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Feola K, Venable AH, Broomfield T, Villegas M, Fu X, Burgess S, Huen SC. Hepatic ketogenesis is not required for starvation adaptation in mice. Mol Metab 2024; 86:101967. [PMID: 38876267 DOI: 10.1016/j.molmet.2024.101967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 06/04/2024] [Accepted: 06/10/2024] [Indexed: 06/16/2024] Open
Abstract
OBJECTIVE In response to bacterial inflammation, anorexia of acute illness is protective and is associated with the induction of fasting metabolic programs such as ketogenesis. Forced feeding during the anorectic period induced by bacterial inflammation is associated with suppressed ketogenesis and increased mortality. As ketogenesis is considered essential in fasting adaptation, we sought to determine the role of ketogenesis in illness-induced anorexia. METHODS A mouse model of inducible hepatic specific deletion of the rate limiting enzyme for ketogenesis (HMG-CoA synthase 2, Hmgcs2) was used to investigate the role of ketogenesis in endotoxemia, a model of bacterial inflammation, and in prolonged starvation. RESULTS Mice deficient of hepatic Hmgcs2 failed to develop ketosis during endotoxemia and during prolonged fasting. Surprisingly, hepatic HMGCS2 deficiency and the lack of ketosis did not affect survival, glycemia, or body temperature in response to endotoxemia. Mice with hepatic ketogenic deficiency also did not exhibit any defects in starvation adaptation and were able to maintain blood glucose, body temperature, and lean mass compared to littermate wild-type controls. Mice with hepatic HMGCS2 deficiency exhibited higher levels of plasma acetate levels in response to fasting. CONCLUSIONS Circulating hepatic-derived ketones do not provide protection against endotoxemia, suggesting that alternative mechanisms drive the increased mortality from forced feeding during illness-induced anorexia. Hepatic ketones are also dispensable for surviving prolonged starvation in the absence of inflammation. Our study challenges the notion that hepatic ketogenesis is required to maintain blood glucose and preserve lean mass during starvation, raising the possibility of extrahepatic ketogenesis and use of alternative fuels as potential means of metabolic compensation.
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Affiliation(s)
- Kyle Feola
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Andrea H Venable
- Department of Internal Medicine (Nephrology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Tatyana Broomfield
- Department of Internal Medicine (Nephrology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Morgan Villegas
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Xiaorong Fu
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Shawn Burgess
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sarah C Huen
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Internal Medicine (Nephrology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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2
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Williams M, Menkovic I, Reitnauer P, Gilbert E, Koeberl D, Young SP, Stiles AR. Critical sample collection delayed? Urine organic acid analysis can still save the day! A new case of HMG-CoA synthase deficiency. Mol Genet Metab Rep 2024; 38:101062. [PMID: 38469099 PMCID: PMC10926198 DOI: 10.1016/j.ymgmr.2024.101062] [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: 12/28/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 03/13/2024] Open
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase (mHS) deficiency is an autosomal recessive disorder of ketone body synthesis caused by biallelic pathogenic variants in HMGCS2. Clinical symptoms are precipitated by prolonged fasting and/or intercurrent illness with onset before the first year of life. Clinically, patients may present with hypo-/ non-ketotic hypoglycemia, metabolic acidosis, hyperammonemia, lethargy, hepatomegaly, and encephalopathy. During periods of decompensation, elevations of 4-hydroxy-6-methyl-2-pyrone (4-HMP), several hydroxylated hexanoic and hexenoic acid species, and medium-chain dicarboxylic acids in the absence of significant ketonuria may be observed in the urine organic acid profile. Abnormalities may also be observed in plasma which includes elevated acetylcarnitine (C2) and 3-hydroxybutyryl/3-hydroxyisobutyryl (C4-OH) carnitine. We report a patient who presented to the ED at 13 months of age with an undetectable point-of-care blood glucose level. Continuous infusion of dextrose-containing intravenous (IV) fluids were required to correct the hypoglycemia and routine chemistries were notable for an anion gap metabolic acidosis, transaminasemia, and elevated creatine kinase and lactate dehydrogenase. Urine and blood ketones were undetectable. Qualitative assessment of urine organic acids collected ∼46 and ∼ 99 h post-admission were significant for mild elevations of 4-HMP and hydroxy-hexanoic and hydroxy-hexenoic acid species with a notable absence of ketones. Previously, biochemical abnormalities in urine have been shown to normalize in as few as 27 h after treatment giving providers a narrow window with which to obtain a critical sample. Direct communication of laboratory findings to the ordering provider guided the molecular testing and assisted in results interpretation to confirm the molecular diagnosis. Our case emphasizes the importance of collecting samples for biochemical analysis even if the critical period has been missed and acute metabolic decompensation seems to be resolved, as residual abnormalities observed in our patient greatly narrowed the differential diagnosis.
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Affiliation(s)
- Monika Williams
- Department of Pediatrics, Division of Pediatric Genetics and Metabolism, UNC, Chapel Hill, NC, USA
| | - Iskren Menkovic
- Biochemical Genetics Laboratory, Duke University Health System, Durham, NC, USA
| | - Pamela Reitnauer
- Pediatric Teaching Program & Pediatric Medical Genetics, Cone Health, Greensboro, NC, USA
| | - Eileen Gilbert
- Biochemical Genetics Laboratory, Duke University Health System, Durham, NC, USA
| | - Dwight Koeberl
- Biochemical Genetics Laboratory, Duke University Health System, Durham, NC, USA
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | - Sarah P. Young
- Biochemical Genetics Laboratory, Duke University Health System, Durham, NC, USA
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | - Ashlee R. Stiles
- Biochemical Genetics Laboratory, Duke University Health System, Durham, NC, USA
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
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3
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Houthuijs KJ, Berden G, Engelke UFH, Gautam V, Wishart DS, Wevers RA, Martens J, Oomens J. An In Silico Infrared Spectral Library of Molecular Ions for Metabolite Identification. Anal Chem 2023. [PMID: 37262385 DOI: 10.1021/acs.analchem.3c01078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Infrared ion spectroscopy (IRIS) continues to see increasing use as an analytical tool for small-molecule identification in conjunction with mass spectrometry (MS). The IR spectrum of an m/z selected population of ions constitutes a unique fingerprint that is specific to the molecular structure. However, direct translation of an IR spectrum to a molecular structure remains challenging, as reference libraries of IR spectra of molecular ions largely do not exist. Quantum-chemically computed spectra can reliably be used as reference, but the challenge of selecting the candidate structures remains. Here, we introduce an in silico library of vibrational spectra of common MS adducts of over 4500 compounds found in the human metabolome database. In total, the library currently contains more than 75,000 spectra computed at the DFT level that can be queried with an experimental IR spectrum. Moreover, we introduce a database of 189 experimental IRIS spectra, which is employed to validate the automated spectral matching routines. This demonstrates that 75% of the metabolites in the experimental data set are correctly identified, based solely on their exact m/z and IRIS spectrum. Additionally, we demonstrate an approach for specifically identifying substructures by performing a search without m/z constraints to find structural analogues. Such an unsupervised search paves the way toward the de novo identification of unknowns that are absent in spectral libraries. We apply the in silico spectral library to identify an unknown in a plasma sample as 3-hydroxyhexanoic acid, highlighting the potential of the method.
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Affiliation(s)
- Kas J Houthuijs
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Nijmegen 6525 ED, The Netherlands
| | - Giel Berden
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Nijmegen 6525 ED, The Netherlands
| | - Udo F H Engelke
- Department of Genetics, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen 6525 GA, The Netherlands
| | - Vasuk Gautam
- Department of Biological Sciences, University of Alberta, Edmonton AB T6G 2E9, Canada
| | - David S Wishart
- Department of Biological Sciences, University of Alberta, Edmonton AB T6G 2E9, Canada
- Department of Computing Science, University of Alberta, Edmonton, AB T6G 2E8, Canada
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2B7, Canada
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ron A Wevers
- Department of Genetics, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen 6525 GA, The Netherlands
| | - Jonathan Martens
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Nijmegen 6525 ED, The Netherlands
| | - Jos Oomens
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Nijmegen 6525 ED, The Netherlands
- van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam 1098 XH, The Netherlands
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Salazar D, Kloke KM, Guerrero RB, Ferreira CR, Blau N. Clinical and biochemical footprints of inherited metabolic disorders. XI. Gastrointestinal symptoms. Mol Genet Metab 2023; 138:107528. [PMID: 36774919 PMCID: PMC10509718 DOI: 10.1016/j.ymgme.2023.107528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/28/2023] [Accepted: 01/29/2023] [Indexed: 02/04/2023]
Abstract
Inherited metabolic disorders presenting with gastrointestinal (GI) symptoms are characterized by the dysfunction of the esophagus, stomach, small and large intestines, and pancreas. We have summarized associations of signs and symptoms in 339 inherited metabolic diseases presenting with GI symptoms. Feeding difficulties represent the most common abnormality reported for IMDs with GI involvement (37%) followed by intestinal problems (30%), vomiting (22%), stomach and pancreas involvement (8% each), and esophagus involvement (4%). This represents the eleventh of a series of articles attempting to create and maintain a comprehensive list of clinical and metabolic differential diagnoses according to system involvement.
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Affiliation(s)
- Denise Salazar
- Quest Diagnostics Nichols Institute, San Juan Capistrano, CA, United States of America.
| | - Karen M Kloke
- Mayo Clinic Laboratories, Rochester, MN, United States of America.
| | | | - Carlos R Ferreira
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, United States of America.
| | - Nenad Blau
- Division of Metabolism, University Children's Hospital, Zürich, Switzerland.
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5
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Cheng YY, Gregorich Z, Prajnamitra RP, Lundy DJ, Ma TY, Huang YH, Lee YC, Ruan SC, Lin JH, Lin PJ, Kuo CW, Chen P, Yan YT, Tian R, Kamp TJ, Hsieh PC. Metabolic Changes Associated With Cardiomyocyte Dedifferentiation Enable Adult Mammalian Cardiac Regeneration. Circulation 2022; 146:1950-1967. [PMID: 36420731 PMCID: PMC9808601 DOI: 10.1161/circulationaha.122.061960] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 09/29/2022] [Indexed: 11/25/2022]
Abstract
BACKGROUND Cardiac regeneration after injury is limited by the low proliferative capacity of adult mammalian cardiomyocytes (CMs). However, certain animals readily regenerate lost myocardium through a process involving dedifferentiation, which unlocks their proliferative capacities. METHODS We bred mice with inducible, CM-specific expression of the Yamanaka factors, enabling adult CM reprogramming and dedifferentiation in vivo. RESULTS Two days after induction, adult CMs presented a dedifferentiated phenotype and increased proliferation in vivo. Microarray analysis revealed that upregulation of ketogenesis was central to this process. Adeno-associated virus-driven HMGCS2 overexpression induced ketogenesis in adult CMs and recapitulated CM dedifferentiation and proliferation observed during partial reprogramming. This same phenomenon was found to occur after myocardial infarction, specifically in the border zone tissue, and HMGCS2 knockout mice showed impaired cardiac function and response to injury. Finally, we showed that exogenous HMGCS2 rescues cardiac function after ischemic injury. CONCLUSIONS Our data demonstrate the importance of HMGCS2-induced ketogenesis as a means to regulate metabolic response to CM injury, thus allowing cell dedifferentiation and proliferation as a regenerative response.
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Affiliation(s)
- Yuan-Yuan Cheng
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Zachery Gregorich
- Department of Medicine and Stem Cell and Regenerative Medicine Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
| | | | - David J. Lundy
- Graduate Institute of Biomedical Materials and Tissue Engineering, Taipei Medical University, Taipei 110, Taiwan
| | - Ting-Yun Ma
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Yu-Hsuan Huang
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Yi-Chan Lee
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Shu-Chian Ruan
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Jen-Hao Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Po-Ju Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Chiung Wen Kuo
- Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Peilin Chen
- Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Yu-Ting Yan
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Rong Tian
- Mitochondria and Metabolism Center, Department of Anesthesiology and Pain Medicine and Department of Bioengineering, University of Washington, Seattle, WA 98109, USA
| | - Timothy J. Kamp
- Department of Medicine and Stem Cell and Regenerative Medicine Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Patrick C.H. Hsieh
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
- Department of Medicine and Stem Cell and Regenerative Medicine Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
- Graduate Institute of Medical Genomics and Proteomics and Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
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6
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Wu S, Shen L, Chen Q, Gong C, Yang Y, Wei H, Cao B, Chen Y. Clinical, Biochemical, Molecular, and Outcome Features of Mitochondrial 3-Hydroxy-3-Methylglutaryl-CoA Synthase Deficiency in 10 Chinese Patients. Front Genet 2022; 12:816779. [PMID: 35308163 PMCID: PMC8931749 DOI: 10.3389/fgene.2021.816779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 12/31/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency (HMGCS2D) is a rare autosomal recessive metabolic disorder caused by mutations of the HMGCS2 gene. To date, no more than 60 patients have been reported throughout the world. Purpose: To analyze the clinical, biochemical, molecular, and outcome features of HMGCS2D in a case series of 10 new Chinese patients. Methods: This retrospective study includes 10 Chinese patients diagnosed with HMGCS2D. We collected and analyzed clinical data for all patients. We also reviewed clinical data for 39 cases that had been reported previously. Results: All of our patients had experienced their first metabolic crisis before 12 months old. The most common clinical manifestations were anorexia, dyspnea, and disturbance of consciousness (10/10), followed by vomiting (8/10), fever (7/10), cough (4/10), diarrhea, and seizures (3/10). Each patient (10/10) had a different degree of hepatomegaly and increased aminotransferase, severe metabolic acidosis, and hypofibrinogenemia. 9 patients presented with severe hypoglycemia and weak positives on qualitative tests of urinary ketone body. Patient 3 was the only one without hypoglycemia. Five patients had hypocalcemia, five patients had hyperammonemia, four patients had hyperuricemia, and three had hypertriglyceridemia. During the metabolic acidosis episode, we observed high dicarboxylic acid values in urine, and the elevated ratio of blood acetylcarnitine to free carnitine may have been an additional biochemical signature. However, all returned to normal during the interictal interval. Molecular analysis identified 15 variants in the HMGCS2 gene, of which 10 were novel (c.220G>A/p.E74K, c.407A>G/p.D136G, c.422T>A/p.V141D, c.719A>C/p.D240A, c.821G>A/p.R274H, c.39dupA/p.L14Tfs*59, c.1394delA/p.N465Tfs*10, c.788delT/p.L263Cfs*36, c.717T>G/p.Y239*, and c.1017-2A>G). Combining these with previous cases, the known mutation c.1201G>T/p.E401* has been found in 6/40 (15.0%) of mutated alleles in 21 Chinese patients from 20 families, while none have been found in other populations. We found that patients with biallelic truncation mutation appeared to show a more severe clinical condition through a literature review. Conclusion: This study analyzed the phenotypic and genetic features of HMGCS2D in a Chinese case series. We also expanded the HMGCS2 mutational spectrum with 10 novel variants. The c.1201G>T/p.E401* mutation was the most frequent, representing 15.0% of the mutated alleles in reported unrelated Chinese patients, and thus, it may be a hot spot mutation.
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Affiliation(s)
- Shengnan Wu
- Department of Endocrinology and Metabolism, Henan Key Laboratory of Children’s Genetics and Metabolic Diseases, Children’s Hospital Affiliated to Zhengzhou University, Henan Children’s Hospital, Zhengzhou Children’s Hospital, Zhengzhou, China
| | - Linghua Shen
- Department of Endocrinology and Metabolism, Henan Key Laboratory of Children’s Genetics and Metabolic Diseases, Children’s Hospital Affiliated to Zhengzhou University, Henan Children’s Hospital, Zhengzhou Children’s Hospital, Zhengzhou, China
| | - Qiong Chen
- Department of Endocrinology and Metabolism, Henan Key Laboratory of Children’s Genetics and Metabolic Diseases, Children’s Hospital Affiliated to Zhengzhou University, Henan Children’s Hospital, Zhengzhou Children’s Hospital, Zhengzhou, China
| | - Chunxiu Gong
- Department of Endocrinology, Genetics and Metabolism, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, China
| | - Yanling Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Haiyan Wei
- Department of Endocrinology and Metabolism, Henan Key Laboratory of Children’s Genetics and Metabolic Diseases, Children’s Hospital Affiliated to Zhengzhou University, Henan Children’s Hospital, Zhengzhou Children’s Hospital, Zhengzhou, China
| | - Bingyan Cao
- Department of Endocrinology, Genetics and Metabolism, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, China
- *Correspondence: Yongxing Chen, ; Bingyan Cao,
| | - Yongxing Chen
- Department of Endocrinology and Metabolism, Henan Key Laboratory of Children’s Genetics and Metabolic Diseases, Children’s Hospital Affiliated to Zhengzhou University, Henan Children’s Hospital, Zhengzhou Children’s Hospital, Zhengzhou, China
- *Correspondence: Yongxing Chen, ; Bingyan Cao,
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7
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Hurst IA, Calhoun A, Mehren R, Held P, Asamoa-Bonsu Y, Cathers A. Metabolic Emergency in Flight. Air Med J 2022; 41:141-146. [PMID: 35248334 DOI: 10.1016/j.amj.2021.10.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/21/2021] [Indexed: 11/16/2022]
Abstract
Young children with inborn errors of metabolism often present to medical care in extremis, although their symptoms can be nonspecific. Rare metabolic disorders are not always on the statewide newborn screening panels, so infants and children can present later in life with vomiting, altered mental status, seizures, coma, or death, without any indication prior of a metabolic disorder. Swift transport to a pediatric specialty center can be lifesaving and prevent neurologic damage in these patients while awaiting definitive testing for these genetic disorders. Transport of these patients is complicated because they are often critically ill yet do not respond normally to routine resuscitation. In this case, we describe the transport of a patient with a rare, undifferentiated inborn error of metabolism with a pediatric specialty flight team and the considerations made in resuscitation and treatment of this patient in flight.
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Affiliation(s)
- Irene A Hurst
- Department of Emergency Medicine, University of Wisconsin-Madison, Madison, WI; Division of Pediatric Emergency Medicine, University of Wisconsin-Madison, Madison, WI; School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI.
| | - Amy Calhoun
- University of Iowa Stead Family Children's Hospital, Department of Pediatrics, Division of Medical Genetics and Genomics, University of Iowa Healthcare, Iowa City, IA
| | - Ryan Mehren
- UW Med Flight, University of Wisconsin-Madison, Madison, WI
| | - Patrice Held
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI; Department of Pediatrics, University of Wisconsin-Madison, Madison, WI; Wisconsin State Laboratory of Hygiene, Madison, WI
| | - Yaw Asamoa-Bonsu
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI; Division of Pediatric Critical Care, University of Wisconsin-Madison, Madison, WI
| | - Andrew Cathers
- Department of Emergency Medicine, University of Wisconsin-Madison, Madison, WI; School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI; UW Med Flight, University of Wisconsin-Madison, Madison, WI
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8
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Wolfgang MJ, Choi J, Scafidi S. Functional loss of ketogenesis in odontocete cetaceans. J Exp Biol 2021; 224:272651. [PMID: 34605907 PMCID: PMC8601715 DOI: 10.1242/jeb.243062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 09/29/2021] [Indexed: 12/13/2022]
Abstract
Odontocete cetaceans exhibit genomic mutations in key ketogenesis genes. In order to validate an inferred lack of ketogenesis made by observations from genome sequencing, we biochemically analyzed tissues from several odontocete cetacean species and demonstrate that they indeed do not exhibit appreciable hepatic β-hydroxybutyrate (βHB) or its carnitine ester. Furthermore, liver tissue exhibited significantly lower long chain acylcarnitines and increased odd chain acylcarnitines indicative of a decreased reliance on hepatic long chain fatty acid oxidation in these carnivorous mammals. Finally, we performed single molecule, real-time next generation sequencing of liver and brain RNA of Tursiops truncatus and demonstrate that the succinyl-CoA transferase required for acetoacetate catabolism is expressed in the nervous system. These data show that odontocete cetaceans have lost the ability to perform ketogenesis and suggest a hepatocentric coenzyme A recycling function rather than a predominantly systemic-bioenergetic role for ketogenesis in other ketogenic competent mammals such as humans.
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Affiliation(s)
- Michael J. Wolfgang
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA,Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Joseph Choi
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Susanna Scafidi
- Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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9
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Horst EA, Kvidera SK, Baumgard LH. Invited review: The influence of immune activation on transition cow health and performance-A critical evaluation of traditional dogmas. J Dairy Sci 2021; 104:8380-8410. [PMID: 34053763 DOI: 10.3168/jds.2021-20330] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 04/15/2021] [Indexed: 12/11/2022]
Abstract
The progression from gestation into lactation represents the transition period, and it is accompanied by marked physiological, metabolic, and inflammatory adjustments. The entire lactation and a cow's opportunity to have an additional lactation are heavily dependent on how successfully she adapts during the periparturient period. Additionally, a disproportionate amount of health care and culling occurs early following parturition. Thus, lactation maladaptation has been a heavily researched area of dairy science for more than 50 yr. It was traditionally thought that excessive adipose tissue mobilization in large part dictated transition period success. Further, the magnitude of hypocalcemia has also been assumed to partly control whether a cow effectively navigates the first few months of lactation. The canon became that adipose tissue released nonesterified fatty acids (NEFA) and the resulting hepatic-derived ketones coupled with hypocalcemia lead to immune suppression, which is responsible for transition disorders (e.g., mastitis, metritis, retained placenta, poor fertility). In other words, the dogma evolved that these metabolites and hypocalcemia were causal to transition cow problems and that large efforts should be enlisted to prevent increased NEFA, hyperketonemia, and subclinical hypocalcemia. However, despite intensive academic and industry focus, the periparturient period remains a large hurdle to animal welfare, farm profitability, and dairy sustainability. Thus, it stands to reason that there are alternative explanations to periparturient failures. Recently, it has become firmly established that immune activation and the ipso facto inflammatory response are a normal component of transition cow biology. The origin of immune activation likely stems from the mammary gland, tissue trauma during parturition, and the gastrointestinal tract. If inflammation becomes pathological, it reduces feed intake and causes hypocalcemia. Our tenet is that immune system utilization of glucose and its induction of hypophagia are responsible for the extensive increase in NEFA and ketones, and this explains why they (and the severity of hypocalcemia) are correlated with poor health, production, and reproduction outcomes. In this review, we argue that changes in circulating NEFA, ketones, and calcium are simply reflective of either (1) normal homeorhetic adjustments that healthy, high-producing cows use to prioritize milk synthesis or (2) the consequence of immune activation and its sequelae.
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Affiliation(s)
- E A Horst
- Department of Animal Science, Iowa State University, Ames 50011
| | - S K Kvidera
- Department of Animal Science, Iowa State University, Ames 50011
| | - L H Baumgard
- Department of Animal Science, Iowa State University, Ames 50011.
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10
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Heidari M, Soleyman‐Nejad M, Isazadeh A, Shapouri J, Taskhiri MH, Ahangari R, Mohamadi AR, Ebrahimi M, Karimi H, Bolhassani M, Karimi Z, Heidari M. Association of a novel homozygous mutation in the HMGCS2 gene with an HMGCSD in an Iranian patient. Mol Genet Genomic Med 2020; 8:e1507. [PMID: 32969201 PMCID: PMC7667326 DOI: 10.1002/mgg3.1507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 05/08/2020] [Accepted: 07/14/2020] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND 3-Hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase 2 gene (HMGCS2) encodes a mitochondrial enzyme catalyzing the first reaction of ketogenesis metabolic pathway which provides lipid-derived energy for various organs during times of carbohydrate deprivation, such as fasting. Mutations in this gene are responsible for HMG-CoA synthase deficiency (HMGCSD). The aim of present study was to investigate the association of mutation in the HMGCS2 gene with HMGCSD in a patient with atypical symptoms. METHODS The clinical and genetic features of an 8-months-old girl with HMGCSD were evaluated. Molecular genetic testing was conducted using whole-exome sequencing (WES) in order to identify potential disease-causing mutation. The WES finding was confirmed by the polymerase chain reaction (PCR) amplification of the target sequence carried out for the patient and her parents. The PCR products were subjected to direct sequencing using forward and reverse specific primers corresponding to the HMGCS2 gene. RESULTS A novel homozygous missense mutation (c.266G>A p.Gly89Asp) was detected in the HMGCS2 gene. Sanger sequencing along with co-segregation analysis of all family members confirmed this novel pathogenic germline mutation. The mutant gene was found to be pathogenic by bioinformatics analysis. CONCLUSION To our best knowledge, this is the first report of HMGCSD in Iran which would expand our knowledge about the mutational spectrum of the HMGCS2 gene and the phenotype variations of the disease.
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Affiliation(s)
- Masoud Heidari
- Department of Animal BiologyFaculty of Natural SciencesUniversity of TabrizTabrizIran
| | | | - Alireza Isazadeh
- Immunology Research CenterTabriz University of Medical SciencesTabrizIran
| | - Javad Shapouri
- Pediatric Clinical Research and Development CenterQom University of Medical SciencesQomIran
| | - Mohammad Hossein Taskhiri
- Ariagene Medical Genetics LaboratoryQomIran
- Department of Cellular and Molecular GeneticsIslamic Azad University, Qom BranchQomIran
| | - Roghayyeh Ahangari
- Department of Obstetrics and GynecologyNekouei‐Hedayati‐Forghani HospitalQom University of Medical SciencesQomIran
| | | | | | - Hadi Karimi
- Qom Social Welfare and Rehabilitation CenterQomIran
| | | | | | - Mansour Heidari
- Ariagene Medical Genetics LaboratoryQomIran
- Department of Medical GeneticsTehran University of Medical Sciences (TUMSTehranIran
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11
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Rojnueangnit K, Maneechai P, Thaweekul P, Piriyanon P, Khositseth S, Ittiwut C, Chetruengchai W, Kamolvisit W, Theerapanon T, Suphapeetiporn K, Porntaveetus T, Shotelersuk V. Expanding phenotypic and mutational spectra of mitochondrial HMG-CoA synthase deficiency. Eur J Med Genet 2020; 63:104086. [PMID: 33045405 DOI: 10.1016/j.ejmg.2020.104086] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 09/09/2020] [Accepted: 10/04/2020] [Indexed: 11/29/2022]
Abstract
Mitochondrial 3-hydroxy-3 methylglutaryl-CoA synthase-2 deficiency (HMGCS2D) is a rare autosomal recessive inborn error of hepatic ketogenesis, caused by mutations in HMGCS2. As its clinical and laboratory manifestations resemble many other metabolic disorders, HMGCS2D definite diagnosis presents a challenge, frequently requiring molecular tests. Only 26 patients with HMGCS2 mutations have been previously described, and this study reports the first two unrelated Thai patients, a 9-month-old male and an 8-month-old female, with HMGCS2D. During acute episodes, steatorrhea and dyslipidemia occurred, both previously unreported. Increased serum levels of triglycerides, very low density lipoproteins (VLDL), and low density lipoproteins (LDL), along with a decreased serum level of HDL were found. Both patients had hypophosphatemic encephalopathy, and the female had metabolic acidosis without hypoglycemia. Trio whole-exome sequencing (WES) revealed that the male harbored two HMGCS2 mutations, a novel c.1480C>T (p.Arg494*) and a previously reported c.1502G>C (p.Arg501Pro), while the female was compound heterozygous for the c.1502G>C (p.Arg501Pro) and a previously reported mutation, c.520T>C (p.Phe174Leu). Interestingly, c.1502G>C (p.Arg501Pro) was not only found in both of our patients but also detected heterozygously in 9 out of 1081 unrelated individuals (allele frequency of 9/2162; 0.42%) in our in-house Thai exome database. Discovery of this common mutation suggests there could be about 14 babies with HMGCS2D within 800,000 newborns in Thailand annually. Therefore, awareness of HMGCS2D among medical personnel in Thailand should be raised.
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Affiliation(s)
- Kitiwan Rojnueangnit
- Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathumthani, 12120, Thailand
| | - Parisa Maneechai
- Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathumthani, 12120, Thailand
| | - Patcharapa Thaweekul
- Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathumthani, 12120, Thailand
| | - Punnapat Piriyanon
- Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathumthani, 12120, Thailand
| | - Sookkasem Khositseth
- Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathumthani, 12120, Thailand
| | - Chupong Ittiwut
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Wanna Chetruengchai
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Wuttichart Kamolvisit
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Thanakorn Theerapanon
- Genomics and Precision Dentistry Research Unit, Department of Physiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Kanya Suphapeetiporn
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Thantrira Porntaveetus
- Genomics and Precision Dentistry Research Unit, Department of Physiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand.
| | - Vorasuk Shotelersuk
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
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12
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Conlon TA, Fitzsimons PE, Borovickova I, Kirby F, Murphy S, Knerr I, Crushell E. Hypoglycemia is not a defining feature of metabolic crisis in mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency: Further evidence of specific biochemical markers which may aid diagnosis. JIMD Rep 2020; 55:26-31. [PMID: 32905056 PMCID: PMC7463059 DOI: 10.1002/jmd2.12146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 05/25/2020] [Accepted: 05/27/2020] [Indexed: 11/12/2022] Open
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG Co-A) synthase (mHS) deficiency is an autosomal recessive disorder of ketone body synthesis which has traditionally been associated with hypoketotic hypoglycemia, hepatomegaly and encephalopathy, presenting in early childhood following a period of fasting. We report the third case of mHS deficiency presenting in the absence of hypoglycemia, with profound biochemical abnormalities and further evidence of potential specific diagnostic biomarkers. A previously well, 20-month old, unvaccinated male, of nonconsanguineous Polish heritage, presented with encephalopathy, hepatomegaly, severe metabolic acidosis, and mild hyperammonemia following a brief intercurrent illness. The patient was reported to have taken colloidal silver prior to presentation, posing a further diagnostic challenge. Additionally, he developed features suggestive of hemophagocytic lymphohistiocytosis during treatment. While the patient was normoglycemic prior to dextrose administration, the sample was markedly lipemic, with significant hypertriglyceridemia detected. Urine organic acid analysis revealed dicarboxylic aciduria with 4-hydroxy-6-methyl-2-pyrone (4HMP) and the presence of three other previously reported putative biomarkers for mHS deficiency. Glutarate was markedly elevated in the initial chromatogram, with a mild increase in 3-hydroxyglutarate (3HG) persisting. Raised acetylcarnitine was detected on acylcarnitine profile. Molecular genetic analysis of the HMGCS2 gene identified compound heterozygosity for known pathogenic mutations c.634G>A and c.1016+1G>A, confirming the diagnosis of mHS deficiency. This case provides further evidence that hypoglycemia is not invariably present in symptomatic mHS deficiency. We propose that elevated acetylcarnitine, triglycerides, and 3HG are additional biochemical features during acute presentations. With the expansion of novel biomarkers, further cases of this rare disorder may emerge.
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Affiliation(s)
- Tracey A. Conlon
- National Centre for Inherited Metabolic DisordersChildren's Health Ireland at Temple StreetDublinIreland
- School of MedicineUniversity College DublinDublinIreland
| | - Patricia E. Fitzsimons
- Department of Paediatric Laboratory MedicineChildren's Health Ireland at Temple StreetDublinIreland
| | - Ingrid Borovickova
- Department of Paediatric Laboratory MedicineChildren's Health Ireland at Temple StreetDublinIreland
| | - Fidelma Kirby
- Department of Paediatric Intensive CareChildren's Health Ireland at Temple StreetDublinIreland
| | - Sinéad Murphy
- School of MedicineUniversity College DublinDublinIreland
- Department of General PaediatricsChildren's Health Ireland at Temple StreetDublinIreland
| | - Ina Knerr
- National Centre for Inherited Metabolic DisordersChildren's Health Ireland at Temple StreetDublinIreland
- School of MedicineUniversity College DublinDublinIreland
| | - Ellen Crushell
- National Centre for Inherited Metabolic DisordersChildren's Health Ireland at Temple StreetDublinIreland
- School of MedicineUniversity College DublinDublinIreland
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13
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Clinical, biochemical, molecular and therapeutic characteristics of four new patients of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency. Clin Chim Acta 2020; 509:83-90. [PMID: 32470406 DOI: 10.1016/j.cca.2020.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 04/01/2020] [Accepted: 04/04/2020] [Indexed: 11/24/2022]
Abstract
Thirty patients with mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase (HMGCS) deficiency, which is a rare autosomal recessive disorder caused by HMGCS2 gene mutation are known. Here, we present four new patients with this disease. The characteristics including several metabolites of patients were recorded. Next-generation targeted sequencing and multiple sequence alignment of PCR amplified products allowed for mutational analysis of HMGCS2. Minigene assay transcript analysis confirmed pathogenicity of a splice site mutation. All cases had recurrent episodes with infections while they had no symptoms during intermissions. Patient 1, a girl, showed recurrent severe metabolic acidosis after infections from 8 months old and presented with weakness, vomiting and lethargy but had normal blood glucose. After treatment, she revived completely. Patients 2, 3 and 4 were boys who showed episodes of hypoglycemia since 8, 27 and 10 months of age, respectively. Glucose infusion reversed the symptoms. All four patients had hepatomegaly and abdominal imaging showed fatty livers. Serum free fatty acid increased. Urinary dicarboxylic acids and urinary 4-hydroxy-6-methyl-2pyrone presented. Diagnosis was confirmed by HMGCS2 gene analysis and 7 mutations (p.R188H, p.F420S, p.R206C, IVS2 + 1G > T, p.E401*, p.A450Pfs*7 and p.Q427*) of this gene were found. Here we report on the characteristics and genetics of four new patients with HMGCS deficiency. This study will enrich our knowledge of this rare autosomal recessive disorder.
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14
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Kılıç M, Dorum S, Topak A, Yazıcı MU, Ezgu FS, Coskun T. Expanding the clinical spectrum of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency with Turkish cases harboring novel HMGCS2 gene mutations and literature review. Am J Med Genet A 2020; 182:1608-1614. [PMID: 32259399 DOI: 10.1002/ajmg.a.61590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/20/2020] [Accepted: 03/24/2020] [Indexed: 11/10/2022]
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase (mHS) deficiency is a very rare autosomal recessive inborn error of ketone body synthesis and presents with hypoketotic hypoglycemia, metabolic acidosis, lethargy, encephalopathy, and hepatomegaly with fatty liver precipitated by catabolic stress. We report acute presentation of two patients from unrelated two families with novel homozygous c.862C>T and c.725-2A>C mutations, respectively, in HMGCS2 gene. Affected patients had severe hypoketotic hypoglycemia, lethargy, encephalopathy, severe metabolic and lactic acidosis and hepatomegaly after infections. Surprisingly, molecular screening of the second family showed more affected patients without clinical findings. These cases expand the clinic spectrum of this extremely rare disease.
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Affiliation(s)
- Mustafa Kılıç
- Sami Ulus Children Hospital, Metabolism Unit, Ankara, Turkey
| | - Sevil Dorum
- Department of Pediatrics, Metabolism Unit, Yuksek Ihtisas Training and Research Hospital, Bursa, Turkey
| | - Ali Topak
- Medical Genetic Unit, Yuksek Ihtisas Training and Research Hospital, Bursa, Turkey
| | - Mutlu U Yazıcı
- Sami Ulus Children Hospital, Intensive Care Unit, Ankara, Turkey
| | - Fatih S Ezgu
- Department of Pediatrics, Metabolism Unit, Gazi University, Ankara, Turkey
| | - Turgay Coskun
- Department of Pediatrics, Metabolism Unit, Hacettepe University, Ankara, Turkey
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15
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Bagheri-Fam S, Chen H, Wilson S, Ayers K, Hughes J, Sloan-Bena F, Calvel P, Robevska G, Puisac B, Kusz-Zamelczyk K, Gimelli S, Spik A, Jaruzelska J, Warenik-Szymankiewicz A, Faradz S, Nef S, Pié J, Thomas P, Sinclair A, Wilhelm D. The gene encoding the ketogenic enzyme HMGCS2 displays a unique expression during gonad development in mice. PLoS One 2020; 15:e0227411. [PMID: 31910233 PMCID: PMC6946174 DOI: 10.1371/journal.pone.0227411] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 12/18/2019] [Indexed: 11/26/2022] Open
Abstract
Disorders/differences of sex development (DSD) cause profound psychological and reproductive consequences for the affected individuals, however, most are still unexplained at the molecular level. Here, we present a novel gene, 3-hydroxy-3-methylglutaryl coenzyme A synthase 2 (HMGCS2), encoding a metabolic enzyme in the liver important for energy production from fatty acids, that shows an unusual expression pattern in developing fetal mouse gonads. Shortly after gonadal sex determination it is up-regulated in the developing testes following a very similar spatial and temporal pattern as the male-determining gene Sry in Sertoli cells before switching to ovarian enriched expression. To test if Hmgcs2 is important for gonad development in mammals, we pursued two lines of investigations. Firstly, we generated Hmgcs2-null mice using CRISPR/Cas9 and found that these mice had gonads that developed normally even on a sensitized background. Secondly, we screened 46,XY DSD patients with gonadal dysgenesis and identified two unrelated patients with a deletion and a deleterious missense variant in HMGCS2 respectively. However, both variants were heterozygous, suggesting that HMGCS2 might not be the causative gene. Analysis of a larger number of patients in the future might shed more light into the possible association of HMGCS2 with human gonadal development.
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Affiliation(s)
- Stefan Bagheri-Fam
- Department of Anatomy & Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Huijun Chen
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Sean Wilson
- Murdoch Children’s Research Institute, Melbourne, Australia
| | - Katie Ayers
- Murdoch Children’s Research Institute, Melbourne, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Australia
| | - James Hughes
- School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | | | - Pierre Calvel
- Department of Genetics, Medicine & Development, University of Geneva, Geneva, Switzerland
| | - Gorjana Robevska
- Murdoch Children’s Research Institute, Melbourne, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Australia
| | - Beatriz Puisac
- Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, CIBERER-GCV02 and ISS-Aragon, Zaragoza, Spain
| | | | - Stefania Gimelli
- Service of Genetic Medicine, University Geneva Hospitals, Geneva, Switzerland
| | - Anna Spik
- Institute of Human Genetics, Polish Academy of Sciences, Poznań, Poland
| | | | | | - Sultana Faradz
- Center for Biomedical Research Faculty of Medicine Diponegoro University (FMDU), Semarang, Indonesia
| | - Serge Nef
- Service of Genetic Medicine, University Geneva Hospitals, Geneva, Switzerland
| | - Juan Pié
- Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, CIBERER-GCV02 and ISS-Aragon, Zaragoza, Spain
| | - Paul Thomas
- School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | - Andrew Sinclair
- Murdoch Children’s Research Institute, Melbourne, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Australia
| | - Dagmar Wilhelm
- Department of Anatomy & Neuroscience, The University of Melbourne, Melbourne, Australia
- * E-mail:
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16
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Severe clinical manifestation of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency associated with two novel mutations: a case report. BMC Pediatr 2019; 19:344. [PMID: 31597564 PMCID: PMC6784346 DOI: 10.1186/s12887-019-1747-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 09/24/2019] [Indexed: 11/29/2022] Open
Abstract
Background Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase (mHS) deficiency is an autosomal recessive inborn error of metabolism, which will give rise to failure of ketogenesis in liver during illness or fasting. It is a very rare disease with only a few patients reported worldwide, most of which had a good prognosis after proper therapies. Case presentation We report a 9-month-old boy with mHS deficiency presenting with unusually severe and persistent acidosis after diarrhea and reduced oral food intake. The metabolic acidosis persisted even after supplementation with sugar and alkaline solution. Blood purification and assisted respiration alleviated symptoms, but a second onset induced by respiratory infection several days later led to multiple organ failure and death. Urine organic acid analysis during the acute episode revealed a complex pattern of ketogenic dicarboxylic and 3-hydroxydicarboxylic aciduria with prominent elevation of glutaric acid and adipic acid, which seem to be specific to mHS deficiency. Plasma acylcarnitine analysis revealed elevated 3-hydroxybutyrylcarnitine and acetylcarnitine. This is the first report of elevated 3-hydroxybutyrylcarnitine in mHS deficiency. Whole exome sequencing revealed a novel compound heterozygous mutation in HMGCS2 (c.100C > T and c.1465delA). Conclusion This severe case suggests the need for patients with mHS deficiency to avoid recurrent illness because it can induce severe metabolic crisis, possibly leading to death. Such patients may also require special treatment, such as blood purification. Urine organic acid profile during the acute episode may give a hint to the disease.
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17
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Lee T, Takami Y, Yamada K, Kobayashi H, Hasegawa Y, Sasai H, Otsuka H, Takeshima Y, Fukao T. A Japanese case of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency who presented with severe metabolic acidosis and fatty liver without hypoglycemia. JIMD Rep 2019; 48:19-25. [PMID: 31392109 PMCID: PMC6606983 DOI: 10.1002/jmd2.12051] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 05/15/2019] [Accepted: 05/15/2019] [Indexed: 11/17/2022] Open
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency (mHS deficiency) is a rare autosomal recessive inborn error of ketogenesis caused by a mutation in the HMGCS2 gene, which is characterized by non-(hypo)-ketotic hypoglycemia, lethargy, and hepatomegaly during acute infection and/or prolonged fasting. Clinical presentations are similar to fatty acid oxidation defects; however, diagnosis of mHS deficiency is difficult because of poor biochemical markers. We report the case of a 12-month-old Japanese boy with mHS deficiency who presented with a coma, and hepatomegaly, but no hypoglycemia after a febrile episode and poor oral intake. Metabolic acidosis and severe fatty liver were observed. Serum acylcarnitine analysis revealed a slightly decreased free carnitine (C0) level and an increased acetylcarnitine (C2) level. Urinary organic acid analysis revealed hypoketotic dicarboxylic aciduria, and increased excretions of glutarate, and, retrospectively, 4-hydroxy-6-methyl-2-pyrone. Although the patient did not present with hypoglycemia, the severe fatty liver and elevated free fatty acids to total ketone bodies ratio strongly suggested an inborn error of ketogenesis. In the analysis of the HMGCS2 gene, compound heterozygous mutations of c.130_131ins C (L44PfsX29) and c.1156_1157insC (L386PfsX73) were identified, which led to the diagnosis of mHS deficiency. He had recovered without any complication by the therapy, including intravenous glucose infusion. Unlike the previously reported cases of mHS deficiency, our case did not present with hypoglycemia and the fatty liver lasted over several months. mHS deficiency should be taken into consideration when a patient has severe metabolic acidosis and fatty liver with no or subtle ketosis, even without hypoglycemia.
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Affiliation(s)
- Tomoko Lee
- Department of PediatricsHyogo College of MedicineNishinomiyaJapan
| | - Yuichi Takami
- Department of PediatricsJapanese Red Cross Society Himeji HospitalHimejiJapan
| | - Kenji Yamada
- Department of PediatricsShimane University Faculty of MedicineIzumoJapan
| | - Hironori Kobayashi
- Department of PediatricsShimane University Faculty of MedicineIzumoJapan
| | - Yuki Hasegawa
- Department of PediatricsShimane University Faculty of MedicineIzumoJapan
| | - Hideo Sasai
- Department of PediatricsGraduate School of Medicine, Gifu UniversityGifuJapan
| | - Hiroki Otsuka
- Department of PediatricsGraduate School of Medicine, Gifu UniversityGifuJapan
| | | | - Toshiyuki Fukao
- Department of PediatricsGraduate School of Medicine, Gifu UniversityGifuJapan
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18
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Zhang P, Hu X, Guo R, Guo J, Li W, Qian S, Hao C, Liu J. Novel HMGCS2 pathogenic variants in a Chinese family with mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency. Pediatr Investig 2019; 3:86-90. [PMID: 32851297 PMCID: PMC7331301 DOI: 10.1002/ped4.12130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 04/22/2019] [Indexed: 11/10/2022] Open
Abstract
IMPORTANCE Mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase deficiency is a rare and underdiagnosed disorder with fewer than 30 patients reported worldwide. The application of whole-exome sequencing in patients could improve our understanding of this disorder. OBJECTIVE To identify the genetic causes and evaluate the phenotype of mitochondrial HMG-CoA synthase deficiency in a pediatric patient with uncommon features that included ketosis and elevated lactate and ammonia. METHODS The proband was referred to the pediatric intensive care unit of Beijing Children's Hospital and selected for molecular testing with whole-exome sequencing. Her parents and sibling also underwent sequencing for segregation information. RESULTS We identified two novel mutations (c.1347_1351delAGCCT/p.Ala450Profs*7 and c.1201G>T/ p.Glu401*) in the HMG-CoA synthase-2 gene (HMGCS2, NM_005518.3) in the proband and her brother. Both variants were classified as pathogenic variants according to the American College of Medical Genetics and Genomics/ Association for Molecular Pathology guidelines. Metabolic acidosis in the proband was corrected with continuous renal replacement therapy and she left hospital after 21 days of treatment. INTERPRETATION Our results extend the genotypic and phenotypic spectrum of HMGCS2 mutation in mitochondrial HMG-CoA synthase deficiency patients and serve as a reminder for physicians to consider mitochondrial HMG-CoA synthase deficiency in newborns and children with coma and hypoketotic hypoglycemia after fasting.
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Affiliation(s)
- Pengfei Zhang
- Department of Pediatric Intensive Care UnitBeijing Children's HospitalCapital Medical University; National Center for Children's HealthBeijing100045China
| | - Xuyun Hu
- Beijing Key Laboratory for Genetics of Birth DefectsBeijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control CenterBeijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijingChina
- Henan Key Laboratory of Pediatric Inherited & Metabolic DiseasesHenan Children's HospitalZhengzhou Hospital of Beijing Children's HospitalZhengzhouChina
| | - Ruolan Guo
- Beijing Key Laboratory for Genetics of Birth DefectsBeijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control CenterBeijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijingChina
- Henan Key Laboratory of Pediatric Inherited & Metabolic DiseasesHenan Children's HospitalZhengzhou Hospital of Beijing Children's HospitalZhengzhouChina
| | - Jun Guo
- Beijing Key Laboratory for Genetics of Birth DefectsBeijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control CenterBeijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijingChina
- Henan Key Laboratory of Pediatric Inherited & Metabolic DiseasesHenan Children's HospitalZhengzhou Hospital of Beijing Children's HospitalZhengzhouChina
| | - Wei Li
- Beijing Key Laboratory for Genetics of Birth DefectsBeijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control CenterBeijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijingChina
- Henan Key Laboratory of Pediatric Inherited & Metabolic DiseasesHenan Children's HospitalZhengzhou Hospital of Beijing Children's HospitalZhengzhouChina
| | - Suyun Qian
- Department of Pediatric Intensive Care UnitBeijing Children's HospitalCapital Medical University; National Center for Children's HealthBeijing100045China
| | - Chanjuan Hao
- Beijing Key Laboratory for Genetics of Birth DefectsBeijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control CenterBeijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijingChina
- Henan Key Laboratory of Pediatric Inherited & Metabolic DiseasesHenan Children's HospitalZhengzhou Hospital of Beijing Children's HospitalZhengzhouChina
| | - Jun Liu
- Department of Pediatric Intensive Care UnitBeijing Children's HospitalCapital Medical University; National Center for Children's HealthBeijing100045China
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19
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Ma D, Yu D. [Mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase deficiency: a case report and literature review]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2018; 20:930-933. [PMID: 30477625 PMCID: PMC7389032 DOI: 10.7499/j.issn.1008-8830.2018.11.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 10/12/2018] [Indexed: 06/09/2023]
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase deficiency (HMCSD) is caused by HMGCS2 gene mutation. This paper reports the clinical and genetic features of an infant with this disease. The 8-month-old female infant was admitted to the hospital with diarrhea for 1 week and fever and convulsion for 1 day. The child presented with seizures, acidosis, hypoglycemia, abnormal liver function, myocardial injury and coagulation dysfunction. The new homozygous mutation c.1502G>A(p.R501Q) in the HMGCS2 gene was found in the infant by genetic testing. The mutant gene was found to be harmful by bioinformatics software analysis. Urine organic acid analysis indicated that 4-hydroxy-6-methyl-2-pyranone was significantly increased, which was consistent with the results of genetic testing. The infant was definitely diagnosed with HMCSD.
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Affiliation(s)
- Dan Ma
- Department of Rehabilitation Medicine, West China Second University Hospital of Sichuan University, Chengdu 610041, China.
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20
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Jebb D, Hiller M. Recurrent loss of HMGCS2 shows that ketogenesis is not essential for the evolution of large mammalian brains. eLife 2018; 7:38906. [PMID: 30322448 PMCID: PMC6191284 DOI: 10.7554/elife.38906] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 09/09/2018] [Indexed: 12/04/2022] Open
Abstract
Apart from glucose, fatty acid-derived ketone bodies provide metabolic energy for the brain during fasting and neonatal development. We investigated the evolution of HMGCS2, the key enzyme required for ketone body biosynthesis (ketogenesis). Unexpectedly, we found that three mammalian lineages, comprising cetaceans (dolphins and whales), elephants and mastodons, and Old World fruit bats have lost this gene. Remarkably, many of these species have exceptionally large brains and signs of intelligent behavior. While fruit bats are sensitive to starvation, cetaceans and elephants can still withstand periods of fasting. This suggests that alternative strategies to fuel large brains during fasting evolved repeatedly and reveals flexibility in mammalian energy metabolism. Furthermore, we show that HMGCS2 loss preceded brain size expansion in toothed whales and elephants. Thus, while ketogenesis was likely important for brain size expansion in modern humans, ketogenesis is not a universal precondition for the evolution of large mammalian brains. Our brain requires a lot of energy to work properly. Sugars are usually the main type of fuel for the body, but when they run low – for example during a food shortage – fat, in the form of fatty acids, can be used instead. However, the brain cannot directly process these molecules; instead, fatty acids need to go through ketogenesis, a process that turns fat into ketone bodies, which the organ can then burn. Scientists believe that the ability to create ketone bodies was essential for us to evolve large brains. Yet, it is still unclear if all mammals can transform fatty acids into ketone bodies. One way to look into this question is to track whether other species have HMGCS2, the main enzyme that drives ketogenesis. Jebb and Hiller examined the genomes of 70 different species of mammals for the gene that codes for HMGCS2. The comparisons revealed that cetaceans (whales, dolphins and porpoises), Old World fruit bats and the African savanna elephant have all independently lost their working version of HMGCS2. Yet, many members of these three groups have evolved brains that are large for their body size. The genetic analyses showed that dolphins and elephants developed big brains after the enzyme became inactive, challenging the idea that HMGCS2 – and by extension ketogenesis – is always required for the evolution of large brains. These results may also be useful for conservation efforts. Many fruit bats across the world are severely threatened, and their lack of ketogenesis could explain why these animals are highly sensitive to starvation and quickly die when food becomes scarce.
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Affiliation(s)
- David Jebb
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.,Center for Systems Biology Dresden, Dresden, Germany
| | - Michael Hiller
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.,Center for Systems Biology Dresden, Dresden, Germany
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21
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Mitochondrial 3-Hydroxy-3-Methylglutaryl-CoA Synthase Deficiency: Unique Presenting Laboratory Values and a Review of Biochemical and Clinical Features. JIMD Rep 2017; 40:63-69. [PMID: 29030856 PMCID: PMC6122033 DOI: 10.1007/8904_2017_59] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 08/28/2017] [Accepted: 08/29/2017] [Indexed: 01/27/2023] Open
Abstract
We report an 8-month-old infant with decreased consciousness after a febrile episode and reduced oral intake. He was profoundly acidotic but his lactate was normal. Serum triglycerides were markedly elevated and HDL cholesterol was very low. The urine organic acid analysis during the acute episode revealed a complex pattern of relative hypoketotic dicarboxylic aciduria, suggestive of a potential fatty acid oxidation disorder. MRI showed extensive brain abnormalities concerning for a primary energy deficiency. Whole exome sequencing revealed heterozygotic HMGCS2 variants. HMGCS2 encodes mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase-2 (HMGCS2), which catalyzes the irreversible and rate-limiting reaction of ketogenesis in the mitochondrial matrix. Autosomal recessive HMG-CoA synthase deficiency (HMGCS2D) is characterized by hypoketotic hypoglycemia, vomiting, lethargy, and hepatomegaly after periods of prolonged fasting or illness. A retrospective analysis of the urine organic acid analysis identified 4-hydrox-6-methyl-2-pyrone, a recently reported putative biomarker of HMGCS2D. There was also a relative elevation of plasma acetylcarnitine as previously reported in one case. Our patient highlights a unique presentation of HMGCS2D caused by novel variants in HMGCS2. This is the first report of HMGCS2D with a significantly elevated triglyceride level and decreased HDL cholesterol level at presentation. Given this, we suggest that HMGCS2D should be considered in the differential diagnosis when hypertriglyceridemia, or low HDL cholesterol levels are seen in a child who presents with acidosis, mild ketosis, and mental status changes after illness or prolonged fasting. Although HMGCS2D is a rare disorder with nonspecific symptoms, with the advent of next-generation sequencing, and the recognition of novel biochemical biomarkers, the incidence of this condition may become better understood.
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22
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Abstract
Ketone body metabolism is a central node in physiological homeostasis. In this review, we discuss how ketones serve discrete fine-tuning metabolic roles that optimize organ and organism performance in varying nutrient states and protect from inflammation and injury in multiple organ systems. Traditionally viewed as metabolic substrates enlisted only in carbohydrate restriction, observations underscore the importance of ketone bodies as vital metabolic and signaling mediators when carbohydrates are abundant. Complementing a repertoire of known therapeutic options for diseases of the nervous system, prospective roles for ketone bodies in cancer have arisen, as have intriguing protective roles in heart and liver, opening therapeutic options in obesity-related and cardiovascular disease. Controversies in ketone metabolism and signaling are discussed to reconcile classical dogma with contemporary observations.
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Affiliation(s)
- Patrycja Puchalska
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, FL 32827, USA
| | - Peter A Crawford
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, FL 32827, USA.
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23
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Tan Z, Chaudhai R, Zhang S. Polypharmacology in Drug Development: A Minireview of Current Technologies. ChemMedChem 2016; 11:1211-8. [PMID: 27154144 DOI: 10.1002/cmdc.201600067] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/21/2016] [Indexed: 01/09/2023]
Abstract
Polypharmacology, the process in which a single drug is able to bind to multiple targets specifically and simultaneously, is an emerging paradigm in drug development. The potency of a given drug can be increased through the engagement of multiple targets involved in a certain disease. Polypharmacology may also help identify novel applications of existing drugs through drug repositioning. However, many problems and challenges remain in this field. Rather than covering all aspects of polypharmacology, this Minireview is focused primarily on recently reported techniques, from bioinformatics technologies to cheminformatics approaches as well as text-mining-based methods, all of which have made significant contributions to the research of polypharmacology.
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Affiliation(s)
- Zhi Tan
- Integrated Molecular Discovery Laboratory, Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.,The University of Texas Graduate School of Biomedical Sciences, Houston, TX, 77030, USA
| | - Rajan Chaudhai
- Integrated Molecular Discovery Laboratory, Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Shuxing Zhang
- Integrated Molecular Discovery Laboratory, Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. .,The University of Texas Graduate School of Biomedical Sciences, Houston, TX, 77030, USA.
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24
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Pitt JJ, Peters H, Boneh A, Yaplito-Lee J, Wieser S, Hinderhofer K, Johnson D, Zschocke J. Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency: urinary organic acid profiles and expanded spectrum of mutations. J Inherit Metab Dis 2015; 38:459-66. [PMID: 25511235 DOI: 10.1007/s10545-014-9801-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 11/08/2014] [Accepted: 11/25/2014] [Indexed: 10/24/2022]
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase (HMCS2) deficiency results in episodes of hypoglycemia and increases in fatty acid metabolites. Metabolite abnormalities described to date in HMCS2 deficiency are nonspecific and overlap with other inborn errors of metabolism, making the biochemical diagnosis of HMCS2 deficiency difficult. Urinary organic acid profiles from periods of metabolic decompensation were studied in detail in HMCS2-deficient patients from four families. An additional six unrelated patients were identified from clinical presentation and/or qualitative identification of abnormal organic acids. The diagnosis was confirmed by sequencing and deletion/duplication analysis of the HMGCS2 gene. Seven related novel organic acids were identified in urine profiles. Five of them (3,5-dihydroxyhexanoic 1,5 lactone; trans-5-hydroxyhex-2-enoate; 4-hydroxy-6-methyl-2-pyrone; 5-hydroxy-3-ketohexanoate; 3,5-dihydroxyhexanoate) were identified by comparison with synthesized or commercial authentic compounds. We provisionally identified trans-3-hydroxyhex-4-enoate and 3-hydroxy-5-ketohexanoate by their mass spectral characteristics. These metabolites were found in samples taken during periods of decompensation and normalized when patients recovered. When cutoffs of adipic >200 and 4-hydroxy-6-methyl-2-pyrone >20 μmol/mmol creatinine were applied, all eight samples taken from five HMCS2-deficient patients during episodes of decompensation were flagged with a positive predictive value of 80% (95% confidence interval 35-100%). Some ketotic patients had increased 4-hydroxy-6-methyl-2-pyrone. Molecular studies identified a total of 12 novel mutations, including a large deletion of HMGCS2 exon 1 in two families, highlighting the need to perform quantitative gene analyses. There are now 26 known HMGCS2 mutations, which are reviewed in the text. 4-Hydroxy-6-methyl-2-pyrone and related metabolites are markers for HMCS2 deficiency. Detection of these metabolites will streamline the biochemical diagnosis of this disorder.
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Affiliation(s)
- James J Pitt
- Victorian Clinical Genetics Services, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, VIC, 3052, Australia,
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25
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Cotter DG, Ercal B, Huang X, Leid JM, d'Avignon DA, Graham MJ, Dietzen DJ, Brunt EM, Patti GJ, Crawford PA. Ketogenesis prevents diet-induced fatty liver injury and hyperglycemia. J Clin Invest 2014; 124:5175-90. [PMID: 25347470 DOI: 10.1172/jci76388] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 09/18/2014] [Indexed: 02/06/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) spectrum disorders affect approximately 1 billion individuals worldwide. However, the drivers of progressive steatohepatitis remain incompletely defined. Ketogenesis can dispose of much of the fat that enters the liver, and dysfunction in this pathway could promote the development of NAFLD. Here, we evaluated mice lacking mitochondrial 3-hydroxymethylglutaryl CoA synthase (HMGCS2) to determine the role of ketogenesis in preventing diet-induced steatohepatitis. Antisense oligonucleotide-induced loss of HMGCS2 in chow-fed adult mice caused mild hyperglycemia, increased hepatic gluconeogenesis from pyruvate, and augmented production of hundreds of hepatic metabolites, a suite of which indicated activation of the de novo lipogenesis pathway. High-fat diet feeding of mice with insufficient ketogenesis resulted in extensive hepatocyte injury and inflammation, decreased glycemia, deranged hepatic TCA cycle intermediate concentrations, and impaired hepatic gluconeogenesis due to sequestration of free coenzyme A (CoASH). Supplementation of the CoASH precursors pantothenic acid and cysteine normalized TCA intermediates and gluconeogenesis in the livers of ketogenesis-insufficient animals. Together, these findings indicate that ketogenesis is a critical regulator of hepatic acyl-CoA metabolism, glucose metabolism, and TCA cycle function in the absorptive state and suggest that ketogenesis may modulate fatty liver disease.
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26
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Fukao T, Mitchell G, Sass JO, Hori T, Orii K, Aoyama Y. Ketone body metabolism and its defects. J Inherit Metab Dis 2014; 37:541-51. [PMID: 24706027 DOI: 10.1007/s10545-014-9704-9] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Revised: 03/01/2014] [Accepted: 03/10/2014] [Indexed: 12/17/2022]
Abstract
Acetoacetate (AcAc) and 3-hydroxybutyrate (3HB), the two main ketone bodies of humans, are important vectors of energy transport from the liver to extrahepatic tissues, especially during fasting, when glucose supply is low. Blood total ketone body (TKB) levels should be evaluated in the context of clinical history, such as fasting time and ketogenic stresses. Blood TKB should also be evaluated in parallel with blood glucose and free fatty acids (FFA). The FFA/TKB ratio is especially useful for evaluation of ketone body metabolism. Defects in ketogenesis include mitochondrial HMG-CoA synthase (mHS) deficiency and HMG-CoA lyase (HL) deficiency. mHS deficiency should be considered in non-ketotic hypoglycemia if a fatty acid beta-oxidation defect is suspected, but cannot be confirmed. Patients with HL deficiency can develop hypoglycemic crises and neurological symptoms even in adolescents and adults. Succinyl-CoA-3-oxoacid CoA transferase (SCOT) deficiency and beta-ketothiolase (T2) deficiency are two defects in ketolysis. Permanent ketosis is pathognomonic for SCOT deficiency. However, patients with "mild" SCOT mutations may have nonketotic periods. T2-deficient patients with "mild" mutations may have normal blood acylcarnitine profiles even in ketoacidotic crises. T2 deficient patients cannot be detected in a reliable manner by newborn screening using acylcarnitines. We review recent data on clinical presentation, metabolite profiles and the course of these diseases in adults, including in pregnancy.
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Affiliation(s)
- Toshiyuki Fukao
- Department of Pediatrics, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu, 501-1194, Japan,
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27
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Liao P, Wang H, Hemmerlin A, Nagegowda DA, Bach TJ, Wang M, Chye ML. Past achievements, current status and future perspectives of studies on 3-hydroxy-3-methylglutaryl-CoA synthase (HMGS) in the mevalonate (MVA) pathway. PLANT CELL REPORTS 2014; 33:1005-22. [PMID: 24682521 DOI: 10.1007/s00299-014-1592-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 02/24/2014] [Indexed: 05/09/2023]
Abstract
HMGS functions in phytosterol biosynthesis, development and stress responses. F-244 could specifically-inhibit HMGS in tobacco BY-2 cells and Brassica seedlings. An update on HMGS from higher plants is presented. 3-Hydroxy-3-methylglutaryl-coenzyme A synthase (HMGS) is the second enzyme in the mevalonate pathway of isoprenoid biosynthesis and catalyzes the condensation of acetoacetyl-CoA and acetyl-CoA to produce S-3-hydroxy-3-methylglutaryl-CoA (HMG-CoA). Besides HMG-CoA reductase (HMGR), HMGS is another key enzyme in the regulation of cholesterol and ketone bodies in mammals. In plants, it plays an important role in phytosterol biosynthesis. Here, we summarize the past investigations on eukaryotic HMGS with particular focus on plant HMGS, its enzymatic properties, gene expression, protein structure, and its current status of research in China. An update of the findings on HMGS from animals (human, rat, avian) to plants (Brassica juncea, Hevea brasiliensis, Arabidopsis thaliana) will be discussed. Current studies on HMGS have been vastly promoted by developments in biochemistry and molecular biology. Nonetheless, several limitations have been encountered, thus some novel advances in HMGS-related research that have recently emerged will be touched on.
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Affiliation(s)
- Pan Liao
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China,
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28
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Abstract
Recognition of fatty acid oxidation (FAO) disorders is important for the pediatric neurologist as they present with a spectrum of clinical disorders, including progressive lipid storage myopathy, recurrent myoglobinuria, neuropathy, progressive cardiomyopathy, recurrent hypoglycemic hypoketotic encephalopathy or Reye-like syndrome, seizures, and mental retardation. They constitute a critical group of diseases because they are potentially rapidly fatal and a source of major morbidity. There is frequently a family history of sudden infant death syndrome in siblings. Early recognition and prompt institution of therapy and appropriate preventive measures, and in certain cases specific therapy, may be life-saving and may significantly decrease long-term morbidity, particularly with respect to CNS sequelae. All currently known conditions are inherited as autosomal recessive traits. There are now at least 25 enzymes and specific transport proteins in the β-oxidation pathway and 18 have been associated with human disease. The most common defect is medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, which had an incidence of 1 in 8930 live births in one series. The identification of serum acylcarnitines by electrospray ionization-tandem mass spectrometry of dried blood spots on filter paper in newborn screening programs has significantly enhanced the early recognition of these disorders.
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Affiliation(s)
- Ingrid Tein
- Neurometabolic Clinic and Research Laboratory, Division of Neurology and Genetics and Genome Biology Program, Research Institute, Hospital for Sick Children, University of Toronto, Toronto, Canada.
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29
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Abstract
The liver plays a unique, central role in regulating lipid metabolism. In addition to influencing hepatic function and disease, changes in specific pathways of fatty acid (FA) metabolism have wide-ranging effects on the metabolism of other nutrients, extra-hepatic physiology, and the development of metabolic diseases. The high prevalence of nonalcoholic fatty liver disease (NAFLD) has led to increased efforts to characterize the underlying biology of hepatic energy metabolism and FA trafficking that leads to disease development. Recent advances have uncovered novel roles of metabolic pathways and specific enzymes in generating lipids important for cellular processes such as signal transduction and transcriptional activation. These studies have also advanced our understanding of key branch points involving FA partitioning between metabolic pathways and have identified new roles for lipid droplets in these events. This review covers recent advances in our understanding of FA trafficking and its regulation. An emphasis will be placed on branch points in these pathways and how alterations in FA trafficking contribute to NAFLD and related comorbidities.
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30
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Ramos M, Menao S, Arnedo M, Puisac B, Gil-Rodríguez MC, Teresa-Rodrigo ME, Hernández-Marcos M, Pierre G, Ramaswami U, Baquero-Montoya C, Bueno G, Casale C, Hegardt FG, Gómez-Puertas P, Pié J. New case of mitochondrial HMG-CoA synthase deficiency. Functional analysis of eight mutations. Eur J Med Genet 2013; 56:411-5. [PMID: 23751782 DOI: 10.1016/j.ejmg.2013.05.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 05/27/2013] [Indexed: 11/29/2022]
Abstract
Mitochondrial HMG-CoA synthase deficiency is a rare inherited metabolic disorder that affects ketone-body synthesis. Acute episodes include vomiting, lethargy, hepatomegaly, hypoglycaemia, dicarboxylic aciduria, and in severe cases, coma. This deficiency may have been under-diagnosed owing to the absence of specific clinical and biochemical markers, limitations in liver biopsy and the lack of an effective method of expression and enzyme assay for verifying the mutations found. To date, eight patients have been reported with nine allelic variants of the HMGCS2 gene. We present a new method of enzyme expression and a modification of the activity assay that allows, for first time, the functional study of missense mutations found in patients with this deficiency. Four of the missense mutations (p.V54M, p.R188H, p.G212R and p.G388R) did not produce proteins that could have been detected in soluble form by western blot; three produced a total loss of activity (p.Y167C, p.M307T and p.R500H) and one, variant p.F174L, gave an enzyme with a catalytic efficiency of 11.5%. This indicates that the deficiency may occur with partial loss of activity of enzyme. In addition, we describe a new patient with this deficiency, in which we detected the missense allelic variant, c.1162G>A (p.G388R) and the nonsense variant c.1270C>T (p.R424X).
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Affiliation(s)
- Mónica Ramos
- Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology Physiology, Medical School, University of Zaragoza, Spain
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31
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Cotter DG, Schugar RC, Wentz AE, d'Avignon DA, Crawford PA. Successful adaptation to ketosis by mice with tissue-specific deficiency of ketone body oxidation. Am J Physiol Endocrinol Metab 2013; 304:E363-74. [PMID: 23233542 PMCID: PMC3566508 DOI: 10.1152/ajpendo.00547.2012] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
During states of low carbohydrate intake, mammalian ketone body metabolism transfers energy substrates originally derived from fatty acyl chains within the liver to extrahepatic organs. We previously demonstrated that the mitochondrial enzyme coenzyme A (CoA) transferase [succinyl-CoA:3-oxoacid CoA transferase (SCOT), encoded by nuclear Oxct1] is required for oxidation of ketone bodies and that germline SCOT-knockout (KO) mice die within 48 h of birth because of hyperketonemic hypoglycemia. Here, we use novel transgenic and tissue-specific SCOT-KO mice to demonstrate that ketone bodies do not serve an obligate energetic role within highly ketolytic tissues during the ketogenic neonatal period or during starvation in the adult. Although transgene-mediated restoration of myocardial CoA transferase in germline SCOT-KO mice is insufficient to prevent lethal hyperketonemic hypoglycemia in the neonatal period, mice lacking CoA transferase selectively within neurons, cardiomyocytes, or skeletal myocytes are all viable as neonates. Like germline SCOT-KO neonatal mice, neonatal mice with neuronal CoA transferase deficiency exhibit increased cerebral glycolysis and glucose oxidation, and, while these neonatal mice exhibit modest hyperketonemia, they do not develop hypoglycemia. As adults, tissue-specific SCOT-KO mice tolerate starvation, exhibiting only modestly increased hyperketonemia. Finally, metabolic analysis of adult germline Oxct1(+/-) mice demonstrates that global diminution of ketone body oxidation yields hyperketonemia, but hypoglycemia emerges only during a protracted state of low carbohydrate intake. Together, these data suggest that, at the tissue level, ketone bodies are not a required energy substrate in the newborn period or during starvation, but rather that integrated ketone body metabolism mediates adaptation to ketogenic nutrient states.
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Affiliation(s)
- David G Cotter
- Division of Cardiology, Dept. of Medicine, Washington Univ. School of Medicine, St. Louis, MO 63110, USA
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32
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Cotter DG, Schugar RC, Crawford PA. Ketone body metabolism and cardiovascular disease. Am J Physiol Heart Circ Physiol 2013; 304:H1060-76. [PMID: 23396451 DOI: 10.1152/ajpheart.00646.2012] [Citation(s) in RCA: 294] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ketone bodies are metabolized through evolutionarily conserved pathways that support bioenergetic homeostasis, particularly in brain, heart, and skeletal muscle when carbohydrates are in short supply. The metabolism of ketone bodies interfaces with the tricarboxylic acid cycle, β-oxidation of fatty acids, de novo lipogenesis, sterol biosynthesis, glucose metabolism, the mitochondrial electron transport chain, hormonal signaling, intracellular signal transduction pathways, and the microbiome. Here we review the mechanisms through which ketone bodies are metabolized and how their signals are transmitted. We focus on the roles this metabolic pathway may play in cardiovascular disease states, the bioenergetic benefits of myocardial ketone body oxidation, and prospective interactions among ketone body metabolism, obesity, metabolic syndrome, and atherosclerosis. Ketone body metabolism is noninvasively quantifiable in humans and is responsive to nutritional interventions. Therefore, further investigation of this pathway in disease models and in humans may ultimately yield tailored diagnostic strategies and therapies for specific pathological states.
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Affiliation(s)
- David G Cotter
- Department of Medicine, Center for Cardiovascular Research, Washington University, Saint Louis, Missouri 63110, USA
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33
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Sass JO. Inborn errors of ketogenesis and ketone body utilization. J Inherit Metab Dis 2012; 35:23-8. [PMID: 21479626 DOI: 10.1007/s10545-011-9324-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 03/20/2011] [Accepted: 03/21/2011] [Indexed: 10/18/2022]
Abstract
Ketone bodies acetoacetate and 3-hydroxy-n-butyric acid are metabolites derived from fatty acids and ketogenic amino acids such as leucine. They are mainly produced in the liver via reactions catalyzed by the ketogenic enzymes mitochondrial 3-hydroxy-3-methylglutary-coenzyme A synthase and 3-hydroxy-3-methylglutary-coenzyme A lyase. After prolonged starvation, ketone bodies can provide up to two-thirds of the brain's energy requirements. The rate-limiting enzyme of ketone body utilization (ketolysis) is succinyl-coenzyme A:3-oxoacid coenzyme A transferase. The subsequent step of ketolysis is catalyzed by 2-methylactoacetyl-coenzyme A thiolase, which is also involved in isoleucine catabolism. Inborn errors of metabolism affecting those four enzymes are presented and discussed in the context of differential diagnoses. While disorders of ketogenesis can present with hypoketotic hypoglycemia, inborn errors of ketolysis are characterized by metabolic decompensations with ketoacidosis. If those diseases are considered early and appropriate treatment is initiated without delay, patients with inborn errors of ketone body metabolism often have a good clinical outcome.
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Affiliation(s)
- Jörn Oliver Sass
- Zentrum für Kinder- und Jugendmedizin, Labor für Klinische Biochemie und Stoffwechsel, Universitätsklinikum Freiburg, Mathildenstr. 1, 79106 Freiburg, Germany.
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Derks TGJ, van Dijk TH, Grefhorst A, Rake JP, Smit GPA, Kuipers F, Reijngoud DJ. Inhibition of mitochondrial fatty acid oxidation in vivo only slightly suppresses gluconeogenesis but enhances clearance of glucose in mice. Hepatology 2008; 47:1032-42. [PMID: 18302288 DOI: 10.1002/hep.22101] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
UNLABELLED Mitochondrial fatty acid oxidation (mFAO) is considered to be essential for driving gluconeogenesis (GNG) during fasting. However, quantitative in vivo data on de novo synthesis of glucose-6-phosphate upon acute inhibition of mFAO are lacking. We assessed hepatic glucose metabolism in vivo after acute inhibition of mFAO by 30 mg kg(-1) 2-tetradecylglycidic acid (TDGA) in hypoketotic hypoglycemic male C57BL/6J mice by the infusion of [U-(13)C]glucose, [2-(13)C]glycerol, [1-(2)H]galactose, and paracetamol for 6 hours, which was followed by mass isotopomer distribution analysis in blood glucose and urinary paracetamol-glucuronide. During TDGA treatment, endogenous glucose production was unaffected (127 +/- 10 versus 118 +/- 7 micromol kg(-1) minute(-1), control versus TDGA, not significant), but the metabolic clearance rate of glucose was significantly enhanced (15.9 +/- 0.9 versus 26.3 +/- 1.1 mL kg(-1) minute(-1), control versus TDGA,P < 0.05). In comparison with control mice, de novo synthesis of glucose-6-phosphate (G6P) was slightly decreased in TDGA-treated mice (108 +/- 19 versus 85 +/- 6 micromol kg(-1) minute(-1), control versus TDGA, P < 0.05). Recycling of glucose was decreased upon TDGA treatment (26 +/- 14 versus 12 +/- 4 micromol kg(-1) minute(-1), control versus TDGA, P < 0.05). Hepatic messenger RNA (mRNA) levels of genes encoding enzymes involved in de novo G6P synthesis were unaltered, whereas glucose-6-phosphate hydrolase mRNA expressions were increased in TDGA-treated mice. Glucokinase and pyruvate kinase mRNA levels were significantly decreased, whereas pyruvate dehydrogenase kinase isozyme 4 expression was increased 30-fold; this suggested decreased glycolytic activity. CONCLUSION Acute pharmacological inhibition of mFAO using TDGA had no effect on endogenous glucose production and only a marginal effect on de novo G6P synthesis. Hence, fully active mFAO is not essential for maintenance of hepatic GNG in vivo in fasted mice.
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Affiliation(s)
- Terry G J Derks
- Department of Pediatrics, Laboratory of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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35
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Yamazaki Y, Kakizaki S, Takizawa D, Ichikawa T, Sato K, Takagi H, Mori M. Interstrain differences in susceptibility to non-alcoholic steatohepatitis. J Gastroenterol Hepatol 2008; 23:276-82. [PMID: 17868334 DOI: 10.1111/j.1440-1746.2007.05150.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIM The pathophysiological mechanisms leading to the development of non-alcoholic steatohepatitis (NASH) remain unclear. There are differences in the susceptibility to NASH between the different species and sexes. The investigation of the precise mechanism of interstrain differences may provide new means by which the pathophysiological mechanisms of NASH may be understood. METHODS C57BL/6N and C3H/HeN mice were administered a methionine- and choline-deficient (MCD) diet to establish a dietary model of NASH. RESULTS An elevation of the serum alanine aminotransferase and increased infiltration of inflammatory cells were predominant in C57BL/6N mice at 8 weeks. The increase in the steatosis and lipid contents in the liver was greater in C57BL/6N mice than in C3H/HeN mice. The indices of lipid peroxidation demonstrated by F2-isoprostanes or 8-hydroxy-2'-deoxyguanosine also increased in the livers of C57BL/6N mice. Furthermore, Sirius red staining revealed an increase in the degree of fibrosis in C57BL/6N mice given the MCD diet. As a result, the C57BL/6N strain had a higher susceptibility to NASH than the C3H/HeN mice. The carnitine palmitoyltransferase 1A (in beta-oxidation) mRNA and mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase 2 (in ketogenesis) mRNA were downregulated in the C57BL/6N mice in comparison with C3H/HeN mice. There were no differences in the expression of microsomal triglyceride transfer protein or sterol regulatory element binding protein 1 between the C57BL/6N and C3H/HeN mice. CONCLUSION There were interstrain differences in susceptibility to NASH observed in a rodent dietary model. Further evaluations of the precise molecular mechanism of this interstrain difference may provide some indications of the pathophysiological mechanisms of NASH in humans.
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Affiliation(s)
- Yuichi Yamazaki
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
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Aledo R, Mir C, Dalton RN, Turner C, Pié J, Hegardt FG, Casals N, Champion MP. Refining the diagnosis of mitochondrial HMG-CoA synthase deficiency. J Inherit Metab Dis 2006; 29:207-11. [PMID: 16601895 DOI: 10.1007/s10545-006-0214-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Mitochondrial HMG-CoA synthase deficiency is an inherited metabolic disorder caused by a defect in the enzyme that regulates the formation of ketone bodies. Patients present with hypoketotic hypoglycaemia, encephalopathy and hepatomegaly, usually precipitated by an intercurrent infection or prolonged fasting. The diagnosis may easily be missed as previously reported results of routine metabolic investigations, urinary organic acids and plasma acylcarnitines may be nonspecific or normal, and a high index of suspicion is required to proceed to further confirmatory tests. We describe a further acute case in which the combination of urinary organic acids, low free carnitine and changes in the plasma acylcarnitine profile on carnitine supplementation were very suggestive of a defect in ketone synthesis. The diagnosis of mitochondrial HMG-CoA synthase deficiency was confirmed on genotyping, revealing two novel mutations: c.614G > A (R188H) and c.971T > C (M307T). A further sibling, in whom the diagnosis had not been made acutely, was also found to be affected. The possible effects of these mutations on enzyme activity are discussed.
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Affiliation(s)
- R Aledo
- Unit of Biochemistry and Molecular Biology, School of Health Sciences, International University of Catalonia, Spain
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37
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Olpin SE. Implications of impaired ketogenesis in fatty acid oxidation disorders. Prostaglandins Leukot Essent Fatty Acids 2004; 70:293-308. [PMID: 14769488 DOI: 10.1016/j.plefa.2003.06.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2003] [Accepted: 06/01/2003] [Indexed: 01/09/2023]
Abstract
Long-chain fatty acids are important sources of respiratory fuel for many tissues and during fasting the rate of hepatic production of ketone bodies is markedly increased. Many extra hepatic tissues utilize ketone bodies in the fasted state with the advantage that glucose is "spared" for more vital tissues like the brain. This glucose sparing effect of ketones is especially important in infants where there is a high proportional glucose utilization in cerebral tissue. The first reported inherited defect affecting fatty acid oxidation was described in 1973 and to date about 15 separate disorders have been described. Although individually rare, cumulatively fatty acid oxidation defects are relatively common, have major consequences for affected individuals and their families, and carry significant health care implications. The major biochemical consequence of fatty acid oxidation defects is an inability of extra hepatic tissues to utilize fatty acids as an energy source with absent or limited hepatic capacity to generate ketones. Clinically patients usually present in infancy with acute life-threatening hypoketotic hypoglycaemia, liver disease, hyperammonaemia and cerebral oedema, with or without cardiac involvement, usually following a period of catabolic stress. Chronically there may be muscle involvement with hypotonia or exercise intolerance with or without cardiomyopathy. Treatment is generally by the avoidance of fasting, frequent carbohydrate rich feeds and for long-chain defects, the replacement of long-chain dietary fats with medium-chain formulae. Novel approaches to treatment include the use of d,l-3-hydoxybutyrate or heptanoate as an alternative energy source.
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Affiliation(s)
- Simon Edward Olpin
- Department of Clinical Chemistry, Sheffield Children's Hospital, Western Bank, Sheffield S10 2TH, UK
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38
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Abstract
Diagnosis of glucose status requires knowledge of the homeostatic mechanisms that maintain the blood glucose concentration between the narrow range of 2.5 and 7.5 mmol/l during periods of eating or fasting. Hypoglycaemia occurring within the first few hours after eating is suggestive of hyperinsulinism. Most glucose is subsequently converted into glycogen in the liver, and hypoglycaemia occurring during this phase is suggestive of glycogenosis. During fasting, gluconeogenesis progressively replaces glycogen as the major source of blood glucose, and hypoglycaemia occurring during this period is suggestive of impaired gluconeogenesis or fatty acid disorders. Growth hormone, glucagon, cortisol and insulin-like growth factor 1 deficiencies may also play a role. Other causes of hypoglycaemia have also been identified recently, namely glucose transporter disorders, respiratory chain disorders and congenital disorders of glycosylation.
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Affiliation(s)
- Pascale de Lonlay
- Department of Paediatrics, Hôpital Necker -- Enfants Malades, 149 rue de Sèvres, 75743 Paris cedex 15, France.
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Abstract
PURPOSE OF REVIEW At least 22 different inborn errors of metabolism affecting beta-oxidation in skeletal muscle and other tissues have been identified in the past 30 years. Early diagnosis and therapeutic diets offer the best chance for normal growth and development in most patients. RECENT FINDINGS Clinical heterogeneity has become the hallmark of defects in beta-oxidation. In many cases a correct diagnosis will only be made if these disorders are specifically considered and appropriate studies are obtained, since screening tests which detect other inborn errors of metabolism are often normal in patients with beta-oxidation defects. Dietary management provides the only opportunity for therapy in many cases, including carbohydrate supplements intended to provide more extended delivery of glucose to the bloodstream. Use of a novel odd chain fat supplement as an alternative fuel source in long chain fat metabolism defects offers promise of alleviating muscular symptoms not well controlled by diet. The introduction of expanded newborn screening will lead to the recognition of an increasing number of individuals with these disorders, placing greater demand for services on practitioners knowledgeable in their therapy. Study of the clinical outcome in these patients will provide a better understanding of defects of beta-oxidation. SUMMARY Clinical symptoms, diagnostic testing, and issues of newborn screening for this important group of disorders are discussed.
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Affiliation(s)
- Jerry Vockley
- Department of Medical Genetics and Department of Biochemistry and Molecular Biology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
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40
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Sim KG, Hammond J, Wilcken B. Strategies for the diagnosis of mitochondrial fatty acid beta-oxidation disorders. Clin Chim Acta 2002; 323:37-58. [PMID: 12135806 DOI: 10.1016/s0009-8981(02)00182-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Mitochondrial fatty acid beta-oxidation disorders (FAOD) are a group of clinically and biochemically heterogeneous inherited metabolic defects. The spectrum of phenotypes has expanded from hepatic encephalopathy to encompass myopathy, cardiomyopathy, peripheral neuropathy, sudden death and pregnancy complicated by fetal FAOD. Pre-symptomatic diagnosis is important to prevent morbidity and this is now achievable through newborn screening using tandem mass spectrometry (MS/MS). Moreover, most of the diagnosed defects are treatable and the prognosis is generally favourable. This article reviews the features of FAOD, critically evaluates methods of investigation including metabolite analyses in body fluids, in vitro oxidation rates and acylcarnitine profiling studies, enzymatic and mutational tests, and discusses genotype-phenotype correlation, treatment and monitoring options. Based on this knowledge, strategies for the biochemical investigation and differential diagnosis of patients presenting clinically, asymptomatic neonates detected by newborn screening, infants born after complications during late pregnancy, and cases of sudden death with suspected FAOD are presented. Laboratory investigation commonly begins with a search for diagnostic metabolites in physiological fluids, followed by in vitro functional studies if the initial findings are inconclusive, and confirmation by enzymology and molecular analyses. Occasionally a stress test in vivo may be required. At other times there may be no firm diagnosis achieved.
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Affiliation(s)
- Keow G Sim
- New South Wales Biochemical Genetics Service, The Children's Hospital at Westmead, Sydney, Australia. .au
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41
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Zschocke J, Penzien JM, Bielen R, Casals N, Aledo R, Pié J, Hoffmann GF, Hegardt FG, Mayatepek E. The diagnosis of mitochondrial HMG-CoA synthase deficiency. J Pediatr 2002; 140:778-80. [PMID: 12072887 DOI: 10.1067/mpd.2002.123854] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Deficiency of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase, the only disorder exclusively affecting hepatic ketogenesis, is a cause of hypoglycemic coma. We report that the diagnosis can be made by typical laboratory findings (hypoketosis, elevated free fatty acids, normal acylcarnitines, specific urinary organic acids) during acute episodes.
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Affiliation(s)
- Johannes Zschocke
- Division of Metabolic and Endocrine Diseases, University Children's Hospital, Heidelberg, Germany
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42
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Abstract
Genetic disorders of mitochondrial fatty acid beta-oxidation have been recognized within the last 20 years as important causes of morbidity and mortality, highlighting the physiological significance of fatty acids as an energy source. Although the mammalian mitochondrial fatty acid-oxidizing system was recognized at the beginning of the last century, our understanding of its exact nature remains incomplete, and new components are being identified frequently. Originally described as a four-step enzymatic process located exclusively in the mitochondrial matrix, we now recognize that long-chain-specific enzymes are bound to the inner mitochondrial membrane, and some enzymes are expressed in a tissue-specific manner. Much of our new knowledge of fatty acid metabolism has come from the study of patients who were diagnosed with single-gene autosomal recessive defects, a situation that seems to be further evolving with the emergence of phenotypes determined by combinations of multiple genetic and environmental factors. This review addresses the normal process of mitochondrial fatty acid beta-oxidation and discusses the clinical, metabolic, and molecular aspects of more than 20 known inherited diseases of this pathway that have been described to date.
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Affiliation(s)
- Piero Rinaldo
- Department of Laboratory Medicine and Pathology, Mayo Clinic and Foundation, Biochemical Genetics Laboratory, Rochester, Minnesota 55905, USA.
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43
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Bouchard L, Robert MF, Vinarov D, Stanley CA, Thompson GN, Morris A, Leonard JV, Quant P, Hsu BY, Boneh A, Boukaftane Y, Ashmarina L, Wang S, Miziorko H, Mitchell GA. Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency: clinical course and description of causal mutations in two patients. Pediatr Res 2001; 49:326-31. [PMID: 11228257 DOI: 10.1203/00006450-200103000-00005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Hereditary deficiency of mitochondrial HMG-CoA synthase (mHS, OMIM 600234) is a poorly defined, treatable, probably underdiagnosed condition that can cause episodes of severe hypoketotic hypoglycemia. We present clinical follow-up and molecular analysis of the two known mHS-deficient patients. The diagnosis of mHS deficiency is challenging because the symptoms and metabolite pattern are not specific. Moreover, enzyme analysis is technically difficult and requires sampling of an expressing organ such as liver. The patients, now aged 16 and 6 y, have normal development and have had no further decompensations since diagnosis. Patient 1 is homozygous for a phenylalanine-to-leucine substitution at codon 174 (F174L). Interestingly, although the F174 residue is conserved in vertebrate mHS and cytoplasmic HS isozymes, a Leu residue is predicted in the corresponding position of HS-like sequences from Caenorhabditis elegans, Arabidopsis thaliana, and Brassica juncea. Bacterial expression of human F174L-mHS produces a low level of mHS polypeptide with no detectable activity. Similarly, in purified cytoplasmic HS, which in contrast to purified human mHS is stable and can be studied in detail, the corresponding F-->L substitution causes a 10,000-fold decrease in V(max) and a 5-fold reduction in thermal stability. Patient 2 is a genetic compound of a premature termination mutation, R424X, and an as-yet uncharacterized mutant allele that is distinguishable by intragenic single nucleotide polymorphisms that we describe. Molecular studies of mHS are useful in patients with a suggestive clinical presentation.
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Affiliation(s)
- L Bouchard
- Service de génétique médicale, Research Center, Ste-Justine Hospital, 3175 Côte Ste-Catherine, Montreal (Québec), Canada
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44
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Chun KY, Vinarov DA, Miziorko HM. 3-Hydroxy-3-methylglutaryl-CoA synthase: participation of invariant acidic residues in formation of the acetyl-S-enzyme reaction intermediate. Biochemistry 2000; 39:14670-81. [PMID: 11087424 DOI: 10.1021/bi001805m] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Inactivation of HMG-CoA synthase by a carboxyl-directed reagent, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), in a concentration-dependent and substrate-protectable manner suggested that the active site contains reactive acidic amino acids. This observation prompted functional evaluation of 11 invariant acidic amino acids by site-directed mutagenesis. Characterization of the isolated synthase variants' ability to catalyze overall and partial reactions identified three mutant synthases (D99A, D159A, and D203A) that exhibit significant diminution of k(cat) for the overall reaction (10(2)-, 10(3)-, and 10(4)-fold decreases, respectively). D99A, D159A, and D203A form the acetyl-S-enzyme intermediate very slowly (0.0025, 0.0026, 0.0015 U/mg, respectively, measured at pH 7. 0 and 22 degrees C) as compared to the wild-type synthase (1.59 U/mg), where intermediate formation approaches rate-limiting status. Differences in substrate saturation do not account for impaired activities or rates of intermediate formation. The structural integrity of the purified mutants' active sites is demonstrated by their abilities to bind a spin-labeled acyl-CoA analogue (R.CoA) with affinities and stoichiometries comparable to values measured for wild-type synthase. The impact of three distinct amino acids on reaction intermediate formation supports a mechanism of acetyl-S-enzyme formation that probably requires formation and directed collapse of a tetrahedral adduct. (18)O-induced shift of the (13)C NMR signal of (13)C acetyl-S-enzyme demonstrates that an analogous tetrahedral species is produced upon solvent exchange with the acetyl-S-enzyme. Partial discrimination between the functions of D99, D159, and D203 becomes possible based on the observation that D159A and D203A synthases exhibit retarded kinetics of solvent (18)O exchange while D99A fails to support (18)O exchange.
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Affiliation(s)
- K Y Chun
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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45
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Rinaldo P, Matern D. Disorders of fatty acid transport and mitochondrial oxidation: challenges and dilemmas of metabolic evaluation. Genet Med 2000; 2:338-44. [PMID: 11339654 DOI: 10.1097/00125817-200011000-00006] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Inborn errors of fatty acid transport and mitochondrial oxidation (FATMO) have drawn considerable attention in recent years for the rapid pace of discovery of new defects and an ever-increasing spectrum of clinical phenotypes. Several of these disorders are not detected by conventional biochemical investigations, even when a patient is symptomatic with fasting intolerance or functional failure of fatty acid dependent tissue(s). In our view, today's major challenges are the inclusion of FATMO disorders in newborn screening programs and the investigation of the role played by individual disorders in maternal complications of pregnancy, sudden and unexpected death in early life, and pediatric acute/fulminant liver failure. Dilemmas are found in the debate over the limitations, if any, to be imposed on the expansion of newborn screening using tandem mass spectrometry, in the provision of prenatal diagnosis for otherwise treatable disorders, and in the diagnostic workup of "unclassified" cases.
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Affiliation(s)
- P Rinaldo
- Department of Laboratory Medicine & Pathology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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46
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Saudubray JM, de Lonlay P, Touati G, Martin D, Nassogne MC, Castelnau P, Sevin C, Laborde C, Baussan C, Brivet M, Vassault A, Rabier D, Bonnefont JP, Kamoun P. Genetic hypoglycaemia in infancy and childhood: pathophysiology and diagnosis. J Inherit Metab Dis 2000; 23:197-214. [PMID: 10863937 DOI: 10.1023/a:1005675827612] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- J M Saudubray
- Department of Pediatrics, Hôpital Necker Enfants-Malades, Paris, France
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47
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Vinarov DA, Miziorko HM. 3-hydroxy-3-methylglutaryl-coenzyme A synthase reaction intermediates: detection of a covalent tetrahedral adduct by differential isotope shift 13C nuclear magnetic resonance spectroscopy. Biochemistry 2000; 39:3360-8. [PMID: 10727229 DOI: 10.1021/bi9922897] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Binding of [1,2-(13)C]acetyl-CoA to wild-type 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) synthase is characterized by large upfield shifts for C1 (184 ppm, Deltadelta = 20 ppm) and C2 (26 ppm, Deltadelta = 7 ppm) resonances that are attributable to formation of the covalent [1,2 -(13)C]acetyl-S-enzyme reaction intermediate. NMR spectra of [1, 2-(13)C]acetyl-S-enzyme prepared in H(2)(16)O versus H(2)(18)O indicate a 0.055 ppm upfield shift of the C1 resonance in the presence of the heavier isotope. The magnitude of this (18)O-induced (13)C shift suggests that the 184 ppm resonance is attributable to a reaction intermediate in which C1 exhibits substantial carbonyl character. No significant shift of the C2 resonance occurs. These observations suggest that, in the absence of second substrate (acetoacetyl-CoA), enzymatic addition of H(2)(18)O to the C1 carbonyl of acetyl-S-enzyme occurs to transiently produce a tetrahedral species. This tetrahedral adduct exchanges oxygen upon backward collapse to re-form the sp(2)-hybridized thioester carbonyl. In contrast with HMG-CoA synthase, C378G Zoogloea ramigera beta-ketothiolase, which also forms a (13)C NMR-observable covalent acetyl-enzyme species, exhibits no (18)O-induced shift. Formation of the [(13)C]acetyl-S-enzyme reaction intermediate of HMG-CoA synthase in D(2)O versus H(2)O is characterized by a time-dependent isotope-induced upfield shift of the C1 resonance (maximal shift = 0. 185 ppm) in the presence of the heavier isotope. A more modest upfield shift (0.080 ppm) is observed for C378G Z. ramigera beta-ketothiolase in similar experiments. The slow kinetics for the development of the deuterium-induced (13)C shift in the HMG-CoA synthase experiments suggest a specific interaction (hydrogen bond) with a slowly exchangeable proton (deuteron) of a side chain/backbone of an amino acid residue at the active site.
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Affiliation(s)
- D A Vinarov
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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48
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Jones PM, Quinn R, Fennessey PV, Tjoa S, Goodman SI, Fiore S, Burlina AB, Rinaldo P, Boriack RL, Bennett MJ. Improved Stable Isotope Dilution-Gas Chromatography-Mass Spectrometry Method for Serum or Plasma Free 3-Hydroxy-Fatty Acids and Its Utility for the Study of Disorders of Mitochondrial Fatty Acid β-Oxidation. Clin Chem 2000. [DOI: 10.1093/clinchem/46.2.149] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Background: Disorders of fatty acid oxidation (FAO) are difficult to diagnose, primarily because in many of the FAO disorders measurable biochemical intermediates accumulate in body fluids only during acute illness. Increased concentrations of 3-hydroxy-fatty acids (3-OH-FAs) in the blood are indicative of FAO disorders of the long- and short-chain 3-hydroxy-acyl-CoA dehydrogenases, LCHAD and SCHAD. We describe a serum/plasma assay for the measurement of 3-OH-FAs with carbon chain lengths from C6 to C16.
Methods: We used stable isotope dilution gas chromatography-mass spectrometry (GC-MS) with electron impact ionization and selected ion monitoring. Natural and isotope-labeled compounds were synthesized for the assay.
Results: The assay was linear from 0.2 to 50 μmol/L for all six 3-OH-FAs. CVs were 5–15% at concentrations near the upper limits seen in healthy subjects. In 43 subjects, the medians (and ranges) in μmol/L were as follows: 3-OH-C6, 0.8 (0.3–2.2); 3-OH-C8, 0.4 (0.2–1.0); 3-OH-C10, 0.3 (0.2–0.6); 3-OH-C12, 0.3 (0.2–0.6); 3-OH-C14, 0.2 (0.0–0.4); and 3-OH-C16, 0.2 (0.0–0.5). 3-OH-FAs were increased in infants receiving formula containing medium chain triglycerides. Two patients diagnosed with LCHAD deficiency showed marked increases in 3-OH-C14 and 3-OH-C16 concentrations. Two patients diagnosed with SCHAD deficiency showed increased shorter chain 3-OH-FAs but no increases in 3-OH-C14 to 3-OH-C16.
Conclusion: Measuring blood concentrations of the 3-OH-FAs with this assay may be a valuable tool for helping to rapidly identify deficiencies in LCHAD and SCHAD and may also provide useful information about the status of the FAO pathway.
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Affiliation(s)
- Patricia M Jones
- University of Texas Southwestern Medical Center, Department of Pathology, and Children’s Medical Center of Dallas, TX 75235
| | - Rebecca Quinn
- University of Texas Southwestern Medical Center, Department of Pathology, and Children’s Medical Center of Dallas, TX 75235
| | - Paul V Fennessey
- University of Colorado Health Science Center, Department of Pediatrics, Denver, CO 80262
| | - Susan Tjoa
- University of Colorado Health Science Center, Department of Pediatrics, Denver, CO 80262
| | - Stephen I Goodman
- University of Colorado Health Science Center, Department of Pediatrics, Denver, CO 80262
| | - Stephany Fiore
- University of Padua, Department of Pediatrics, I-35128 Padua, Italy
| | - Alberto B Burlina
- Mayo Clinic, Department of Laboratory Medicine and Pathology, Rochester, MN 55905
| | | | - Richard L Boriack
- University of Texas Southwestern Medical Center, Department of Pathology, and Children’s Medical Center of Dallas, TX 75235
| | - Michael J Bennett
- University of Texas Southwestern Medical Center, Department of Pathology, and Children’s Medical Center of Dallas, TX 75235
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49
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Abstract
Inborn errors of the mitochondrial beta-oxidation of long-chain fatty acids represent an evolving field of inherited metabolic disease. Fatty acid oxidation defects demonstrate an abnormal response to the process of fasting adaptation and affect those tissues that utilize fatty acids as an energy source. These tissues include cardiac and skeletal muscle and liver. Muscle directly uses fatty acids as an energy source whilst hepatic metabolism of fatty acids is mostly directed toward the synthesis of ketone bodies for energy utilization by tissues such as brain. The clinical phenotypes of fatty acid oxidation disorders include disease of one or more of these fatty acid-metabolizing tissues. In this review, we provide an overview of the pathway, discuss the disorders that are well established, and describe recent advances in the field. Currently available diagnostic procedures are critically evaluated.
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Affiliation(s)
- M J Bennett
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas 75235, USA.
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50
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Aouizerat BE, Allayee H, Bodnar J, Krass KL, Peltonen L, de Bruin TW, Rotter JI, Lusis AJ. Novel genes for familial combined hyperlipidemia. Curr Opin Lipidol 1999; 10:113-22. [PMID: 10327279 DOI: 10.1097/00041433-199904000-00005] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Familial combined hyperlipidemia (FCHL) is a complex genetic disorder of unknown etiology. Recently, 'modifier' genes of the FCHL phenotype, such as the apolipoprotein AI-CIII-AIV gene cluster and LPL, have been identified in several populations. A 'major' gene for FCHL has been identified in a Finnish isolate which maps to a region syntenic to murine chromosome 3 where a locus for combined hyperlipidemia has been identified. We review these and other recent studies which indicate that FCHL is genetically heterogeneous.
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Affiliation(s)
- B E Aouizerat
- Department of Microbiology and Molecular Genetics, University of California, Los Angeles 90095-1679, USA
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