mol Genet Metab 2012; 106:18-24. [PMID: 22459206 PMCID: PMC3506186 DOI: 10.1016/j.ymgme.2012.02.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 02/23/2012] [Accepted: 02/23/2012] [Indexed: 12/31/2022]
Abstract
Although the retina is thought to primarily rely on glucose for fuel, inherited deficiency of one or more activities of mitochondrial trifunctional protein results in a pigmentary retinopathy leading to vision loss. Many other enzymatic deficiencies in fatty acid oxidation pathways have been described, none of which results in retinal complications. The etiology of retinopathy among patients with defects in trifunctional protein is unknown. Trifunctional protein is a heteroctomer; two genes encode the alpha and beta subunits of TFP respectively, HADHA and HADHB. A common mutation in HADHA, c.1528G>C, leads to a single amino acid substitution, p. Glu474Gln, and impairs primarily long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) activity leading to LCHAD deficiency (LCHADD). Other mutations in HADHA or HADHB often lead to significant reduction in all three enzymatic activities and result in trifunctional protein deficiency (TFPD). Despite many similarities in clinical presentation and phenotype, there is growing evidence that they can result in different chronic complications. This review will outline the clinical similarities and differences between LCHADD and TFPD, describe the course of the associated retinopathy, propose a genotype/phenotype correlation with the severity of retinopathy, and discuss the current theories about the etiology of the retinopathy.
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Affiliation(s)
- Autumn L Fletcher
- Department of Molecular & Medical Genetics, School of Medicine, Oregon Health & Science University, Mail Code L-103, 3181 SW Sam Jackson Park Rd Portland, OR 97239, USA.
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Channick RN, Lorenzo ME, Wu CC, Hoang MP. Case records of the Massachusetts General Hospital. Case 11-2012. A 60-year-old man with weakness, rash, and renal failure. N Engl J Med 2012; 366:1434-43. [PMID: 22494124 DOI: 10.1056/nejmcpc1111571] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Saini-Chohan HK, Mitchell RW, Vaz FM, Zelinski T, Hatch GM. Delineating the role of alterations in lipid metabolism to the pathogenesis of inherited skeletal and cardiac muscle disorders: Thematic Review Series: Genetics of Human Lipid Diseases. J Lipid Res 2011; 53:4-27. [PMID: 22065858 DOI: 10.1194/jlr.r012120] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
As the specific composition of lipids is essential for the maintenance of membrane integrity, enzyme function, ion channels, and membrane receptors, an alteration in lipid composition or metabolism may be one of the crucial changes occurring during skeletal and cardiac myopathies. Although the inheritance (autosomal dominant, autosomal recessive, and X-linked traits) and underlying/defining mutations causing these myopathies are known, the contribution of lipid homeostasis in the progression of these diseases needs to be established. The purpose of this review is to present the current knowledge relating to lipid changes in inherited skeletal muscle disorders, such as Duchenne/Becker muscular dystrophy, myotonic muscular dystrophy, limb-girdle myopathic dystrophies, desminopathies, rostrocaudal muscular dystrophy, and Dunnigan-type familial lipodystrophy. The lipid modifications in familial hypertrophic and dilated cardiomyopathies, as well as Barth syndrome and several other cardiac disorders associated with abnormal lipid storage, are discussed. Information on lipid alterations occurring in these myopathies will aid in the design of improved methods of screening and therapy in children and young adults with or without a family history of genetic diseases.
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Affiliation(s)
- Harjot K Saini-Chohan
- Department of Pharmacology and Therapeutics, Academic Medical Center, Amsterdam, The Netherlands
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Boutron A, Acquaviva C, Vianey-Saban C, de Lonlay P, de Baulny HO, Guffon N, Dobbelaere D, Feillet F, Labarthe F, Lamireau D, Cano A, de Villemeur TB, Munnich A, Saudubray JM, Rabier D, Rigal O, Brivet M. Comprehensive cDNA study and quantitative analysis of mutant HADHA and HADHB transcripts in a French cohort of 52 patients with mitochondrial trifunctional protein deficiency. Mol Genet Metab 2011; 103:341-8. [PMID: 21549624 DOI: 10.1016/j.ymgme.2011.04.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 04/13/2011] [Accepted: 04/13/2011] [Indexed: 11/18/2022]
Abstract
BACKGROUND Deficiency of mitochondrial trifunctional protein (MTP) is caused by mutations in the HADHA and HADHB genes, which have been mostly delineated at the genomic DNA level and have not been always elucidated. AIM To identify mutations in a French cohort of 52 MTP deficient patients and the susceptibility of mutations generating premature termination codons (PTCs) to the nonsense mRNA mediated decay (NMD). METHODS Mutation screening in fibroblasts was performed at the cDNA level and real-time RT-PCR was used to compare the levels of the different PTC-bearing mRNAs before and after a treatment of fibroblasts by emetine, a translation inhibitor. RESULTS A mutation detection rate of 100% was achieved. A total of 22 novel mutations were identified, including a large-sized genomic deletion in HADHB gene. A high proportion of all identified mutations were non-sense, frameshift and splicing mutations, generating (PTCs), distributed essentially on HADHA coding regions. We could demonstrate that the majority of mutations resulting in PTCs conform to the established rules governing the susceptibility to NMD. CONCLUSION Our results emphasize the value of cDNA analysis in the characterization of HADHA and HADHB mutations and further strengthen the model of haploinsufficiency as a major pathomechanism in MTP defects.
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Affiliation(s)
- A Boutron
- Biochimie, Hopital de Bicêtre, Hôpitaux Universitaires Paris-Sud, APHP, Paris, France
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Inborn errors of energy metabolism associated with myopathies. J Biomed Biotechnol 2010; 2010:340849. [PMID: 20589068 PMCID: PMC2877206 DOI: 10.1155/2010/340849] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 01/19/2010] [Accepted: 02/22/2010] [Indexed: 12/31/2022] Open
Abstract
Inherited neuromuscular disorders affect approximately one in 3,500 children. Structural muscular defects are most common; however functional impairment of skeletal and cardiac muscle in both children and adults may be caused by inborn errors of energy metabolism as well. Patients suffering from metabolic myopathies due to compromised energy metabolism may present with exercise intolerance, muscle pain, reversible or progressive muscle weakness, and myoglobinuria. In this review, the physiology of energy metabolism in muscle is described, followed by the presentation of distinct disorders affecting skeletal and cardiac muscle: glycogen storage diseases types III, V, VII, fatty acid oxidation defects, and respiratory chain defects (i.e., mitochondriopathies). The diagnostic work-up and therapeutic options in these disorders are discussed.
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