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ACG Clinical Guideline: Diagnosis and Management of Idiosyncratic Drug-Induced Liver Injury. Am J Gastroenterol 2021; 116:878-898. [PMID: 33929376 DOI: 10.14309/ajg.0000000000001259] [Citation(s) in RCA: 137] [Impact Index Per Article: 45.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 01/25/2021] [Indexed: 12/11/2022]
Abstract
Idiosyncratic drug-induced liver injury (DILI) is common in gastroenterology and hepatology practices, and it can have multiple presentations, ranging from asymptomatic elevations in liver biochemistries to hepatocellular or cholestatic jaundice, liver failure, or chronic hepatitis. Antimicrobials, herbal and dietary supplements, and anticancer therapeutics (e.g., tyrosine kinase inhibitors or immune-checkpoint inhibitors) are the most common classes of agents to cause DILI in the Western world. DILI is a diagnosis of exclusion, and thus, careful assessment for other etiologies of liver disease should be undertaken before establishing a diagnosis of DILI. Model for end-stage liver disease score and comorbidity burden are important determinants of mortality in patients presenting with suspected DILI. DILI carries a mortality rate up to 10% when hepatocellular jaundice is present. Patients with DILI who develop progressive jaundice with or without coagulopathy should be referred to a tertiary care center for specialized care, including consideration for potential liver transplantation. The role of systemic corticosteroids is controversial, but they may be administered when a liver injury event cannot be distinguished between autoimmune hepatitis or DILI or when a DILI event presents with prominent autoimmune hepatitis features.
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POLG1-Related Epilepsy: Review of Diagnostic and Therapeutic Findings. Brain Sci 2020; 10:brainsci10110768. [PMID: 33113942 PMCID: PMC7690674 DOI: 10.3390/brainsci10110768] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/14/2020] [Accepted: 10/20/2020] [Indexed: 11/30/2022] Open
Abstract
Background: The clinical spectrum associated with POLG1 gene mutations ranges from non-syndromic epilepsy or mild isolated neurological signs to neurodegenerative disorders. Our aim was to review diagnostic findings, therapeutic approaches and outcomes of reported cases of epilepsy related to POLG1 mutation. Methods: The articles for review were identified through a systematic research on PubMed and EMBASE databases from January 2003 to April 2020, searching for the terms “Epilepsy AND POLG OR polymerase gamma,” OR “POLG1”. Results: Forty-eight articles were selected for review, which included 195 patients. Two main peaks of age at epilepsy onset were found: at ages 1 and 13 years. The most frequent seizure type was myoclonic. The occurrence of Status Epilepticus was reported in 46.4% of cases. Epileptiform and slow abnormalities were most frequently seen over occipital regions. Brain Magnetic Resonance Imaging (MRI) revealed increased T2 signal intensities in thalamic regions. Genetic analysis revealed a prevalence of A467T, W748S and G848S (74.2% of patients) mutations. Survival at 5 years was estimated at very low levels (30.2% of patients). Conclusion: In this review, we included cases with both pediatric and adult epilepsy onset. The analysis of data regarding prognosis showed that survival is related to age at onset of epilepsy.
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Abstract
The POLG gene encodes the mitochondrial DNA polymerase that is responsible for replication of the mitochondrial genome. Mutations in POLG can cause early childhood mitochondrial DNA (mtDNA) depletion syndromes or later-onset syndromes arising from mtDNA deletions. POLG mutations are the most common cause of inherited mitochondrial disorders, with as many as 2% of the population carrying these mutations. POLG-related disorders comprise a continuum of overlapping phenotypes with onset from infancy to late adulthood. The six leading disorders caused by POLG mutations are Alpers-Huttenlocher syndrome, which is one of the most severe phenotypes; childhood myocerebrohepatopathy spectrum, which presents within the first 3 years of life; myoclonic epilepsy myopathy sensory ataxia; ataxia neuropathy spectrum; autosomal recessive progressive external ophthalmoplegia; and autosomal dominant progressive external ophthalmoplegia. This Review describes the clinical features, pathophysiology, natural history and treatment of POLG-related disorders, focusing particularly on the neurological manifestations of these conditions.
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Mc Kiernan PJ. Recent advances in liver transplantation for metabolic disease. J Inherit Metab Dis 2017; 40:491-495. [PMID: 28168361 DOI: 10.1007/s10545-017-0020-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 01/18/2017] [Accepted: 01/23/2017] [Indexed: 02/07/2023]
Abstract
The indications and outcomes of liver transplantation for metabolic disease have been reviewed recently and this short review concentrates on recent developments and advances. Recently recognized metabolic causes of acute liver failure are reviewed and their implications for transplantation discussed. Newly described indications for liver transplantation in systemic metabolic diseases are described and an update is given on the role of auxiliary and domino liver transplantation.
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MESH Headings
- Amino Acid Metabolism, Inborn Errors/genetics
- Amino Acid Metabolism, Inborn Errors/surgery
- Animals
- Brain Diseases, Metabolic, Inborn/genetics
- Brain Diseases, Metabolic, Inborn/surgery
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/surgery
- Enzyme Replacement Therapy
- Epiphyses/abnormalities
- Epiphyses/surgery
- Glycine N-Methyltransferase/deficiency
- Glycine N-Methyltransferase/genetics
- Humans
- Intestinal Pseudo-Obstruction/genetics
- Intestinal Pseudo-Obstruction/surgery
- Liver Failure, Acute/surgery
- Liver Neoplasms/surgery
- Liver Transplantation/trends
- Metabolic Diseases/surgery
- Mitochondrial Encephalomyopathies/genetics
- Mitochondrial Encephalomyopathies/surgery
- Muscular Dystrophy, Oculopharyngeal
- Neoplasm Proteins/genetics
- Ophthalmoplegia/congenital
- Osteochondrodysplasias/genetics
- Osteochondrodysplasias/surgery
- Purpura/genetics
- Purpura/surgery
- Refsum Disease, Infantile/genetics
- Refsum Disease, Infantile/surgery
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Affiliation(s)
- P J Mc Kiernan
- Division of Gastroenterology/Hepatology/Nutrition Children's Hospital of Pittsburgh of UPMC, Pittsburgh Liver Research Centre, University of Pitttsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA.
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DeBalsi KL, Longley MJ, Hoff KE, Copeland WC. Synergistic Effects of the in cis T251I and P587L Mitochondrial DNA Polymerase γ Disease Mutations. J Biol Chem 2017; 292:4198-4209. [PMID: 28154168 DOI: 10.1074/jbc.m116.773341] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 01/26/2017] [Indexed: 01/28/2023] Open
Abstract
Human mitochondrial DNA (mtDNA) polymerase γ (Pol γ) is the only polymerase known to replicate the mitochondrial genome. The Pol γ holoenzyme consists of the p140 catalytic subunit (POLG) and the p55 homodimeric accessory subunit (POLG2), which enhances binding of Pol γ to DNA and promotes processivity of the holoenzyme. Mutations within POLG impede maintenance of mtDNA and cause mitochondrial diseases. Two common POLG mutations usually found in cis in patients primarily with progressive external ophthalmoplegia generate T251I and P587L amino acid substitutions. To determine whether T251I or P587L is the primary pathogenic allele or whether both substitutions are required to cause disease, we overproduced and purified WT, T251I, P587L, and T251I + P587L double variant forms of recombinant Pol γ. Biochemical characterization of these variants revealed impaired DNA binding affinity, reduced thermostability, diminished exonuclease activity, defective catalytic activity, and compromised DNA processivity, even in the presence of the p55 accessory subunit. However, physical association with p55 was unperturbed, suggesting intersubunit affinities similar to WT. Notably, although the single mutants were similarly impaired, a dramatic synergistic effect was found for the double mutant across all parameters. In conclusion, our analyses suggest that individually both T251I and P587L substitutions functionally impair Pol γ, with greater pathogenicity predicted for the single P587L variant. Combining T251I and P587L induces extreme thermal lability and leads to synergistic nucleotide and DNA binding defects, which severely impair catalytic activity and correlate with presentation of disease in patients.
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Affiliation(s)
- Karen L DeBalsi
- From the Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709
| | - Matthew J Longley
- From the Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709
| | - Kirsten E Hoff
- From the Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709
| | - William C Copeland
- From the Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709
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Incidence of Primary Mitochondrial Disease in Children Younger Than 2 Years Presenting With Acute Liver Failure. J Pediatr Gastroenterol Nutr 2016; 63:592-597. [PMID: 27482763 PMCID: PMC5113754 DOI: 10.1097/mpg.0000000000001345] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND Mitochondrial liver disease (MLD), and in particular mitochondrial DNA (mtDNA) depletion syndrome (MDS) is an important cause of acute liver failure (ALF) in infancy. Early and accurate diagnosis is important because liver transplantation (LT) is often contraindicated. It is unclear which methods are the best to diagnose MLD in the setting of ALF. OBJECTIVE The aim of the study was to determine the incidence of MLD in children younger than 2 years with ALF and the utility of routine investigations to detect MLD. METHODS Thirty-nine consecutive infants with ALF were admitted to a single unit from 2009 to 2011. All were extensively investigated using an established protocol. Genes implicated in mitochondrial DNA depletion syndrome were sequenced in all cases and tissue mtDNA copy number measured where available. RESULTS Five infants (17%) had genetically proven MLD: DGUOK (n = 2), POLG (n = 2), and MPV17 (1). Four of these died, whereas 1 recovered. Two had normal muscle mtDNA copy number and 3 had normal muscle respiratory chain enzymes. An additional 8 children had low hepatic mtDNA copy number but pathogenic mutations were not detected. One of these developed fatal multisystemic disease after LT, whereas 5 who survived remain well without evidence of multisystemic disease up to 6 years later. Magnetic resonance spectroscopy did not distinguish between those with and without MLD. CONCLUSIONS Low liver mtDNA copy number may be a secondary phenomenon in ALF.Screening for mtDNA maintenance gene mutations may be the most efficient way to confirm MLD in ALF in the first 2 years of life.
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Anagnostou ME, Ng YS, Taylor RW, McFarland R. Epilepsy due to mutations in the mitochondrial polymerase gamma (POLG)
gene: A clinical and molecular genetic review. Epilepsia 2016; 57:1531-1545. [DOI: 10.1111/epi.13508] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2016] [Indexed: 01/01/2023]
Affiliation(s)
- Maria-Eleni Anagnostou
- Wellcome Trust Centre for Mitochondrial Research; Institute of Neuroscience; Newcastle University; Newcastle upon Tyne United Kingdom
| | - Yi Shiau Ng
- Wellcome Trust Centre for Mitochondrial Research; Institute of Neuroscience; Newcastle University; Newcastle upon Tyne United Kingdom
| | - Robert W. Taylor
- Wellcome Trust Centre for Mitochondrial Research; Institute of Neuroscience; Newcastle University; Newcastle upon Tyne United Kingdom
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research; Institute of Neuroscience; Newcastle University; Newcastle upon Tyne United Kingdom
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Bennett B, Helbling D, Meng H, Jarzembowski J, Geurts AM, Friederich MW, Van Hove JLK, Lawlor MW, Dimmock DP. Potentially diagnostic electron paramagnetic resonance spectra elucidate the underlying mechanism of mitochondrial dysfunction in the deoxyguanosine kinase deficient rat model of a genetic mitochondrial DNA depletion syndrome. Free Radic Biol Med 2016; 92:141-151. [PMID: 26773591 PMCID: PMC5047058 DOI: 10.1016/j.freeradbiomed.2016.01.001] [Citation(s) in RCA: 13] [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: 11/02/2015] [Revised: 01/04/2016] [Accepted: 01/06/2016] [Indexed: 01/19/2023]
Abstract
A novel rat model for a well-characterized human mitochondrial disease, mitochondrial DNA depletion syndrome with associated deoxyguanosine kinase (DGUOK) deficiency, is described. The rat model recapitulates the pathologic and biochemical signatures of the human disease. The application of electron paramagnetic (spin) resonance (EPR) spectroscopy to the identification and characterization of respiratory chain abnormalities in the mitochondria from freshly frozen tissue of the mitochondrial disease model rat is introduced. EPR is shown to be a sensitive technique for detecting mitochondrial functional abnormalities in situ and, here, is particularly useful in characterizing the redox state changes and oxidative stress that can result from depressed expression and/or diminished specific activity of the distinct respiratory chain complexes. As EPR requires no sample preparation or non-physiological reagents, it provides information on the status of the mitochondrion as it was in the functioning state. On its own, this information is of use in identifying respiratory chain dysfunction; in conjunction with other techniques, the information from EPR shows how the respiratory chain is affected at the molecular level by the dysfunction. It is proposed that EPR has a role in mechanistic pathophysiological studies of mitochondrial disease and could be used to study the impact of new treatment modalities or as an additional diagnostic tool.
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Affiliation(s)
- Brian Bennett
- National Biomedical EPR Center, Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Daniel Helbling
- Human Molecular Genetics Center and Division of Genetics, Department of Pediatrics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Hui Meng
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Jason Jarzembowski
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Aron M Geurts
- Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Marisa W Friederich
- Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Mailstop 8400, 13121 East 17th Avenue, Aurora, CO 80045, USA.
| | - Johan L K Van Hove
- Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Mailstop 8400, 13121 East 17th Avenue, Aurora, CO 80045, USA.
| | - Michael W Lawlor
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - David P Dimmock
- Human Molecular Genetics Center and Division of Genetics, Department of Pediatrics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
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Abstract
PURPOSE OF REVIEW Drug-induced liver injury (DILI) is an underrecognized cause of pediatric liver disease, accounts for almost 20% of pediatric acute liver failure cases, and is a major reason for liver transplantation in the USA. This article reviews the pathogenesis of DILI, approach to diagnosis and management, and highlights recent pediatric DILI case series. RECENT FINDINGS Select individuals have an increased propensity to develop DILI. Known genetic polymorphisms of enzymes and host factors play an important role in medication management and influence the clinical outcome in 20-25% of all drug therapies. Children are more likely to have mitochondrial dysfunction from drugs, increasing their susceptibility to severe liver injury or acute liver failure. Antibiotics and central nervous system agents account for the majority of pediatric DILI in the West, although herbals are becoming more common. SUMMARY Clinical features of DILI vary and overlap so exclusion of other conditions, identification of latency period and risk factors, and use of a searchable database can aid evaluation. Treatment consists of cessation of the offending agent and supportive care. Areas needing further research include elucidating mechanisms, identifying at risk individuals, and therapeutic interventions.
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McKiernan P. Acute liver failure after valproate exposure: Liver transplantation may be indicated beyond childhood. Liver Transpl 2014; 20:1287-9. [PMID: 25179873 DOI: 10.1002/lt.23988] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 08/24/2014] [Indexed: 01/12/2023]
Affiliation(s)
- Patrick McKiernan
- Liver Unit, Birmingham Children's Hospital, Birmingham, United Kingdom
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11
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Hunt CM, Yuen NA, Stirnadel-Farrant HA, Suzuki A. Age-related differences in reporting of drug-associated liver injury: data-mining of WHO Safety Report Database. Regul Toxicol Pharmacol 2014; 70:519-26. [PMID: 25236535 DOI: 10.1016/j.yrtph.2014.09.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 08/18/2014] [Accepted: 09/09/2014] [Indexed: 02/06/2023]
Abstract
BACKGROUND/AIMS Age-differences in the frequency and manifestations of drug-induced liver injury are not fully characterized. Data-mining analyses were performed to assess the impact of age on liver event reporting frequency with different phenotypes and agents. METHODS 236 drugs associated with hepatotoxicity were evaluated using the Empirical Bayes Geometric Mean (EBGM) of the relative reporting ratio with 90% confidence interval (EB05 and EB95) calculated for the age groups: 0-17, 18-64, and⩾65years (or elderly), for overall, serious (acute liver failure), hepatocellular, and cholestatic liver injury, using the WHO Safety Report Database. RESULTS Overall, cases of age 0-17, 18-64, and 65years or older comprised 6%, 62%, and 32% of liver event reports. Acute liver failure and hepatocellular injury were more frequently reported among children compared to adults and the elderly while reports with cholestatic injury were more frequent among the elderly (p<0.00001). A potential to cause mitochondrial dysfunction was more prevalent among the drugs with increased pediatric reporting frequency while high lipophilicity and biliary excretion were more common among the drugs associated with higher reporting frequency in the elderly. CONCLUSION Age-specific phenotypes and potential drug properties associated with age-specific hepatotoxicity were identified in reported liver events; further analyses are warranted.
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Affiliation(s)
- Christine M Hunt
- Division of Gastroenterology, Duke University Medical Center, Durham, NC, United States; Durham Veterans Administration Medical Center, Durham, NC, United States.
| | - Nancy A Yuen
- Global Clinical Safety and Pharmacovigilance, GlaxoSmithKline, Research Triangle Park, NC, United States
| | | | - Ayako Suzuki
- Division of Gastroenterology, University of Arkansas for Medical Sciences, Little Rock, AR, United States; Division of Gastroenterology, Central Arkansas Veterans Healthcare System, Little Rock, AR, United States
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Luís PBM, Ruiter J, IJlst L, de Almeida IT, Duran M, Wanders RJA, Silva MFB. Valproyl-CoA inhibits the activity of ATP- and GTP-dependent succinate:CoA ligases. J Inherit Metab Dis 2014; 37:353-7. [PMID: 24154984 DOI: 10.1007/s10545-013-9657-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 09/23/2013] [Accepted: 09/26/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Valproic acid (VPA) is an effective antiepileptic drug that may induce progressive microvesicular steatosis. The impairment of mitochondrial function may be an important metabolic effect of VPA treatment with potential adverse consequences. OBJECTIVE To investigate the influence of VPA on the activity of GTP- and ATP-specific succinate:CoA ligases (G-SUCL and A-SUCL). METHODS The GTP- and ATP-specific SUCL activities were measured in human fibroblasts in the reverse direction, i.e. the formation of succinyl-CoA. These were assessed at different concentrations of succinate in the presence of VPA, valproyl-CoA and zinc chloride, an established inhibitor of the enzymes. Activities were measured using an optimized HPLC procedure. RESULTS Valproyl-CoA (1 mM) inhibited the activity of A-SUCL and G-SUCL by 45-55% and 25-50%, respectively. VPA (1 mM) had no influence on the activity of the two enzymes. DISCUSSION Valproyl-CoA appears to affect the activity of SUCL, especially with the ATP-specific enzyme. Considering the key role of SUCL in the Krebs cycle, interference with its activity might impair the cellular energy status. Moreover, A-SUCL is bound to the nucleoside diphosphate kinase (NDPK), which is responsible for the mitochondrial (deoxy)nucleotide synthesis. An inhibition of A-SUCL might influence the activity of NDPK inducing an imbalance of nucleotides in the mitochondria and eventually mitochondrial DNA depletion. This may account for the potential liver failure associated with valproate therapy, reported in patients with deficiencies within the mitochondrial DNA replicase system such as polymerase gamma 1.
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Affiliation(s)
- Paula B M Luís
- Research Institute for Medicines and Pharmaceutical Sciences - iMED.UL, Faculty of Pharmacy, University of Lisbon, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal
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Felker D, Lynn A, Wang S, Johnson DE. Evidence for a potential protective effect of carnitine-pantothenic acid co-treatment on valproic acid-induced hepatotoxicity. Expert Rev Clin Pharmacol 2014; 7:211-8. [DOI: 10.1586/17512433.2014.871202] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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14
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Milone M, Wong LJ. Diagnosis of mitochondrial myopathies. Mol Genet Metab 2013; 110:35-41. [PMID: 23911206 DOI: 10.1016/j.ymgme.2013.07.007] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Revised: 07/10/2013] [Accepted: 07/10/2013] [Indexed: 01/01/2023]
Abstract
Mitochondria are ubiquitous organelles and play crucial roles in vital functions, most importantly, the oxidative phosphorylation and energy metabolism. Therefore, mitochondrial dysfunction can affect multiple tissues, with muscle and nerve preferentially affected. Mitochondrial myopathy is a common clinical phenotype, which is characterized by early fatigue and/or fixed muscle weakness; rhabdomyolysis can seldom occur. Muscle biopsy often identifies signs of diseased mitochondria by morphological studies, while biochemical analysis may identify respiratory chain deficiencies. The clinical, morphological and biochemical data guide molecular analysis. Being the mitochondrial function under the control of both mitochondrial DNA and nuclear DNA, the search for mitochondrial DNA mutations and mitochondrial DNA quantitation, may not be sufficient for the molecular diagnosis of mitochondrial myopathies. Approximately 1500 nuclear genes can affect mitochondrial structure and function and the targeting of such genes may be necessary to reach the diagnosis. The identification of causative molecular defects in nuclear or mitochondrial genome leads to the definite diagnosis of mitochondrial myopathy.
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Affiliation(s)
- Margherita Milone
- Department of Neurology, Neuromuscular Division, Mayo Clinic, Rochester, MN, USA
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15
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Khurana DS, Valencia I, Goldenthal MJ, Legido A. Mitochondrial dysfunction in epilepsy. Semin Pediatr Neurol 2013; 20:176-87. [PMID: 24331359 DOI: 10.1016/j.spen.2013.10.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Epilepsy is the most common neurologic disorder worldwide and is characterized by recurrent unprovoked seizures. The mitochondrial (mt) respiratory chain is the final common pathway for cellular energy production through the process of oxidative phosphorylation. As neurons are terminally differentiated cells that lack significant regenerative capacity and have a high energy demand, they are more vulnerable to mt dysfunction. Therefore, epileptic seizures have been well described in several diseases such as mt encephalomyopathy, lactic acidosis, and stroke-like episodes and myoclonic epilepsy and ragged red fibers, which are caused by gene mutations in mtDNA, among others. Mutations in nuclear DNA regulating mt function are also being described (eg, POLG gene mutation). The role of mitochondria (mt) in acquired epilepsies, which account for about 60% of all epilepsies, is equally important but less well understood. Oxidative stress is one of the possible mechanisms in the pathogenesis of epilepsy resulting from mt dysfunction gradually disrupting the intracellular Ca(2+) homeostasis, which modulates neuronal excitability and synaptic transmission, making neurons more vulnerable to additional stress, and leading to energy failure and neuronal loss in epilepsy. Antiepileptic drugs (AEDs) also affect mt function in several ways. There must be caution when treating epilepsy in patients with known mt disorders as some AEDs are toxic to the mt. This review summarizes our current knowledge of the effect of mt disorders on epilepsy, of epileptic seizures on mt, and of AEDs on mt function and the implications of all these interactions for the management of epilepsy in patients with or without mt disease.
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Affiliation(s)
- Divya S Khurana
- Section of Neurology, Departments of Pediatrics and Neurology, St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA.
| | - Ignacio Valencia
- Section of Neurology, Departments of Pediatrics and Neurology, St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA
| | - Michael J Goldenthal
- Section of Neurology, Departments of Pediatrics and Neurology, St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA
| | - Agustín Legido
- Section of Neurology, Departments of Pediatrics and Neurology, St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA
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16
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Kang HC, Lee YM, Kim HD. Mitochondrial disease and epilepsy. Brain Dev 2013; 35:757-61. [PMID: 23414619 DOI: 10.1016/j.braindev.2013.01.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 12/27/2012] [Accepted: 01/06/2013] [Indexed: 11/30/2022]
Abstract
Mitochondrial diseases are a group of diseases caused by dysfunctional mitochondria, organelles that generate energy for the cell. Mitochondrial diseases are often caused by mutations, acquired, or inherited in the mitochondrial DNA or nuclear genes that code for respiratory chain complexes in the mitochondrion. Mitochondrial diseases involve multiple organs and show heterogeneous and unpredictable progression. The most common clinical presentation of mitochondrial diseases is encephalomyopathy, and epileptic seizures can frequently occur as a presenting sign of mitochondrial encephalopathy. While whether mitochondrial dysfunction or epilepsy is the cause or consequence is still debatable, they may be interrelated to create a vicious cycle. Epileptic phenotypes vary in different mitochondrial diseases. At present, there are no curative treatments for mitochondrial diseases, and the efficacy of many anticonvulsants, vitamins, nutritional supplements, and the ketogenic diet remain to be proven. Understanding the pathophysiology of mitochondrial diseases may further facilitate effective diagnostic and therapeutic approaches to these diseases.
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Affiliation(s)
- Hoon-Chul Kang
- Division of Pediatric Neurology, Department of Pediatrics, Pediatric Epilepsy Clinic, Severance Children's Hospital, Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
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17
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Nanau RM, Neuman MG. Adverse drug reactions induced by valproic acid. Clin Biochem 2013; 46:1323-38. [PMID: 23792104 DOI: 10.1016/j.clinbiochem.2013.06.012] [Citation(s) in RCA: 188] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 06/11/2013] [Accepted: 06/12/2013] [Indexed: 12/11/2022]
Abstract
Valproic acid is a widely-used first-generation antiepileptic drug, prescribed predominantly in epilepsy and psychiatric disorders. VPA has good efficacy and pharmacoeconomic profiles, as well as a relatively favorable safety profile. However, adverse drug reactions have been reported in relation with valproic acid use, either as monotherapy or polytherapy with other antiepileptic drugs or antipsychotic drugs. This systematic review discusses valproic acid adverse drug reactions, in terms of hepatotoxicity, mitochondrial toxicity, hyperammonemic encephalopathy, hypersensitivity syndrome reactions, neurological toxicity, metabolic and endocrine adverse events, and teratogenicity.
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Affiliation(s)
- Radu M Nanau
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, In Vitro Drug Safety and Biotechnology, Toronto, Ontario, Canada
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18
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Abstract
Alpers-Huttenlocher syndrome is an uncommon mitochondrial disease most often associated with mutations in the mitochondrial DNA replicase, polymerase-γ. Alterations in enzyme activity result in reduced levels or deletions in mitochondrial DNA. Phenotypic manifestations occur when the functional content of mitochondrial DNA reaches a critical nadir. The tempo of disease progression and onset varies among patients, even in identical genotypes. The classic clinical triad of seizures, liver degeneration, and progressive developmental regression helps define the disorder, but a wide range of clinical expression occurs. The majority of patients are healthy before disease onset, and seizures herald the disorder in most patients. Seizures can rapidly progress to medical intractability, with frequent episodes of epilepsia partialis continua or status epilepticus. Liver involvement may precede or occur after seizure onset. Regardless, eventual liver failure is common. Both the tempo of disease progression and range of organ involvement vary from patient to patient, and are only partly explained by pathogenic effects of genetic mutations. Diagnosis involves the constellation of organ involvement, not the sequence of signs. This disorder is relentlessly progressive and ultimately fatal.
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Abstract
Mitochondrial disorders are a heterogeneous group of disorders resulting from primary dysfunction of the respiratory chain. Muscle tissue is highly metabolically active, and therefore myopathy is a common element of the clinical presentation of these disorders, although this may be overshadowed by central neurological features. This review is aimed at a general medical and neurologist readership and provides a clinical approach to the recognition, investigation, and treatment of mitochondrial myopathies. Emphasis is placed on practical management considerations while including some recent updates in the field.
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Affiliation(s)
- Gerald Pfeffer
- Institute of Genetic Medicine, Newcastle University, Newcastle NE13BZ, United Kingdom
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20
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Chiu CT, Wang Z, Hunsberger JG, Chuang DM. Therapeutic potential of mood stabilizers lithium and valproic acid: beyond bipolar disorder. Pharmacol Rev 2013; 65:105-42. [PMID: 23300133 PMCID: PMC3565922 DOI: 10.1124/pr.111.005512] [Citation(s) in RCA: 282] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The mood stabilizers lithium and valproic acid (VPA) are traditionally used to treat bipolar disorder (BD), a severe mental illness arising from complex interactions between genes and environment that drive deficits in cellular plasticity and resiliency. The therapeutic potential of these drugs in other central nervous system diseases is also gaining support. This article reviews the various mechanisms of action of lithium and VPA gleaned from cellular and animal models of neurologic, neurodegenerative, and neuropsychiatric disorders. Clinical evidence is included when available to provide a comprehensive perspective of the field and to acknowledge some of the limitations of these treatments. First, the review describes how action at these drugs' primary targets--glycogen synthase kinase-3 for lithium and histone deacetylases for VPA--induces the transcription and expression of neurotrophic, angiogenic, and neuroprotective proteins. Cell survival signaling cascades, oxidative stress pathways, and protein quality control mechanisms may further underlie lithium and VPA's beneficial actions. The ability of cotreatment to augment neuroprotection and enhance stem cell homing and migration is also discussed, as are microRNAs as new therapeutic targets. Finally, preclinical findings have shown that the neuroprotective benefits of these agents facilitate anti-inflammation, angiogenesis, neurogenesis, blood-brain barrier integrity, and disease-specific neuroprotection. These mechanisms can be compared with dysregulated disease mechanisms to suggest core cellular and molecular disturbances identifiable by specific risk biomarkers. Future clinical endeavors are warranted to determine the therapeutic potential of lithium and VPA across the spectrum of central nervous system diseases, with particular emphasis on a personalized medicine approach toward treating these disorders.
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Affiliation(s)
- Chi-Tso Chiu
- Molecular Neurobiology Section, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
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21
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Mitochondrial disorders. Neurogenetics 2012. [DOI: 10.1017/cbo9781139087711.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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22
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Millichap JG. POLG Novel Mutation with Alpers Syndrome. Pediatr Neurol Briefs 2012. [DOI: 10.15844/pedneurbriefs-26-2-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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23
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Naess K, Barbaro M, Bruhn H, Wibom R, Nennesmo I, von Döbeln U, Larsson NG, Nemeth A, Lesko N. Complete Deletion of a POLG1 Allele in a Patient with Alpers Syndrome. JIMD Rep 2011; 4:67-73. [PMID: 23430898 DOI: 10.1007/8904_2011_73] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 06/10/2011] [Accepted: 06/21/2011] [Indexed: 12/23/2022] Open
Abstract
Mutations in the gene encoding the catalytic subunit of polymerase γ (POLG1) are a major cause of human mitochondrial disease. More than 150 different point mutations in the gene have been reported to be disease causing, resulting in a large range of clinical symptoms. Depending on the mutation or combination of mutations, disease onset can occur in early infancy or late in adult life. Here, we describe the use of multiplex ligation-dependent probe amplification (MLPA) analysis to detect deletions within POLG1, which could otherwise go undetected by solely sequencing of the gene. We present a case where an entire POLG1 allele is deleted, with a known pathogenic mutation (W748S) on the remaining allele. The deletion was found in a boy with Alpers syndrome, presenting at 18 months of age with slightly retarded motor development, balance problems, and seizures. Administration of valproic acid (VPA) led to rapidly progressive fatal liver failure in our patient, and we would like to highlight the need to carry out complete POLG1 gene analysis before administration of VPA in cases of pediatric seizure disorders of unknown origin. Debut and severity of the disease in this patient was unique when compared to homozygous or heterozygous patients with the W748S mutation, leading to the conclusion that gene dosage plays a role in the clinical phenotype of this disease.
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Affiliation(s)
- Karin Naess
- Department of Laboratory Medicine, Division of Metabolic Diseases, Karolinska Institutet, CMMS C2-71 Karolinska University Hospital Huddinge, 141 86, Stockholm, Sweden
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24
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Mindikoglu AL, King D, Magder LS, Ozolek JA, Mazariegos GV, Shneider BL. Valproic acid-associated acute liver failure in children: case report and analysis of liver transplantation outcomes in the United States. J Pediatr 2011; 158:802-7. [PMID: 21167499 PMCID: PMC3075355 DOI: 10.1016/j.jpeds.2010.10.033] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 09/24/2010] [Accepted: 10/21/2010] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To determine whether valproic acid (VPA)-associated acute liver failure (ALF; VPA-ALF) explains the poor outcomes after liver transplantation (LT) in children. STUDY DESIGN Organ Procurement and Transplantation Network data of pediatric patients who underwent LT for VPA-ALF and ALF caused by other drugs (non-VPA-drug-induced acute liver failure [DIALF]) were analyzed. Pre- and post-transplant variables and post-LT survival were compared between VPA-ALF and non-VPA-DIALF. RESULTS Seventeen children were transplanted for VPA-ALF. Of the 17 children, 82% died within 1 year of LT. Pre- and post-transplant parameters of VPA versus non-VPA-DIALF were comparable with two exceptions. The median alanine aminotransferase level at transplant was remarkably lower in VPA-ALF compared with non-VPA-DIALF (45 versus 1179 IU/L, P = .004). One-year survival probability was worse in VPA-ALF than non-VPA-DIALF (20% versus 69%, P < .0001). Median post-LT survival time for VPA-ALF was 2.8 months. CONCLUSION Children who underwent LT for VPA-ALF had a significantly lower survival probability than children with non-VPA-DIALF. Current data suggest that VPA-ALF in children represents an "unmasking" of mitochondrial disease. VPA-ALF should be a contraindication for LT, even in the absence of a documented mitochondrial disease.
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Affiliation(s)
- Ayse L. Mindikoglu
- Department of Medicine, Division of Gastroenterology and Hepatology, University of Maryland School of Medicine, Baltimore, MD
| | - Dale King
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology and Nutrition, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Laurence S. Magder
- Department of Epidemiology and Public Health, Division of Biostatistics and Bioinformatics, University of Maryland School of Medicine, Baltimore, MD
| | - John A. Ozolek
- Department of Pathology, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - George V. Mazariegos
- Hillman Center for Pediatric Transplantation, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Benjamin L. Shneider
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology and Nutrition, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA
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25
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Begriche K, Massart J, Robin MA, Borgne-Sanchez A, Fromenty B. Drug-induced toxicity on mitochondria and lipid metabolism: mechanistic diversity and deleterious consequences for the liver. J Hepatol 2011; 54:773-94. [PMID: 21145849 DOI: 10.1016/j.jhep.2010.11.006] [Citation(s) in RCA: 365] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 11/05/2010] [Accepted: 11/09/2010] [Indexed: 02/08/2023]
Abstract
Numerous investigations have shown that mitochondrial dysfunction is a major mechanism of drug-induced liver injury, which involves the parent drug or a reactive metabolite generated through cytochromes P450. Depending of their nature and their severity, the mitochondrial alterations are able to induce mild to fulminant hepatic cytolysis and steatosis (lipid accumulation), which can have different clinical and pathological features. Microvesicular steatosis, a potentially severe liver lesion usually associated with liver failure and profound hypoglycemia, is due to a major inhibition of mitochondrial fatty acid oxidation (FAO). Macrovacuolar steatosis, a relatively benign liver lesion in the short term, can be induced not only by a moderate reduction of mitochondrial FAO but also by an increased hepatic de novo lipid synthesis and a decreased secretion of VLDL-associated triglycerides. Moreover, recent investigations suggest that some drugs could favor lipid deposition in the liver through primary alterations of white adipose tissue (WAT) homeostasis. If the treatment is not interrupted, steatosis can evolve toward steatohepatitis, which is characterized not only by lipid accumulation but also by necroinflammation and fibrosis. Although the mechanisms involved in this aggravation are not fully characterized, it appears that overproduction of reactive oxygen species by the damaged mitochondria could play a salient role. Numerous factors could favor drug-induced mitochondrial and metabolic toxicity, such as the structure of the parent molecule, genetic predispositions (in particular those involving mitochondrial enzymes), alcohol intoxication, hepatitis virus C infection, and obesity. In obese and diabetic patients, some drugs may induce acute liver injury more frequently while others may worsen the pre-existent steatosis (or steatohepatitis).
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Affiliation(s)
- Karima Begriche
- Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA
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26
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Schaller A, Hahn D, Jackson CB, Kern I, Chardot C, Belli DC, Gallati S, Nuoffer JM. Molecular and biochemical characterisation of a novel mutation in POLG associated with Alpers syndrome. BMC Neurol 2011; 11:4. [PMID: 21235791 PMCID: PMC3032677 DOI: 10.1186/1471-2377-11-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2010] [Accepted: 01/14/2011] [Indexed: 12/24/2022] Open
Abstract
Background DNA polymerase γ (POLG) is the only known mitochondrial DNA (mtDNA) polymerase. It mediates mtDNA replication and base excision repair. Mutations in the POLG gene lead to reduction of functional mtDNA (mtDNA depletion and/or deletions) and are therefore predicted to result in defective oxidative phosphorylation (OXPHOS). Many mutations map to the polymerase and exonuclease domains of the enzyme and produce a broad clinical spectrum. The most frequent mutation p.A467T is localised in the linker region between these domains. In compound heterozygote patients the p.A467T mutation has been described to be associated amongst others with fatal childhood encephalopathy. These patients have a poorer survival rate compared to homozygotes. Methods mtDNA content in various tissues (fibroblasts, muscle and liver) was quantified using quantitative PCR (qPCR). OXPHOS activities in the same tissues were assessed using spectrophotometric methods and catalytic stain of BN-PAGE. Results We characterise a novel splice site mutation in POLG found in trans with the p.A467T mutation in a 3.5 years old boy with valproic acid induced acute liver failure (Alpers-Huttenlocher syndrome). These mutations result in a tissue specific depletion of the mtDNA which correlates with the OXPHOS-activities. Conclusions mtDNA depletion can be expressed in a high tissue-specific manner and confirms the need to analyse primary tissue. Furthermore, POLG analysis optimises clinical management in the early stages of disease and reinforces the need for its evaluation before starting valproic acid treatment.
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Affiliation(s)
- André Schaller
- Division of Human Genetics, University Hospital Bern, Bern, Switzerland.
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27
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Abstract
The nervous system contains some of the body's most metabolically demanding cells that are highly dependent on ATP produced via mitochondrial oxidative phosphorylation. Thus, the neurological system is consistently involved in patients with mitochondrial disease. Symptoms differ depending on the part of the nervous system affected. Although almost any neurological symptom can be due to mitochondrial disease, there are select symptoms that are more suggestive of a mitochondrial problem. Certain symptoms that have become sine qua non with underlying mitochondrial cytopathies can serve as diagnostic "red-flags." Here, the typical and atypical presentations of mitochondrial disease in the nervous system are reviewed, focusing on "red flag" neurological symptoms as well as associated symptoms that can occur in, but are not specific to, mitochondrial disease. The multitudes of mitochondrial syndromes are not reviewed in-depth, though a select few are discussed in some detail.
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Affiliation(s)
- Sumit Parikh
- Neurogenetics and Metabolism, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
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28
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Finsterer J. Treatment of central nervous system manifestations in mitochondrial disorders. Eur J Neurol 2010; 18:28-38. [DOI: 10.1111/j.1468-1331.2010.03086.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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29
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Hunt CM. Mitochondrial and immunoallergic injury increase risk of positive drug rechallenge after drug-induced liver injury: a systematic review. Hepatology 2010; 52:2216-22. [PMID: 21105110 DOI: 10.1002/hep.24022] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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30
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Abstract
Disruption of the most fundamental cellular energy process, the mitochondrial respiratory chain, results in a diverse and variable group of multisystem disorders known collectively as mitochondrial disease. The frequent involvement of the brain, nerves, and muscles, often in the same patient, places neurologists at the forefront of the interesting and challenging process of diagnosing and caring for these patients. Mitochondrial diseases are among the most frequently inherited neurological disorders, and can be caused by mutations in mitochondrial or nuclear DNA. Substantial progress has been made over the past decade in understanding the genetic basis of these disorders, with important implications for the general neurologist in terms of the diagnosis, investigation, and multidisciplinary management of these patients.
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Affiliation(s)
- Robert McFarland
- Mitochondrial Research Group, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK
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31
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Fontana RJ, Seeff LB, Andrade RJ, Björnsson E, Day CP, Serrano J, Hoofnagle JH. Standardization of nomenclature and causality assessment in drug-induced liver injury: summary of a clinical research workshop. Hepatology 2010; 52:730-42. [PMID: 20564754 PMCID: PMC3616501 DOI: 10.1002/hep.23696] [Citation(s) in RCA: 220] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
UNLABELLED Idiosyncratic drug-induced liver injury (DILI) is an important but relatively infrequent cause of potentially severe acute and chronic liver injury. The aim of this clinical research workshop was to review and attempt to standardize the current nomenclature and terminology used in DILI research. Because DILI is a diagnosis of exclusion, selected elements of the medical history, laboratory tests, and previous reports were proposed to improve causality assessment. Definitions and diagnostic criteria regarding the onset of DILI, evolution of liver injury, risk factors, and mandatory testing versus optional testing for competing causes were reviewed. In addition, the role of intentional and inadvertent rechallenge, liver histology, and host genetic polymorphisms in establishing the diagnosis and prognosis of DILI were reviewed. Consensus was established regarding the need to develop a web-of-knowledge database that provides concise, reliable, and updated information on cases of liver injury due to drugs and herbal and dietary supplements. In addition, the need to develop drug-specific computerized causality assessment methods that are derived from prospectively phenotyped cases was a high priority. Proposed scales for grading DILI severity and assessing the likelihood of an agent causing DILI and written criteria for improving the reliability, accuracy, and reproducibility of expert opinion were reviewed. Finally, the unique challenges of assessing causality in children, patients with underlying liver disease, and subjects taking herbal and dietary supplements were discussed. CONCLUSION Workshop participants concluded that multicenter referral networks enrolling patients with suspected DILI according to standardized methodologies are needed. These networks should also collect biological samples that may provide crucial insights into the mechanism(s) of DILI with the ultimate aim of preventing future cases of DILI.
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Affiliation(s)
- Robert J Fontana
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48103, USA.
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32
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Steinlein OK. Gene polymorphisms and their role in epilepsy treatment and prognosis. Naunyn Schmiedebergs Arch Pharmacol 2010; 382:109-18. [PMID: 20556360 DOI: 10.1007/s00210-010-0531-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Accepted: 05/27/2010] [Indexed: 12/16/2022]
Abstract
The human genome carries an enormous number of genetic variants, many of them of functional consequence. In epilepsy, they are likely to be involved in drug-specific treatment efficacy, unwanted or even toxic drug reactions, teratogenic risks in pregnancy as well as in the long-term prognosis of patients with epilepsy. As in many other disorders with a complex genetic background, the associated genetic variants that could be verified successfully in replication studies are still only a few. However, new techniques and improved research strategies are likely to increase their number in the foreseeable future, although at a much slower pace as initially expected.
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Affiliation(s)
- Ortrud K Steinlein
- Institute of Human Genetics, University Hospital, Ludwig-Maximilians-University of Munich, Goethestr. 29, 80336, Munich, Germany.
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33
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Kisler JE, Whittaker RG, McFarland R. Mitochondrial diseases in childhood: a clinical approach to investigation and management. Dev Med Child Neurol 2010; 52:422-33. [PMID: 20163433 DOI: 10.1111/j.1469-8749.2009.03605.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Mitochondrial diseases are a common cause of inherited neurological disorders in children. Although dysfunction of the central nervous system is prominent, multisystem involvement also occurs. Diagnosis relies on characteristic clinical features, an understanding of mitochondrial genetics, and a logical, informed approach to investigations. There is a significant body of recent literature on advances in mitochondrial genetics and the investigation of mitochondrial diseases. However, to our knowledge there remains a paucity of published information on the management of these disorders. Management of the complex constellation of neurological and multisystem clinical features is challenging, and is reliant on a multidisciplinary approach. The care of the child and family is dependent on clear communication between health professionals from primary, secondary, and tertiary care as well as specialist input from quaternary services. The aim of this review is to provide paediatric neurologists, paediatricians, and allied health professionals with a structured approach to the diagnosis and management of children with suspected or confirmed mitochondrial disease.
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Affiliation(s)
- Jill Edith Kisler
- Department of Paediatric Neurology, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
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34
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Berger I, Segal I, Shmueli D, Saada A. The effect of antiepileptic drugs on mitochondrial activity: a pilot study. J Child Neurol 2010; 25:541-5. [PMID: 20413803 DOI: 10.1177/0883073809352888] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mitochondria are probably a target in antiepileptic drug-induced hepatotoxicity accompanied by oxidative stress. Most studies discuss valproic acid. The information regarding other antiepileptic drugs is scarce. Most studies used in vitro methods and animal models. In this study, the authors have investigated the effect of antiepileptic drugs, other than valproic acid, on the oxidative phosphorylation process in children, by measuring mitochondrial adenosine triphosphate (ATP) production and the enzymatic activities of respiratory chain complexes II-IV in peripheral white blood cells. The results demonstrate that several antiepileptic drugs can affect the mitochondrial oxidative phosphorylation. The authors have concluded that the effect of antiepileptic drugs on the mitochondria is not limited only to valproic acid, but can affect different mitochondrial pathways and can be performed in humans by relatively simple methods, using small samples of peripheral white blood cells.
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Affiliation(s)
- Itai Berger
- The Neuro-Pediatric Unit, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
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35
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Saneto RP, Lee IC, Koenig MK, Bao X, Weng SW, Naviaux RK, Wong LJC. POLG DNA testing as an emerging standard of care before instituting valproic acid therapy for pediatric seizure disorders. Seizure 2010; 19:140-6. [PMID: 20138553 DOI: 10.1016/j.seizure.2010.01.002] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Revised: 12/31/2009] [Accepted: 01/07/2010] [Indexed: 11/17/2022] Open
Abstract
PURPOSE To review our clinical experience and determine if there are appropriate signs and symptoms to consider POLG sequencing prior to valproic acid (VPA) dosing in patients with seizures. METHODS Four patients who developed VPA-induced hepatotoxicity were examined for POLG sequence variations. A subsequent chart review was used to describe clinical course prior to and after VPA dosing. RESULTS Four patients of multiple different ethnicities, age 3-18 years, developed VPA-induced hepatotoxicity. All were given VPA due to intractable partial seizures. Three of the patients had developed epilepsia partialis continua. The time from VPA exposure to liver failure was between 2 and 3 months. Liver failure was reversible in one patient. Molecular studies revealed homozygous p.R597W or p.A467T mutations in two patients. The other two patients showed compound heterozygous mutations, p.A467T/p.Q68X and p.L83P/p.G888S. Clinical findings and POLG mutations were diagnostic of Alpers-Huttenlocher syndrome. CONCLUSION Our cases underscore several important findings: POLG mutations have been observed in every ethnic group studied to date; early predominance of epileptiform discharges over the occipital region is common in POLG-induced epilepsy; the EEG and MRI findings varying between patients and stages of the disease; and VPA dosing at any stage of Alpers-Huttenlocher syndrome can precipitate liver failure. Our data support an emerging proposal that POLG gene testing should be considered in any child or adolescent who presents or develops intractable seizures with or without status epilepticus or epilepsia partialis continua, particularly when there is a history of psychomotor regression.
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Affiliation(s)
- Russell P Saneto
- Division of Pediatric Neurology, Seattle Children's Hospital/University of Washington, Seattle, WA 98105, USA
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36
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Tarnopolsky MA. MITOCHONDRIAL CYTOPATHIES IN CHILDREN AND ADULTS. Continuum (Minneap Minn) 2009. [DOI: 10.1212/01.con.0000348880.16694.08] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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38
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Abstract
BACKGROUND Given the number of publications appearing annually regarding drug-induced liver injury (DILI), there remains a need to concisely summarize each year's new crop of case series and reports as well as the advances in mechanisms of liver injury and in the field of pharmacogenomics relating to DILI. OBJECTIVE To present an up-to-date review of the past year's most important clinical studies and reports of DILI, placing them into context of previous publications. METHODS A Medline search was conducted of all manuscripts appearing in the fields "hepatotoxicity" and "drug-induced liver injury" during the calendar year 2008. The most clinically relevant English language case reports and studies exploring mechanisms and risk factors for DILI were then chosen for review, and supplemented with older literature where appropriate. CONCLUSIONS As in past years, 2008 was replete with publications dealing with virtually all facets of DILI, including updated incidence and prevalence data, as well as the latest information regarding mechanisms of liver injury. Data from the first 300 patients in the National Institute of Health-sponsored DILI Network registry of > 100 non-acetaminophen causes were presented. Antimicrobials and CNS drugs were responsible for > 60% of cases, with herbals and dietary supplements being increasingly reported. Identification of genetic predispositions to DILI is coming of age with the FDA calling for the testing of human leukocyte antigen B(*)5701 before the use of abacavir to reduce the risk of hypersensitivity reactions. Several groups emphasized the pitfalls in utilizing Roussel Uclaf Causality Assessment Method and other causality assessment methodologies, and an updated review appeared on the use of potentially hepatotoxic medications in patients with underlying liver disease.
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Affiliation(s)
- Gordon Liss
- Georgetown University Medical Center, Division of Gastroenterology, 3800 Reservoir Road, NW, Washington, DC 20007, USA
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39
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Wolf NI, Rahman S, Schmitt B, Taanman JW, Duncan AJ, Harting I, Wohlrab G, Ebinger F, Rating D, Bast T. Status epilepticus in children with Alpers’ disease caused byPOLG1mutations: EEG and MRI features. Epilepsia 2009; 50:1596-607. [DOI: 10.1111/j.1528-1167.2008.01877.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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40
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Kasiviswanathan R, Longley MJ, Chan SSL, Copeland WC. Disease mutations in the human mitochondrial DNA polymerase thumb subdomain impart severe defects in mitochondrial DNA replication. J Biol Chem 2009; 284:19501-10. [PMID: 19478085 DOI: 10.1074/jbc.m109.011940] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Forty-five different point mutations in POLG, the gene encoding the catalytic subunit of the human mitochondrial DNA polymerase (pol gamma), cause the early onset mitochondrial DNA depletion disorder, Alpers syndrome. Sequence analysis of the C-terminal polymerase region of pol gamma revealed a cluster of four Alpers mutations at highly conserved residues in the thumb subdomain (G848S, c.2542g-->a; T851A, c.2551a-->g; R852C, c.2554c-->t; R853Q, c.2558g-->a) and two Alpers mutations at less conserved positions in the adjacent palm subdomain (Q879H, c.2637g-->t and T885S, c.2653a-->t). Biochemical characterization of purified, recombinant forms of pol gamma revealed that Alpers mutations in the thumb subdomain reduced polymerase activity more than 99% relative to the wild-type enzyme, whereas the palm subdomain mutations retained 50-70% wild-type polymerase activity. All six mutant enzymes retained physical and functional interaction with the pol gamma accessory subunit (p55), and none of the six mutants exhibited defects in misinsertion fidelity in vitro. However, differential DNA binding by these mutants suggests a possible orientation of the DNA with respect to the polymerase during catalysis. To our knowledge this study represents the first structure-function analysis of the thumb subdomain in pol gamma and examines the consequences of mitochondrial disease mutations in this region.
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Affiliation(s)
- Rajesh Kasiviswanathan
- Laboratory of Molecular Genetics, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA
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41
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Abstract
Large interindividual variation in efficacy and adverse effects of anti-epileptic therapy presents opportunities and challenges in pharmacogenomics. Although the first true association of genetic polymorphism in drug-metabolizing enzymes with anti-epileptic drug dose was reported 10 years ago, most of the findings have had little impact on clinical practice so far. Most studies performed to date examined candidate genes and were focused on candidate gene selection. Genome-wide association and whole-genome sequencing technologies empower hypothesis-free comprehensive screening of genetic variation across the genome and now the main challenge remaining is to select and study clinically relevant phenotypes suitable for genetic studies. Here we review the current state of epilepsy pharmacogenetics focusing on phenotyping questions and discuss what characteristics we need to study to get answers.
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Affiliation(s)
- Dalia Kasperavičiūtė
- Department of Clinical & Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - Sanjay M Sisodiya
- Department of Clinical & Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
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Wortmann SB, Rodenburg RJT, Jonckheere A, de Vries MC, Huizing M, Heldt K, van den Heuvel LP, Wendel U, Kluijtmans LA, Engelke UF, Wevers RA, Smeitink JAM, Morava E. Biochemical and genetic analysis of 3-methylglutaconic aciduria type IV: a diagnostic strategy. Brain 2008; 132:136-46. [DOI: 10.1093/brain/awn296] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Current awareness: Pharmacoepidemiology and drug safety. Pharmacoepidemiol Drug Saf 2008. [DOI: 10.1002/pds.1489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
PURPOSE OF REVIEW Mitochondrial diseases are a major category of childhood illness that produce a wide variety of symptoms and multisystemic disorders. This review highlights recent clinically important developments in diagnostic evaluation and treatment of mitochondrial diseases. RECENT FINDINGS Major advances have been made in understanding the genetic bases of mitochondrial diseases. Molecular defects have recently been reported in mitochondrial DNA maintenance, RNA translation and protein import and in mitochondrial fusion and fission, opening new areas of cell disorder. Diagnostic testing is struggling to keep pace with these fundamental discoveries. The diagnostic approach to children suspected of mitochondrial disease is rapidly evolving but few patients have a molecular diagnosis. A better notion of the prognosis of affected children is emerging from studies of long-term outcome. Some therapeutic successes are reported, such as in coenzyme Q deficiency conditions. SUMMARY Mitochondrial diseases can present with signs in almost any organ. Well planned clinical evaluation is the key to successful diagnostic work-up of mitochondrial diseases. An approach is presented for further testing in specialized laboratories. Mitochondrial diseases can be caused by mutations in mitochondrial DNA or, more commonly in children, in nuclear genes. Mitochondrial DNA mutations pose special challenges for genetic counseling and prenatal diagnosis. Supportive treatment and avoidance of environmental stresses are important aspects of patient care. Specific treatment of mitochondrial diseases is in its infancy and is a major challenge for pediatric medicine.
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Reversible Valproate Hepatotoxicity and Associated Mitochondrial Disease. Pediatr Neurol Briefs 2008. [DOI: 10.15844/pedneurbriefs-22-2-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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