1
|
Wang Y, Hang L, Shou W, Li C, Dong F, Feng X, Jin R, Li B, Xiao S. Case Report: A novel RRM2B variant in a Chinese infant with mitochondrial DNA depletion syndrome and collective analyses of RRM2B variants for disease etiology. Front Pediatr 2024; 12:1363728. [PMID: 38737634 PMCID: PMC11084280 DOI: 10.3389/fped.2024.1363728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 04/10/2024] [Indexed: 05/14/2024] Open
Abstract
Background There are few reports of infantile mitochondrial DNA depletion syndrome (MDDS) caused by variants in RRM2B and the correlation between genotype and phenotype has rarely been analyzed in detail. This study investigated an infantile patient with MDDS, from clinical characteristics to genetic causes. Methods Routine physical examinations, laboratory assays, which included gas chromatography-mass spectrometry of blood and urine, and MRI scans were performed to obtain an exact diagnosis. Whole-exome sequencing was used to pinpoint the abnormal gene and bioinformatic analyses were performed on the identified variant. Results The case presented with progressive neurologic deterioration, failure to thrive, respiratory distress and lactic acidosis. Sequencing revealed that the patient had a homozygous novel missense variant, c.155T>C (p.Ile52Thr), in exon 2 of the RRM2B gene. Multiple lines of bioinformatic evidence suggested that this was a likely detrimental variant. In addition, reported RRM2B variants were compiled from the relevant literature to analyze disease etiology. We found a distinctive distribution of genotypes across disease manifestations of different severity. Pathogenic alleles of RRM2B were significantly enriched in MDDS cases. Conclusion The novel variant is a likely genetic cause of MDDS. It expands our understanding of the pathogenic variant spectrum and the contribution of the RRM2B gene to the disease spectrum of MDDS.
Collapse
Affiliation(s)
- Yanjun Wang
- Pediatric Intensive Care Unit, Kunming Children’s Hospital, Children’s Hospital Affiliated to Kunming Medical University, Kunming, China
| | - Ling Hang
- Pediatric Intensive Care Unit, Kunming Children’s Hospital, Children’s Hospital Affiliated to Kunming Medical University, Kunming, China
| | - Weihua Shou
- Kunming Key Laboratory of Children Infection and Immunity, Yunnan Key Laboratory of Children’s Major Disease Research, Yunnan Medical Center for Pediatric Diseases, Yunnan Institute of Pediatrics, Kunming Children’s Hospital, Kunming, China
| | - Cuifen Li
- Pediatric Intensive Care Unit, Kunming Children’s Hospital, Children’s Hospital Affiliated to Kunming Medical University, Kunming, China
| | - Fangling Dong
- Pediatric Intensive Care Unit, Kunming Children’s Hospital, Children’s Hospital Affiliated to Kunming Medical University, Kunming, China
| | - Xingxing Feng
- Department of Clinical Laboratory, Kunming Children’s Hospital, Children’s Hospital Affiliated to Kunming Medical University, Kunming, China
| | - Ruohong Jin
- Pediatric Intensive Care Unit, Kunming Children’s Hospital, Children’s Hospital Affiliated to Kunming Medical University, Kunming, China
| | - Bin Li
- Pediatric Intensive Care Unit, Kunming Children’s Hospital, Children’s Hospital Affiliated to Kunming Medical University, Kunming, China
| | - Shufang Xiao
- Pediatric Intensive Care Unit, Kunming Children’s Hospital, Children’s Hospital Affiliated to Kunming Medical University, Kunming, China
| |
Collapse
|
2
|
Gilea AI, Magistrati M, Notaroberto I, Tiso N, Dallabona C, Baruffini E. The Saccharomyces cerevisiae mitochondrial DNA polymerase and its contribution to the knowledge about human POLG-related disorders. IUBMB Life 2023; 75:983-1002. [PMID: 37470284 DOI: 10.1002/iub.2770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 07/05/2023] [Indexed: 07/21/2023]
Abstract
Most eukaryotes possess a mitochondrial genome, called mtDNA. In animals and fungi, the replication of mtDNA is entrusted by the DNA polymerase γ, or Pol γ. The yeast Pol γ is composed only of a catalytic subunit encoded by MIP1. In humans, Pol γ is a heterotrimer composed of a catalytic subunit homolog to Mip1, encoded by POLG, and two accessory subunits. In the last 25 years, more than 300 pathological mutations in POLG have been identified as the cause of several mitochondrial diseases, called POLG-related disorders, which are characterized by multiple mtDNA deletions and/or depletion in affected tissues. In this review, at first, we summarize the biochemical properties of yeast Mip1, and how mutations, especially those introduced recently in the N-terminal and C-terminal regions of the enzyme, affect the in vitro activity of the enzyme and the in vivo phenotype connected to the mtDNA stability and to the mtDNA extended and point mutability. Then, we focus on the use of yeast harboring Mip1 mutations equivalent to the human ones to confirm their pathogenicity, identify the phenotypic defects caused by these mutations, and find both mechanisms and molecular compounds able to rescue the detrimental phenotype. A closing chapter will be dedicated to other polymerases found in yeast mitochondria, namely Pol ζ, Rev1 and Pol η, and to their genetic interactions with Mip1 necessary to maintain mtDNA stability and to avoid the accumulation of spontaneous or induced point mutations.
Collapse
Affiliation(s)
- Alexandru Ionut Gilea
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Martina Magistrati
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Ilenia Notaroberto
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Natascia Tiso
- Department of Biology, University of Padova, Padova, Italy
| | - Cristina Dallabona
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Enrico Baruffini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| |
Collapse
|
3
|
Conti F, Di Martino S, Drago F, Bucolo C, Micale V, Montano V, Siciliano G, Mancuso M, Lopriore P. Red Flags in Primary Mitochondrial Diseases: What Should We Recognize? Int J Mol Sci 2023; 24:16746. [PMID: 38069070 PMCID: PMC10706469 DOI: 10.3390/ijms242316746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/22/2023] [Accepted: 11/23/2023] [Indexed: 12/18/2023] Open
Abstract
Primary mitochondrial diseases (PMDs) are complex group of metabolic disorders caused by genetically determined impairment of the mitochondrial oxidative phosphorylation (OXPHOS). The unique features of mitochondrial genetics and the pivotal role of mitochondria in cell biology explain the phenotypical heterogeneity of primary mitochondrial diseases and the resulting diagnostic challenges that follow. Some peculiar features ("red flags") may indicate a primary mitochondrial disease, helping the physician to orient in this diagnostic maze. In this narrative review, we aimed to outline the features of the most common mitochondrial red flags offering a general overview on the topic that could help physicians to untangle mitochondrial medicine complexity.
Collapse
Affiliation(s)
- Federica Conti
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
| | - Serena Di Martino
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
| | - Filippo Drago
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
| | - Claudio Bucolo
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
- Center for Research in Ocular Pharmacology-CERFO, University of Catania, 95213 Catania, Italy
| | - Vincenzo Micale
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
| | - Vincenzo Montano
- Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy (P.L.)
| | - Gabriele Siciliano
- Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy (P.L.)
| | - Michelangelo Mancuso
- Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy (P.L.)
| | - Piervito Lopriore
- Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy (P.L.)
| |
Collapse
|
4
|
Vallbona-Garcia A, Hamers IHJ, van Tienen FHJ, Ochoteco-Asensio J, Berendschot TTJM, de Coo IFM, Benedikter BJ, Webers CAB, Smeets HJM, Gorgels TGMF. Low mitochondrial DNA copy number in buffy coat DNA of primary open-angle glaucoma patients. Exp Eye Res 2023; 232:109500. [PMID: 37178956 DOI: 10.1016/j.exer.2023.109500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 04/22/2023] [Accepted: 05/09/2023] [Indexed: 05/15/2023]
Abstract
Primary open-angle glaucoma (POAG) is characterized by optic nerve degeneration and irreversible loss of retinal ganglion cells (RGCs). The pathophysiology is not fully understood. Since RGCs have a high energy demand, suboptimal mitochondrial function may put the survival of these neurons at risk. In the present study, we explored whether mtDNA copy number or mtDNA deletions could reveal a mitochondrial component in POAG pathophysiology. Buffy coat DNA was isolated from EDTA blood of age- and sex-matched study groups, namely POAG patients with high intraocular pressure (IOP) at diagnosis (high tension glaucoma: HTG; n = 97), normal tension glaucoma patients (NTG, n = 37), ocular hypertensive controls (n = 9), and cataract controls (without glaucoma; n = 32), all without remarkable comorbidities. The number of mtDNA copies was assessed through qPCR quantification of the mitochondrial D-loop and nuclear B2M gene. Presence of the common 4977 base pair mtDNA deletion was assessed by a highly sensitive breakpoint PCR. Analysis showed that HTG patients had a lower number of mtDNA copies per nuclear DNA than NTG patients (p-value <0.01, Dunn test) and controls (p-value <0.001, Dunn test). The common 4977 base pair mtDNA deletion was not detected in any of the participants. A lower mtDNA copy number in blood of HTG patients suggests a role for a genetically defined, deficient mtDNA replication in the pathology of HTG. This may cause a low number of mtDNA copies in RGCs, which together with aging and high IOP, may lead to mitochondrial dysfunction, and contribute to glaucoma pathology.
Collapse
Affiliation(s)
- Antoni Vallbona-Garcia
- University Eye Clinic Maastricht, Maastricht University Medical Center+, Maastricht, the Netherlands; Department of Toxicogenomics, Maastricht University, Maastricht, the Netherlands; School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands.
| | - Ilse H J Hamers
- Department of Toxicogenomics, Maastricht University, Maastricht, the Netherlands
| | - Florence H J van Tienen
- Department of Toxicogenomics, Maastricht University, Maastricht, the Netherlands; School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | | | - Tos T J M Berendschot
- University Eye Clinic Maastricht, Maastricht University Medical Center+, Maastricht, the Netherlands
| | - Irenaeus F M de Coo
- Department of Toxicogenomics, Maastricht University, Maastricht, the Netherlands
| | - Birke J Benedikter
- University Eye Clinic Maastricht, Maastricht University Medical Center+, Maastricht, the Netherlands; School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Carroll A B Webers
- University Eye Clinic Maastricht, Maastricht University Medical Center+, Maastricht, the Netherlands
| | - Hubert J M Smeets
- Department of Toxicogenomics, Maastricht University, Maastricht, the Netherlands; School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Theo G M F Gorgels
- University Eye Clinic Maastricht, Maastricht University Medical Center+, Maastricht, the Netherlands; School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| |
Collapse
|
5
|
A novel RRM2B mutation associated with mitochondrial DNA depletion syndrome. Mol Genet Metab Rep 2022; 32:100887. [PMID: 35756861 PMCID: PMC9218228 DOI: 10.1016/j.ymgmr.2022.100887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/10/2022] [Accepted: 06/10/2022] [Indexed: 11/22/2022] Open
Abstract
Mitochondrial DNA (mtDNA) depletion syndromes are disorders characterized by infantile-onset, severe progression, and the drastic loss of mtDNA content in affected tissues. In a patient who showed severe hypotonia, proximal tubulopathy and sensorineural hearing loss after birth, we observed severe mtDNA depletion and impaired respiratory chain activity in muscle due to heterozygous variants c.686G > T and c.551-2A > G in RRM2B, encoding the p53R2 subunit of the ribonucleotide reductase.
Collapse
|
6
|
Abstract
Mitochondrial hepatopathies are a subset of mitochondrial diseases defined by primary dysfunction of hepatocyte mitochondria leading to a phenotype of hepatocyte cell injury, steatosis, or liver failure. Increasingly, the diagnosis is established by new sequencing approaches that combine analysis of both nuclear DNA and mitochondrial DNA and allow for timely diagnosis in most patients. Despite advances in diagnostics, for most affected children their disorders are relentlessly progressive, and result in substantial morbidity and mortality. Treatment remains mainly supportive; however, novel therapeutics and a more definitive role for liver transplantation hold promise for affected children.
Collapse
Affiliation(s)
- Mary Ayers
- University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC, 4401 Penn Avenue, Pittsburgh, PA 15224, USA
| | - Simon P Horslen
- University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC, 4401 Penn Avenue, Pittsburgh, PA 15224, USA
| | - Anna María Gómez
- University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC, 4401 Penn Avenue, Pittsburgh, PA 15224, USA
| | - James E Squires
- University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
| |
Collapse
|
7
|
Compound Heterozygous Mutations Presented with Quadriparesis and Menopause. A Case Report. Twin Res Hum Genet 2022; 25:74-76. [DOI: 10.1017/thg.2022.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Mitochondrion regulates cellular metabolism with the aid of its respiratory complexes; any defect within these complexes can result in mitochondrial malfunction and various conditions. One such mutation can occur in SLC25A10, resulting in mitochondrial DNA depletion syndrome. It should be noted that the pattern of inheritance of this syndrome is autosomal recessive. However, we present a case with compound heterozygous mutations within this gene resulting in disease. An 18-year-old female was referred to our clinic due to menopause with a medical history of hearing loss, spasticity, hypotonia and quadriparesis. The child’s birth and development were uneventful until the initiation of movement reduction and hypotonia when she was 12 months old. Afterward, the hypotonia progressed to quadriparesis and spasticity throughout the years. Our patient became completely quadriplegic up to the age of 3 and became completely deaf at 10. Her puberty onset was at the age of 9, and no significant event took place until she was 17 years old when suddenly her periods, which were regular until that time, became irregular and ceased after a year; hence, a thorough evaluation began, but similar to her previous evaluations all tests were insignificant. Nonetheless, we suspected an underlying metabolic or genetic defect; thus, we ordered a whole-exome sequencing (WES) workup and found simultaneous heterozygous mutations within SLC25A10, HFE and TTN genes that could explain her condition. When all other tests fail, and we suspect an underlying genetic or metabolic cause, WES can be of great value.
Collapse
|
8
|
Wang H, Han Y, Li S, Chen Y, Chen Y, Wang J, Zhang Y, Zhang Y, Wang J, Xia Y, Yuan J. Mitochondrial DNA Depletion Syndrome and Its Associated Cardiac Disease. Front Cardiovasc Med 2022; 8:808115. [PMID: 35237671 PMCID: PMC8882844 DOI: 10.3389/fcvm.2021.808115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/23/2021] [Indexed: 12/06/2022] Open
Abstract
Mitochondria is a ubiquitous, energy-supplying (ATP-based) organelle found in nearly all eukaryotes. It acts as a “power plant” by producing ATP through oxidative phosphorylation, providing energy for the cell. The bioenergetic functions of mitochondria are regulated by nuclear genes (nDNA). Mitochondrial DNA (mtDNA) and respiratory enzymes lose normal structure and function when nuclear genes encoding the related mitochondrial factors are impaired, resulting in deficiency in energy production. Massive generation of reactive oxygen species and calcium overload are common causes of mitochondrial diseases. The mitochondrial depletion syndrome (MDS) is associated with the mutations of mitochondrial genes in the nucleus. It is a heterogeneous group of progressive disorders characterized by the low mtDNA copy number. TK2, FBXL4, TYPM, and AGK are genes known to be related to MDS. More recent studies identified new mutation loci associated with this disease. Herein, we first summarize the structure and function of mitochondria, and then discuss the characteristics of various types of MDS and its association with cardiac diseases.
Collapse
Affiliation(s)
- Haiying Wang
- Department of Physiology, Institute of Basic Medical College, Jining Medical University, Jining, China
| | - Yijun Han
- Clinical Medical College, Jining Medical University, Jining, China
| | - Shenwei Li
- Institute of Basic Medical College, Jining Medical University, Jining, China
| | - Yunan Chen
- Institute of Basic Medical College, Jining Medical University, Jining, China
| | - Yafen Chen
- Institute of Basic Medical College, Jining Medical University, Jining, China
| | - Jing Wang
- Dongying Fifth People's Hospital, Dongying, China
| | - Yuqing Zhang
- Institute of Basic Medical College, Jining Medical University, Jining, China
| | - Yawen Zhang
- Institute of Basic Medical College, Jining Medical University, Jining, China
| | - Jingsuo Wang
- Institute of Basic Medical College, Jining Medical University, Jining, China
| | - Yong Xia
- Key Laboratory of Precision Oncology of Shandong Higher Education, Institute of Precision Medicine, Jining Medical University, Jining, China
- Yong Xia
| | - Jinxiang Yuan
- The Collaborative Innovation Center, Jining Medical University, Jining, China
- *Correspondence: Jinxiang Yuan
| |
Collapse
|
9
|
Berardo A, Engelstad K, Hirano M. Advances in Thymidine Kinase 2 Deficiency: Clinical Aspects, Translational Progress, and Emerging Therapies. J Neuromuscul Dis 2022; 9:225-235. [PMID: 35094997 PMCID: PMC9028656 DOI: 10.3233/jnd-210786] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Defects in the replication, maintenance, and repair of mitochondrial DNA (mtDNA) constitute a growing and genetically heterogeneous group of mitochondrial disorders. Multiple genes participate in these processes, including thymidine kinase 2 (TK2) encoding the mitochondrial matrix protein TK2, a critical component of the mitochondrial nucleotide salvage pathway. TK2 deficiency (TK2d) causes mtDNA depletion, multiple deletions, or both, which manifest predominantly as mitochondrial myopathy. A wide clinical spectrum phenotype includes a severe, rapidly progressive, early onset form (median survival: < 2 years); a less severe childhood-onset form; and a late-onset form with a variably slower rate of progression. Clinical presentation typically includes progressive weakness of limb, neck, facial, oropharyngeal, and respiratory muscle, whereas limb myopathy with ptosis, ophthalmoparesis, and respiratory involvement is more common in the late-onset form. Deoxynucleoside monophosphates and deoxynucleosides that can bypass the TK2 enzyme defect have been assessed in a mouse model, as well as under open-label compassionate use (expanded access) in TK2d patients, indicating clinical efficacy with a favorable side-effect profile. This treatment is currently undergoing testing in clinical trials intended to support approval in the US and European Union (EU). In the early expanded access program, growth differentiation factor 15 (GDF-15) appears to be a useful biomarker that correlates with therapeutic response. With the advent of a specific treatment and given the high morbidity and mortality associated with TK2d, clinicians need to know how to recognize and diagnose this disorder. Here, we summarize translational research about this rare condition emphasizing clinical aspects.
Collapse
Affiliation(s)
- Andres Berardo
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, USA
| | - Kristin Engelstad
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, USA
| | - Michio Hirano
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, USA
| |
Collapse
|
10
|
Saccharomyces cerevisiae as a Tool for Studying Mutations in Nuclear Genes Involved in Diseases Caused by Mitochondrial DNA Instability. Genes (Basel) 2021; 12:genes12121866. [PMID: 34946817 PMCID: PMC8701800 DOI: 10.3390/genes12121866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/20/2021] [Accepted: 11/23/2021] [Indexed: 01/03/2023] Open
Abstract
Mitochondrial DNA (mtDNA) maintenance is critical for oxidative phosphorylation (OXPHOS) since some subunits of the respiratory chain complexes are mitochondrially encoded. Pathological mutations in nuclear genes involved in the mtDNA metabolism may result in a quantitative decrease in mtDNA levels, referred to as mtDNA depletion, or in qualitative defects in mtDNA, especially in multiple deletions. Since, in the last decade, most of the novel mutations have been identified through whole-exome sequencing, it is crucial to confirm the pathogenicity by functional analysis in the appropriate model systems. Among these, the yeast Saccharomyces cerevisiae has proved to be a good model for studying mutations associated with mtDNA instability. This review focuses on the use of yeast for evaluating the pathogenicity of mutations in six genes, MPV17/SYM1, MRM2/MRM2, OPA1/MGM1, POLG/MIP1, RRM2B/RNR2, and SLC25A4/AAC2, all associated with mtDNA depletion or multiple deletions. We highlight the techniques used to construct a specific model and to measure the mtDNA instability as well as the main results obtained. We then report the contribution that yeast has given in understanding the pathogenic mechanisms of the mutant variants, in finding the genetic suppressors of the mitochondrial defects and in the discovery of molecules able to improve the mtDNA stability.
Collapse
|
11
|
Doğulu N, Tuna Kırsaçlıoğlu C, Köse E, Ünlüsoy Aksu A, Kuloğlu Z, Kansu A, Eminoğlu FT. The clinical variations and diagnostic challenges of deoxyguanosine kinase deficiency: a descriptive case series. J Pediatr Endocrinol Metab 2021; 34:1341-1347. [PMID: 34167177 DOI: 10.1515/jpem-2021-0108] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 05/03/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Deoxyguanosine kinase (DGUOK) deficiency is one of the leading causes of the mitochondrial DNA-depletion syndromes (MDDS) associated with hepatocerebral involvement. Herein, we present four cases of DGUOK deficiency to emphasize the clinical variability of disease and the challenges in the diagnosis of DGUOK deficiency. CASE PRESENTATION Hepatomegaly, hyperlactatemia, elevated alpha fetoprotein (AFP), alanine, and transaminase levels were detected in all patients, and cholestasis, coagulopathy, and hypotonia were common findings. All patients had a low birth weight, one patient underwent liver transplantation (LT). Clinical and laboratory findings of two patients and one patient suggested neonatal hemochromatosis and type 1 tyrosinemia, respectively. All patients were diagnosed with DGUOK deficiency by performing molecular genetic analysis. CONCLUSIONS Mitochondrial DNA-depletion syndromes should be kept in mind in cases in which hypotonicity, lactic acidosis, and neonatal cholestasis are observed. DGUOK deficiency may present in different clinics suggesting neonatal hemochromatosis or tyrosinemia type 1.
Collapse
Affiliation(s)
- Neslihan Doğulu
- Department of Pediatric Metabolism, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Ceyda Tuna Kırsaçlıoğlu
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Engin Köse
- Department of Pediatric Metabolism, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Aysel Ünlüsoy Aksu
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Ankara City Hospital, Ankara, Turkey
| | - Zarife Kuloğlu
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Aydan Kansu
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Fatma Tuba Eminoğlu
- Department of Pediatric Metabolism, Ankara University Faculty of Medicine, Ankara, Turkey
| |
Collapse
|
12
|
Fukunaga H. Mitochondrial DNA Copy Number and Developmental Origins of Health and Disease (DOHaD). Int J Mol Sci 2021; 22:ijms22126634. [PMID: 34205712 PMCID: PMC8235559 DOI: 10.3390/ijms22126634] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 12/11/2022] Open
Abstract
Mitochondrial dysfunction is known to contribute to mitochondrial diseases, as well as to a variety of aging-based pathologies. Mitochondria have their own genomes (mitochondrial DNA (mtDNA)) and the abnormalities, such as point mutations, deletions, and copy number variations, are involved in mitochondrial dysfunction. In recent years, several epidemiological studies and animal experiments have supported the Developmental Origin of Health and Disease (DOHaD) theory, which states that the environment during fetal life influences the predisposition to disease and the risk of morbidity in adulthood. Mitochondria play a central role in energy production, as well as in various cellular functions, such as apoptosis, lipid metabolism, and calcium metabolism. In terms of the DOHaD theory, mtDNA copy number may be a mediator of health and disease. This paper summarizes the results of recent epidemiological studies on the relationship between environmental factors and mtDNA copy number during pregnancy from the perspective of DOHaD theory. The results of these studies suggest a hypothesis that mtDNA copy number may reflect environmental influences during fetal life and possibly serve as a surrogate marker of health risks in adulthood.
Collapse
Affiliation(s)
- Hisanori Fukunaga
- Center for Environmental and Health Sciences, Hokkaido University, N12 W7 Kita-ku, Sapporo 060-0812, Japan
| |
Collapse
|
13
|
Jacinto S, Guerreiro P, de Oliveira RM, Cunha-Oliveira T, Santos MJ, Grazina M, Rego AC, Outeiro TF. MPV17 Mutations Are Associated With a Quiescent Energetic Metabolic Profile. Front Cell Neurosci 2021; 15:641264. [PMID: 33815063 PMCID: PMC8011494 DOI: 10.3389/fncel.2021.641264] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 02/08/2021] [Indexed: 02/03/2023] Open
Abstract
Mutations in the MPV17 gene are associated with hepatocerebral form of mitochondrial depletion syndrome. The mechanisms through which MPV17 mutations cause respiratory chain dysfunction and mtDNA depletion is still unclear. The MPV17 gene encodes an inner membrane mitochondrial protein that was recently described to function as a non-selective channel. Although its exact function is unknown, it is thought to be important in the maintenance of mitochondrial membrane potential (ΔΨm). To obtain more information about the role of MPV17 in human disease, we investigated the effect of MPV17 knockdown and of selected known MPV17 mutations associated with MPV17 disease in vitro. We used different approaches in order to evaluate the cellular consequences of MPV17 deficiency. We found that lower levels of MPV17 were associated with impaired mitochondrial respiration and with a quiescent energetic metabolic profile. All the mutations studied destabilized the protein, resulting in reduced protein levels. We also demonstrated that different mutations caused different cellular abnormalities, including increased ROS production, decreased oxygen consumption, loss of ΔΨm, and mislocalization of MPV17 protein. Our study provides novel insight into the molecular effects of MPV17 mutations and opens novel possibilities for testing therapeutic strategies for a devastating group of disorders.
Collapse
Affiliation(s)
- Sandra Jacinto
- Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.,Serviço de Neurologia Pediátrica, Hospital Dona Estefânia, Centro Hospitalar Universitário Lisboa Central-EPE, Lisboa, Portugal
| | - Patrícia Guerreiro
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.,Switch Laboratory, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium.,Switch Laboratory, Department of Cellular and Molecular Medicine, Katholiek Universiteit (KU), Leuven, Belgium
| | - Rita Machado de Oliveira
- CEDOC - Chronic Diseases Research Center, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
| | | | - Maria João Santos
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal.,CIBB - Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Portugal
| | - Manuela Grazina
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal.,CIBB - Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Portugal
| | - Ana Cristina Rego
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Tiago F Outeiro
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.,Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom.,Max Planck Institute for Experimental Medicine, Göttingen, Germany
| |
Collapse
|
14
|
Acute liver failure due to DGUOK deficiency-is liver transplantation justified? Clin Res Hepatol Gastroenterol 2021; 45:101408. [PMID: 32278775 DOI: 10.1016/j.clinre.2020.02.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 02/27/2020] [Accepted: 02/27/2020] [Indexed: 02/04/2023]
Abstract
BACKGROUND Deoxyguanosine kinase (DGUOK) deficiency is one of the causes of the hepatocerebral form of mitochondrial depletion syndrome (MDS). It is characterized by an early onset of liver failure with concomitant neurological deterioration. In the current literature, there are only few reports regarding long-term observation of children with DGUOK deficiency. Liver transplantation (LTx) is controversial due to extrahepatic involvement and unpredictable outcome. METHODS Five patients (2 boys) from 4 different families with hepatocerebral MDS associated with DGUOK mutations diagnosed with liver failure were treated in our hospital between 2010-2019. RESULTS In all children clinical symptoms developed within the first days of live and hypoglycemia (hypoketotic), conjugated hyperbilirubinemia (cholestasis), severe lactic acidosis, and coagulopathy were observed. Two neonates had low birth-weight for gestational age and failed to thrive. Mild neurological involvement as hypotonia was observed in all children. Three children died at the age of 2, 6 months and 6,5 months of age, respectively, due to end-stage liver failure. In one case, LTx was not considered, in two patients (sisters) parents did not agree to this procedure. LTx was subsequently performed in two patients at the age of 6 and 7 months, respectively, one from deceased, and one from living related donor, in both before the final confirmation of DGUOK mutations. One boy died 2 months after LTx due to post-LTx procedure-related complications; one is still alive with 3years of follow-up, with good liver function and mild neurological disturbances. The diagnosis of DGUOK deficiency was confirmed by biallelic DGUOK mutations detection. Equally, patients were compound heterozygotes (three cases) and homozygotes (two cases). Three known molecular variants, including regulatory substitutions (c.1A>G, c.3G>A) and in-frame insertion (c.813_814insTTT) were identified. CONCLUSIONS Prognosis in patients with DGUOK deficiency is generally poor. Based on a review of the literature and our experience liver transplantation in selected patients with DGUOK mutation does not appear to be contraindicated, especially in those without or with minimal neurologic abnormalities.
Collapse
|
15
|
Prediction of the Impact of Deleterious Nonsynonymous Single Nucleotide Polymorphisms on the Human RRM2B Gene: A Molecular Modeling Study. BIOMED RESEARCH INTERNATIONAL 2020; 2020:7614634. [PMID: 32775440 PMCID: PMC7399733 DOI: 10.1155/2020/7614634] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/04/2020] [Accepted: 07/06/2020] [Indexed: 01/19/2023]
Abstract
RRM2B gene encodes ribonucleoside-diphosphate reductase subunit M2 B, the p53-inducible small subunit (p53R2) of ribonucleotide reductase (RNR), an enzyme catalyzing dNTP synthesis for mitochondrial DNA. Defects in this gene may cause severe mitochondrial disease affecting mainly the nervous system. This study is aimed at examining the effect of deleterious nonsynonymous SNP (nsSNP) on the structure of the RRM2B protein, using a variety of prediction tools followed by a molecular modeling analysis. After using 13 algorithms, 19 nsSNPs were predicted deleterious. Among these variants, 18 decreased the protein stability and 16 were localized in very highly conserved regions. Protein 3D structure analysis showed that 18 variants changed amino acid interactions. These results concur with what has been found in experimental trials; 7 deleterious nsSNPs were previously reported in patients suffering from genetic disorders affecting the nervous system. Thus, our study will provide useful information to design more efficient and fast genetic tests to find RRM2B gene mutations.
Collapse
|
16
|
Shimura M, Kuranobu N, Ogawa-Tominaga M, Akiyama N, Sugiyama Y, Ebihara T, Fushimi T, Ichimoto K, Matsunaga A, Tsuruoka T, Kishita Y, Umetsu S, Inui A, Fujisawa T, Tanikawa K, Ito R, Fukuda A, Murakami J, Kaji S, Kasahara M, Shiraki K, Ohtake A, Okazaki Y, Murayama K. Clinical and molecular basis of hepatocerebral mitochondrial DNA depletion syndrome in Japan: evaluation of outcomes after liver transplantation. Orphanet J Rare Dis 2020; 15:169. [PMID: 32703289 PMCID: PMC7379809 DOI: 10.1186/s13023-020-01441-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 06/15/2020] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Hepatocerebral mitochondrial DNA depletion syndrome (MTDPS) is a disease caused by defects in mitochondrial DNA maintenance and leads to liver failure and neurological complications during infancy. Liver transplantation (LT) remains controversial due to poor outcomes associated with extrahepatic symptoms. The purposes of this study were to clarify the current clinical and molecular features of hepatocerebral MTDPS and to evaluate the outcomes of LT in MTDPS patients in Japan. RESULTS We retrospectively assessed the clinical and genetic findings, as well as the clinical courses, of 23 hepatocerebral MTDPS patients from a pool of 999 patients who were diagnosed with mitochondrial diseases between 2007 and 2019. Causative genes were identified in 18 of 23 patients: MPV17 (n = 13), DGUOK (n = 3), POLG (n = 1), and MICOS13 (n = 1). Eight MPV17-deficient patients harbored c.451dupC and all three DGUOK-deficient patients harbored c.143-307_170del335. The most common initial manifestation was failure to thrive (n = 13, 56.5%). The most frequent liver symptom was cholestasis (n = 21, 91.3%). LT was performed on 12 patients, including nine MPV17-deficient and two DGUOK-deficient patients. Among the 12 transplanted patients, five, including one with mild intellectual disability, survived; while seven who had remarkable neurological symptoms before LT died. Five of the MPV17-deficient survivors had either c.149G > A or c.293C > T. CONCLUSIONS MPV17 was the most common genetic cause of hepatocerebral MTDPS. The outcome of LT for MTDPS was not favorable, as previously reported, however, patients harboring MPV17 mutations associated with mild phenotypes such as c.149G > A or c.293C > T, and exhibiting no marked neurologic manifestations before LT, had a better prognosis after LT.
Collapse
Affiliation(s)
- Masaru Shimura
- Center for Medical Genetics, Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Naomi Kuranobu
- Division of Pediatrics and Perinatology, Tottori University Faculty of Medicine, 36-1 Nishi-cho, Yonago, Tottori, 683-8504, Japan
| | - Minako Ogawa-Tominaga
- Center for Medical Genetics, Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Nana Akiyama
- Center for Medical Genetics, Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Yohei Sugiyama
- Center for Medical Genetics, Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Tomohiro Ebihara
- Center for Medical Genetics, Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Takuya Fushimi
- Center for Medical Genetics, Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Keiko Ichimoto
- Center for Medical Genetics, Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Ayako Matsunaga
- Center for Medical Genetics, Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Tomoko Tsuruoka
- Center for Medical Genetics, Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Yoshihito Kishita
- Diagnostics and Therapeutic of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Hongo 2-1-1, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Shuichiro Umetsu
- Department of Pediatric Hepatology and Gastroenterology, Saiseikai Yokohama City Tobu Hospital, 3-6-1, Shimosueyoshi, Tsurumi-ku, Yokohama, Kanagawa, 230-0012, Japan
| | - Ayano Inui
- Department of Pediatric Hepatology and Gastroenterology, Saiseikai Yokohama City Tobu Hospital, 3-6-1, Shimosueyoshi, Tsurumi-ku, Yokohama, Kanagawa, 230-0012, Japan
| | - Tomoo Fujisawa
- Department of Pediatric Hepatology and Gastroenterology, Saiseikai Yokohama City Tobu Hospital, 3-6-1, Shimosueyoshi, Tsurumi-ku, Yokohama, Kanagawa, 230-0012, Japan
| | - Ken Tanikawa
- Department of Diagnostic Pathology, Yame General Hospital, 540-2, Takatsuka, Yame-shi, Fukuoka, 834-0034, Japan
| | - Reiko Ito
- Department of General Pediatrics and Interdisciplinary Medicine, National Center for Child Health and Development, 2-10-1, Okura, Setagaya-ku, Tokyo, 157-8535, Japan
| | - Akinari Fukuda
- Organ Transplantation Center, National Center for Child Health and Development, 2-10-1, Okura, Setagaya-ku, Tokyo, 157-8535, Japan
| | - Jun Murakami
- Division of Pediatrics and Perinatology, Tottori University Faculty of Medicine, 36-1 Nishi-cho, Yonago, Tottori, 683-8504, Japan
| | - Shunsaku Kaji
- Department of Pediatrics, Tsuyama Chuo Hospital, Kawasaki 1756, Tsuyama-shi, Okayama, 708-0841, Japan
| | - Mureo Kasahara
- Organ Transplantation Center, National Center for Child Health and Development, 2-10-1, Okura, Setagaya-ku, Tokyo, 157-8535, Japan
| | - Kazuo Shiraki
- Division of Pediatrics and Perinatology, Tottori University Faculty of Medicine, 36-1 Nishi-cho, Yonago, Tottori, 683-8504, Japan
| | - Akira Ohtake
- Department of Pediatrics & Clinical Genomics, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan.,Center for Intractable Diseases, Saitama Medical University Hospital, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan
| | - Yasushi Okazaki
- Diagnostics and Therapeutic of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Hongo 2-1-1, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Kei Murayama
- Center for Medical Genetics, Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan.
| |
Collapse
|
17
|
Hu B, Yang M, Liao Z, Wei H, Zhao C, Li D, Hu S, Jiang X, Shi M, Luo Q, Zhang D, Nie Q, Zhang X, Li H. Mutation of TWNK Gene Is One of the Reasons of Runting and Stunting Syndrome Characterized by mtDNA Depletion in Sex-Linked Dwarf Chicken. Front Cell Dev Biol 2020; 8:581. [PMID: 32766243 PMCID: PMC7381202 DOI: 10.3389/fcell.2020.00581] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 06/16/2020] [Indexed: 11/16/2022] Open
Abstract
Runting and stunting syndrome (RSS), which is characterized by low body weight, generally occurs early in life and leads to considerable economic losses in the commercial broiler industry. Our previous study has suggested that RSS is associated with mitochondria dysfunction in sex-linked dwarf (SLD) chickens. However, the molecular mechanism of RSS remains unknown. Based on the molecular diagnostics of mitochondrial diseases, we identified a recessive mutation c. 409G > A (p. Ala137Thr) of Twinkle mitochondrial DNA helicase (TWNK) gene and mitochondrial DNA (mtDNA) depletion in RSS chickens’ livers from strain N301. Bioinformatics investigations supported the pathogenicity of the TWNK mutation that is located on the extended peptide linker of Twinkle primase domain and might further lead to mtDNA depletion in chicken. Furthermore, overexpression of wild-type TWNK increases mtDNA copy number, whereas overexpression of TWNK A137T causes mtDNA depletion in vitro. Additionally, the TWNK c. 409G > A mutation showed significant associations with body weight, daily gain, pectoralis weight, crureus weight, and abdominal fat weight. Taken together, we corroborated that the recessive TWNK c. 409G > A (p. Ala137Thr) mutation is associated with RSS characterized by mtDNA depletion in SLD chicken.
Collapse
Affiliation(s)
- Bowen Hu
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China
| | - Minmin Yang
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China
| | - Zhiying Liao
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China
| | - Haohui Wei
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China
| | - Changbin Zhao
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China
| | - Dajian Li
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China
| | - Shuang Hu
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China
| | | | - Meiqing Shi
- Division of Immunology, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD, United States
| | - Qingbin Luo
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China
| | - Dexiang Zhang
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China
| | - Qinghua Nie
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China
| | - Xiquan Zhang
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China
| | - Hongmei Li
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of AgroAnimal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China
| |
Collapse
|
18
|
Shinagawa A, Hugdal S, Babu J, Rangaswamy R. Progressive cavitating leukoencephalopathy associated with a homozygous POLG mutation of 264C>G (p.F88L). Radiol Case Rep 2020; 15:908-913. [PMID: 32382377 PMCID: PMC7201157 DOI: 10.1016/j.radcr.2020.04.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 11/22/2022] Open
Abstract
Progressive cavitating leukoencephalopathy is a childhood neurodegenerative syndrome characterized by brain MR imaging findings of patchy leukoencephalopathy with cavities and vascular permeability, initially affecting the corpus callosum and centrum semiovale, and eventually coalescing into large cystic regions of white matter. We report a case of progressive cavitating leukoencephalopathy in a 2-year-old female patient presenting as intermittent motor deficits which partially resolved over several months. Whole exome sequencing revealed a homozygous c.264C>G (p.F88L) POLG variant of uncertain pathogenicity which was potentially related to this presentation. Further testing and information are needed to prove the pathogenicity of this variant, but considering other studies which report similar genotypes in association with differing phenotypes, the current case report supports a possible pathogenicity. This case could therefore represent the first reported instance of progressive cavitating leukoencephalopathy in the presence of a POLG mutation.
Collapse
Affiliation(s)
- Austin Shinagawa
- University of Nevada, Reno School of Medicine, 1664 N. Virginia Street, Reno, NV 89557, USA
| | - Stephen Hugdal
- University of Nevada, Reno School of Medicine, 1664 N. Virginia Street, Reno, NV 89557, USA
| | - Jay Babu
- University of Nevada, Reno Department of Biology, Reno, NV, USA
| | - Rajesh Rangaswamy
- Renown Regional Medical Center, Department of Radiology, Reno, NV, USA
| |
Collapse
|
19
|
[DGUOK-related mitochondrial DNA depletion syndrome: a case report and literature review]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2020; 22. [PMID: 32204766 PMCID: PMC7389589 DOI: 10.7499/j.issn.1008-8830.2020.03.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A boy, aged 4 months, had the major clinical manifestations of prolonged jaundice and hepatomegaly. Multiple biochemical tests revealed abnormal liver function along with elevated alpha-fetoprotein and lactate. Genetic analysis confirmed that the boy had the mutations of c.589C>T(p.Gln197Ter) and c.687G>C(p.Trp229Cys) in the DGUOK gene, both of which were novel mutations and were determined to be pathogenic and likely pathogenic respectively, by a variety of bioinformatics tools and the ACMG standard. Therefore, the boy was confirmed to have DGUOK-related mitochondrial DNA depletion syndrome. Literature review showed that onset of liver disease in infancy was the main clinical feature of this disease, and some children presented with nervous system manifestations. Abnormal laboratory results included abnormal liver function, increases in blood lactate, serum ferritin and alpha-fetoprotein, and hypoglycemia. Such children had marked heterogeneity of DGUOK gene mutations, with missense mutations as the most common type. This disease tended to have a poor prognosis, and 79.6% of the children died before the age of 3 years.
Collapse
|
20
|
Chinopoulos C. Quantification of mitochondrial DNA from peripheral tissues: Limitations in predicting the severity of neurometabolic disorders and proposal of a novel diagnostic test. Mol Aspects Med 2019; 71:100834. [PMID: 31740079 DOI: 10.1016/j.mam.2019.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 11/07/2019] [Accepted: 11/12/2019] [Indexed: 11/25/2022]
Abstract
Neurometabolic disorders stem from errors in metabolic processes yielding a neurological phenotype. A subset of those disorders encompasses mitochondrial abnormalities partially due to mitochondrial DNA (mtDNA) depletion. mtDNA depletion can be attributed to inheritance, spontaneous mutations or acquired from drug-related toxicities. In the armamentarium of diagnostic procedures, mtDNA quantification is a standard for disease classification. However, alterations in mtDNA obtained from peripheral tissues such as skin fibroblasts and blood cells do not often reflect the severity of the affected organ, in this case, the brain. The purpose of this review is to highlight the pitfalls of quantitating mtDNA from peripheral -and not limited to-tissues for diagnosing patients suffering from a variety of mtDNA depletion syndromes exhibiting neurologic abnormalities. In lieu, a qualitative test of mitochondrial substrate-level phosphorylation -even from peripheral tissues-reflecting the ability of mitochondria to rely on glutaminolysis in the presence of respiratory chain defects is proposed as a novel diagnostic assessment of mitochondrial functionality.
Collapse
Affiliation(s)
- Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Tuzolto St. 37-47, Budapest, 1094, Hungary.
| |
Collapse
|
21
|
Mahjoub G, Habibzadeh P, Dastsooz H, Mirzaei M, Kavosi A, Jamali L, Javanmardi H, Katibeh P, Faghihi MA, Dastgheib SA. Clinical and molecular characterization of three patients with Hepatocerebral form of mitochondrial DNA depletion syndrome: a case series. BMC MEDICAL GENETICS 2019; 20:167. [PMID: 31664948 PMCID: PMC6819644 DOI: 10.1186/s12881-019-0893-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 09/10/2019] [Indexed: 12/31/2022]
Abstract
Background Mitochondrial DNA depletion syndromes (MDS) are clinically and phenotypically heterogeneous disorders resulting from nuclear gene mutations. The affected individuals represent a notable reduction in mitochondrial DNA (mtDNA) content, which leads to malfunction of the components of the respiratory chain. MDS is classified according to the type of affected tissue; the most common type is hepatocerebral form, which is attributed to mutations in nuclear genes such as DGUOK and MPV17. These two genes encode mitochondrial proteins and play major roles in mtDNA synthesis. Case presentation In this investigation patients in three families affected by hepatocerebral form of MDS who were initially diagnosed with tyrosinemia underwent full clinical evaluation. Furthermore, the causative mutations were identified using next generation sequencing and were subsequently validated using sanger sequencing. The effect of the mutations on the gene expression was also studied using real-time PCR. A pathogenic heterozygous frameshift deletion mutation in DGUOK gene was identified in parents of two affected patients (c.706–707 + 2 del: p.k236 fs) presenting with jaundice, impaired fetal growth, low-birth weight, and failure to thrive who died at the age of 3 and 6 months in family I. Moreover, a novel splice site mutation in MPV17 gene (c.461 + 1G > C) was identified in a patient with jaundice, muscle weakness, and failure to thrive who died due to hepatic failure at the age of 4 months. A 5-month-old infant presenting with jaundice, dark urine, poor sucking, and feeding problems was also identified to have another novel mutation in MPV17 gene leading to stop gain mutation (c.277C > T: p.(Gln93*)). Conclusions These patients had overlapping clinical features with tyrosinemia. MDS should be considered a differential diagnosis in patients presenting with signs and symptoms of tyrosinemia.
Collapse
Affiliation(s)
- Ghazale Mahjoub
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Parham Habibzadeh
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran.,Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Hassan Dastsooz
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran.,Italian Institute for Genomic Medicine (IIGM), University of Turin, Turin, Italy
| | - Malihe Mirzaei
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Arghavan Kavosi
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Laila Jamali
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Haniyeh Javanmardi
- Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Pegah Katibeh
- Department of Pediatrics, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Ali Faghihi
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran.,Center for Therapeutic Innovation, Department of Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, USA
| | - Seyed Alireza Dastgheib
- Department of Medical Genetics, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
| |
Collapse
|
22
|
The natural history of infantile mitochondrial DNA depletion syndrome due to RRM2B deficiency. Genet Med 2019; 22:199-209. [DOI: 10.1038/s41436-019-0613-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 07/09/2019] [Indexed: 01/21/2023] Open
|
23
|
Li X, Li L, Sun Y, Lv F, Zhang G, Liu W, Zhang M, Jiang H, Liu S. Whole exome sequencing reveals two novel compound heterozygous mutations in TWNK as a cause of the hepatocerebral form of mitochondrial DNA depletion syndrome: a case report. BMC MEDICAL GENETICS 2019; 20:146. [PMID: 31455269 PMCID: PMC6712797 DOI: 10.1186/s12881-019-0875-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 08/11/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND Although Mitochondrial DNA depletion syndrome (MDS) can be classified into three forms: myopathic, encephalomyopathic and hepatocerebral form, it is difficult to identify its form due to its clinical heterogeneity. Therefore, it is very important to conduct molecular genetic analysis on suspected patients. This study presented a male 38 weeks and 5 days infant with liver cytolysis and leukodystrophy. CASE PRESENTATION A male infant proband was admitted to the department of NICU for feeding intolerance, irregular rhythm of respiration, hypoglycemia, lactic acidosis, liver cytolysis and neurological abnormalities. He was onset of mild jaundice with leukodystrophy and high lactate and phenylderivatives for urine organic acids on the 7th day. Whole exome sequencing (WES) and Sanger sequencing were performed to screen and confirm the suspicious pathogenic mutations. The results revealed this proband carried two compound heterozygous mutations in TWNK: c.1186 C > T / p.Pro396Ser and c.1844 G > C / p.Gly615Ala inherited by an autosomal recessive form from his parents, of which protein conservative analysis and structural modeling supported the pathogenicity of the two mutations. Unfortunately, the conditions described above were not improved until he was discharged from the hospital on the 23rd day and died at 4 months of age. CONCLUSIONS In this study, we investigated a Chinese family with the hepatocerebral form of MDS and conducted WES and Sanger sequencing to explore the causative mutations for this proband born from non-consanguineous and healthy parents. We identified two novel TWNK c.1186 C > T/ c.1844 G > C compound heterozygous mutations which were probably the disease-causing mutations of hepatocerebral form of MDS and described the clinical manifestations of the proband, which expanded the phenotypic spectrum of MDS caused by variants in TWNK. This study also emphasized WES technology can provide the genetic diagnosis of Mendelian genetic disease.
Collapse
Affiliation(s)
- Xianghong Li
- Department of Neonatology, The Affiliated Hospital of Qingdao University, Qingdao, 266000, China
| | - Liangshan Li
- Medical Genetic Department, The Affiliated Hospital of Qingdao University, Qingdao, 266000, China
| | - Yaqi Sun
- Shandong Provincial Key Laboratory of Metabolic Diseases and Qingdao Key Laboratory of Gout, The Affiliated Hospital of Qingdao University, Qingdao, 266000, China
| | - Fuyan Lv
- Qingdao Women and Children's Hospital, Qingdao, 266034, China
| | - Guoqing Zhang
- Department of Orthopaedic Surgery, the Affiliated Hospital of Qingdao University, Qingdao, 266000, China
| | - Wenmiao Liu
- Medical Genetic Department, The Affiliated Hospital of Qingdao University, Qingdao, 266000, China
| | - Meiyan Zhang
- Department of Neonatology, The Affiliated Hospital of Qingdao University, Qingdao, 266000, China
| | - Hong Jiang
- Department of Neonatology, The Affiliated Hospital of Qingdao University, Qingdao, 266000, China.
| | - Shiguo Liu
- Medical Genetic Department, The Affiliated Hospital of Qingdao University, Qingdao, 266000, China.
| |
Collapse
|
24
|
Iwanicka-Pronicka K, Ciara E, Piekutowska-Abramczuk D, Halat P, Pajdowska M, Pronicki M. Congenital cochlear deafness in mitochondrial diseases related to RRM2B and SERAC1 gene defects. A study of the mitochondrial patients of the CMHI hospital in Warsaw, Poland. Int J Pediatr Otorhinolaryngol 2019; 121:143-149. [PMID: 30909120 DOI: 10.1016/j.ijporl.2019.03.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 03/07/2019] [Accepted: 03/10/2019] [Indexed: 01/11/2023]
Abstract
OBJECTIVES Although hearing loss is a well-known symptom of mitochondria-related disorders, it is not clear how often it is a congenital and cochlear impairment. The Newborn Hearing Screening Program (NHSP) enables to distinguish congenital cochlear deafness from an acquired hearing deficit. The initial aim of the study was to research the frequency of the congenital cochlear hearing loss among patients with various gene defects resulting in mitochondrial disorders. The research process brought on an additional gain: basing on our preliminary study group of 80 patients, in 12 patients altogether we identified two defected genes responsible for mitochondrial disorders, whose carriers did not pass the NHSP. Finally, these patients were diagnosed with the congenital cochlear deafness. MATERIAL AND METHODS The results of the NHSP in the patients with mitochondrial disorders diagnosed in our tertiary reference center were analyzed. Only the cases with confirmed mutations were qualified for the study group. The NHSP database included 80 patients with mutations in 31 different genes: 25 nuclear-encoded and 6 mtDNA-encoded. We searched the literature for the presence of a congenital hearing impairment (CHI) in mitochondrial disorders caused by changes in 278 already known genes. RESULTS For 68 patients from the study group the NHSP test indicated a proper cochlear function and thus suggested normal hearing. For 12 mitochondrial patients, the NHSP test indicated the requirement for the further audiological diagnosis, and finally CHI was confirmed in 8 of them. This latter subset included patients with pathogenic variants in RRM2B and SERAC1, known as "deafness-causing genes". Contrary to our initial expectations, the patients carrying mutations in other "deafness-causing genes": MPV17, POLG, COX10, as well as other mitochondria-related genes, all reported in literature, did not indicate any CHI following the NHSP test. CONCLUSION Our study indicates that the cochlear CHI is a phenotypic feature of the RRM2B and SERAC1 related defects. The diagnosis of the CHI following the NHSP allows to early distinguish those defects from other mitochondria-related disorders in which the NHSP test result is correct. Wider studies are needed to assess the significance of this observation.
Collapse
Affiliation(s)
- Katarzyna Iwanicka-Pronicka
- - Department of Audiology and Phoniatrics, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, Warsaw, Poland; - Department of Medical Genetics, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, Warsaw, Poland.
| | - Elżbieta Ciara
- - Department of Medical Genetics, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, Warsaw, Poland
| | - Dorota Piekutowska-Abramczuk
- - Department of Medical Genetics, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, Warsaw, Poland
| | - Paulina Halat
- - Department of Medical Genetics, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, Warsaw, Poland
| | - Magdalena Pajdowska
- - Department of Clinical Biochemistry, Radioimmunology, and Experimental Medicine, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, Warsaw, Poland
| | - Maciej Pronicki
- - Department of Pathology, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, Warsaw, Poland
| |
Collapse
|
25
|
CPEO and Mitochondrial Myopathy in a Patient with DGUOK Compound Heterozygous Pathogenetic Variant and mtDNA Multiple Deletions. Case Rep Neurol Med 2019; 2019:5918632. [PMID: 30956829 PMCID: PMC6431376 DOI: 10.1155/2019/5918632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 02/19/2019] [Indexed: 11/21/2022] Open
Abstract
The classic features of deoxyguanosine kinase (DGUOK) deficiency are infantile onset hepatic failure with nystagmus and hypotonia; mitochondrial DNA studies on affected tissue reveal mitochondrial DNA depletion. Later, it has been shown that the mutations in the same gene may present with adult-onset mitochondrial myopathy and mitochondrial DNA multiple deletions in skeletal muscle. Here we report the case of a 42-year-old Italian woman presenting with a chronic progressive external ophthalmoplegia and myopathy with mtDNA multiple deletions and the compound heterozygous c.462T>A (p.Asn154Lys) and c.707+2T>G pathogenic variants in DGUOK.
Collapse
|
26
|
Guyatt AL, Brennan RR, Burrows K, Guthrie PAI, Ascione R, Ring SM, Gaunt TR, Pyle A, Cordell HJ, Lawlor DA, Chinnery PF, Hudson G, Rodriguez S. A genome-wide association study of mitochondrial DNA copy number in two population-based cohorts. Hum Genomics 2019; 13:6. [PMID: 30704525 PMCID: PMC6357493 DOI: 10.1186/s40246-018-0190-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 12/27/2018] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Mitochondrial DNA copy number (mtDNA CN) exhibits interindividual and intercellular variation, but few genome-wide association studies (GWAS) of directly assayed mtDNA CN exist. We undertook a GWAS of qPCR-assayed mtDNA CN in the Avon Longitudinal Study of Parents and Children (ALSPAC) and the UK Blood Service (UKBS) cohort. After validating and harmonising data, 5461 ALSPAC mothers (16-43 years at mtDNA CN assay) and 1338 UKBS females (17-69 years) were included in a meta-analysis. Sensitivity analyses restricted to females with white cell-extracted DNA and adjusted for estimated or assayed cell proportions. Associations were also explored in ALSPAC children and UKBS males. RESULTS A neutrophil-associated locus approached genome-wide significance (rs709591 [MED24], β (change in SD units of mtDNA CN per allele) [SE] - 0.084 [0.016], p = 1.54e-07) in the main meta-analysis of adult females. This association was concordant in magnitude and direction in UKBS males and ALSPAC neonates. SNPs in and around ABHD8 were associated with mtDNA CN in ALSPAC neonates (rs10424198, β [SE] 0.262 [0.034], p = 1.40e-14), but not other study groups. In a meta-analysis of unrelated individuals (N = 11,253), we replicated a published association in TFAM (β [SE] 0.046 [0.017], p = 0.006), with an effect size much smaller than that observed in the replication analysis of a previous in silico GWAS. CONCLUSIONS In a hypothesis-generating GWAS, we confirm an association between TFAM and mtDNA CN and present putative loci requiring replication in much larger samples. We discuss the limitations of our work, in terms of measurement error and cellular heterogeneity, and highlight the need for larger studies to better understand nuclear genomic control of mtDNA copy number.
Collapse
Affiliation(s)
- Anna L. Guyatt
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Rebecca R. Brennan
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle, UK
- Institute of Genetic Medicine, Newcastle University, Newcastle, UK
| | - Kimberley Burrows
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Philip A. I. Guthrie
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Raimondo Ascione
- Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Susan M. Ring
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Tom R. Gaunt
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Angela Pyle
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle, UK
| | | | - Debbie A. Lawlor
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Patrick F. Chinnery
- Department of Clinical Neurosciences and MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Gavin Hudson
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle, UK
- Institute of Genetic Medicine, Newcastle University, Newcastle, UK
| | - Santiago Rodriguez
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| |
Collapse
|
27
|
Abstract
Mutations in the nuclear gene DGUOK, encoding deoxyguanosine kinase, cause an infantile hepatocerebral type of mitochondrial depletion syndrome (MDS). We report 6 MDS patients harboring bi-allelic DGUOK mutations, of which 3 are novel, including a large intragenic Austrian founder deletion. One patient was diagnosed with hepatocellular carcinoma aged 6 months, supporting a link between mitochondrial DNA depletion and tumorigenesis; liver transplantation proved beneficial with regard to both tumor treatment and psychomotor development.
Collapse
|
28
|
Kanungo S, Morton J, Neelakantan M, Ching K, Saeedian J, Goldstein A. Mitochondrial disorders. ANNALS OF TRANSLATIONAL MEDICINE 2018; 6:475. [PMID: 30740406 DOI: 10.21037/atm.2018.12.13] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Primary mitochondrial disorders are a group of clinically variable and heterogeneous inborn errors of metabolism (IEMs), resulting from defects in cellular energy, and can affect every organ system of the body. Clinical presentations vary and may include symptoms of fatigue, skeletal muscle weakness, exercise intolerance, short stature, failure to thrive, blindness, ptosis and ophthalmoplegia, nystagmus, hearing loss, hypoglycemia, diabetes mellitus, learning difficulties, intellectual disability, seizures, stroke-like episodes, spasticity, dystonia, hypotonia, pain, neuropsychiatric symptoms, gastrointestinal reflux, dysmotility, gastrointestinal pseudo-obstruction, cardiomyopathy, cardiac conduction defects, and other endocrine, renal, cardiac, and liver problems. Most phenotypic manifestations are multi-systemic, with presentations varying at different age of onset and may show great variability within members of the same family; making these truly complex IEMs. Most primary mitochondrial diseases are autosomal recessive (AR); but maternally-inherited [from mitochondrial (mt) DNA], autosomal dominant and X-linked inheritance are also known. Mitochondria are unique energy-generating cellular organelles, geared for survival and contain their own unique genetic coding material, a circular piece of mtDNA about 16,000 base pairs in size. Additional nuclear (n)DNA encoded genes maintain mitochondrial biogenesis by supervising mtDNA replication, repair and synthesis, which is modified during increased energy demands or physiological stress. Despite our growing knowledge of the hundreds of genetic etiologies for this group of disorders, diagnosis can also remain elusive due to unique aspects of mitochondrial genetics. Though cure and FDA-approved therapies currently elude these IEMs, and current suggested therapies which include nutritional supplements and vitamins are of questionable efficacy; multi-center, international clinical trials are in progress for primary mitochondrial disorders.
Collapse
Affiliation(s)
- Shibani Kanungo
- Department of Pediatric and Adolescent Medicine, Western Michigan University Homer Stryker MD School of Medicine, Kalamazoo, Michigan, USA
| | - Jacob Morton
- Department of Pediatric and Adolescent Medicine, Western Michigan University Homer Stryker MD School of Medicine, Kalamazoo, Michigan, USA
| | - Mekala Neelakantan
- Department of Pediatric and Adolescent Medicine, Western Michigan University Homer Stryker MD School of Medicine, Kalamazoo, Michigan, USA
| | - Kevin Ching
- Department of Pediatric and Adolescent Medicine, Western Michigan University Homer Stryker MD School of Medicine, Kalamazoo, Michigan, USA
| | - Jasmine Saeedian
- Department of Pediatric and Adolescent Medicine, Western Michigan University Homer Stryker MD School of Medicine, Kalamazoo, Michigan, USA
| | - Amy Goldstein
- Children's Hospital of Philadelphia and Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| |
Collapse
|
29
|
AlJabri MF, Kamal NM, Halabi A, Korbi H, Alsayyali MM, Alzahrani YA. Lethal neonatal mitochondrial phenotype caused by a novel polymerase subunit gamma mutation: A case report. Medicine (Baltimore) 2018; 97:e12591. [PMID: 30290626 PMCID: PMC6200512 DOI: 10.1097/md.0000000000012591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
RATIONALE Polymerase subunit gamma (POLG) is a gene that codes for the catalytic subunit of the mitochondrial DNA polymerase, which is involved in the replication of mitochondrial DNA. Mutations in these genes are associated with a range of clinical syndromes characterized by secondary mtDNA defect including mtDNA mutation and mtDNA depletion which may culminate in complete failure of energy production (respiratory changes complex 1 defect) as in this case. PATIENT CONCERNS We herein report a full term Saudi female neonate born to consanguineous parents, who was noticed immediately after birth to have severe hypotonia, poor respiratory effort, and dysmorphic features. She had 3 siblings who died with same clinical scenario in neonatal period. DIAGNOSES Molecular genetic testing revealed a novel compound heterozygous mutation of POLG gene c.680G>A (p.Arg227Gin) and c.3098C>T (p.Ala1033Val). INTERVENTIONS The patient remained in neonatal intensive care unit with multidisciplinary team management and was ventilator dependent until she passed away. OUTCOMES The detected mutation had led to complete failure of energy production (respiratory changes complex 1 defect) until she died at the age of 5 months. LESSONS Mitochondrial respiratory chain defect should be considered in patients with severe neonatal hypotonia,encephalopathy, and respiratory failure especially in highly consanguineous population.
Collapse
Affiliation(s)
| | - Naglaa M. Kamal
- Pediatric Hepatology, Faculty of Medicine, Cairo University, Egypt
- Pediatric Hepatology
| | | | | | | | - Yahea A. Alzahrani
- Neuroradiology, College of Medicine, Taif University, Taif, Saudi Arabia
| |
Collapse
|
30
|
Brockhage R, Slone J, Ma Z, Hegde MR, Valencia CA, Huang T. Validation of the diagnostic potential of mtDNA copy number derived from whole genome sequencing. J Genet Genomics 2018; 45:S1673-8527(18)30098-5. [PMID: 29910094 DOI: 10.1016/j.jgg.2018.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 06/03/2018] [Accepted: 06/04/2018] [Indexed: 02/05/2023]
Affiliation(s)
- Rachel Brockhage
- Division of Human Genetics, Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Jesse Slone
- Division of Human Genetics, Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Zeqiang Ma
- PerkinElmer Genomics, Branford, CT 06405, USA
| | - Madhuri R Hegde
- PerkinElmer Genomics, Branford, CT 06405, USA; Department of Human Genetics, Emory University, Atlanta, GA 30322, USA; School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - C Alexander Valencia
- PerkinElmer Genomics, Branford, CT 06405, USA; West China Hospital, Sichuan University, Chengdu 610041, China
| | - Taosheng Huang
- Division of Human Genetics, Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Human Aging Research Institute, Nanchang University, Nanchang 330031, China.
| |
Collapse
|
31
|
Nicastro E, D'Antiga L. Next generation sequencing in pediatric hepatology and liver transplantation. Liver Transpl 2018; 24:282-293. [PMID: 29080241 DOI: 10.1002/lt.24964] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/04/2017] [Accepted: 10/18/2017] [Indexed: 02/07/2023]
Abstract
Next generation sequencing (NGS) has revolutionized the analysis of human genetic variations, offering a highly cost-effective way to diagnose monogenic diseases (MDs). Because nearly half of the children with chronic liver disorders have a genetic cause and approximately 20% of pediatric liver transplantations are performed in children with MDs, NGS offers the opportunity to significantly improve the diagnostic yield in this field. Among the NGS strategies, the use of targeted gene panels has proven useful to rapidly and reliably confirm a clinical suspicion, whereas the whole exome sequencing (WES) with variants filtering has been adopted to assist the diagnostic workup in unclear clinical scenarios. WES is powerful but challenging because it detects a great number of variants of unknown significance that can be misinterpreted and lead to an incorrect diagnosis. In pediatric hepatology, targeted NGS can be very valuable to discriminate neonatal/infantile cholestatic disorders, disclose genetic causes of acute liver failure, and diagnose the subtype of inborn errors of metabolism presenting with a similar phenotype (such as glycogen storage disorders, mitochondrial cytopathies, or nonalcoholic fatty liver disease). The inclusion of NGS in diagnostic processes will lead to a paradigm shift in medicine, changing our approach to the patient as well as our understanding of factors affecting genotype-phenotype match. In this review, we discuss the opportunities and the challenges offered nowadays by NGS, and we propose a novel algorithm for cholestasis of infancy adopted in our center, including targeted NGS as a pivotal tool for the diagnosis of liver-based MDs. Liver Transplantation 24 282-293 2018 AASLD.
Collapse
Affiliation(s)
- Emanuele Nicastro
- Pediatric Hepatology, Gastroenterology and Transplantation, Hospital Papa Giovanni XXIII, Bergamo, Italy
| | - Lorenzo D'Antiga
- Pediatric Hepatology, Gastroenterology and Transplantation, Hospital Papa Giovanni XXIII, Bergamo, Italy
| |
Collapse
|
32
|
Fang W, Song P, Xie X, Wang J, Lu Y, Li G, Abuduxikuer K. A fatal case of mitochondrial DNA depletion syndrome with novel compound heterozygous variants in the deoxyguanosine kinase gene. Oncotarget 2017; 8:84309-84319. [PMID: 29137425 PMCID: PMC5663597 DOI: 10.18632/oncotarget.20905] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 08/17/2017] [Indexed: 12/02/2022] Open
Abstract
The deoxyguanosine kinase (DGUOK) gene controls mitochondrial DNA (mtDNA) maintenance, and variation in the gene can alter or abolish the anabolism of mitochondrial deoxyribonucleotides. A Chinese female infant, whose symptoms included weight stagnation, jaundice, hypoglycemia, coagulation disorders, abnormal liver function, and multiple abnormal signals in the brain, died at about 10 months old. Genetic testing revealed a compound heterozygote of alleles c.128T>C (p.I43T) and c.313C>T (p.R105*) of the DGUOK gene. c.128T>C (p.I43T) is a novel variant located in exon 1 (NM_080916) in the first beta sheet of DGUOK. Her mother was an allele c.313C>T (p.R105*) heterozygote, which is located in DGUOK exon 2 (NM_080916) between the third and fourth alpha helixes. c.313C>T (p.R105*) is predicted to result in a 173 amino acid residue truncation at the C terminus of DGUOK. There are as many as 112 infantile mtDNA depletion syndrome (MDS) cases in the literature related to DGUOK gene variants. These variants include missense mutations, nucleotide deletion, nucleotide insertion, and nucleotide duplication. Integrated data showed that mutations affected both conserved and non-conserved DGUOK amino acids and are associated with patient deaths.
Collapse
Affiliation(s)
- Weiyuan Fang
- The Center for Pediatric Liver Disease, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Peng Song
- Advanced Training Program, Children's Hospital of Fudan University, Shanghai 201102, China.,Department of Infectious Diseases, Tangshan Maternal and Children Health Hospital, Tangshan City, Hebei Province 063000, China
| | - Xinbao Xie
- The Center for Pediatric Liver Disease, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Jianshe Wang
- The Center for Pediatric Liver Disease, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Yi Lu
- The Center for Pediatric Liver Disease, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Gang Li
- Institute of Pediatrics, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Kuerbanjiang Abuduxikuer
- The Center for Pediatric Liver Disease, Children's Hospital of Fudan University, Shanghai 201102, China
| |
Collapse
|
33
|
Piper JD, Piper PW. Benzoate and Sorbate Salts: A Systematic Review of the Potential Hazards of These Invaluable Preservatives and the Expanding Spectrum of Clinical Uses for Sodium Benzoate. Compr Rev Food Sci Food Saf 2017; 16:868-880. [PMID: 33371618 DOI: 10.1111/1541-4337.12284] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 06/08/2017] [Accepted: 06/10/2017] [Indexed: 12/30/2022]
Abstract
Sodium benzoate and potassium sorbate are extremely useful agents for food and beverage preservation, yet concerns remain over their complete safety. Benzoate can react with the ascorbic acid in drinks to produce the carcinogen benzene. A few children develop allergy to this additive while, as a competitive inhibitor of D-amino acid oxidase, benzoate can also influence neurotransmission and cognitive functioning. Model organism and cell culture studies have raised some issues. Benzoate has been found to exert teratogenic and neurotoxic effects on zebrafish embryos. In addition, benzoate and sorbate are reported to cause chromosome aberrations in cultured human lymphocytes; also to be potently mutagenic toward the mitochondrial DNA in aerobic yeast cells. Whether the substantial human consumption of these compounds could significantly increase levels of such damages in man is still unclear. There is no firm evidence that it is a risk factor in type 2 diabetes. The clinical administration of sodium benzoate is of proven benefit for many patients with urea cycle disorders, while recent studies indicate it may also be advantageous in the treatment of multiple sclerosis, schizophrenia, early-stage Alzheimer's disease and Parkinson's disease. Nevertheless, exposure to high amounts of this agent should be approached with caution, especially since it has the potential to generate a shortage of glycine which, in turn, can negatively influence brain neurochemistry. We discuss here how a small fraction of the population might be rendered-either through their genes or a chronic medical condition-particularly susceptible to any adverse effects of sodium benzoate.
Collapse
Affiliation(s)
- Joseph D Piper
- Centre for Genomics and Child Health, Blizard Inst., Queen Mary Univ. of London, London, E1 2AT, United Kingdom
| | - Peter W Piper
- Dept. of Molecular Biology and Biotechnology, Univ. of Sheffield, Sheffield, S10 2TN, United Kingdom
| |
Collapse
|
34
|
Thymidine kinase 2 and alanyl-tRNA synthetase 2 deficiencies cause lethal mitochondrial cardiomyopathy: case reports and review of the literature. Cardiol Young 2017; 27:936-944. [PMID: 27839525 DOI: 10.1017/s1047951116001876] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Cardiomyopathy is a common manifestation in neonates and infants with mitochondrial disorders. In this study, we report two cases manifesting with fatal mitochondrial hypertrophic cardiomyopathy, which include the third known patient with thymidine kinase 2 deficiency and the ninth patient with alanyl-tRNA synthetase 2 deficiency. The girl with thymidine kinase 2 deficiency had hypertrophic cardiomyopathy together with regression of gross motor development at the age of 13 months. Neurological symptoms and cardiac involvement progressed into severe myopathy, psychomotor arrest, and cardiorespiratory failure at the age of 22 months. The imaging methods and autoptic studies proved that she suffered from unique findings of leucoencephalopathy, severe, mainly cerebellar neuronal degeneration, and hepatic steatosis. The girl with alanyl-tRNA synthetase 2 deficiency presented with cardiac failure and underlying hypertrophic cardiomyopathy within 12 hours of life and subsequently died at 9 weeks of age. Muscle biopsy analyses demonstrated respiratory chain complex I and IV deficiencies, and histological evaluation revealed massive mitochondrial accumulation and cytochrome c oxidase-negative fibres in both cases. Exome sequencing in the first case revealed compound heterozygozity for one novel c.209T>C and one previously published c.416C>T mutation in the TK2 gene, whereas in the second case homozygozity for the previously described mutation c.1774C>T in the AARS2 gene was determined. The thymidine kinase 2 mutations resulted in severe mitochondrial DNA depletion (to 12% of controls) in the muscle. We present, for the first time, severe leucoencephalopathy and hepatic steatosis in a patient with thymidine kinase 2 deficiency and the finding of a ragged red fibre-like image in the muscle biopsy in a patient with alanyl-tRNA synthetase 2 deficiency.
Collapse
|
35
|
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.
Collapse
|
36
|
Nascimento A, Ortez C, Jou C, O'Callaghan M, Ramos F, Garcia-Cazorla À. Neuromuscular Manifestations in Mitochondrial Diseases in Children. Semin Pediatr Neurol 2016; 23:290-305. [PMID: 28284391 DOI: 10.1016/j.spen.2016.11.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Mitochondrial diseases exhibit significant clinical and genetic heterogeneity. Mitochondria are highly dynamic organelles that are the major contributor of adenosine triphosphate, through oxidative phosphorylation. These disorders may be developed at any age, with isolated or multiple system involvement, and in any pattern of inheritance. Defects in the mitochondrial respiratory chain impair energy production and almost invariably involve skeletal muscle and peripheral nerves, causing exercise intolerance, cramps, recurrent myoglobinuria, or fixed weakness, which often affects extraocular muscles and results in droopy eyelids (ptosis), progressive external ophthalmoplegia, peripheral ataxia, and peripheral polyneuropathy. This review describes the main neuromuscular symptomatology through different syndromes reported in the literature and from our experience. We want to highlight the importance of searching for the "clue clinical signs" associated with inheritance pattern as key elements to guide the complex diagnosis process and genetic studies in mitochondrial diseases.
Collapse
Affiliation(s)
- Andrés Nascimento
- Department of Neurology, Neuromuscular Units, Hospital Sant Joan de Déu, Instituto de Salud Carlos III, Barcelona, Spain; Center for Biomedical Research on Rare Diseases (CIBERER), Institute of Pediatric Research Sant Joan de Déu, Madrid, Spain.
| | - Carlos Ortez
- Department of Neurology, Neuromuscular Units, Hospital Sant Joan de Déu, Instituto de Salud Carlos III, Barcelona, Spain
| | - Cristina Jou
- Department of Neurology, Neuromuscular Units, Hospital Sant Joan de Déu, Instituto de Salud Carlos III, Barcelona, Spain; Center for Biomedical Research on Rare Diseases (CIBERER), Institute of Pediatric Research Sant Joan de Déu, Madrid, Spain
| | - Mar O'Callaghan
- Center for Biomedical Research on Rare Diseases (CIBERER), Institute of Pediatric Research Sant Joan de Déu, Madrid, Spain; Department of Neurology, Neurometabolic Units, Hospital Sant Joan de Déu, Instituto de Salud Carlos III, Barcelona, Spain
| | - Federico Ramos
- Center for Biomedical Research on Rare Diseases (CIBERER), Institute of Pediatric Research Sant Joan de Déu, Madrid, Spain; Department of Neurology, Neurometabolic Units, Hospital Sant Joan de Déu, Instituto de Salud Carlos III, Barcelona, Spain
| | - Àngels Garcia-Cazorla
- Center for Biomedical Research on Rare Diseases (CIBERER), Institute of Pediatric Research Sant Joan de Déu, Madrid, Spain; Department of Neurology, Neurometabolic Units, Hospital Sant Joan de Déu, Instituto de Salud Carlos III, Barcelona, Spain
| |
Collapse
|
37
|
Qualls C, Kornfeld M, Joste N, Ali AM, Appenzeller O. MPV17-related hepatocerebral mitochondrial DNA depletion syndrome (MPV17-NNH) revisited. eNeurologicalSci 2016; 2:8-13. [PMID: 29473055 PMCID: PMC5818138 DOI: 10.1016/j.ensci.2016.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Accepted: 01/26/2016] [Indexed: 11/25/2022] Open
Abstract
MPV17-related hepatocerebral mitochondrial DNA depletion syndrome (previously known as Navajo neurohepatopathy) was discovered in children in the Four Corner's region of New Mexico approximately 40 years ago. This disease is associated with a single missense mutation in exon 2 in the MPV17 gene. The syndrome has now been recognized world-wide. We find that huge quantities of neurotoxins were present in archived nervous tissues from such patients. Arsenic was increased 18 ×, cadmium ~ 10 ×, cobalt 2.5 × and manganese 2.3 ×; the largest increase was in mercury content 16,000 × compared to contemporaneous fresh-frozen normal nervous tissues. In the Four Corner's region of NM the life span is reduced compared to other parts of the United States and in our patients with MPV17-NNH the average life span was 5.4 years ± 2.7 (SE) years. We now live in the Anthropocene an epoch characterized by large additions to the biosphere of neurotoxins. The effects of such toxic loads on human health and disease remain to be assessed. We speculate how such high neurotoxin content in tissues, which is likely to increase during the Anthropocene, may have influenced MPV17-NNH and similar phenotypes in different parts of the world. Our results imply that selenium supplementation to the diet in the Four Corner's region of NM might be beneficial to normal people and in the management of patients with MPV17-NNH syndrome.
Collapse
Affiliation(s)
- Clifford Qualls
- Department of Mathematics and Statistics, University of New Mexico, Albuquerque, NM 87122, United States
| | - Mario Kornfeld
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87122, United States
| | - Nancy Joste
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87122, United States
| | - Abdul-Mehdi Ali
- Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87122, United States
| | - Otto Appenzeller
- Department of Neurology, NMHEMC Research Foundation, Albuquerque, NM 87122, United States
| |
Collapse
|
38
|
Villalpando Carrión S, Espriu Ramírez MX, Romero Baizabal BL, Sadowinski-Pine S. [Infant with progressive jaundice, cirrhosis and proximal tubulopathy]. BOLETIN MEDICO DEL HOSPITAL INFANTIL DE MEXICO 2016; 73:129-138. [PMID: 29421194 DOI: 10.1016/j.bmhimx.2015.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 12/03/2015] [Indexed: 06/08/2023] Open
Affiliation(s)
- Salvador Villalpando Carrión
- Departamento de Gastroenterología y Nutrición, Hospital Infantil de México Federico Gómez, Ciudad de México, México.
| | | | | | | |
Collapse
|
39
|
Rajakulendran S, Pitceathly RDS, Taanman JW, Costello H, Sweeney MG, Woodward CE, Jaunmuktane Z, Holton JL, Jacques TS, Harding BN, Fratter C, Hanna MG, Rahman S. A Clinical, Neuropathological and Genetic Study of Homozygous A467T POLG-Related Mitochondrial Disease. PLoS One 2016; 11:e0145500. [PMID: 26735972 PMCID: PMC4703200 DOI: 10.1371/journal.pone.0145500] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/06/2015] [Indexed: 02/06/2023] Open
Abstract
Mutations in the nuclear gene POLG (encoding the catalytic subunit of DNA polymerase gamma) are an important cause of mitochondrial disease. The most common POLG mutation, A467T, appears to exhibit considerable phenotypic heterogeneity. The mechanism by which this single genetic defect results in such clinical diversity remains unclear. In this study we evaluate the clinical, neuropathological and mitochondrial genetic features of four unrelated patients with homozygous A467T mutations. One patient presented with the severe and lethal Alpers-Huttenlocher syndrome, which was confirmed on neuropathology, and was found to have a depletion of mitochondrial DNA (mtDNA). Of the remaining three patients, one presented with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS), one with a phenotype in the Myoclonic Epilepsy, Myopathy and Sensory Ataxia (MEMSA) spectrum and one with Sensory Ataxic Neuropathy, Dysarthria and Ophthalmoplegia (SANDO). All three had secondary accumulation of multiple mtDNA deletions. Complete sequence analysis of muscle mtDNA using the MitoChip resequencing chip in all four cases demonstrated significant variation in mtDNA, including a pathogenic MT-ND5 mutation in one patient. These data highlight the variable and overlapping clinical and neuropathological phenotypes and downstream molecular defects caused by the A467T mutation, which may result from factors such as the mtDNA genetic background, nuclear genetic modifiers and environmental stressors.
Collapse
Affiliation(s)
- Sanjeev Rajakulendran
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery and the MRC Centre for Neuromuscular Diseases, Queen Square, London WC1N 3BG, United Kingdom
| | - Robert D. S. Pitceathly
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, United Kingdom and Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King’s College London SE5 8AF, United Kingdom
| | - Jan-Willem Taanman
- Department of Clinical Neurosciences, UCL Institute of Neurology, London NW3 2PF, United Kingdom
| | - Harry Costello
- Mitochondrial Research Group, Genetics and Genomic Medicine, UCL Institute of Child Health, London WC1N 1EH, United Kingdom
| | - Mary G. Sweeney
- Department of Neurogenetics, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, United Kingdom
| | - Cathy E. Woodward
- Department of Neurogenetics, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, United Kingdom
| | - Zane Jaunmuktane
- Division of Neuropathology, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, United Kingdom
| | - Janice L. Holton
- Division of Neuropathology, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, United Kingdom
| | - Thomas S. Jacques
- Developmental Biology and Cancer Programme, UCL Institute of Child Health and Department of Histopathology, Great Ormond Street Hospital for Children Foundation Trust, London WC1N 1EH, United Kingdom
| | - Brian N. Harding
- Division of Neuropathology, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Carl Fratter
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford OX3 7LE, United Kingdom
| | - Michael G. Hanna
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery and the MRC Centre for Neuromuscular Diseases, Queen Square, London WC1N 3BG, United Kingdom
| | - Shamima Rahman
- Mitochondrial Research Group, Genetics and Genomic Medicine, UCL Institute of Child Health, London WC1N 1EH, United Kingdom
- Metabolic Unit, Great Ormond Street Hospital, London WC1N 3JH, United Kingdom
- * E-mail:
| |
Collapse
|
40
|
Hänninen RL, Ahonen S, Màrquez M, Myöhänen MJ, Hytönen MK, Lohi H. Canine MPV17 truncation without clinical manifestations. Biol Open 2015; 4:1253-8. [PMID: 26353863 PMCID: PMC4610228 DOI: 10.1242/bio.013870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mitochondrial DNA depletion syndromes (MDS) are often serious autosomal recessively inherited disorders characterized by tissue-specific mtDNA copy number reduction. Many genes, including MPV17, are associated with the hepatocerebral form of MDS. MPV17 encodes for a mitochondrial inner membrane protein with a poorly characterized function. Several MPV17 mutations have been reported in association with a heterogeneous group of early-onset manifestations, including liver disease and neurological problems. Mpv17-deficient mice present renal and hearing defects. We describe here a MPV17 truncation mutation in dogs. We found a 1-bp insertion in exon 4 of the MPV17 gene, resulting in a frameshift and early truncation of the encoded protein. The mutation halves MPV17 expression in the lymphocytes of the homozygous dogs and the truncated protein is not translated in transfected cells. The insertion mutation is recurrent and exists in many unrelated breeds, although is highly enriched in the Boxer breed. Unexpectedly, despite the truncation of MPV17, we could not find any common phenotypes in the genetically affected dogs. The lack of observable phenotype could be due to a late onset, mild symptoms or potential tissue-specific compensatory mechanisms. This study suggests species-specific differences in the manifestation of the MPV17 defects and establishes a novel large animal model to further study MPV17 function and role in mitochondrial biology.
Collapse
Affiliation(s)
- Reetta L Hänninen
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki and Folkhälsan Research Center, Helsinki 00014, Finland
| | - Saija Ahonen
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki and Folkhälsan Research Center, Helsinki 00014, Finland
| | - Merce Màrquez
- Banc de Teixits Animals de Catalunya (BTAC), Department Medicina i Cirurgia Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Barcelona 08193, Spain
| | - Maarit J Myöhänen
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki 00014, Finland
| | - Marjo K Hytönen
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki and Folkhälsan Research Center, Helsinki 00014, Finland
| | - Hannes Lohi
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki and Folkhälsan Research Center, Helsinki 00014, Finland
| |
Collapse
|
41
|
Franzolin E, Salata C, Bianchi V, Rampazzo C. The Deoxynucleoside Triphosphate Triphosphohydrolase Activity of SAMHD1 Protein Contributes to the Mitochondrial DNA Depletion Associated with Genetic Deficiency of Deoxyguanosine Kinase. J Biol Chem 2015; 290:25986-96. [PMID: 26342080 PMCID: PMC4646252 DOI: 10.1074/jbc.m115.675082] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Indexed: 11/22/2022] Open
Abstract
The dNTP triphosphohydrolase SAMHD1 is a nuclear antiviral host restriction factor limiting HIV-1 infection in macrophages and a major regulator of dNTP concentrations in human cells. In normal human fibroblasts its expression increases during quiescence, contributing to the small dNTP pool sizes of these cells. Down-regulation of SAMHD1 by siRNA expands all four dNTP pools, with dGTP undergoing the largest relative increase. The deoxyguanosine released by SAMHD1 from dGTP can be phosphorylated inside mitochondria by deoxyguanosine kinase (dGK) or degraded in the cytosol by purine nucleoside phosphorylase. Genetic mutations of dGK cause mitochondrial (mt) DNA depletion in noncycling cells and hepato-cerebral mtDNA depletion syndrome in humans. We studied if SAMHD1 and dGK interact in the regulation of the dGTP pool during quiescence employing dGK-mutated skin fibroblasts derived from three unrelated patients. In the presence of SAMHD1 quiescent mutant fibroblasts manifested mt dNTP pool imbalance and mtDNA depletion. When SAMHD1 was silenced by siRNA transfection the composition of the mt dNTP pool approached that of the controls, and mtDNA copy number increased, compensating the depletion to various degrees in the different mutant fibroblasts. Chemical inhibition of purine nucleoside phosphorylase did not improve deoxyguanosine recycling by dGK in WT cells. We conclude that the activity of SAMHD1 contributes to the pathological phenotype of dGK deficiency. Our results prove the importance of SAMHD1 in the regulation of all dNTP pools and suggest that dGK inside mitochondria has the function of recycling the deoxyguanosine derived from endogenous dGTP degraded by SAMHD1 in the nucleus.
Collapse
Affiliation(s)
- Elisa Franzolin
- From the Department of Biology, University of Padova, 35131 Padova, Italy and
| | - Cristiano Salata
- Department of Molecular Medicine, University of Padova, 35121 Padova, Italy
| | - Vera Bianchi
- From the Department of Biology, University of Padova, 35131 Padova, Italy and
| | - Chiara Rampazzo
- From the Department of Biology, University of Padova, 35131 Padova, Italy and
| |
Collapse
|
42
|
Li A, Li L, Sun X, Ni Y, Chen X, Guo A, Chen X. Increased Expression of Mitochondrial Inner-Membrane Protein Mpv17 After Intracerebral Hemorrhage in Adult Rats. Neurochem Res 2015; 40:1620-30. [PMID: 26123482 DOI: 10.1007/s11064-015-1644-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 05/15/2015] [Accepted: 06/17/2015] [Indexed: 01/18/2023]
Abstract
The Mpv17 gene encodes a mitochondrial inner-membrane protein that has been implicated in several cell activities. Almost all studies have previously indicated that loss of function or gene-inactivated in Mpv17 can induce the development of disease. Here, we explored the roles of Mpv17 protein in the pathophysiology of intracerebral hemorrhage (ICH). An ICH rat model was established and assessed by behavioral tests. Using western blot and immunohistochemistry, significant up-regulation of Mpv17 was found in neurons in brain areas surrounding the hematoma following ICH. The increase of Mpv17 expression was found to be accompanied by the enhanced expression of p53, Bax, cytochrome c (Cyt c) and active caspase-3, and decreased expression of Bcl-2 in the pathological process of rat ICH. Furthermore, immunofluorescent staining revealed that Mpv17 co-localized with p53, Bax and active caspase-3 in neurons, suggesting its biological function in the process of neuronal apoptosis. Our in vitro study, using Mpv17 RNA interference in primary cortical neurons, indicated that Mpv17 might exert its anti-apoptotic function in neuronal apoptosis. Thus, Mpv17 may play a role in protecting the brain from secondary damage following ICH.
Collapse
Affiliation(s)
- Aihong Li
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, China
| | | | | | | | | | | | | |
Collapse
|
43
|
Lodi T, Dallabona C, Nolli C, Goffrini P, Donnini C, Baruffini E. DNA polymerase γ and disease: what we have learned from yeast. Front Genet 2015; 6:106. [PMID: 25852747 PMCID: PMC4362329 DOI: 10.3389/fgene.2015.00106] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/02/2015] [Indexed: 11/16/2022] Open
Abstract
Mip1 is the Saccharomyces cerevisiae DNA polymerase γ (Pol γ), which is responsible for the replication of mitochondrial DNA (mtDNA). It belongs to the family A of the DNA polymerases and it is orthologs to human POLGA. In humans, mutations in POLG(1) cause many mitochondrial pathologies, such as progressive external ophthalmoplegia (PEO), Alpers' syndrome, and ataxia-neuropathy syndrome, all of which present instability of mtDNA, which results in impaired mitochondrial function in several tissues with variable degrees of severity. In this review, we summarize the genetic and biochemical knowledge published on yeast mitochondrial DNA polymerase from 1989, when the MIP1 gene was first cloned, up until now. The role of yeast is particularly emphasized in (i) validating the pathological mutations found in human POLG and modeled in MIP1, (ii) determining the molecular defects caused by these mutations and (iii) finding the correlation between mutations/polymorphisms in POLGA and mtDNA toxicity induced by specific drugs. We also describe recent findings regarding the discovery of molecules able to rescue the phenotypic defects caused by pathological mutations in Mip1, and the construction of a model system in which the human Pol γ holoenzyme is expressed in yeast and complements the loss of Mip1.
Collapse
Affiliation(s)
- Tiziana Lodi
- Department of Life Sciences, University of Parma Parma, Italy
| | | | - Cecilia Nolli
- Department of Life Sciences, University of Parma Parma, Italy
| | - Paola Goffrini
- Department of Life Sciences, University of Parma Parma, Italy
| | - Claudia Donnini
- Department of Life Sciences, University of Parma Parma, Italy
| | | |
Collapse
|
44
|
Sezer T, Ozçay F, Balci O, Alehan F. Novel deoxyguanosine kinase gene mutations in the hepatocerebral form of mitochondrial DNA depletion syndrome. J Child Neurol 2015; 30:124-8. [PMID: 24423689 DOI: 10.1177/0883073813517000] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Deoxyguanosine kinase (DGUOK) gene mutations have been identified in the hepatocerebral form of mitochondrial DNA depletion syndromes. We report here clinical and laboratory features of 3 infants with novel DGUOK gene mutations, c.130G>A (Glu44Lys), c.493G>A (Glu165Lys), and c.707+3_6delTAAG.
Collapse
Affiliation(s)
- Taner Sezer
- Division of Pediatric Neurology, Baskent University School of Medicine, Ankara, Turkey
| | - Figen Ozçay
- Division of Pediatric Gastroenterology Hepatology and Nutrition, Baskent University School of Medicine, Ankara, Turkey
| | - Oya Balci
- Division of Pediatric Gastroenterology Hepatology and Nutrition, Baskent University School of Medicine, Ankara, Turkey
| | - Füsun Alehan
- Division of Pediatric Neurology, Baskent University School of Medicine, Ankara, Turkey
| |
Collapse
|
45
|
Polymorphisms in DNA polymerase γ affect the mtDNA stability and the NRTI-induced mitochondrial toxicity in Saccharomyces cerevisiae. Mitochondrion 2014; 20:52-63. [PMID: 25462018 PMCID: PMC4309887 DOI: 10.1016/j.mito.2014.11.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 11/10/2014] [Accepted: 11/11/2014] [Indexed: 12/23/2022]
Abstract
Several pathological mutations have been identified in human POLG gene, encoding for the catalytic subunit of Pol γ, the solely mitochondrial replicase in animals and fungi. However, little is known regarding non-pathological polymorphisms found in this gene. Here we studied, in the yeast model Saccharomyces cerevisiae, eight human polymorphisms. We found that most of them are not neutral but enhanced both mtDNA extended mutability and the accumulation of mtDNA point mutations, either alone or in combination with a pathological mutation. In addition, we found that the presence of some SNPs increased the stavudine and/or zalcitabine-induced mtDNA mutability and instability. We studied the effects of 8 human polymorphisms in Pol γ in the model system yeast. Most polymorphisms increase mtDNA extended and point mutability. Treatment with NRTIs determines mtDNA instability in wt and mutant strains. Some polymorphisms make Mip1 more sensitive to NRTIs-induced mtDNA toxicity.
Collapse
|
46
|
Knierim E, Seelow D, Gill E, von Moers A, Schuelke M. Clinical application of whole exome sequencing reveals a novel compound heterozygous TK2-mutation in two brothers with rapidly progressive combined muscle-brain atrophy, axonal neuropathy, and status epilepticus. Mitochondrion 2014; 20:1-6. [PMID: 25446393 DOI: 10.1016/j.mito.2014.10.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Revised: 10/05/2014] [Accepted: 10/29/2014] [Indexed: 10/24/2022]
Abstract
Mutations in several genes cause mtDNA depletion associated with encephalomyopathy. Due to phenotypic overlap, it is difficult to conclude from clinical phenotype to genetic defect. Here we report on two brothers who presented with rapid fatty muscle degeneration, axonal neuropathy, rapid loss of supratentorial white and gray matter, and status epilepticus. Whole exome sequencing coupled with 'identity-by-state' (IBS) analysis revealed a compound heterozygous missense mutation (p.M117V, p.A139V) in the thymidine kinase 2 (TK2) gene that segregated with the phenotype. Both mutations were located in the thymidine binding pouch of the enzyme. Residual mtDNA copy numbers in muscle were 8.5%, but normal in blood and fibroblasts. Our results broaden the clinical phenotype spectrum of TK2 mutations and promote WES as a useful method in the clinical setting for mutation detection, even in untypical cases. If two or more affected siblings from a non-consanguineous family can be investigated, IBS-analysis provides a powerful tool to narrow the number of disease candidates, similarly to autozygosity mapping in consanguineous families.
Collapse
Affiliation(s)
- Ellen Knierim
- NeuroCure Clinical Research Center (NCRC), Charité-Universitätsmedizin Berlin, Germany; Department of Neuropediatrics, Charité-Universitätsmedizin Berlin, Germany
| | - Dominik Seelow
- NeuroCure Clinical Research Center (NCRC), Charité-Universitätsmedizin Berlin, Germany; Department of Neuropediatrics, Charité-Universitätsmedizin Berlin, Germany
| | - Esther Gill
- NeuroCure Clinical Research Center (NCRC), Charité-Universitätsmedizin Berlin, Germany
| | | | - Markus Schuelke
- NeuroCure Clinical Research Center (NCRC), Charité-Universitätsmedizin Berlin, Germany; Department of Neuropediatrics, Charité-Universitätsmedizin Berlin, Germany.
| |
Collapse
|
47
|
Hynynen J, Komulainen T, Tukiainen E, Nordin A, Arola J, Kälviäinen R, Jutila L, Röyttä M, Hinttala R, Majamaa K, Mäkisalo H, Uusimaa J. Acute liver failure after valproate exposure in patients with POLG1 mutations and the prognosis after liver transplantation. Liver Transpl 2014; 20:1402-12. [PMID: 25065347 DOI: 10.1002/lt.23965] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 07/21/2014] [Accepted: 07/21/2014] [Indexed: 01/12/2023]
Abstract
Patients with mutations in the POLG1 gene encoding mitochondrial DNA polymerase gamma have an increased risk of valproate-induced liver failure. POLG1 mutations are common, and these patients often suffer from intractable seizures. The role of liver transplantation in the treatment of patients with mitochondrial diseases has been controversial. We studied valproate-induced liver failure associated with POLG1 mutations and the prognosis for these patients after liver transplantation. POLG1 was analyzed in blood DNA, mitochondrial DNA (mtDNA) was quantified in liver samples, and clinical data were collected. Five patients with valproate-induced liver failure associated with POLG1 mutations were retrospectively identified. Three patients were previously suspected to have Wilson's disease. Four patients with homozygous p.W748S and p.E1143G mutations had mtDNA depletion in the liver. One of these patients died before anticipated transplantation; the other 3 patients with liver transplantation have survived 4 to 19 years. Two patients have presented with occasional epileptic seizures, and 1 patient has been seizure-free for 11 years. One patient with a heterozygous p.Q1236H mutation (but without mtDNA depletion in the liver) died suddenly 2 years after liver transplantation. In conclusion, the POLG1 mutation status and the age at presentation of valproate-induced liver failure can affect the prognosis after liver transplantation. A heterozygous POLG1 p.Q1236H mutation was related to valproate-induced liver failure without mtDNA depletion, whereas patients homozygous for POLG1 p.W748S and p.E1143G mutations had mtDNA depletion. An analysis of the POLG1 gene should be performed for all patients with suspected mitochondrial disease before the introduction of valproate therapy, and treatment with valproic acid should be avoided in these patients.
Collapse
Affiliation(s)
- Johanna Hynynen
- Institute of Clinical Medicine, Department of Pediatrics, University of Oulu, Oulu, Finland; Medical Research Center, Oulu University Hospital, University of Oulu, Oulu, Finland
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Balasubramaniam S, Duley JA, Christodoulou J. Inborn errors of purine metabolism: clinical update and therapies. J Inherit Metab Dis 2014; 37:669-86. [PMID: 24972650 DOI: 10.1007/s10545-014-9731-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 05/27/2014] [Accepted: 06/02/2014] [Indexed: 12/20/2022]
Abstract
Inborn errors of purine metabolism exhibit broad neurological, immunological, haematological and renal manifestations. Limited awareness of the phenotypic spectrum, the recent descriptions of newer disorders and considerable genetic heterogeneity, have contributed to long diagnostic odysseys for affected individuals. These enzymes are widely but not ubiquitously distributed in human tissues and are crucial for synthesis of essential nucleotides, such as ATP, which form the basis of DNA and RNA, oxidative phosphorylation, signal transduction and a range of molecular synthetic processes. Depletion of nucleotides or accumulation of toxic intermediates contributes to the pathogenesis of these disorders. Maintenance of cellular nucleotides depends on the three aspects of metabolism of purines (and related pyrimidines): de novo synthesis, catabolism and recycling of these metabolites. At present, treatments for the clinically significant defects of the purine pathway are restricted: purine 5'-nucleotidase deficiency with uridine; familial juvenile hyperuricaemic nephropathy (FJHN), adenine phosphoribosyl transferase (APRT) deficiency, hypoxanthine phosphoribosyl transferase (HPRT) deficiency and phosphoribosyl-pyrophosphate synthetase superactivity (PRPS) with allopurinol; adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) deficiencies have been treated by bone marrow transplantation (BMT), and ADA deficiency with enzyme replacement with polyethylene glycol (PEG)-ADA, or erythrocyte-encapsulated ADA; myeloadenylate deaminase (MADA) and adenylosuccinate lyase (ADSL) deficiencies have had trials of oral ribose; PRPS, HPRT and adenosine kinase (ADK) deficiencies with S-adenosylmethionine; and molybdenum cofactor deficiency of complementation group A (MOCODA) with cyclic pyranopterin monophosphate (cPMP). In this review we describe the known inborn errors of purine metabolism, their phenotypic presentations, established diagnostic methodology and recognised treatment options.
Collapse
Affiliation(s)
- Shanti Balasubramaniam
- Metabolic Unit, Princess Margaret Hospital, Roberts Road, Subiaco, Perth, WA, 6008, Australia
| | | | | |
Collapse
|
49
|
Abstract
Parkinson’s disease (PD) is a progressively debilitating neurodegenerative syndrome. Although best described as a movement disorder, the condition has prominent autonomic, cognitive, psychiatric, sensory and sleep components. Striatal dopaminergic innervation and nigral neurons are progressively lost, with associated Lewy pathology readily apparent on autopsy. Nevertheless, knowledge of the molecular events leading to this pathophysiology is limited. Current therapies offer symptomatic benefit but they fail to slow progression and patients continue to deteriorate. Recent discoveries in sporadic, Mendelian and more complex forms of parkinsonism provide novel insight into disease etiology; 28 genes, including those encoding alpha-synuclein (SNCA), leucine-rich repeat kinase 2 (LRRK2) and microtubule-associated protein tau (MAPT), have been linked and/or associated with PD. A consensus regarding the affected biological pathways and molecular processes has also started to emerge. In early-onset and more a typical PD, deficits in mitophagy pathways and lysosomal function appear to be prominent. By contrast, in more typical late-onset PD, chronic, albeit subtle, dysfunction in synaptic transmission, early endosomal trafficking and receptor recycling, as well as chaperone-mediated autophagy, provide a unifying synthesis of the molecular pathways involved. Disease-modification (neuroprotection) is no longer such an elusive goal given the unparalleled opportunity for diagnosis, translational neuroscience and therapeutic development provided by genetic discovery.
Collapse
Affiliation(s)
- Michelle K Lin
- Djavad Mowafaghian Centre for Brain Health, Centre for Applied Neurogenetics, Department of Medical Genetics, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Matthew J Farrer
- Djavad Mowafaghian Centre for Brain Health, Centre for Applied Neurogenetics, Department of Medical Genetics, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| |
Collapse
|
50
|
Jacob HJ, Abrams K, Bick DP, Brodie K, Dimmock DP, Farrell M, Geurts J, Harris J, Helbling D, Joers BJ, Kliegman R, Kowalski G, Lazar J, Margolis DA, North P, Northup J, Roquemore-Goins A, Scharer G, Shimoyama M, Strong K, Taylor B, Tsaih SW, Tschannen MR, Veith RL, Wendt-Andrae J, Wilk B, Worthey EA. Genomics in clinical practice: lessons from the front lines. Sci Transl Med 2014; 5:194cm5. [PMID: 23863829 DOI: 10.1126/scitranslmed.3006468] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The price of whole-genome and -exome sequencing has fallen to the point where these methods can be applied to clinical medicine. Here, we outline the lessons we have learned in converting a sequencing laboratory designed for research into a fully functional clinical program.
Collapse
Affiliation(s)
- Howard J Jacob
- Human and Molecular Genetic Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|