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Thiamine-Responsive and Non-responsive Patients with PDHC-E1 Deficiency: A Retrospective Assessment. JIMD Rep 2014; 15:13-27. [PMID: 24718837 DOI: 10.1007/8904_2014_293] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 01/03/2014] [Accepted: 01/09/2014] [Indexed: 03/29/2023] Open
Abstract
UNLABELLED Pyruvate dehydrogenase complex (PDHC) deficiency is a disorder of energy metabolism that leads to a range of clinical manifestations. We sought to characterise clinical manifestations and biochemical, neuroimaging and molecular findings in thiamine-responsive and nonresponsive PDHC-deficient patients and to identify potential pitfalls in the diagnosis of PDHC deficiency. We retrospectively reviewed all medical records of all PDHC-deficient patients (n = 19; all had PDHA1 gene mutations) and one patient with severe PDHC deficiency secondary to 3-hydroxyisobutyryl-CoA hydrolase deficiency managed at our centre between 1982 and 2012. Responsiveness to thiamine was based on clinical parameters. Seventeen patients received thiamine treatment: eight did not respond, four showed sustained response and the others responded temporarily/questionably. Sustained response was noted at thiamine doses >400 mg/day. Age at presentation was 0-6 and 12-27 months in the nonresponsive (n = 8) and responsive (n = 4) patients, respectively. Corpus callosum abnormalities were noted in 4/8 nonresponsive patients. Basal ganglia involvement (consistent with Leigh disease) was found in four patients (including 2/4 thiamine-responsive patients). Diagnosis through mutation analysis was more sensitive and specific than through enzymatic analysis. We conclude that patients presenting at age >12 months with relapsing ataxia and possibly Leigh syndrome are more likely to be thiamine responsive than those presenting with neonatal lactic acidosis and corpus callosum abnormalities. However, this distinction is equivocal and treatment with thiamine (>400 mg/day) should be commenced on all patients suspected of having PDHC deficiency. Mutation analysis is the preferable first-line diagnostic test to avoid missing thiamine-responsive patients and misdiagnosing patients with secondary PDHC deficiency. SHORT SUMMARY Thiamine responsiveness is more likely in patients presenting at age >12 months with relapsing ataxia and possibly Leigh syndrome than in those presenting with neonatal lactic acidosis and corpus callosum abnormalities. Thiamine doses >400 mg/day are required for sustained response. Mutation analysis is more sensitive and specific than enzymatic analysis as a first-line diagnostic test.
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2
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Patel KP, O’Brien TW, Subramony SH, Shuster J, Stacpoole PW. The spectrum of pyruvate dehydrogenase complex deficiency: clinical, biochemical and genetic features in 371 patients. Mol Genet Metab 2012; 106:385-94. [PMID: 22896851 PMCID: PMC4003492 DOI: 10.1016/j.ymgme.2012.03.017] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
CONTEXT Pyruvate dehydrogenase complex (PDC) deficiency is a genetic mitochondrial disorder commonly associated with lactic acidosis, progressive neurological and neuromuscular degeneration and, usually, death during childhood. There has been no recent comprehensive analysis of the natural history and clinical course of this disease. OBJECTIVE We reviewed 371 cases of PDC deficiency, published between 1970 and 2010, that involved defects in subunits E1α and E1β and components E1, E2, E3 and the E3 binding protein of the complex. DATA SOURCES AND EXTRACTION English language peer-reviewed publications were identified, primarily by using PubMed and Google Scholar search engines. RESULTS Neurodevelopmental delay and hypotonia were the commonest clinical signs of PDC deficiency. Structural brain abnormalities frequently included ventriculomegaly, dysgenesis of the corpus callosum and neuroimaging findings typical of Leigh syndrome. Neither gender nor any clinical or neuroimaging feature differentiated the various biochemical etiologies of the disease. Patients who died were younger, presented clinically earlier and had higher blood lactate levels and lower residual enzyme activities than subjects who were still alive at the time of reporting. Survival bore no relationship to the underlying biochemical or genetic abnormality or to gender. CONCLUSIONS Although the clinical spectrum of PDC deficiency is broad, the dominant clinical phenotype includes presentation during the first year of life; neurological and neuromuscular degeneration; structural lesions revealed by neuroimaging; lactic acidosis and a blood lactate:pyruvate ratio ≤ 20.
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Affiliation(s)
- Kavi P. Patel
- Department of Medicine (Division of Endocrinology, Metabolism and
Diabetes), College of Medicine, University of Florida, Gainesville, FL 32611,
USA
| | - Thomas W. O’Brien
- Department of Biochemistry and Molecular Biology, College of
Medicine, University of Florida, Gainesville, FL 32611, USA
| | | | - Jonathan Shuster
- Department of Epidemiology and Health Policy Research, College of
Medicine, University of Florida, Gainesville, FL 32611, USA
| | - Peter W. Stacpoole
- Department of Medicine (Division of Endocrinology, Metabolism and
Diabetes), College of Medicine, University of Florida, Gainesville, FL 32611,
USA
- Department of Biochemistry and Molecular Biology, College of
Medicine, University of Florida, Gainesville, FL 32611, USA
- Corresponding author at: UF College of Medicine, 1600 SW
Archer Road M2-238, P.O. Box 100226, Gainesville, FL 32610, USA. Fax: +1
352 273 9013. (P.W. Stacpoole)
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3
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Patel KP, O'Brien TW, Subramony SH, Shuster J, Stacpoole PW. The spectrum of pyruvate dehydrogenase complex deficiency: clinical, biochemical and genetic features in 371 patients. Mol Genet Metab 2012; 105:34-43. [PMID: 22079328 PMCID: PMC3754811 DOI: 10.1016/j.ymgme.2011.09.032] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 09/27/2011] [Accepted: 09/27/2011] [Indexed: 01/01/2023]
Abstract
CONTEXT Pyruvate dehydrogenase complex (PDC) deficiency is a genetic mitochondrial disorder commonly associated with lactic acidosis, progressive neurological and neuromuscular degeneration and, usually, death during childhood. There has been no recent comprehensive analysis of the natural history and clinical course of this disease. OBJECTIVE We reviewed 371 cases of PDC deficiency, published between 1970 and 2010, that involved defects in subunits E1α and E1β and components E1, E2, E3 and the E3 binding protein of the complex. DATA SOURCES AND EXTRACTION English language peer-reviewed publications were identified, primarily by using PubMed and Google Scholar search engines. RESULTS Neurodevelopmental delay and hypotonia were the commonest clinical signs of PDC deficiency. Structural brain abnormalities frequently included ventriculomegaly, dysgenesis of the corpus callosum and neuroimaging findings typical of Leigh syndrome. Neither gender nor any clinical or neuroimaging feature differentiated the various biochemical etiologies of the disease. Patients who died were younger, presented clinically earlier and had higher blood lactate levels and lower residual enzyme activities than subjects who were still alive at the time of reporting. Survival bore no relationship to the underlying biochemical or genetic abnormality or to gender. CONCLUSIONS Although the clinical spectrum of PDC deficiency is broad, the dominant clinical phenotype includes presentation during the first year of life; neurological and neuromuscular degeneration; structural lesions revealed by neuroimaging; lactic acidosis and a blood lactate:pyruvate ratio ≤20.
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Affiliation(s)
- Kavi P. Patel
- Department of Medicine (Division of Endocrinology and Metabolism), College of Medicine, University of Florida, Gainesville, FL, 32611, USA
| | - Thomas W. O'Brien
- Department of Biochemistry and Molecular Biology College of Medicine, University of Florida, Gainesville, FL, 32611, USA
| | | | - Jonathan Shuster
- Epidemiology and Health Policy Research College of Medicine, University of Florida, Gainesville, FL, 32611, USA
| | - Peter W. Stacpoole
- Department of Medicine (Division of Endocrinology and Metabolism), College of Medicine, University of Florida, Gainesville, FL, 32611, USA
- Department of Biochemistry and Molecular Biology College of Medicine, University of Florida, Gainesville, FL, 32611, USA
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4
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Dismorfias faciales asociadas a aciduria cetoglutárica. An Pediatr (Barc) 2011; 74:204-6. [DOI: 10.1016/j.anpedi.2010.11.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 10/19/2010] [Accepted: 11/01/2010] [Indexed: 11/21/2022] Open
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5
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Neiberger RE, George JC, Perkins LA, Theriaque DW, Hutson AD, Stacpoole PW. Renal manifestations of congenital lactic acidosis. Am J Kidney Dis 2002; 39:12-23. [PMID: 11774096 DOI: 10.1053/ajkd.2002.29872] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Congenital lactic acidoses (CLAs) constitute a group of rare inborn errors of mitochondrial metabolism in which cellular energy failure is the defining biochemical abnormality. We report the principal manifestations of renal dysfunction in 35 children with CLA caused by defects in either the pyruvate dehydrogenase multienzyme complex or one or more components of the respiratory chain. The most prominent renal abnormalities included bicarbonaturia, phosphaturia, hypercalciuria, complete Fanconi's syndrome, proteinuria, and decreased glomerular filtration rate. These data were compared with those from 79 previously published cases. Clinical manifestations of renal dysfunction in CLA are common and may be the first presenting sign of the disease. The glomerulus and proximal renal tubule appear to be the anatomic sites most vulnerable to abnormal mitochondrial energy transduction. We propose that the primary defect in mitochondrial energy metabolism, together with the consequent intracellular accumulation of lactate and hydrogen ions, precipitates a state of tissue injury that, unless interrupted, becomes self-perpetuating and ultimately leads to renal cell death.
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Affiliation(s)
- Richard E Neiberger
- Department of Pediatrics, Division of Nephrology, and the General Clinical Research Center, University of Florida, Gainesville, FL, USA.
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6
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Seyda A, Chun K, Packman S, Robinson BH. A case of PDH-E1 alpha mosaicism in a male patient with severe metabolic lactic acidosis. J Inherit Metab Dis 2001; 24:551-9. [PMID: 11757583 DOI: 10.1023/a:1012463726810] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have characterized a novel mutation in a male patient that affects the coding sequence of PDH-E1 alpha gene and changes arginine-141 to a leucine. This nucleotide substitution was found in about 75% of the studied DNA (fibroblasts, liver and muscle), a scenario that would indicate a case of E1 alpha mosaicism in a male patient. When the mutant E1 alpha protein was expressed in human skin fibroblasts with zero endogenous pyruvate dehydrogenase complex activity and E1 alpha protein expression, no significant restoration of activity was recorded, in contrast to the wild-type cDNA. even though both wild-type and mutant protein levels were comparable. We concluded that the R141L mutation is a severe one and that it must have occurred in one of the E1 alpha alleles during early embryogenesis.
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MESH Headings
- Acidosis, Lactic/genetics
- Acidosis, Lactic/metabolism
- Blotting, Western
- Cell Line
- Cells, Cultured
- Cloning, Molecular
- DNA, Complementary/biosynthesis
- DNA, Complementary/genetics
- Fibroblasts
- Humans
- Immunohistochemistry
- Karyotyping
- Male
- Mosaicism/genetics
- Pyruvate Dehydrogenase (Lipoamide)/genetics
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
- Tissue Distribution
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Affiliation(s)
- A Seyda
- Research Institute, Hospital for Sick Children, Department of Biochemistry, University of Toronto, Ontario, Canada
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7
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Samson JF, Barth PG, de Vries JI, Menko FH, Ruitenbeek W, van Oost BA, Jakobs C. Familial mitochondrial encephalopathy with fetal ultrasonographic ventriculomegaly and intracerebral calcifications. Eur J Pediatr 1994; 153:510-6. [PMID: 7957369 DOI: 10.1007/bf01957007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In two sibs antenatal ultrasonography revealed identical intracranial calcification, ventricular widening and microcephaly. The first pregnancy was artificially terminated at 19 weeks. Post-mortem examination of the brain revealed destructive calcification and extracerebral neuronal heterotopia. The second sib went to term but died 48 h after birth from irreversible lactic acidosis. Autopsy showed extensive encephalopathy with cavitation and calcification in the cerebral hemispheres, polymicrogyria, multiple neuronal heterotopia, partial callosal dysgenesis, and severe Leigh syndrome, together forming a continuum of early and late brain disruption. Mitochondrial respiratory chain abnormalities, mainly affecting complexes I and IV, and deficiency of pyruvate dehydrogenase complex were detected in skeletal muscle and in liver. A normal functioning of the respiratory chain was found in the fibroblasts. Analysis of mtDNA from muscle, liver and blood revealed normal amounts of intact mtDNA without any of the known point mutations associated with MELAS, MERRF or Leigh syndromes. The early fetal disruption and necrotic changes in the brains of sibs indicate a specific genetically determined disorder which affects neuronal migration, a finding not previously associated with respiratory chain disorders. The present disorder may mimic antenatal congenital infectious encephalopathy because of the combined finding of microcephaly and destructive intracerebral calcification.
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Affiliation(s)
- J F Samson
- Department of Paediatrics, Free University Hospital, Amsterdam, The Netherlands
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8
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Tóth PP, el-Shanti H, Eivins S, Rhead WJ, Klein JM. Transient improvement of congenital lactic acidosis in a male infant with pyruvate decarboxylase deficiency treated with dichloroacetate. J Pediatr 1993; 123:427-30. [PMID: 8355121 DOI: 10.1016/s0022-3476(05)81751-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A comatose male newborn infant with congenital lactic acidosis caused by pyruvate decarboxylase deficiency was treated with dichloroacetate (DCA), which stimulated an 88% drop in serum lactate concentration and reversed his coma. The response to DCA was temporary and the lactic acidosis worsened until his death, but DCA may confer more lasting benefit in less severely affected infants.
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Affiliation(s)
- P P Tóth
- Department of Obstetrics/Gynecology, University of Iowa, Iowa City 52242
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9
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Fitzgerald J, Hutchison WM, Dahl HH. Isolation and characterisation of the mouse pyruvate dehydrogenase E1 alpha genes. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1131:83-90. [PMID: 1581363 DOI: 10.1016/0167-4781(92)90102-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We have characterized two mouse genes that code for the E1 alpha subunit of pyruvate dehydrogenase (PDH), Pdha-1 and Pdha-2. The coding regions show a high degree of homology with each other and with the human PDH genes, PDAH1 and PDHA2. Conserved regions include mitochondrial import sequences, phosphorylation sites and a putative TPP binding site. The PDH genes have an analogous chromosomal arrangement to PGK genes in that two isoforms code for a functionally and structurally similar product. Pdha-1 codes for a somatic isoform and maps to the X-chromosome. Pdha-2 is located on an autosome, is intronless and only expressed in spermatogenic cells. Comparison of human and mouse PDH and PGK gene sequences shows that the somatic sequences are more conserved relative to the testis-specific isoforms, and that the mouse PDH E1 alpha genes have experienced a faster rate of DNA change compared to their human counterparts.
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Affiliation(s)
- J Fitzgerald
- Murdoch Institute for Research into Birth Defects, Royal Children's Hospital, Melbourne, Australia
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10
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De Meirleir L, Lissens W, Vamos E, Liebaers I. Pyruvate dehydrogenase (PDH) deficiency caused by a 21-base pair insertion mutation in the E1 alpha subunit. Hum Genet 1992; 88:649-52. [PMID: 1551669 DOI: 10.1007/bf02265291] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We report the molecular characterization of a case of a functional PDH-E1 (E1 subunit of pyruvate dehydrogenase) deficiency, a cause of severe congenital lactic acidosis. Residual PDH-E1 activity was reduced to 10% of normal values, although the subunit appeared to be quantitatively and qualitatively normal at the protein level as determined by Western blotting. The sequence of PDH-E1 alpha mRNA and the corresponding genomic DNA revealed an in-frame 21-bp insertion between codons 305 and 306 of the normal E1 alpha cDNA. The mutational insert commences with a novel GAT codon and is a nearly perfect tandem duplication of the wild type DNA sequence. A serine phosphorylation site regulating the activity of the PDH complex is altered by this insertion, which in all likelihood is responsible for the functional enzymatic deficiency leading to lactic acidosis.
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Affiliation(s)
- L De Meirleir
- Laboratory of Medical Genetics, Vrije Universiteit Brussel (VUB), Belgium
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11
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Dahl HH, Brown GK, Brown RM, Hansen LL, Kerr DS, Wexler ID, Patel MS, De Meirleir L, Lissens W, Chun K. Mutations and polymorphisms in the pyruvate dehydrogenase E1 alpha gene. Hum Mutat 1992; 1:97-102. [PMID: 1301207 DOI: 10.1002/humu.1380010203] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We present an update on mutations and polymorphisms in the human X chromosome located pyruvate dehydrogenase E1 alpha gene. A total of 20 different mutations are tabulated. The mutations include deletions, insertions, and point mutations. Certain sequences seem particularly prone to mutation. Most of the mutations are found in exons 10 and 11. Furthermore, four of the mutations are seen in unrelated patients. Little is known about how the mutations affect the structure or function of the pyruvate dehydrogenase complex.
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Affiliation(s)
- H H Dahl
- Murdoch Institute for Research Into Birth Defects, Royal Children's Hospital, Parkville, Melbourne, Australia
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12
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Abstract
Organic acidemias are disorders of intermediary metabolism that lead to accumulation of organic acids in biologic fluids, disturb acid-base balance, and derange intracellular biochemical pathways. Their clinical presentation reflects the resultant systemic disease and progressive encephalopathy. While in some organic acidemias, disturbed acid-base metabolism is the predominant presenting feature, in others it is less prominent or even absent. The etiologies of the more than 50 different phenotypes include impaired metabolism of branched-chain amino acids, vitamins, glucose, lipids, glutathione, and gamma-aminobutyric acid and defects of oxidative phosphorylation. Most organic acidemias present with neurologic manifestations, which include acutely or subacutely progressive encephalopathy that involves different parts of the nervous system. The age of presentation and the associated systemic, hematologic, and immune findings provide additional guidelines for differential diagnosis. We summarize major organic acidemias, while emphasizing their usual and unusual neurologic presentations.
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Affiliation(s)
- P T Ozand
- Department of Pediatrics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
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13
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Cain ST, Akers RF, Routtenberg A. Functional regulation of brain pyruvate dehydrogenase: Postnatal development, anesthesia and food-deprivation. Neurochem Int 1991. [DOI: 10.1016/0197-0186(91)90075-o] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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14
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Endo H, Miyabayashi S, Tada K, Narisawa K. A four-nucleotide insertion at the E1 alpha gene in a patient with pyruvate dehydrogenase deficiency. J Inherit Metab Dis 1991; 14:793-9. [PMID: 1779625 DOI: 10.1007/bf01799952] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- H Endo
- Department of Biochemical Genetics, Tohoku University School of Medicine, Sendai, Japan
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15
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Huh TL, Casazza JP, Huh JW, Chi YT, Song BJ. Characterization of two cDNA clones for pyruvate dehydrogenase E1 beta subunit and its regulation in tricarboxylic acid cycle-deficient fibroblast. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38301-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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16
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Sperl W, Ruitenbeek W, Kerkhof CM, Sengers RC, Trijbels JM, Guggenbichler JP, Janssen AJ, Bakkeren JA. Deficiency of the alpha and beta subunits of pyruvate dehydrogenase in a patient with lactic acidosis and unexpected sudden death. Eur J Pediatr 1990; 149:487-92. [PMID: 2189731 DOI: 10.1007/bf01959401] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
An infant with moderate muscular hypotonia and congenital lactic acidosis died suddenly at the age of 3 months. Autopsy revealed no abnormalities responsible for this unexpected death. Measurement of mitochondrial enzymes involved in energy production indicated a severely decreased total pyruvate dehydrogenase complex (PDHC) activity in muscle tissue (0.23 nmoles x min-1 x mg protein-1, control range 2.8-8.7) and moderately decreased PDHC activity in fibroblasts (0.27 nmoles x min-1 x mg protein-1, control range 0.37-2.32). The activity of the first component E1 (pyruvate dehydrogenase) in muscle tissue was 10 times lower than that of controls (0.008 nmoles x min-1 x mg protein-1, control range 0.10-0.25). The activities of dihydrolipoyl dehydrogenase (E3) and various other mitochondrial enzymes were normal. Immunochemical analysis in skeletal muscle tissue and fibroblasts demonstrated a decrease in the amount of the alpha and beta subunits of E1. The features of this patient are compared with those of other patients reported in the literature with immunochemically confirmed combined E1 alpha and beta deficiency.
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Affiliation(s)
- W Sperl
- Department of Paediatrics, University of Nijmegen, The Netherlands
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17
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Abstract
The nature of PDC deficiency has been characterized at the levels of total and component catalytic activities as well as at the levels of component proteins and specific mRNAs. Defects in 14 cases were shown to involve the E1 component, and there was one case each of an apparent E2 and E3 deficiency. Defects involving the E1 component exhibit heterogeneous expression of E1 proteins and mRNAs, indicating that different types of mutations cause E1 deficiency. E1 deficiencies can occur either in the presence or absence of E1 proteins, representing catalytic mutations or mutations affecting the expression of E1 proteins, respectively. In every case where the content of E1 proteins is reduced, both the E1 alpha and the E1 beta peptides are simultaneously affected. This is likely to be due to rapid degradation of any E1 peptide that is not complexed into the alpha 2 beta 2 conformation. Among subjects with reduced levels of both E1 peptides, some had normal amounts of specific E1 alpha and E1 beta mRNAs. In these subjects, the primary mutations affect either translational or post-translational processes leading to the formation of mature E1 proteins in the mitochondria. In contrast, two cases of simultaneous reduction of both E1 alpha and E1 beta proteins had decreases in the amounts of E1 alpha mRNA only. Mutations in these cases may impair the transcription, nuclear processing, or stability of E1 alpha mRNA. E1 deficiency may manifest in a variable manner. Further characterization of this phenomenon might provide insight into the discrepancy between the clinical severity of the defect and the residual level of PDC catalytic activity. Available information indicates that the E1 alpha gene is located on the X chromosome, but sex distribution of E1 alpha defects suggests that the mode of inheritance may not follow a simple X-linked pattern. The availability of specific PDC antibodies and cDNA clones, as well as the application of molecular biological techniques, should facilitate the characterization of the molecular basis of various PDC deficiencies. This information should provide better understanding of the function of PDC, pathophysiology of PDC deficiency, and mechanisms of inheritance and expression of these genes.
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Affiliation(s)
- L Ho
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
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18
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ENDO HITOSHI, HASEGAWA KIYOSHI, NARISAWA KUNIAKI, TADA KEIYA, KAGAWA YASUO, OHTA SHIGEO. Identification of a Gene for the Pyruvate Dehydrogenase E1? Subunit with a Deletion of Four Nucleotides from a Patient with Pyruvate Dehydrogenase Complex Deficiency. Ann N Y Acad Sci 1989. [DOI: 10.1111/j.1749-6632.1989.tb15039.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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19
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Brown GK, Brown RM, Scholem RD, Kirby DM, Dahl HH. The clinical and biochemical spectrum of human pyruvate dehydrogenase complex deficiency. Ann N Y Acad Sci 1989; 573:360-8. [PMID: 2517465 DOI: 10.1111/j.1749-6632.1989.tb15011.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- G K Brown
- Murdoch Institute for Research into Birth Defects, Royal Children's Hospital, Melbourne, Australia
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20
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Abstract
Dichloroacetate (DCA) exerts multiple effects on pathways of intermediary metabolism. It stimulates peripheral glucose utilization and inhibits gluconeogeneis, thereby reducing hyperglycemia in animals and humans with diabetes mellitus. It inhibits lipogenesis and cholesterolgenesis, thereby decreasing circulating lipid and lipoprotein levels in short-term studies in patients with acquired or hereditary disorders of lipoprotein metabolism. By stimulating the activity of pyruvate dehydrogenase, DCA facilitates oxidation of lactate and decreases morbidity in acquired and congenital forms of lactic acidosis. The drug improves cardiac output and left ventricular mechanical efficiency under conditions of myocardial ischemia or failure, probably by facilitating myocardial metabolism of carbohydrate and lactate as opposed to fat. DCA may also enhance regional lactate removal and restoration of brain function in experimental states of cerebral ischemia. DCA appears to inhibit its own metabolism, which may influence the duration of its pharmacologic actions and lead to toxicity. DCA can cause a reversible peripheral neuropathy that may be related to thiamine deficiency and may be ameliorated or prevented with thiamine supplementation. Other toxic effects of DCA may be species-specific and reflect marked interspecies variation in pharmacokinetics. Despite its potential toxicity and limited clinical experience, DCA and its derivatives may prove to be useful in probing regulatory aspects of intermediary metabolism and in the acute or chronic treatment of several metabolic disorders.
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Affiliation(s)
- P W Stacpoole
- Department of Medicine, University of Florida, College of Medicine, Gainesville 32610
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22
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Endo H, Miyabayashi S, Hasegawa K, Narisawa K, Tada K, Kagawa Y, Ohta S. Cloning of a defective gene encoding the pyruvate dehydrogenase E1 alpha subunit from a patient with its deficiency. J Inherit Metab Dis 1989; 12:363-7. [PMID: 2515391 DOI: 10.1007/bf01799243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- H Endo
- Department of Biochemistry, Jichi Medical School, Tochigi, Japan
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23
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Wexler ID, Kerr DS, Ho L, Lusk MM, Pepin RA, Javed AA, Mole JE, Jesse BW, Thekkumkara TJ, Pons G. Heterogeneous expression of protein and mRNA in pyruvate dehydrogenase deficiency. Proc Natl Acad Sci U S A 1988; 85:7336-40. [PMID: 3140238 PMCID: PMC282181 DOI: 10.1073/pnas.85.19.7336] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Deficiency of pyruvate dehydrogenase [pyruvate:lipoamide 2-oxidoreductase (decarboxylating and acceptor-acetylating), EC 1.2.4.1], the first component of the pyruvate dehydrogenase complex, is associated with lactic acidosis and central nervous system dysfunction. Using both specific antibodies to pyruvate dehydrogenase and cDNAs coding for its two alpha and beta subunits, we characterized pyruvate dehydrogenase deficiency in 11 patients. Three different patterns were found on immunologic and RNA blot analyses. (i) Seven patients had immunologically detectable crossreactive material for the alpha and beta proteins of pyruvate dehydrogenase. (ii) Two patients had no detectable crossreactive protein for either the alpha or beta subunit but had normal amounts of mRNA for both alpha and beta subunits. (iii) The remaining two patients also had no detectable crossreactive protein but had diminished amounts of mRNA for the alpha subunit of pyruvate dehydrogenase only. These results indicate that loss of pyruvate dehydrogenase activity may be associated with either absent or catalytically inactive proteins, and in those cases in which this enzyme is absent, mRNA for one of the subunits may also be missing. When mRNA for one of the subunits is lacking, both protein subunits are absent, suggesting that a mutation affecting the expression of one of the subunit proteins causes the remaining uncomplexed subunit to be unstable. The results show that several different mutations account for the molecular heterogeneity of pyruvate dehydrogenase deficiency.
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Affiliation(s)
- I D Wexler
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH 44106
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24
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Robinson BH. Cell culture studies on patients with mitochondrial diseases: molecular defects in pyruvate dehydrogenase. J Bioenerg Biomembr 1988; 20:313-23. [PMID: 3136149 DOI: 10.1007/bf00769635] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
There is a group of inborn errors of metabolism that result in the condition of chronic lacticacidemia of childhood. Nearly all of the defects that can be identified occur in mitochondrial proteins, and can be demonstrated in cultured skin fibroblasts from the patients concerned. One approach to the diagnosis of these defects involves a simple incubation of the fibroblast culture with glucose-containing medium followed by the measurement of accumulated lactate and pyruvate. The total amounts of lactate and pyruvate and the ratio between them is different in cells from patients with defects in the pyruvate dehydrogenase complex or the respiratory chain. Measurement of 1-14C-pyruvate oxidation to 14CO2 can also reveal defective oxidative metabolism. Localization of the defects can be achieved using individual assays for the enzymes concerned. The clinical sequelae of the different defects is discussed.
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Affiliation(s)
- B H Robinson
- Department of Pediatrics, University of Toronto, Canada
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Abstract
Dysfunctioning of human mitochondria is found in a rapidly increasing number of patients. The mitochondrial system for energy transduction is very vulnerable to damage by genetic and environmental factors. A primary mitochondrial disease is caused by a genetic defect in a mitochondrial enzyme or translocator. More than 60 mitochondrial enzyme deficiencies have been reported. Secondary mitochondrial defects are caused by lack of compounds to enable a proper mitochondrial function or by inhibition of that function. This may result from malnutrition, circulatory or hormonal disturbances, viral infection, poisoning, or an extramitochondrial error of metabolism. Once mitochondrial ATP synthesis decreases, secondary mitochondrial lesions may be generated further, due to changes in synthesis and degradation of mitochondrial phospholipids and proteins, to mitochondrial antibody formation following massive degradation, to accumulation of toxic products as excess acyl-CoA, to the depletion of Krebs cycle intermediates, and to the increase of free radical formation and lipid peroxidation.
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Affiliation(s)
- H R Scholte
- Department of Biochemistry I, Erasmus University Rotterdam, The Netherlands
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De Meirleir L, MacKay N, Lam Hon Wah AM, Robinson BH. Isolation of a full-length complementary DNA coding for human E1 alpha subunit of the pyruvate dehydrogenase complex. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)77975-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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27
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Robinson BH, MacMillan H, Petrova-Benedict R, Sherwood WG. Variable clinical presentation in patients with defective E1 component of pyruvate dehydrogenase complex. J Pediatr 1987; 111:525-33. [PMID: 3116190 DOI: 10.1016/s0022-3476(87)80112-9] [Citation(s) in RCA: 146] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Clinical findings are presented for 30 patients with lactic acidemia in whom activity of the pyruvate dehydrogenase complex in fibroblasts was significantly (P = less than 0.01) below that of control cell lines. Residual activity of the activated complex ranged from 1.6% to 68.5% of control activity. Seven patients died before 6 months of age, and another five before reaching 2 years of age. Sixteen of the surviving patients and the five who died between 6 months and 2 years all had psychomotor retardation. Seventeen children had structural central nervous system damage, as determined either by computed tomography or at autopsy. The extent and location of damage varied from cerebral atrophy to the development of cystic lesions in the cerebral cortex, basal ganglia, and brain stem. Two patients had ataxic episodes only and were not developmentally delayed. This cohort of patients strongly resembles a comparable group assembled from various other reports.
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Affiliation(s)
- B H Robinson
- Department of Pediatrics and Biochemistry, University of Toronto, Canada
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28
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Abstract
Mitochondrial disorders, namely defects of fatty acid oxidation, defects of pyruvate metabolism and defects of the respiratory chain are heterogenous in clinical picture and in response to therapeutic attempts. Defects of fatty acid metabolism are amenable to therapy by dietary means, carnitine substitution and in some cases with vitamins. Defects in pyruvate metabolism do not respond to therapy except in some special cases. Therapeutic attempts include dietary measures, vitamins as coenzyme precursors. Defects in the respiratory chain appear to respond to treatment only in exceptional cases. Evaluation of treatment effects appears to be singularly difficult. General measures that can be of benefit to different defects are discussed.
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Affiliation(s)
- H Przyrembel
- Division of Metabolic Diseases, University Children's Hospital, Rotterdam, The Netherlands
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