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Wang C, Li M, Liu Z, Guo Y, Liu H, Zhao P. Genetic evaluation in indeterminate acute liver failure: A post hoc analysis. Arab J Gastroenterol 2024; 25:125-128. [PMID: 38705812 DOI: 10.1016/j.ajg.2024.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 01/28/2024] [Accepted: 03/20/2024] [Indexed: 05/07/2024]
Abstract
BACKGROUND AND STUDY AIMS There are limited data regarding indeterminate acute liver failure (ALF). The study aims to perform a post hoc analysis using genetic methods for the ALF cases with indeterminate etiology. PATIENTS AND METHODS Stored blood samples from these patients with indeterminate ALF were collected. Whole-exome sequencing (WES) was used to evaluate the pathogenesis of indeterminate ALF. RESULTS A total of 16 samples from 11 adult patients and 5 pediatric patients with indeterminate ALF were available. Among the adult patients, one female patient was identified with two heterozygous variants (c.2333G > T (p.Arg778Leu) and c.2310C > G (p.Leu770 = )) in the adenosine triphosphatase copper-transporting beta (ATP7B) gene, and two male patients were found to harbor heterozygous and homozygous variants (c.686C > A (p.Pro229Gln) plus homozygousvariantA(TA)6TAAinsTA (-), andc.1456 T > G (p.Tyr486Asp) plus c.211G > A (p.Gly71Arg)) in the uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene. For the pediatric patients, single heterozygous variant (c.2890C > T (p.Arg964Cys)) in the polymerase gamma (POLG) gene was found in 1 male child, and two heterozygous variants (c.1909A > G (p.Lys637Glu) and c.3646G > A (p.Val1216Ile)) in the tetratricopeptide repeat domain 37 (TTC37) gene were found in 1 female child. No variants clinically associated with known liver diseases were revealed in the remaining patients. CONCLUSION These results expand the knowledge of ALF with indeterminate etiology. WES is helpful to reveal possible candidate genes for indeterminate ALF, but incomplete consistency between the genotype and phenotype in some cases still challenge the accurate diagnosis.
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Affiliation(s)
- Chunya Wang
- Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China
| | - Meina Li
- Faculty of Military Health Services, Second Military Medical University, Shanghai 200433,China
| | - Zhenhua Liu
- Department of Pathology, Seventh Medical Center, Chinese PLA General Hospital, Beijing 100010, China
| | - Yupeng Guo
- College of Public Health, Mudanjiang Medical University, Mudanjiang 157011, Heilongjiang, China
| | - Huijuan Liu
- Fifth Medical Center (formerly Beijing 302 Hospital), Chinese PLA General Hospital, Beijing 100039, China
| | - Pan Zhao
- Fifth Medical Center (formerly Beijing 302 Hospital), Chinese PLA General Hospital, Beijing 100039, China.
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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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Helbling D, Buchaklian A, Wang J, Wong LJ, Dimmock D. Reduced mitochondrial DNA content and heterozygous nuclear gene mutations in patients with acute liver failure. J Pediatr Gastroenterol Nutr 2013; 57:438-43. [PMID: 23783014 PMCID: PMC4966813 DOI: 10.1097/mpg.0b013e31829ef4b4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
OBJECTIVES Historically, mitochondrial disorders have been associated with predominantly multisystem or neurological symptoms. If present, hepatic complications were thought to be a late feature. Recently, mutations in at least 4 nuclear genes have been identified in infants presenting with rapidly progressive hepatic failure, which may be precipitated by infection or drugs. We aimed to determine whether hepatic mitochondrial DNA (mtDNA) depletion is associated with apparently isolated hepatic failure in individuals with acute liver failure (ALF) of known or unknown etiologies undergoing liver transplant (LT). In addition, we wished to establish whether there was an excess of mutations in gene known to cause hepatic mtDNA depletion. METHODS Using previously established methods, we demonstrated that end-stage liver disease from known causes did not lead to hepatic mtDNA depletion. RESULTS Using thresholds derived from receiver-operator curve analysis, 66% of cases with ALF had probable or definite mtDNA depletion, including 34% with definite mtDNA depletion. There was a small but significant increase in the proportion of patients undergoing LT for ALF with heterozygous mutations known to lead to mtDNA depletion and hepatic failure compared with controls (P = 0.001). CONCLUSIONS Liver disease severe enough to require LT does not cause secondary mtDNA depletion; however, the majority of patients undergoing LT for ALF had reduced mtDNA content, which fell within the range seen in patients with classic mtDNA depletion. A subset of patients with ALF has mutations in genes known to lead to mtDNA depletion and hepatic failure. Together, these results suggest defective mtDNA maintenance is associated with ALF.
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Affiliation(s)
- Daniel Helbling
- Division of Genetics, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA.
| | - Adam Buchaklian
- Division of Genetics, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA.
| | - Jing Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
| | - Lee-Jun Wong
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
| | - David Dimmock
- Division of Genetics, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
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Mudd SH, Wagner C, Luka Z, Stabler SP, Allen RH, Schroer R, Wood T, Wang J, Wong LJ. Two patients with hepatic mtDNA depletion syndromes and marked elevations of S-adenosylmethionine and methionine. Mol Genet Metab 2012; 105:228-36. [PMID: 22137549 PMCID: PMC3264801 DOI: 10.1016/j.ymgme.2011.11.006] [Citation(s) in RCA: 19] [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: 09/22/2011] [Revised: 11/07/2011] [Accepted: 11/07/2011] [Indexed: 02/07/2023]
Abstract
This paper reports studies of two patients proven by a variety of studies to have mitochondrial depletion syndromes due to mutations in either their MPV17 or DGUOK genes. Each was initially investigated metabolically because of plasma methionine concentrations as high as 15-21-fold above the upper limit of the reference range, then found also to have plasma levels of S-adenosylmethionine (AdoMet) 4.4-8.6-fold above the upper limit of the reference range. Assays of S-adenosylhomocysteine, total homocysteine, cystathionine, sarcosine, and other relevant metabolites and studies of their gene encoding glycine N-methyltransferase produced evidence suggesting they had none of the known causes of elevated methionine with or without elevated AdoMet. Patient 1 grew slowly and intermittently, but was cognitively normal. At age 7 years he was found to have hepatocellular carcinoma, underwent a liver transplant and died of progressive liver and renal failure at age almost 9 years. Patient 2 had a clinical course typical of DGUOK deficiency and died at age 8 ½ months. Although each patient had liver abnormalities, evidence is presented that such abnormalities are very unlikely to explain their elevations of AdoMet or the extent of their hypermethioninemias. A working hypothesis is presented suggesting that with mitochondrial depletion the normal usage of AdoMet by mitochondria is impaired, AdoMet accumulates in the cytoplasm of affected cells poor in glycine N-methyltransferase activity, the accumulated AdoMet causes methionine to accumulate by inhibiting activity of methionine adenosyltransferase II, and that both AdoMet and methionine consequently leak abnormally into the plasma.
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Affiliation(s)
- S Harvey Mudd
- Laboratory of Molecular Biology, National Institute of Mental Health, Bethesda, MD 20892, USA.
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Abstract
Mitochondrial respiratory chain (RC) disorders (RCDs) are a group of genetically and clinically heterogeneous diseases because of the fact that protein components of the RC are encoded by both mitochondrial and nuclear genomes and are essential in all cells. In addition, the biogenesis, structure, and function of mitochondria, including DNA replication, transcription, and translation, all require nuclear-encoded genes. In this review, primary molecular defects in the mitochondrial genome and major classes of nuclear genes causing mitochondrial RCDs, including genes underlying mitochondrial DNA (mtDNA) depletion syndrome, as well as genes encoding RC subunits, complex assembly genes, and translation factors, are described. Diagnostic methodologies used to detect common point mutations, large deletions, and unknown point mutations in the mtDNA and to quantify mutation heteroplasmy are also discussed. Finally, the selection of nuclear genes for gold standard sequence analysis, application of novel technologies including oligonucleotide array comparative genomic hybridization, and massive parallel sequencing of target genes are reviewed.
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Affiliation(s)
- Lee-Jun C Wong
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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Dimmock D, Tang LY, Schmitt ES, Wong LJC. Quantitative evaluation of the mitochondrial DNA depletion syndrome. Clin Chem 2010; 56:1119-27. [PMID: 20448188 DOI: 10.1373/clinchem.2009.141549] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND The mitochondrial DNA (mtDNA) depletion syndromes (MDDSs) are autosomal recessive disorders characterized by a reduction in cellular mtDNA content. Mutations in at least 9 genes [POLG, polymerase (DNA directed), gamma; DGUOK, deoxyguanosine kinase; TK2, thymidine kinase, mitochondrial; TYMP, thymidine phosphorylase; MPV17, MpV17 mitochondrial inner membrane protein; SUCLA2, succinate-CoA ligase, ADP-forming, beta subunit; SUCLG1, succinate-CoA ligase, alpha subunit; RRM2B, RRM2B, ribonucleotide reductase M2 B (TP53 inducible); and C10orf2, chromosome 10 open reading frame 2 (also known as TWINKLE)] have been reported to cause mtDNA depletion. In the clinical setting, a simple method to quantify mtDNA depletion would be useful before undertaking gene sequence analysis. METHODS Real-time quantitative PCR (qPCR) was used to measure the mtDNA content in blood, muscle, and liver samples and in skin fibroblast cultures from individuals suspected of mitochondrial disorders, with or without deleterious mutations in genes responsible for MDDS. RESULTS The mtDNA content was quantified in 776 tissue samples (blood, n = 341; muscle, n = 325; liver, n = 63; skin fibroblasts, n = 47) from control individuals. mtDNA content increased with age in muscle tissue, decreased with age in blood samples, and appeared to be unaffected by age in liver samples. In 165 samples (blood, n = 122; muscle, n = 21; liver, n = 15; skin fibroblasts, n = 7) from patients with molecularly proven MDDSs, severe mtDNA depletion was detected in liver and muscle tissue with high specificity and sensitivity. Blood samples were specific but not sensitive for detecting mtDNA depletion, and skin fibroblasts were not valuable for evaluating mtDNA depletion. Mutations in the POLG, RRM2B, and MPV17 genes were prospectively identified in 1 blood, 1 liver, and 3 muscle samples. CONCLUSIONS Muscle and liver tissues, but not blood or skin fibroblasts, are potentially useful for rapid screening for mtDNA depletion with real-time qPCR.
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Affiliation(s)
- David Dimmock
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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Chan SSL, Naviaux RK, Basinger AA, Casas KA, Copeland WC. De novo mutation in POLG leads to haplotype insufficiency and Alpers syndrome. Mitochondrion 2009; 9:340-5. [PMID: 19501198 DOI: 10.1016/j.mito.2009.05.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 05/06/2009] [Accepted: 05/26/2009] [Indexed: 11/28/2022]
Abstract
Mutations in POLG are a major contributor to pediatric and adult mitochondrial diseases. However, the consequences of many POLG mutations are not well understood. We investigated the molecular cause of Alpers syndome in a patient harboring the POLG mutations A467T in trans with c.2157+5_+6 gc-->ag in intron 12. Analysis of transcripts arising from the c.2157+5_+6 gc-->ag allele revealed alternative splicing with an insertion of 30 intronic nucleotides leading to a premature termination codon. These transcripts were subsequently removed through nonsense-mediated decay, leading to haplotype insufficiency due to expression of the A467T allele and decreased expression of the c.2157+5_+6 gc-->ag allele, which is likely responsible for the Alpers syndrome phenotype.
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Affiliation(s)
- Sherine S L Chan
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institute of Health, Research Triangle Park, NC 27709, USA
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