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Kühn S, Williams ME, Dercksen M, Sass JO, van der Sluis R. The glycine N-acyltransferases, GLYAT and GLYATL1, contribute to the detoxification of isovaleryl-CoA - an in-silico and in vitro validation. Comput Struct Biotechnol J 2023; 21:1236-1248. [PMID: 36817957 PMCID: PMC9932296 DOI: 10.1016/j.csbj.2023.01.041] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 01/27/2023] [Accepted: 01/29/2023] [Indexed: 02/01/2023] Open
Abstract
Isovaleric acidemia (IVA), due to isovaleryl-CoA dehydrogenase (IVD) deficiency, results in the accumulation of isovaleryl-CoA, isovaleric acid and secondary metabolites. The increase in these metabolites decreases mitochondrial energy production and increases oxidative stress. This contributes to the neuropathological features of IVA. A general assumption in the literature exists that glycine N-acyltransferase (GLYAT) plays a role in alleviating the symptoms experienced by IVA patients through the formation of N-isovalerylglycine. GLYAT forms part of the phase II glycine conjugation pathway in the liver and detoxifies excess acyl-CoA's namely benzoyl-CoA. However, very few studies support GLYAT as the enzyme that conjugates isovaleryl-CoA to glycine. Furthermore, GLYATL1, a paralogue of GLYAT, conjugates phenylacetyl-CoA to glutamine. Therefore, GLYATL1 might also be a candidate for the formation of N-isovalerylglycine. Based on the findings from the literature review, we proposed that GLYAT or GLYATL1 can form N-isovalerylglycine in IVA patients. To test this hypothesis, we performed an in-silico analysis to determine which enzyme is more likely to conjugate isovaleryl-CoA with glycine using AutoDock Vina. Thereafter, we performed in vitro validation using purified enzyme preparations. The in-silico and in vitro findings suggested that both enzymes could form N-isovaleryglycine albeit at lower affinities than their preferred substrates. Furthermore, an increase in glycine concentration does not result in an increase in N-isovalerylglycine formation. The results from the critical literature appraisal, in-silico, and in vitro validation, suggest the importance of further investigating the reaction kinetics and binding behaviors between these substrates and enzymes in understanding the pathophysiology of IVA.
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Affiliation(s)
- Stefan Kühn
- Focus Area for Human Metabolomics, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa
| | - Monray E. Williams
- Focus Area for Human Metabolomics, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa
| | - Marli Dercksen
- Focus Area for Human Metabolomics, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa
| | - Jörn Oliver Sass
- Research Group Inborn Errors of Metabolism, Institute for Functional Gene Analytics, Department of Natural Sciences, Bonn-Rhein-Sieg University of Applied Sciences, von-Liebig-Str. 20, 53359 Rheinbach, Germany
| | - Rencia van der Sluis
- Focus Area for Human Metabolomics, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa,Corresponding author.
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Ravanelli S, Li Q, Annibal A, Trifunovic A, Antebi A, Hoppe T. Reprograming of proteasomal degradation by branched chain amino acid metabolism. Aging Cell 2022; 21:e13725. [PMID: 36168305 PMCID: PMC9741504 DOI: 10.1111/acel.13725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 08/03/2022] [Accepted: 09/09/2022] [Indexed: 12/14/2022] Open
Abstract
Branched-chain amino acid (BCAA) metabolism is a central hub for energy production and regulation of numerous physiological processes. Controversially, both increased and decreased levels of BCAAs are associated with longevity. Using genetics and multi-omics analyses in Caenorhabditis elegans, we identified adaptive regulation of the ubiquitin-proteasome system (UPS) in response to defective BCAA catabolic reactions after the initial transamination step. Worms with impaired BCAA metabolism show a slower turnover of a GFP-based proteasome substrate, which is suppressed by loss-of-function of the first BCAA catabolic enzyme, the branched-chain aminotransferase BCAT-1. The exogenous supply of BCAA-derived carboxylic acids, which are known to accumulate in the body fluid of patients with BCAA metabolic disorders, is sufficient to regulate the UPS. The link between BCAA intermediates and UPS function presented here sheds light on the unexplained role of BCAAs in the aging process and opens future possibilities for therapeutic interventions.
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Affiliation(s)
- Sonia Ravanelli
- Institute for GeneticsUniversity of CologneCologneGermany,Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Qiaochu Li
- Institute for GeneticsUniversity of CologneCologneGermany,Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Andrea Annibal
- Max Planck Institute for Biology of AgeingCologneGermany
| | - Aleksandra Trifunovic
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany,Center for Molecular Medicine Cologne (CMMC)University of CologneCologneGermany,Institute for Mitochondrial Diseases and Ageing, Medical FacultyUniversity of CologneCologneGermany
| | - Adam Antebi
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany,Max Planck Institute for Biology of AgeingCologneGermany
| | - Thorsten Hoppe
- Institute for GeneticsUniversity of CologneCologneGermany,Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany,Center for Molecular Medicine Cologne (CMMC)University of CologneCologneGermany
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Chinen Y, Nakamura S, Tamashiro K, Sakamoto O, Tashiro K, Inokuchi T, Nakanishi K. Isovaleric acidemia: Therapeutic response to supplementation with glycine, l-carnitine, or both in combination and a 10-year follow-up case study. Mol Genet Metab Rep 2017; 11:2-5. [PMID: 30547004 PMCID: PMC6282653 DOI: 10.1016/j.ymgmr.2017.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 03/01/2017] [Accepted: 03/02/2017] [Indexed: 01/20/2023] Open
Abstract
Isovaleric acidemia (IVA) is an organic acid disease caused by a deficiency of isovaleryl-CoA dehydrogenase. Deficiency of this enzyme leads to accumulation of organic acids, such as isovalerylcarnitine and isovalerylglycine. The proposed IVA treatments include leucine restriction and l-carnitine and/or glycine supplementation, which convert isovaleric acid into non-toxic isovalerylcarnitine and isovalerylglycine, respectively. We examined the therapeutic response using the leucine load test and performed a 10-year follow-up in the patient. Methods We evaluated the patient with IVA beginning at 5 years of age, when he presented with a mild to intermediate metabolic phenotype. Ammonia, free carnitine, isovalerylcarnitine, and isovalerylglycine were analyzed in the urine and blood after a meal consisting of 1600 mg leucine with glycine alone (250 mg/kg/day), l-carnitine alone (100 mg/kg/day), or both glycine and l-carnitine for four days each. Results (Leucine load test) Three hours after the meal, serum ammonia levels increased most dramatically with glycine treatment alone, then with both in combination, and least with l-carnitine alone. Urinary isovalerylglycine levels increased 2-fold more with glycine supplementation than those following supplementation with both agents or with l-carnitine alone. Treatment with both agents resulted in a gradual increase in urinary acylcarnitine levels during the 6-h period following the leucine load, reaching concentrations comparable to those observed with l-carnitine alone. (Clinical course) After initiation of both glycine (200 mg/kg/day) and l-carnitine (100 mg/kg/day) supplementation at 5 years of age, doses were gradually reduced to 111.7 mg/kg/day and 55.8 mg/kg/day, respectively, at 15 years of age. His mind and body had developed without any sequelae. Discussion We concluded that l-carnitine conjugated isovaleric acid earlier than glycine. Additionally, during the 10-year follow-up period, the patient displayed no clinical deterioration.
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Affiliation(s)
- Yasutsugu Chinen
- Department of Pediatrics, Faculty of Medicine, University of the Ryukyus, Nishihara 903-0125, Japan
| | - Sadao Nakamura
- Department of Pediatrics, Faculty of Medicine, University of the Ryukyus, Nishihara 903-0125, Japan
| | - Kunihito Tamashiro
- Department of Pediatrics, Faculty of Medicine, University of the Ryukyus, Nishihara 903-0125, Japan
| | - Osamu Sakamoto
- Department of Pediatrics, Tohoku University School of Medicine, Sendai 980-8574, Japan
| | - Kyoko Tashiro
- Research Institute of Medical Mass Spectrometry, Kurume University School of Medicine, Kurume 830-0011, Japan
| | - Takahiro Inokuchi
- Research Institute of Medical Mass Spectrometry, Kurume University School of Medicine, Kurume 830-0011, Japan
| | - Koichi Nakanishi
- Department of Pediatrics, Faculty of Medicine, University of the Ryukyus, Nishihara 903-0125, Japan
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Badenhorst CPS, Erasmus E, van der Sluis R, Nortje C, van Dijk AA. A new perspective on the importance of glycine conjugation in the metabolism of aromatic acids. Drug Metab Rev 2014; 46:343-61. [PMID: 24754494 DOI: 10.3109/03602532.2014.908903] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A number of endogenous and xenobiotic organic acids are conjugated to glycine, in animals ranging from mosquitoes to humans. Glycine conjugation has generally been assumed to be a detoxification mechanism, increasing the water solubility of organic acids in order to facilitate urinary excretion. However, the recently proposed glycine deportation hypothesis states that the role of the amino acid conjugations, including glycine conjugation, is to regulate systemic levels of amino acids that are also utilized as neurotransmitters in the central nervous systems of animals. This hypothesis is based on the observation that, compared to glucuronidation, glycine conjugation does not significantly increase the water solubility of aromatic acids. In this review it will be argued that the major role of glycine conjugation is to dispose of the end products of phenylpropionate metabolism. Furthermore, glucuronidation, which occurs in the endoplasmic reticulum, would not be ideal for the detoxification of free benzoate, which has been shown to accumulate in the mitochondrial matrix. Glycine conjugation, however, prevents accumulation of benzoic acid in the mitochondrial matrix by forming hippurate, a less lipophilic conjugate that can be more readily transported out of the mitochondria. Finally, it will be explained that the glycine conjugation of benzoate, a commonly used preservative, exacerbates the dietary deficiency of glycine in humans. Because the resulting shortage of glycine can negatively influence brain neurochemistry and the synthesis of collagen, nucleic acids, porphyrins, and other important metabolites, the risks of using benzoate as a preservative should not be underestimated.
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Van Calcar SC, Baker MW, Williams P, Jones SA, Xiong B, Thao MC, Lee S, Yang MK, Rice GM, Rhead W, Vockley J, Hoffman G, Durkin MS. Prevalence and mutation analysis of short/branched chain acyl-CoA dehydrogenase deficiency (SBCADD) detected on newborn screening in Wisconsin. Mol Genet Metab 2013; 110:111-5. [PMID: 23712021 PMCID: PMC5006389 DOI: 10.1016/j.ymgme.2013.03.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Revised: 03/29/2013] [Accepted: 03/29/2013] [Indexed: 11/17/2022]
Abstract
Short/branched chain acyl-CoA dehydrogenase deficiency (SBCADD), also called 2-methylbutyryl CoA dehydrogenase deficiency (2-MBCDD), is a disorder of l-isoleucine metabolism of uncertain clinical significance. SBCADD is inadvertently detected on expanded newborn screening by elevated 2-methylbutyrylcarnitine (C5), which has the same mass to charge (m/s) on tandem mass spectrometry (MS/MS) as isovalerylcarnitine (C5), an analyte that is elevated in isovaleric acidemia (IVA), a disorder in leucine metabolism. SBCADD cases identified in the Hmong-American population have been found in association with the c.1165 A>G mutation in the ACADSB gene. The purposes of this study were to: (a) estimate the prevalence of SBCADD and carrier frequency of the c.1165 A>G mutation in the Hmong ethnic group; (b) determine whether the c.1165 A>G mutation is common to all Hmong newborns screening positive for SBCADD; and (c) evaluate C5 acylcarnitine cut-off values to detect and distinguish between SBCADD and IVA diagnoses. During the first 10years of expanded newborn screening using MS/MS in Wisconsin (2001-2011), 97 infants had elevated C5 values (≥0.44μmol/L), of whom five were Caucasian infants confirmed to have IVA. Of the remaining 92 confirmed SBCADD cases, 90 were of Hmong descent. Mutation analysis was completed on an anonymous, random sample of newborn screening cards (n=1139) from Hmong infants. Fifteen infants, including nine who had screened positive for SBCADD based on a C5 acylcarnitine concentration ≥0.44μmol/L, were homozygous for the c.1165 A>G mutation. This corresponds to a prevalence in this ethnic group of being homozygous for the mutation of 1.3% (95% confidence interval 0.8-2.2%) and of being heterozygous for the mutation of 21.8% (95% confidence interval 19.4-24.3%), which is consistent with the Hardy-Weinberg equilibrium. Detection of homozygous individuals who were not identified on newborn screening suggests that the C5 screening cut-off would need to be as low as 0.20μmol/L to detect all infants homozygous for the ACADSB c.1165 A>G mutation. However, lowering the screening cut-off to 0.20 would also result in five "false positive" (non-homozygous) screening results in the Hmong population for every c.1165 A>G homozygote detected. Increasing the cut-off to 0.60μmol/L and requiring elevated C5/C2 (acetylcarnitine) and C5/C3 (propionylcarnitine) ratios to flag a screen as abnormal would reduce the number of infants screening positive, but would still result in an estimated 5 infants with SBCADD per year who would require follow-up and additional biochemical testing to distinguish between SBCADD and IVA diagnoses. Further research is needed to determine the clinical outcomes of SBCADD detected on newborn screening and the c.1165 A>G mutation before knowing whether the optimal screening cut-off would minimize true positives or false negatives for SBCADD associated with this mutation.
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Affiliation(s)
- Sandra C. Van Calcar
- Biochemical Genetics Program, Waisman Center, University of Wisconsin–Madison, Madison, WI, USA
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Mei W. Baker
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- Biochemical Genetics Laboratory, Wisconsin State Laboratory of Hygiene, University of Wisconsin–Madison, Madison, WI, USA
- Newborn Screening Program, Wisconsin State Laboratory of Hygiene, University of Wisconsin–Madison, Madison, WI, USA
| | - Phillip Williams
- Biochemical Genetics Laboratory, Wisconsin State Laboratory of Hygiene, University of Wisconsin–Madison, Madison, WI, USA
| | - Susan A. Jones
- Biochemical Genetics Laboratory, Wisconsin State Laboratory of Hygiene, University of Wisconsin–Madison, Madison, WI, USA
| | - Blia Xiong
- Biochemical Genetics Program, Waisman Center, University of Wisconsin–Madison, Madison, WI, USA
| | - Mai Choua Thao
- Biochemical Genetics Program, Waisman Center, University of Wisconsin–Madison, Madison, WI, USA
| | - Sheng Lee
- Biochemical Genetics Program, Waisman Center, University of Wisconsin–Madison, Madison, WI, USA
| | - Mai Khou Yang
- Biochemical Genetics Program, Waisman Center, University of Wisconsin–Madison, Madison, WI, USA
| | - Greg M. Rice
- Biochemical Genetics Program, Waisman Center, University of Wisconsin–Madison, Madison, WI, USA
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- Biochemical Genetics Laboratory, Wisconsin State Laboratory of Hygiene, University of Wisconsin–Madison, Madison, WI, USA
| | - William Rhead
- Genetics Clinic, Children’s Hospital of Wisconsin, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jerry Vockley
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Gary Hoffman
- Newborn Screening Program, Wisconsin State Laboratory of Hygiene, University of Wisconsin–Madison, Madison, WI, USA
| | - Maureen S. Durkin
- Biochemical Genetics Program, Waisman Center, University of Wisconsin–Madison, Madison, WI, USA
- Department of Population Health Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- Corresponding author at: Population Heath Sciences, University of Wisconsin School of Medicine and Public Health, 1500 Highland Ave., Madison, WI 53705, USA., Fax: +1 608 263 2820., (M.S. Durkin)
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Nasser M, Javaheri H, Fedorowicz Z, Noorani Z. Carnitine supplementation for inborn errors of metabolism. Cochrane Database Syst Rev 2012; 2012:CD006659. [PMID: 22336821 PMCID: PMC7390060 DOI: 10.1002/14651858.cd006659.pub3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Inborn errors of metabolism are genetic conditions which can lead to abnormalities in the synthesis and metabolism of proteins, carbohydrates, or fats. It has been proposed that in some instances carnitine supplementation should be provided to infants with a suspected metabolic disease as an interim measure, particularly whilst awaiting test results. Carnitine supplementation is used in the treatment of primary carnitine deficiency, and also where the deficiency is a secondary complication of several inborn errors of metabolism, such as organic acidaemias and fatty acid oxidation defects in children and adults. OBJECTIVES To assess the effectiveness and safety of carnitine supplementation in the treatment of inborn errors of metabolism. SEARCH METHODS We searched the Cystic Fibrosis and Genetic Disorders Group's Inborn Errors of Metabolism Trials Register, the Cochrane Central Register of Controlled Trials (The Cochrane Library 2007, Issue 4) and MEDLINE via Ovid (1950 to July week 4 2007), LILACS (15/05/2008) and Iranmedex (15/05/2008) and also the reference lists of retrieved articles.Date of most recent search of the Group's Inborn Errors of Metabolism Register: 27 October 2011. SELECTION CRITERIA Randomised controlled trials and quasi-randomised controlled trials comparing carnitine supplementation (in different dose, frequency, or duration) versus placebo in children and adults diagnosed with an inborn error of metabolism. DATA COLLECTION AND ANALYSIS Two authors independently screened and assessed the eligibility of the identified trials. MAIN RESULTS No trials were included in the review. AUTHORS' CONCLUSIONS There are no published or ongoing randomised controlled clinical trials relevant to this review question. Therefore, in the absence of any high level evidence, clinicians should base their decisions on clinical experience and in conjunction with preferences of the individual where appropriate. This does not mean that carnitine is ineffective or should not be used in any inborn error of metabolism. However, given the lack of evidence both on the effectiveness and safety of carnitine and on the necessary dose and frequency to be prescribed, the current prescribing practice should continue to be observed and monitored with care until further evidence is available. Methodologically sound trials, reported according to the Consolidated Standards of Reporting Trials (CONSORT) statement, are required. It should be considered whether placebo-controlled trials in potentially lethal diseases, e.g. carnitine transporter disorder or glutaric aciduria type I, are ethical.
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Affiliation(s)
- Mona Nasser
- Peninsula Dental School, University of Plymouth, Plymouth,
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Castelnovi C, Moseley K, Yano S. Maternal isovaleric acidemia: Observation of distinctive changes in plasma amino acids and carnitine profiles during pregnancy. Clin Chim Acta 2010; 411:2101-3. [DOI: 10.1016/j.cca.2010.08.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 08/16/2010] [Accepted: 08/16/2010] [Indexed: 11/28/2022]
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Abstract
BACKGROUND Inborn errors of metabolism are genetic conditions which can lead to abnormalities in the synthesis and metabolism of proteins, carbohydrates, or fats. It has been proposed that in some instances carnitine supplementation should be provided to infants with a suspected metabolic disease as an interim measure, particularly whilst awaiting test results. Carnitine supplementation is used in the treatment of primary carnitine deficiency, and also where the deficiency is a secondary complication of several inborn errors of metabolism, such as organic acidaemias and fatty acid oxidation defects in children and adults. OBJECTIVES To assess the effectiveness and safety of carnitine supplementation in the treatment of inborn errors of metabolism. SEARCH STRATEGY We searched the Cystic Fibrosis and Genetic Disorders Group's Inborn Errors of Metabolism Trials Register, the Cochrane Central Register of Controlled Trials (The Cochrane Library 2007, Issue 4) and MEDLINE via Ovid (1950 to July week 4 2007), LILACS (15/05/2008) and Iranmedex (15/05/2008) and also the reference lists of retrieved articles.Date of most recent search of the Group's Inborn Errors of Metabolism Register: 27 October 2008. SELECTION CRITERIA Randomised controlled trials and quasi-randomised controlled trials comparing carnitine supplementation (in different dose, frequency, or duration) versus placebo in children and adults diagnosed with an inborn error of metabolism. DATA COLLECTION AND ANALYSIS Two authors independently screened and assessed the eligibility of the identified trials. MAIN RESULTS No trials were included in the review. AUTHORS' CONCLUSIONS There are no published or ongoing randomised controlled clinical trials relevant to this review question. Therefore, in the absence of any high level evidence, clinicians should base their decisions on clinical experience and in conjunction with preferences of the individual where appropriate. This does not mean that carnitine is ineffective or should not be used in any inborn error of metabolism. However, given the lack of evidence both on the effectiveness and safety of carnitine and on the necessary dose and frequency to be prescribed, the current prescribing practice should continue to be observed and monitored with care until further evidence is available. Methodologically sound trials, reported according to the Consolidated Standards of Reporting Trials (CONSORT) statement, are required. It should be considered whether placebo-controlled trials in potentially lethal diseases, e.g. carnitine transporter disorder or glutaric aciduria type I, are ethical.
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Affiliation(s)
- Mona Nasser
- Department of Health Information, Institute for Quality and Efficiency in Health care, Dillenburger Street, 27, D-51105, Köln, Germany, D-51105.
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Sherman EA, Strauss KA, Tortorelli S, Bennett MJ, Knerr I, Morton DH, Puffenberger EG. Genetic mapping of glutaric aciduria, type 3, to chromosome 7 and identification of mutations in c7orf10. Am J Hum Genet 2008; 83:604-9. [PMID: 18926513 DOI: 10.1016/j.ajhg.2008.09.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Revised: 09/25/2008] [Accepted: 09/29/2008] [Indexed: 10/21/2022] Open
Abstract
While screening Old Order Amish children for glutaric aciduria type 1 (GA1) between 1989 and 1993, we found three healthy children who excreted abnormal quantities of glutaric acid but low 3-hydroxyglutaric acid, a pattern consistent with glutaric aciduria type 3 (GA3). None of these children had the GCDH c.1262C-->T mutation that causes GA1 among the Amish. Using single-nucleotide polymorphism (SNP) genotypes, we identified a shared homozygous 4.7 Mb region on chromosome 7. This region contained 25 genes including C7orf10, an open reading frame with a putative mitochondrial targeting sequence and coenzyme-A transferase domain. Direct sequencing of C7orf10 revealed that the three Amish individuals were homozygous for a nonsynonymous sequence variant (c.895C-->T, Arg299Trp). We then sequenced three non-Amish children with GA3 and discovered two nonsense mutations (c.322C-->T, Arg108Ter, and c.424C-->T, Arg142Ter) in addition to the Amish mutation. Two pathogenic alleles were identified in each of the six patients. There was no consistent clinical phenotype associated with GA3. In affected individuals, urine molar ratios of glutarate to its derivatives (3-hydroxyglutarate, glutarylcarnitine, and glutarylglycine) were elevated, suggesting impaired formation of glutaryl-CoA. These observations refine our understanding of the lysine-tryptophan degradation pathway and have important implications for the pathophysiology of GA1.
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Vockley J, Ensenauer R. Isovaleric acidemia: new aspects of genetic and phenotypic heterogeneity. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2006; 142C:95-103. [PMID: 16602101 PMCID: PMC2652706 DOI: 10.1002/ajmg.c.30089] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Isovaleric acidemia (IVA) is an autosomal recessive inborn error of leucine metabolism caused by a deficiency of the mitochondrial enzyme isovaleryl-CoA dehydrogenase (IVD) resulting in the accumulation of derivatives of isovaleryl-CoA. It was the first organic acidemia recognized in humans and can cause significant morbidity and mortality. Early diagnosis and treatment with a protein restricted diet and supplementation with carnitine and glycine are effective in promoting normal development in severely affected individuals. Both intra- and interfamilial variability have been recognized. Initially, two phenotypes with either an acute neonatal or a chronic intermittent presentation were described. More recently, a third group of individuals with mild biochemical abnormalities who can be asymptomatic have been identified through newborn screening of blood spots by tandem mass spectrometry. IVD is a flavoenzyme that catalyzes the conversion of isovaleryl-CoA to 3-methylcrotonyl-CoA and transfers electrons to the electron transfer flavoprotein. Human IVD has been purified from tissue and recombinant sources and its biochemical and physical properties have been extensively studied. Molecular analysis of the IVD gene from patients with IVA has allowed characterization of different types of mutations in this gene. One missense mutation, 932C>T (A282V), is particularly common in patients identified through newborn screening with mild metabolite elevations and who have remained asymptomatic to date. This mutation leads to a partially active enzyme with altered catalytic properties; however, its effects on clinical outcome and the necessity of therapy are still unknown. A better understanding of the heterogeneity of this disease and the relevance of genotype/phenotype correlations to clinical management of patients are among the challenges remaining in the study of this disorder in the coming years.
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Affiliation(s)
- Jerry Vockley
- Department of Pediatrics, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh, 3705 Fifth Avenue, Pittsburgh, PA 15238, USA.
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Infusionstherapie und Ernährung von Risikogruppen. INFUSIONSTHERAPIE UND DIÄTETIK IN DER PÄDIATRIE 2005. [PMCID: PMC7136897 DOI: 10.1007/3-540-27897-4_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Besondere Situationen erfordern ein besonderes Vorgehen. Während bisher das »Standardvorgehen« bezüglich der Ernährung von pädiatrischen Patienten dargestellt wurde, beschäftigt sich das vorliegende Kapitel mit »Sondersituationen« der pädiatrischen Infusionstherapie und Ernährung. Behandlungssituationen, die ein besonderes Vorgehen bei der Therapie oder spezielle Aufmerksamkeit bei der Anpassung der Ernährung erfordern, entstehen in der Regel durch 4 mögliche Situationen:
spezifische Physiologie von Patientengruppen (z. B. Früh- oder Neugeborene), Auswirkungen von therapeutischen Maßnahmen (z. B. Operationen), Pathophysiologie von Erkrankungen (z. B. angeborene Stoffwechselerkrankungen, Erkrankungen des onkologischen, rheumatischen oder atopischen Formenkreises, Anorexia nervosa, Bulimie oder Adipositas) oder besondere körperliche Belastungen [z. B. (Leistungs-)Sport].
Bekannte Strategien werden systematisch und prägnant dargestellt und diskutiert. Die Beschäftigung mit der Ernährung von »Risikogruppen« übt das Erkennen und den Umgang von potenziellen Gefahrensituationen bei der Verordnung von bilanzierter Ernährung. So sollte auch derjenige von dem Kapitel profitieren, der sich mit den behandelten Patientengruppen, Situationen, Erkrankungen üblicherweise nicht beschäftigen muss.
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Abstract
Isovaleric acidemia is a rare autosomal recessive inborn error of leucine catabolism caused by deficiency of isovaleryl coenzyme A dehydrogenase. This enzymatic deficiency leads to severe metabolic derangement, manifested clinically as vomiting, dehydration, and acidosis progressing to seizures, coma, and death. The two phenotypic expressions are the acute severe and the chronic intermittent form. The acute severe phenotype typically results in death during early infancy, whereas patients with the chronic intermittent form are asymptomatic at baseline but have episodes of acute metabolic decompensation, usually in the setting of infection, physical exertion, or ingestion of protein-rich food. This case illustrates how inborn errors of metabolism resulting in organic acidemia can be manifested in adults and why the internist needs to be aware of them.
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Affiliation(s)
- Jeffrey A Feinstein
- Department of Internal Medicine, Wilford Hall Medical Center, Lackland AFB, TX 78236, USA
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