1
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Wei LY, Chen XQ, Huang L, Shan QW, Tang Q. Liver transplantation for mitochondrial DNA depletion syndrome caused by MPV17 deficiency: a case report and literature review. Front Surg 2024; 11:1348806. [PMID: 39055132 PMCID: PMC11269130 DOI: 10.3389/fsurg.2024.1348806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Accepted: 06/24/2024] [Indexed: 07/27/2024] Open
Abstract
Objective To study the effectiveness of liver transplantation (LT) in treating mitochondrial DNA depletion syndrome (MDS) caused by the MPV17 gene variant. Case presentation A boy aged 2.8 years presented with edema of the lower limbs and abdomen, which persisted for over 10 days and was of unknown origin; this was accompanied by abnormal liver function, intractable hypoglycemia, and hyperlactatemia. During the second week of onset, he developed acute-on-chronic liver failure and was diagnosed with MDS due to homozygous variant c.293C>T in the MPV17 gene. Subsequently, he underwent LT from a cadaveric donor. At follow-up after 15 months, his liver function was found to be normal, without any symptoms. Additionally, a literature review was performed that included MDS patients with the MPV17 variant who underwent LT. The results demonstrated that the survival rates for MDS patients who underwent LT were 69.5%, 38.6%, 38.6%, and 38.6% at 1-year, 5-year, 10-year, and 20-year intervals, respectively. Sub-group analyses revealed the survival rate of MDS patients with isolated liver disease (83.33%, 5/6) was higher than that of hepatocerebral MDS patients (44.44%, 8/18). Fifteen variants were identified in the MPV17 gene, and patients with the c.293C>T (p.P98l) variant exhibited the highest survival rate. Conclusion Hepatocerebral MDS patients without neurological symptoms may benefit from LT.
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Affiliation(s)
- Liu-Yuan Wei
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
- Department of Pediatrics, The Fourth Affiliated Hospital of Guangxi Medical University, Liuzhou Worker's Hospital, Liuzhou, China
| | - Xiu-Qi Chen
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Li Huang
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Qing-Wen Shan
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Qing Tang
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
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2
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Huang AC, Ebel NH, Romero D, Martin B, Jhun I, Brown M, Enns GM, Esquivel C, Bonham C. Outcomes after liver transplantation in MPV17 deficiency (Navajo neurohepatopathy): A single-center case series. Pediatr Transplant 2022; 26:e14274. [PMID: 35466509 DOI: 10.1111/petr.14274] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 02/22/2022] [Accepted: 03/09/2022] [Indexed: 02/03/2023]
Abstract
BACKGROUND MPV17-related mitochondrial DNA maintenance defect (MPV17 deficiency) is a rare, autosomal recessive mitochondrial DNA depletion syndrome with a high mortality rate in infancy and early childhood due to progression to liver failure. Liver transplantation for children with MPV17 deficiency has been considered controversial due to uncertainty about the potential progression of extrahepatic manifestations following liver transplantation. METHODS We describe our institution's experience for two infants diagnosed with infantile MPV17 deficiency who presented in acute on chronic liver failure, but with normal development and normal neurological status who successfully underwent liver transplantation. RESULTS Both patients underwent successful liver transplantation with normal development and neurological status at 3 years and 16 months post-transplant, respectively. CONCLUSIONS In this rare disease population, we describe two infants with MPV17 deficiency who underwent liver transplantation for acute on chronic liver failure who continue to have normal development, without progression of neurological disease. MPV17 deficiency should not be considered a contraindication to liver transplantation.
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Affiliation(s)
- Alice C Huang
- Division of Pediatric Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Noelle H Ebel
- Division of Pediatric Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, Lucile Packard Children's Hospital Stanford, Stanford University, Palo Alto, California, USA
| | - Danielle Romero
- Department of Pediatric Liver Transplant, Lucile Packard Children's Hospital Stanford, Stanford University, Palo Alto, California, USA
| | - Brock Martin
- Department of Pathology, Stanford University, Palo Alto, California, USA
| | - Iny Jhun
- Department of Pathology, Stanford University, Palo Alto, California, USA
| | - Megan Brown
- Department of Pediatric Liver Transplant, Lucile Packard Children's Hospital Stanford, Stanford University, Palo Alto, California, USA
| | - Gregory M Enns
- Division of Medical Genetics, Department of Pediatrics, Lucile Packard Children's Hospital Stanford, Stanford University, Palo Alto, California, USA
| | - Carlos Esquivel
- Division of Abdominal Transplantation, Department of Surgery, Stanford University, Palo Alto, California, USA
| | - Clark Bonham
- Division of Abdominal Transplantation, Department of Surgery, Stanford University, Palo Alto, California, USA
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3
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Bian WP, Pu SY, Xie SL, Wang C, Deng S, Strauss PR, Pei DS. Loss of mpv17 affected early embryonic development via mitochondria dysfunction in zebrafish. Cell Death Discov 2021; 7:250. [PMID: 34537814 PMCID: PMC8449779 DOI: 10.1038/s41420-021-00630-w] [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: 02/16/2021] [Revised: 08/06/2021] [Accepted: 08/26/2021] [Indexed: 11/09/2022] Open
Abstract
MVP17 encodes a mitochondrial inner-membrane protein, and mutation of human MVP17 can cause mitochondria DNA depletion syndrome (MDDS). However, the underlying function of mpv17 is still elusive. Here, we developed a new mutant with mpv17 knockout by using the CRISPR/Cas9 system. The mpv17-/- zebrafish showed developmental defects in muscles, liver, and energy supply. The mpv17-/- larvae hardly survived beyond a month, and they showed abnormal growth during the development stage. Abnormal swimming ability was also found in the mpv17-/- zebrafish. The transmission electron microscope (TEM) observation indicated that the mpv17-/- zebrafish underwent severe mitochondria dysfunction and the disorder of mitochondrial cristae. As an energy producer, the defects of mitochondria significantly reduced ATP content in mpv17-/- zebrafish, compared to wild-type zebrafish. We hypothesized that the disorder of mitochondria cristae was contributed to the dysfunction of muscle and liver in the mpv17-/- zebrafish. Moreover, the content of major energy depot triglycerides (TAG) was decreased dramatically. Interestingly, after rescued with normal exogenous mitochondria by microinjection, the genes involved in the TAG metabolism pathway were recovered to a normal level. Taken together, this is the first report of developmental defects in muscles, liver, and energy supply via mitochondria dysfunction, and reveals the functional mechanism of mpv17 in zebrafish.
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Affiliation(s)
- Wan-Ping Bian
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, 400714, Chongqing, China
| | - Shi-Ya Pu
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, 400714, Chongqing, China.,School of Public Health and Management, Chongqing Medical University, 400016, Chongqing, China
| | - Shao-Lin Xie
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, 400714, Chongqing, China
| | - Chao Wang
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, 400714, Chongqing, China
| | - Shun Deng
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, 400714, Chongqing, China
| | - Phyllis R Strauss
- Department of Biology, College of Science, Northeastern University, Boston, MA, 02115, USA
| | - De-Sheng Pei
- School of Public Health and Management, Chongqing Medical University, 400016, Chongqing, China.
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4
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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.
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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
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5
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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.
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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.
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6
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Intramitochondrial Src kinase links mitochondrial dysfunctions and aggressiveness of breast cancer cells. Cell Death Dis 2019; 10:940. [PMID: 31819039 PMCID: PMC6901437 DOI: 10.1038/s41419-019-2134-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 10/09/2019] [Accepted: 11/06/2019] [Indexed: 12/13/2022]
Abstract
High levels and activity of Src kinase are common among breast cancer subtypes, and several inhibitors of the kinase are currently tested in clinical trials. Alterations in mitochondrial activity is also observed among the different types of breast cancer. Src kinase is localized in several subcellular compartments, including mitochondria where it targets several proteins to modulate the activity of the organelle. Although the subcellular localization of other oncogenes modulates the potency of known treatments, nothing is known about the specific role of intra-mitochondrial Src (mtSrc) in breast cancer. The aim of this work was to determine whether mtSrc kinase has specific impact on breast cancer cells. We first observed that activity of mtSrc is higher in breast cancer cells of the triple negative subtype. Over-expression of Src specifically targeted to mitochondria reduced mtDNA levels, mitochondrial membrane potential and cellular respiration. These alterations of mitochondrial functions led to lower cellular viability, shorter cell cycle and increased invasive capacity. Proteomic analyses revealed that mtSrc targets the mitochondrial single-stranded DNA-binding protein, a regulator of mtDNA replication. Our findings suggest that mtSrc promotes aggressiveness of breast cancer cells via phosphorylation of mitochondrial single-stranded DNA-binding protein leading to reduced mtDNA levels and mitochondrial activity. This study highlights the importance of considering the subcellular localization of Src kinase in the development of potent therapy for breast cancer.
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7
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Rius R, Riley LG, Guo Y, Menezes M, Compton AG, Van Bergen NJ, Gayevskiy V, Cowley MJ, Cummings BB, Adams L, Ellaway C, Thorburn DR, Hakonarson H, Christodoulou J. Cryptic intronic NBAS variant reveals the genetic basis of recurrent liver failure in a child. Mol Genet Metab 2019; 126:77-82. [PMID: 30558828 DOI: 10.1016/j.ymgme.2018.12.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 12/05/2018] [Accepted: 12/05/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND In almost half of patients with acute liver failure the cause is unknown, making targeted treatment and decisions about liver transplantation a challenge. Monogenic disorders may contribute to a significant proportion of these undiagnosed patients, and so the incorporation of technologies such as next generation sequencing (NGS) in the clinic could aid in providing a definitive diagnosis. However, this technology may present a major challenge in interpretation of sequence variants, particularly those in non-coding regions. RESULTS In this report we describe a case of Infantile liver failure syndrome 2 (ILFS2; MIM 616483) due to novel bi-allelic variants in the NBAS gene. A missense variant NM_015909.3(NBAS):c.2617C > T, NP_056993.2(NBAS):p.(Arg873Trp) was identified by whole genome sequencing (WGS). By combining WGS and reverse transcription-polymerase chain reaction (RT-PCR) we were able to identify a novel deep intronic variant, NM_015909.3(NBAS):c.2423 + 404G > C, leading to the inclusion of a pseudo-exon. This mechanism has not been described previously in this syndrome. CONCLUSIONS This study highlights the utility of analyzing NGS data in conjunction with investigating complementary DNA (cDNA) using techniques such as RT-PCR for detection of variants that otherwise would be likely to be missed in common NGS bioinformatic analysis pipelines. Combining these approaches, particularly when the phenotype match is strong, could lead to an increase in the diagnostic yield in acute liver failure and thus aid in targeted treatment, accurate genetic counseling and restoration of reproductive confidence.
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Affiliation(s)
- Rocio Rius
- Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Lisa G Riley
- Kids Research, The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Child & Adolescent Health, Sydney Medical School, University of Sydney, Sydney, Australia
| | - Yiran Guo
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, USA
| | - Minal Menezes
- Kids Research, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Alison G Compton
- Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Nicole J Van Bergen
- Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Velimir Gayevskiy
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Mark J Cowley
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, NSW, Australia; St Vincent's Clinical School, UNSW Sydney, Sydney, Australia; Children's Cancer Institute, Kensington, Australia
| | - Beryl B Cummings
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, USA
| | - Louisa Adams
- Western Sydney Genetics Program, Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Carolyn Ellaway
- Discipline of Child & Adolescent Health, Sydney Medical School, University of Sydney, Sydney, Australia; Western Sydney Genetics Program, Children's Hospital at Westmead, Sydney, NSW, Australia
| | - David R Thorburn
- Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Hakon Hakonarson
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, USA
| | - John Christodoulou
- Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Australia.
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8
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Finsterer J. Leigh-like syndrome with mild mtDNA depletion due to the SUCLG1 variant c.626C > T. Mol Genet Metab Rep 2018; 18:7. [PMID: 30560055 PMCID: PMC6288973 DOI: 10.1016/j.ymgmr.2018.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 12/01/2018] [Indexed: 12/02/2022] Open
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9
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Kremer LS, Wortmann SB, Prokisch H. "Transcriptomics": molecular diagnosis of inborn errors of metabolism via RNA-sequencing. J Inherit Metab Dis 2018; 41:525-532. [PMID: 29372369 PMCID: PMC5959960 DOI: 10.1007/s10545-017-0133-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 12/05/2017] [Accepted: 12/28/2017] [Indexed: 02/02/2023]
Abstract
Exome wide sequencing techniques have revolutionized molecular diagnostics in patients with suspected inborn errors of metabolism or neuromuscular disorders. However, the diagnostic yield of 25-60% still leaves a large fraction of individuals without a diagnosis. This indicates a causative role for non-exonic regulatory variants not covered by whole exome sequencing. Here we review how systematic RNA-sequencing analysis (RNA-seq, "transcriptomics") lead to a molecular diagnosis in 10-35% of patients in whom whole exome sequencing failed to do so. Importantly, RNA-sequencing based discoveries cannot only guide molecular diagnosis but might also unravel therapeutic intervention points such as antisense oligonucleotide treatment for splicing defects as recently reported for spinal muscular atrophy.
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Affiliation(s)
- Laura S Kremer
- Institute of Human Genetics, Technische Universität München, Trogerstrasse 32, 81675, Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, Munich, Germany
| | - Saskia B Wortmann
- Institute of Human Genetics, Helmholtz Zentrum München, Munich, Germany
- Department of Pediatrics, Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Holger Prokisch
- Institute of Human Genetics, Technische Universität München, Trogerstrasse 32, 81675, Munich, Germany.
- Institute of Human Genetics, Helmholtz Zentrum München, Munich, Germany.
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10
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El-Hattab AW, Wang J, Dai H, Almannai M, Staufner C, Alfadhel M, Gambello MJ, Prasun P, Raza S, Lyons HJ, Afqi M, Saleh MAM, Faqeih EA, Alzaidan HI, Alshenqiti A, Flore LA, Hertecant J, Sacharow S, Barbouth DS, Murayama K, Shah AA, Lin HC, Wong LJC. MPV17-related mitochondrial DNA maintenance defect: New cases and review of clinical, biochemical, and molecular aspects. Hum Mutat 2018; 39:461-470. [PMID: 29282788 DOI: 10.1002/humu.23387] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/04/2017] [Accepted: 12/15/2017] [Indexed: 02/02/2023]
Abstract
Mitochondrial DNA (mtDNA) maintenance defects are a group of diseases caused by deficiency of proteins involved in mtDNA synthesis, mitochondrial nucleotide supply, or mitochondrial dynamics. One of the mtDNA maintenance proteins is MPV17, which is a mitochondrial inner membrane protein involved in importing deoxynucleotides into the mitochondria. In 2006, pathogenic variants in MPV17 were first reported to cause infantile-onset hepatocerebral mtDNA depletion syndrome and Navajo neurohepatopathy. To date, 75 individuals with MPV17-related mtDNA maintenance defect have been reported with 39 different MPV17 pathogenic variants. In this report, we present an additional 25 affected individuals with nine novel MPV17 pathogenic variants. We summarize the clinical features of all 100 affected individuals and review the total 48 MPV17 pathogenic variants. The vast majority of affected individuals presented with an early-onset encephalohepatopathic disease characterized by hepatic and neurological manifestations, failure to thrive, lactic acidemia, and mtDNA depletion detected mainly in liver tissue. Rarely, MPV17 deficiency can cause a late-onset neuromyopathic disease characterized by myopathy and peripheral neuropathy with no or minimal liver involvement. Approximately half of the MPV17 pathogenic variants are missense. A genotype with biallelic missense variants, in particular homozygous p.R50Q, p.P98L, and p.R41Q, can carry a relatively better prognosis.
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Affiliation(s)
- Ayman W El-Hattab
- Division of Clinical Genetics and Metabolic Disorders, Pediatric Department, Tawam Hospital, Al-Ain, United Arab Emirates
| | - Julia Wang
- Medical Scientist Training Program and Program in Developmental Biology, Baylor College of Medicine, Houston, Texas
| | - Hongzheng Dai
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Mohammed Almannai
- Section of Medical Genetics, King Fahad Medical City, Children's Specialist Hospital, Riyadh, Saudi Arabia
| | - Christian Staufner
- Division of Neuropediatrics and Metabolic Medicine, Department of General Pediatrics, University Hospital Heidelberg, Heidelberg, Germany
| | - Majid Alfadhel
- King Abdullah International Medical Research Centre, King Saud bin Abdulaziz University for Health Sciences, Division of Genetics, Department of Pediatrics, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (NGHA), Riyadh, Saudi Arabia
| | - Michael J Gambello
- Division of Medical Genetics, Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia
| | - Pankaj Prasun
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Saleem Raza
- Department of Pediatrics, St John Hospital and Medical Center and Wayne State University School of Medicine, Detroit, Michigan
| | - Hernando J Lyons
- Department of Pediatrics, St John Hospital and Medical Center and Wayne State University School of Medicine, Detroit, Michigan
| | - Manal Afqi
- Section of Medical Genetics, King Fahad Medical City, Children's Specialist Hospital, Riyadh, Saudi Arabia
| | - Mohammed A M Saleh
- Section of Medical Genetics, King Fahad Medical City, Children's Specialist Hospital, Riyadh, Saudi Arabia
| | - Eissa A Faqeih
- Section of Medical Genetics, King Fahad Medical City, Children's Specialist Hospital, Riyadh, Saudi Arabia
| | - Hamad I Alzaidan
- Department of Medical Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Abduljabbar Alshenqiti
- Department of Medical Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Leigh Anne Flore
- Division of Genetic, Genomic, and Metabolic Disorders, Children's Hospital of Michigan and Wayne State University, Detroit, Michigan
| | - Jozef Hertecant
- Division of Clinical Genetics and Metabolic Disorders, Pediatric Department, Tawam Hospital, Al-Ain, United Arab Emirates
| | - Stephanie Sacharow
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts
| | - Deborah S Barbouth
- Division of Clinical and Translational Genetics, Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami, Miller School of Medicine, Miami, Florida
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Amit A Shah
- Division of Gastroenterology, Hepatology, and Nutrition, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Henry C Lin
- Division of Gastroenterology, Hepatology, and Nutrition, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Lee-Jun C Wong
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
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11
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Pyal A, Paramasivam A, Meena AK, Bhavana VB, Thangaraj K. MPV17 hepatocerebral mitochondrial DNA depletion syndrome presenting as acute flaccid paralysis - A case report. Mitochondrion 2017; 37:41-45. [PMID: 28673863 DOI: 10.1016/j.mito.2017.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 04/29/2017] [Accepted: 06/19/2017] [Indexed: 12/01/2022]
Abstract
Mutations in human MPV17 have been reported in patients with severe mitochondrial DNA (mtDNA) depletion manifesting as early childhood onset failure to thrive, hypoglycemia, encephalopathy and progressive liver failure. We describe an 11 year old girl, born to consanguineous parents, who presented with rapidly progressive weakness of all 4 limbs with symmetrical proximal and distal weakness, gastrointestinal disease and leukoencephalopathy. Genetic analysis of the patient revealed a homozygous pathogenic mutation c.121C>T (p.R41W) in the MPV17 gene. Further, screening for this mutation in the parents revealed the presence of heterozygous mutation in both the parents, suggesting the recessive nature of the disease.
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Affiliation(s)
- Anjan Pyal
- Department of Neurology, Nizam's Institute of Medical Sciences, Hyderabad, India
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12
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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.
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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
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13
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Löllgen S, Weiher H. The role of the Mpv17 protein mutations of which cause mitochondrial DNA depletion syndrome (MDDS): lessons from homologs in different species. Biol Chem 2015; 396:13-25. [PMID: 25205723 DOI: 10.1515/hsz-2014-0198] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 06/27/2014] [Indexed: 01/30/2023]
Abstract
Mitochondrial DNA depletion syndromes (MDDS) are severe pediatric diseases with diverse clinical manifestations. Gene mutations that underlie MDDS have been associated with alterations in the mitochondrial DNA (mtDNA) replication machinery or in mitochondrial deoxyribonucleoside triphosphate pools. However, the nuclear gene MPV17, whose mutated forms are associated with hepatocerebral MDDS in humans, plays a so-far unknown role in mtDNA maintenance. A high degree of conservation has been determined between MPV17 and its mouse (Mpv17), zebrafish (tra) and yeast (SYM1) homologs, respectively, whereby mutants in these cause very different phenotypes. While dysfunction in this gene in humans causes fatal liver disease, kidney pathology is induced in mice. Moreover, in zebrafish inactivation of the Mpv17 homolog was detected as a viable dyscolouration mutant. Knock out of the yeast ortholog results in a temperature-sensitive metabolic growth phenotype. Detailed analyses on common denominators between these different phenotypes strengthen the hypothesis that the Mpv17 protein forms a channel in the inner mitochondrial membrane, allowing small molecules - in vertebrates probably nucleotides, and in yeast probably intermediates of the tricarboxylic acid cycle - to pass. Moreover, a function modifying the pathologic manifestations of MPV17-related disease in mice has been identified. This signaling pathway remarkably involves the non-mitochondrial catalytic subunit of DNA-dependent protein kinase (PRKDC), important in double-strand break repair resistance against reactive oxygen-induced genotoxic stress.
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14
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Al Sarkhy A, Al-Sunaid A, Abdullah A, AlFadhel M, Eiyad W. A novel MPV17 gene mutation in a Saudi infant causing fatal progressive liver failure. Ann Saudi Med 2014; 34:175-8. [PMID: 24894789 PMCID: PMC6074855 DOI: 10.5144/0256-4947.2014.175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We describe in this report the clinical, biochemical, and molecular features of a Saudi infant with hepatocerebral MDS secondary to a novel homozygous mutation in the MPV17 gene. An automated sequencing of the nuclear MPV17 gene was performed. The coding region (7 exons) of the MPV17 gene was amplified using an M13-tagged intronic primer and screened by direct sequencing of the PCR-amplified products (GenBank Association Number NM_002437.4). The sequencing of the entire coding region and intron-exon boundaries of MPV17 gene revealed a single homozygous variant, -c.278A > C(p.Q93P), which predicts the substitution of a highly conserved amino acid. This particular sequence variant has not been previously reported as a single-nucleotide polymorphism (SNP) or pathogenic mutation. Diagnostic workup for neonatal liver disorders should include mutation screening for known genes. The new advances in molecular genetics can help clinicians establish the diagnosis in a timely fashion, which may prevent a child from undergoing invasive and expensive investigations.
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Affiliation(s)
- Ahmed Al Sarkhy
- Gastroenterology Division, Pediatric Medicine, King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia
| | - Areej Al-Sunaid
- Gastroenterology Division, Department of Pediatrics, King Abdulaziz Medical City, Riyadh, Saudi Arabia
| | - Ahmad Abdullah
- Gastroenterology Division, Department of Pediatrics, King Abdulaziz Medical City, Riyadh, Saudi Arabia
| | - Majid AlFadhel
- Gastroenterology Division, Department of Pediatrics, King Abdulaziz Medical City, Riyadh, Saudi Arabia
| | - Wafa Eiyad
- Genetic division, Department of Pediatrics, King Saud Bin AbdulAziz University for Health Sciences, King AbdulAziz Medical City, Riyadh, Saudi Arabia
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15
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Bottani E, Giordano C, Civiletto G, Di Meo I, Auricchio A, Ciusani E, Marchet S, Lamperti C, d'Amati G, Viscomi C, Zeviani M. AAV-mediated liver-specific MPV17 expression restores mtDNA levels and prevents diet-induced liver failure. Mol Ther 2014; 22:10-7. [PMID: 24247928 PMCID: PMC3880585 DOI: 10.1038/mt.2013.230] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 08/21/2013] [Indexed: 12/23/2022] Open
Abstract
Mutations in human MPV17 cause a hepatocerebral form of mitochondrial DNA depletion syndrome (MDS) hallmarked by early-onset liver failure, leading to premature death. Liver transplantation and frequent feeding using slow-release carbohydrates are the only available therapies, although surviving patients eventually develop slowly progressive peripheral and central neuropathy. The physiological role of Mpv17, including its functional link to mitochondrial DNA (mtDNA) maintenance, is still unclear. We show here that Mpv17 is part of a high molecular weight complex of unknown composition, which is essential for mtDNA maintenance in critical tissues, i.e. liver, of a Mpv17 knockout mouse model. On a standard diet, Mpv17-/- mouse shows hardly any symptom of liver dysfunction, but a ketogenic diet (KD) leads these animals to liver cirrhosis and failure. However, when expression of human MPV17 is carried out by adeno-associated virus (AAV)-mediated gene replacement, the Mpv17 knockout mice are able to reconstitute the Mpv17-containing supramolecular complex, restore liver mtDNA copy number and oxidative phosphorylation (OXPHOS) proficiency, and prevent liver failure induced by the KD. These results open new therapeutic perspectives for the treatment of MPV17-related liver-specific MDS.
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Affiliation(s)
- Emanuela Bottani
- Unit of Molecular Neurogenetics, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy
| | - Carla Giordano
- Department of Radiological, Oncological, and Pathological Sciences, Sapienza University, Roma, Italy
| | - Gabriele Civiletto
- Unit of Molecular Neurogenetics, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy
| | - Ivano Di Meo
- Unit of Molecular Neurogenetics, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy
| | - Alberto Auricchio
- Department of Pediatrics, Division of Medical Genetics, Telethon Institute of Genetics and Medicine, “Federico II” University, Naples, Italy
| | - Emilio Ciusani
- Laboratory of Clinical Pathology and Medical Genetics, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy
| | - Silvia Marchet
- Unit of Molecular Neurogenetics, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy
| | - Costanza Lamperti
- Unit of Molecular Neurogenetics, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy
| | - Giulia d'Amati
- Department of Radiological, Oncological, and Pathological Sciences, Sapienza University, Roma, Italy
| | - Carlo Viscomi
- Unit of Molecular Neurogenetics, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy
| | - Massimo Zeviani
- Unit of Molecular Neurogenetics, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy
- MRC-Mitochondrial Biology Unit, Cambridge, UK
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16
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Iida R, Ueki M, Fujihara J, Takeshita H, Kimura-Kataoka K, Yasuda T. Three Nonsynonymous Single Nucleotide Polymorphisms in the RhitH Gene Cause Reduction of the Repression Activity That Leads to Upregulation of M-LPH, a Participant in Mitochondrial Function. Biores Open Access 2013; 2:440-7. [PMID: 24380054 PMCID: PMC3869441 DOI: 10.1089/biores.2013.0042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Human Mpv17-like protein (M-LPH) has been suggested to play a role in mitochondrial function. In this study, we identified a RhitH (human regulator of heat-induced transcription) binding site in intron 1 of the M-LPH gene. Tissue distribution analysis showed that M-LPH was specifically distributed in tissues with high mitochondrial metabolism. Functional and genetic analyses of nonsynonymous single nucleotide polymorphisms (SNPs) in the RhitH gene revealed that p.Cys461Ser, p.Thr465Ala, and p.Leu495Gln, corresponding to substitutions in the zinc fingers, cause reductions in the repression activity that lead to upregulation of M-LPH expression. The analyses also showed that the minor allele frequencies of these SNPs are extremely low in worldwide populations.
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Affiliation(s)
- Reiko Iida
- Division of Life Science, Faculty of Medical Sciences, University of Fukui , Fukui, Japan . ; Research and Education Program for Life Science, Faculty of Medical Sciences, University of Fukui , Fukui, Japan
| | - Misuzu Ueki
- Division of Medical Genetics & Biochemistry, Faculty of Medical Sciences, University of Fukui , Fukui, Japan
| | - Junko Fujihara
- Department of Legal Medicine, Center for Integrated Research in Science, Shimane University School of Medicine , Izumo, Japan
| | - Haruo Takeshita
- Department of Legal Medicine, Center for Integrated Research in Science, Shimane University School of Medicine , Izumo, Japan
| | - Kaori Kimura-Kataoka
- Department of Legal Medicine, Center for Integrated Research in Science, Shimane University School of Medicine , Izumo, Japan
| | - Toshihiro Yasuda
- Research and Education Program for Life Science, Faculty of Medical Sciences, University of Fukui , Fukui, Japan . ; Division of Medical Genetics & Biochemistry, Faculty of Medical Sciences, University of Fukui , Fukui, Japan
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17
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Abstract
To highlight differences between early-onset and adult mitochondrial depletion syndromes (MDS) concerning etiology and genetic background, pathogenesis, phenotype, clinical presentation and their outcome. MDSs most frequently occur in neonates, infants, or juveniles and more rarely in adolescents or adults. Mutated genes phenotypically presenting with adult-onset MDS include POLG1, TK2, TyMP, RRM2B, or PEO1/twinkle. Adult MDS manifest similarly to early-onset MDS, as myopathy, encephalo-myopathy, hepato-cerebral syndrome, or with chronic progressive external ophthalmoplegia (CPEO), fatigue, or only minimal muscular manifestations. Diagnostic work-up or treatment is not at variance from early-onset cases. Histological examination of muscle may be normal but biochemical investigations may reveal multiple respiratory chain defects. The outcome appears to be more favorable in adult than in early-onset forms. Mitochondrial depletion syndromes is not only a condition of neonates, infants, or juveniles but rarely also occurs in adults, presenting with minimal manifestations or manifestations like in the early-onset forms. Outcome of adult-onset MDS appears more favorable than early-onset MDS.
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18
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Rahman S. Gastrointestinal and hepatic manifestations of mitochondrial disorders. J Inherit Metab Dis 2013; 36:659-73. [PMID: 23674168 DOI: 10.1007/s10545-013-9614-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 04/13/2013] [Accepted: 04/16/2013] [Indexed: 12/23/2022]
Abstract
Inherited defects of oxidative phosphorylation lead to heterogeneous, often multisystem, mitochondrial diseases. This review highlights those mitochondrial syndromes with prominent gastrointestinal and hepatic symptoms, categorised according to underlying disease mechanism. Mitochondrial encephalopathies with major gastrointestinal involvement include mitochondrial neurogastrointestinal encephalopathy and ethylmalonic encephalopathy, which are each associated with highly specific clinical and metabolic profiles. Mitochondrial hepatopathies are most frequently caused by defects of mitochondrial DNA maintenance and expression. Although mitochondrial disorders are notorious for extreme clinical, biochemical and genetic heterogeneity, there are some pathognomonic clinical and metabolic clues that suggest a specific diagnosis, and these are highlighted. An approach to diagnosis of these complex disorders is presented, together with a genetic classification, including mitochondrial DNA disorders and nuclear-encoded defects of mitochondrial DNA maintenance and translation, OXPHOS complex assembly and mitochondrial membrane lipids. Finally, supportive and experimental therapeutic options for these currently incurable diseases are reviewed, including liver transplantation, allogeneic haematopoietic stem cell transplantation and gene therapy.
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Affiliation(s)
- Shamima Rahman
- Mitochondrial Research Group, Clinical and Molecular Genetics Unit, UCL Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK.
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19
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Clinical, biochemical, cellular and molecular characterization of mitochondrial DNA depletion syndrome due to novel mutations in the MPV17 gene. Eur J Hum Genet 2013; 22:184-91. [PMID: 23714749 PMCID: PMC3895632 DOI: 10.1038/ejhg.2013.112] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 04/15/2013] [Accepted: 04/17/2013] [Indexed: 11/29/2022] Open
Abstract
Mitochondrial DNA (mtDNA) depletion syndromes (MDS) are severe autosomal recessive disorders associated with decreased mtDNA copy number in clinically affected tissues. The hepatocerebral form (mtDNA depletion in liver and brain) has been associated with mutations in the POLG, PEO1 (Twinkle), DGUOK and MPV17 genes, the latter encoding a mitochondrial inner membrane protein of unknown function. The aims of this study were to clarify further the clinical, biochemical, cellular and molecular genetic features associated with MDS due to MPV17 gene mutations. We identified 12 pathogenic mutations in the MPV17 gene, of which 11 are novel, in 17 patients from 12 families. All patients manifested liver disease. Poor feeding, hypoglycaemia, raised serum lactate, hypotonia and faltering growth were common presenting features. mtDNA depletion in liver was demonstrated in all seven cases where liver tissue was available. Mosaic mtDNA depletion was found in primary fibroblasts by PicoGreen staining. These results confirm that MPV17 mutations are an important cause of hepatocerebral mtDNA depletion syndrome, and provide the first demonstration of mosaic mtDNA depletion in human MPV17 mutant fibroblast cultures. We found that a severe clinical phenotype was associated with profound tissue-specific mtDNA depletion in liver, and, in some cases, mosaic mtDNA depletion in fibroblasts.
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20
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El-Hattab AW, Scaglia F. Mitochondrial DNA depletion syndromes: review and updates of genetic basis, manifestations, and therapeutic options. Neurotherapeutics 2013; 10:186-98. [PMID: 23385875 PMCID: PMC3625391 DOI: 10.1007/s13311-013-0177-6] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Mitochondrial DNA (mtDNA) depletion syndromes (MDS) are a genetically and clinically heterogeneous group of autosomal recessive disorders that are characterized by a severe reduction in mtDNA content leading to impaired energy production in affected tissues and organs. MDS are due to defects in mtDNA maintenance caused by mutations in nuclear genes that function in either mitochondrial nucleotide synthesis (TK2, SUCLA2, SUCLG1, RRM2B, DGUOK, and TYMP) or mtDNA replication (POLG and C10orf2). MDS are phenotypically heterogeneous and usually classified as myopathic, encephalomyopathic, hepatocerebral or neurogastrointestinal. Myopathic MDS, caused by mutations in TK2, usually present before the age of 2 years with hypotonia and muscle weakness. Encephalomyopathic MDS, caused by mutations in SUCLA2, SUCLG1, or RRM2B, typically present during infancy with hypotonia and pronounced neurological features. Hepatocerebral MDS, caused by mutations in DGUOK, MPV17, POLG, or C10orf2, commonly have an early-onset liver dysfunction and neurological involvement. Finally, TYMP mutations have been associated with mitochondrial neurogastrointestinal encephalopathy (MNGIE) disease that typically presents before the age of 20 years with progressive gastrointestinal dysmotility and peripheral neuropathy. Overall, MDS are severe disorders with poor prognosis in the majority of affected individuals. No efficacious therapy is available for any of these disorders. Affected individuals should have a comprehensive evaluation to assess the degree of involvement of different systems. Treatment is directed mainly toward providing symptomatic management. Nutritional modulation and cofactor supplementation may be beneficial. Liver transplantation remains controversial. Finally, stem cell transplantation in MNGIE disease shows promising results.
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Affiliation(s)
- Ayman W. El-Hattab
- />Division of Medical Genetics, Department of Pediatrics, The Children’s Hospital, King Fahad Medical City and Faculty of Medicine, King Saud bin Abdulaziz University for Health Science, Riyadh, Kingdom of Saudi Arabia
| | - Fernando Scaglia
- />Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM225, Houston, TX 77030 USA
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21
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Navarro-Sastre A, Tort F, Garcia-Villoria J, Pons MR, Nascimento A, Colomer J, Campistol J, Yoldi ME, López-Gallardo E, Montoya J, Unceta M, Martinez MJ, Briones P, Ribes A. Mitochondrial DNA depletion syndrome: new descriptions and the use of citrate synthase as a helpful tool to better characterise the patients. Mol Genet Metab 2012; 107:409-15. [PMID: 22980518 DOI: 10.1016/j.ymgme.2012.08.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 08/25/2012] [Indexed: 01/21/2023]
Abstract
Mitochondrial DNA depletion syndrome (MDS) is a clinically heterogeneous group of mitochondrial disorders characterised by a quantitative reduction of the mitochondrial DNA copy number. Three main clinical forms of MDS: myopathic, encephalomyopathic and hepatocerebral have been defined, although patients may present with other MDS associated clinical symptoms and signs that cover a wide spectrum of onset age and disease. We studied 52 paediatric individuals suspected to have MDS. These patients have been divided into three different groups, and the appropriate MDS genes have been screened according to their clinical and biochemical phenotypes. Mutational study of DGUOK, MPV17, SUCLA2, SUCLG1 and POLG allowed us to identify 3 novel mutations (c.1048G>A and c.1049G>T in SUCLA2 and c.531+4A>T in SUCLG1) and 7 already known mutations in 10 patients (8 families). Seventeen patients presented with mtDNA depletion in liver or muscle, but the cause of mtDNA depletion still remains unknown in 8 of them. When possible, we quantified mtDNA/nDNA and CS activity in the same tissue sample, providing an additional tool for the study of MDS. The ratio (mtDNA/nDNA)/CS has shed some light in the discrepant results between the mtDNA copy number and the enzymatic respiratory chain activities of some cases.
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Affiliation(s)
- Aleix Navarro-Sastre
- Division of Inborn Errors of Metabolism, Department of Biochemistry and Molecular Genetics, Hospital Clinic, Instituto de Investigación Biomédica Pi Sunyer, 08028 Barcelona, Spain
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22
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Blakely EL, Butterworth A, Hadden RD, Bodi I, He L, McFarland R, Taylor RW. MPV17 mutation causes neuropathy and leukoencephalopathy with multiple mtDNA deletions in muscle. Neuromuscul Disord 2012; 22:587-91. [PMID: 22508010 PMCID: PMC3387382 DOI: 10.1016/j.nmd.2012.03.006] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 03/15/2012] [Accepted: 03/20/2012] [Indexed: 11/18/2022]
Abstract
Disorders of mitochondrial DNA (mtDNA) maintenance are clinically and genetically heterogeneous, embracing recessive mtDNA depletion syndromes affecting children and adult-onset multiple mtDNA deletion disorders. Here we show that mutation of MPV17 – a gene implicated in severe, infantile hepatocerebral mtDNA depletion disorders characterised by a loss of mtDNA copies – can also cause clonally-expanded mtDNA deletion and focal cytochrome c oxidase (COX) deficiency in skeletal muscle associated with an adult presentation of neuropathy and leukoencephalopathy. The mpv17 protein is therefore intimately involved in both the mtDNA replication and repair processes and associated with both quantitative and qualitative mtDNA abnormalities.
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Affiliation(s)
- Emma L. Blakely
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Anna Butterworth
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Robert D.M. Hadden
- Department of Neurology, King’s College Hospital, Denmark Hill, London SE5 9RS, UK
| | - Istvan Bodi
- Clinical Neuropathology, Academic Neuroscience Building, King’s College Hospital, Denmark Hill, London SE5 9RS, UK
| | - Langping He
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Robert McFarland
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Robert W. Taylor
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Corresponding author. Tel.: +44 191 2223685; fax: +44 191 2824373.
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23
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Merkle AN, Nascene DR, McKinney AM. MR imaging findings in the reticular formation in siblings with MPV17-related mitochondrial depletion syndrome. AJNR Am J Neuroradiol 2012; 33:E34-5. [PMID: 21511859 DOI: 10.3174/ajnr.a2455] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Hepatocerebral MPV17-MDS is quite rare (<30 confirmed cases), with limited findings described on MR imaging. We report 2 siblings having abnormalities within the reticular formation of the lower brain stem and within the reticulospinal tracts at the cervicocranial junction on T2WI. The presence of these MR imaging findings (relative to previous reports) raises the possibility that they represent subtle but characteristic findings corresponding to clinically observed abnormalities of tone encountered with this recently described disorder.
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Affiliation(s)
- A N Merkle
- Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Missing mitochondrial Mpv17 gene function induces tissue-specific cell-death pathway in the degenerating inner ear. Cell Tissue Res 2012; 347:343-56. [PMID: 22322422 DOI: 10.1007/s00441-012-1326-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 01/11/2012] [Indexed: 12/11/2022]
Abstract
The Mpv17 gene encodes a mitochondrial inner-membrane protein that has been implicated in the metabolism of reactive oxygen species. The loss of function in Mpv17-/- mice leads to early sensorineural deafness associated with severe inner ear degeneration and late onset of kidney failure. The present study demonstrates that the onset of the degeneration of the cochlear neuroepithelia is related to the onset of auditory function and appears to be first restricted to the outer hair cells (OHC), which subsequently undergo rapid degeneration. At the age of 18 days, the OHC lateral membrane degenerates and extensive vacuolization of the cytoplasm is followed by lysis of the OHCs. Such degenerative processes have been seen for the first time in relation to auditory dysfunction. The structural degeneration pattern of the OHC appears to be similar to the described paraptotic processes (an alternative form of programmed cell death) discussed in the literature as a cause of cytoplasmic neurodegeneration. In contrast, the melanocyte-like intermediate cells that are of neural crest origin and that are located in the stria vascularis, undergo apoptosis, as documented ultrastructurally. A lack of Mpv17 protein function in mitochondria thus seems to initiate tissue-specific cell-death pathways resulting in the pathology seen during the degeneration process.
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Mudd SH, Wagner C, Luka Z, Stabler SP, Allen RH, Schroer R, Wood T, Wang J, Wong LJ. Two patients with hepatic mtDNA depletion syndromes and marked elevations of S-adenosylmethionine and methionine. Mol Genet Metab 2012; 105:228-36. [PMID: 22137549 PMCID: PMC3264801 DOI: 10.1016/j.ymgme.2011.11.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 11/07/2011] [Accepted: 11/07/2011] [Indexed: 02/07/2023]
Abstract
This paper reports studies of two patients proven by a variety of studies to have mitochondrial depletion syndromes due to mutations in either their MPV17 or DGUOK genes. Each was initially investigated metabolically because of plasma methionine concentrations as high as 15-21-fold above the upper limit of the reference range, then found also to have plasma levels of S-adenosylmethionine (AdoMet) 4.4-8.6-fold above the upper limit of the reference range. Assays of S-adenosylhomocysteine, total homocysteine, cystathionine, sarcosine, and other relevant metabolites and studies of their gene encoding glycine N-methyltransferase produced evidence suggesting they had none of the known causes of elevated methionine with or without elevated AdoMet. Patient 1 grew slowly and intermittently, but was cognitively normal. At age 7 years he was found to have hepatocellular carcinoma, underwent a liver transplant and died of progressive liver and renal failure at age almost 9 years. Patient 2 had a clinical course typical of DGUOK deficiency and died at age 8 ½ months. Although each patient had liver abnormalities, evidence is presented that such abnormalities are very unlikely to explain their elevations of AdoMet or the extent of their hypermethioninemias. A working hypothesis is presented suggesting that with mitochondrial depletion the normal usage of AdoMet by mitochondria is impaired, AdoMet accumulates in the cytoplasm of affected cells poor in glycine N-methyltransferase activity, the accumulated AdoMet causes methionine to accumulate by inhibiting activity of methionine adenosyltransferase II, and that both AdoMet and methionine consequently leak abnormally into the plasma.
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Affiliation(s)
- S Harvey Mudd
- Laboratory of Molecular Biology, National Institute of Mental Health, Bethesda, MD 20892, USA.
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AlSaman A, Tomoum H, Invernizzi F, Zeviani M. Hepatocerebral form of mitochondrial DNA depletion syndrome due to mutation in MPV17 gene. Saudi J Gastroenterol 2012; 18:285-9. [PMID: 22824774 PMCID: PMC3409892 DOI: 10.4103/1319-3767.98439] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Mitochondrial DNA depletion syndromes (MDSs) are autosomal recessive diseases characterized by a severe decrease in mitochondrial DNA content leading to dysfunction of the affected organ. Autosomal recessive mutations in MPV17 have been identified in the hepatocerebral form of MDS. We describe the clinical features, biochemical and molecular results of a Saudi infant with a new mutation of MPV17 and compared the features to those of previously reported cases. We stress the importance of such rare cases particularly in countries with high consanguineous marriage rate.
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Affiliation(s)
- Abdulaziz AlSaman
- Department of Pediatric Neurology, King Fahad Medical City, Riyadh, Saudi Arabia.
| | - Hoda Tomoum
- Department of Pediatric Neurology, King Fahad Medical City, Riyadh, Saudi Arabia,,Department of Pediatrics, Ain Shams University, Cairo, Egypt
| | - Federica Invernizzi
- Unit of Molecular Neurogenetics, Fondazione Istituto Neurologico “Carlo Besta”, Milano, Italy
| | - Massimo Zeviani
- Unit of Molecular Neurogenetics, Fondazione Istituto Neurologico “Carlo Besta”, Milano, Italy
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Clinical and cellular consequences of the mutation m.12300G>A in the mitochondrial tRNA(Leu(CUN)) gene. Mitochondrion 2011; 12:288-93. [PMID: 22094595 DOI: 10.1016/j.mito.2011.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 10/27/2011] [Accepted: 10/28/2011] [Indexed: 11/22/2022]
Abstract
We report, for the first time, a patient with an overlap MERRF-NARP syndrome who carries the mutation m.12300G>A in the mitochondrial tRNA(Leu(CUN)) gene. The mutation was heteroplamic and more abundant in her muscle and fibroblast than in blood from her oligosymptomatic mother. Single muscle fiber analysis revealed that the proportion of mutant mtDNA in ragged red fibers was higher than that in normal fibers. Combined defects of mitochondrial respiratory chain complexes were detected in muscle, fibroblasts and transmitochondrial hybrid cells. Significant reduction of total ATP and mitochondrial membrane potential and an increased production of reactive oxygen species were observed.
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Kuramoto T, Kuwamura M, Tokuda S, Izawa T, Nakane Y, Kitada K, Akao M, Guénet JL, Serikawa T. A mutation in the gene encoding mitochondrial Mg²+ channel MRS2 results in demyelination in the rat. PLoS Genet 2011; 7:e1001262. [PMID: 21253565 PMCID: PMC3017111 DOI: 10.1371/journal.pgen.1001262] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2010] [Accepted: 11/29/2010] [Indexed: 01/30/2023] Open
Abstract
The rat demyelination (dmy) mutation serves as a unique model system to investigate the maintenance of myelin, because it provokes severe myelin breakdown in the central nervous system (CNS) after normal postnatal completion of myelination. Here, we report the molecular characterization of this mutation and discuss the possible pathomechanisms underlying demyelination. By positional cloning, we found that a G-to-A transition, 177 bp downstream of exon 3 of the Mrs2 (MRS2 magnesium homeostasis factor (Saccharomyces cerevisiae)) gene, generated a novel splice acceptor site which resulted in functional inactivation of the mutant allele. Transgenic rescue with wild-type Mrs2-cDNA validated our findings. Mrs2 encodes an essential component of the major Mg2+ influx system in mitochondria of yeast as well as human cells. We showed that the dmy/dmy rats have major mitochondrial deficits with a markedly elevated lactic acid concentration in the cerebrospinal fluid, a 60% reduction in ATP, and increased numbers of mitochondria in the swollen cytoplasm of oligodendrocytes. MRS2-GFP recombinant BAC transgenic rats showed that MRS2 was dominantly expressed in neurons rather than oligodendrocytes and was ultrastructurally observed in the inner membrane of mitochondria. Our observations led to the conclusion that dmy/dmy rats suffer from a mitochondrial disease and that the maintenance of myelin has a different mechanism from its initial production. They also established that Mg2+ homeostasis in CNS mitochondria is essential for the maintenance of myelin. The myelin sheath that surrounds the axon of a neuron acts as a biological insulator. Its major function is to increase the speed at which impulses propagate along myelinated fibers in the central nervous system, as well as the peripheral nervous system. Alterations or damage affecting this structure (demyelination) result in the disruption of signals between the brain and other parts of the body. In the rat, mutations producing demyelination have been frequently identified and characterized and have contributed to a better understanding of the genetics of myelin development, physiology, and pathology. This paper reports the molecular characterization of a recessive allele responsible for the progressive disruption of myelin that was initially observed in mutant rats, previously named demyelination (dmy). This mutation generates an additional splicing acceptor site in an intron of the mitochondrial Mg2+ transporter gene (Mrs2), resulting in the insertion of a 83-bp genomic DNA segment into the Mrs2 transcript and complete functional inactivation of the mutant allele. We firstly defined the biological function of MRS2 in mammals and demonstrated the crucial and unexpected role of MRS2 in myelin physiology. Our findings might be helpful in the development of new therapeutic strategies for demyelinating syndromes.
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Affiliation(s)
- Takashi Kuramoto
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
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Navarro-Sastre A, García-Silva MT, Martín-Hernández E, Lluch M, Briones P, Ribes A. Functional splicing assay supporting that c.70 + 5G > A mutation in the MPV17 gene is disease causing. J Inherit Metab Dis 2010; 33 Suppl 3:S293-6. [PMID: 20614188 DOI: 10.1007/s10545-010-9155-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 05/27/2010] [Accepted: 06/07/2010] [Indexed: 11/25/2022]
Abstract
Mitochondrial DNA depletion syndrome (MDS) is a group of disorders characterized by a quantitative reduction of the mitochondrial DNA copy number and inherited as autosomal recessive traits. Patients affected by this group of diseases present with a wide variety of symptoms depending on the altered gene. MPV17 is one of the genes causing combined encephalopathy and liver failure and at present there is no treatment for this devastating disease. The gene codes for an inner mitochondrial membrane protein, but its function is still unknown, and therefore, the only way to offer prenatal diagnosis relies on DNA studies. Consequently, mutations have to be well characterized. We previously described a patient homozygous for a novel intronic mutation in the MPV17 gene (c.70 + 5G > A). Here we report the use of a functional splicing assay based on the use of minigenes to support that c.70 + 5G > A mutation is disease causing. We carried out three prenatal diagnoses on three consecutive pregnancies of the previously described family. After two affected fetuses, a healthy baby was born homozygous for the wild-type allele.
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Affiliation(s)
- Aleix Navarro-Sastre
- Sección de Errores Congénitos del Metabolismo, IBC, Servicio de Bioquímica y Genética Molecular and CIBER de Enfermedades Raras, Hospital Clínic, Edificio Helios III, 08028 Barcelona, Spain
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Suomalainen A, Isohanni P. Mitochondrial DNA depletion syndromes--many genes, common mechanisms. Neuromuscul Disord 2010; 20:429-37. [PMID: 20444604 DOI: 10.1016/j.nmd.2010.03.017] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Revised: 03/25/2010] [Accepted: 03/29/2010] [Indexed: 02/07/2023]
Abstract
Mitochondrial DNA depletion syndrome has become an important cause of inherited metabolic disorders, especially in children, but also in adults. The manifestations vary from tissue-specific mtDNA depletion to wide-spread multisystemic disorders. Nine genes are known to underlie this group of disorders, and many disease genes are still unidentified. However, the disease mechanisms seem to be intimately associated with mtDNA replication and nucleotide pool regulation. We review here the current knowledge on the clinical and molecular genetic features of mitochondrial DNA depletion syndrome.
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Affiliation(s)
- Anu Suomalainen
- Research Program of Molecular Neurology, Biomedicum-Helsinki, University of Helsinki, Helsinki, Finland.
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El-Hattab AW, Li FY, Schmitt E, Zhang S, Craigen WJ, Wong LJC. MPV17-associated hepatocerebral mitochondrial DNA depletion syndrome: new patients and novel mutations. Mol Genet Metab 2010; 99:300-8. [PMID: 20074988 DOI: 10.1016/j.ymgme.2009.10.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 10/07/2009] [Accepted: 10/07/2009] [Indexed: 12/27/2022]
Abstract
Mitochondrial DNA depletion syndromes are autosomal recessive diseases characterized by a severe decrease in mitochondrial DNA content leading to dysfunction of the affected organ. They are phenotypically heterogeneous and classified as myopathic, encephalomyopathic, or hepatocerebral. The latter group has been associated with mutations in TWINKLE,POLG1, DGUOK genes and recently with mutations in the MPV17 gene. MPV17 encodes a mitochondrial inner membrane protein and plays an as yet poorly understood role in mitochondrial DNA maintenance. Mutations in the MPV17 gene have been reported in patients who came to medical attention during infancy with liver failure, hypoglycemia, failure-to-thrive and neurological symptoms. In addition, a homozygous p.R50Q mutation has been identified in patients with Navajo neurohepatopathy. To date, 13 different mutations in 21 patients have been reported. We report eight new patients with seven novel mutations, including four missense mutations (c.262A>G (p.K88E), c.280G>C (p.G94R), c.293C>T (p.P98L), and c.485C>A (p.A162D)), one in-frame deletion (c.271_273del3 (p.L91del)), one splice site substitution (c.186+2T>C), and one insertion (c.22_23insC). The p.R50Q mutation, which occurs in a CpG dinucleotide, is the most common MPV17 mutation and, to date, has only been found in the homozygous state. Clinically, patients homozygous for p.R50Q or compound heterozygous for the p.G94R and p.P98L mutations have a better prognosis, with all the other mutations associated with early death if not treated by liver transplantation. Localizing the mutations within the predicted MPV17 protein structure reveals clustering of mutations in the region of the putative protein kinase C phosphorylation site.
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Affiliation(s)
- Ayman W El-Hattab
- Department of Molecular and Human Genetics, Baylor College of Medicine, 1 Baylor plaza, Houston, TX 77030, USA
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Dallabona C, Marsano RM, Arzuffi P, Ghezzi D, Mancini P, Zeviani M, Ferrero I, Donnini C. Sym1, the yeast ortholog of the MPV17 human disease protein, is a stress-induced bioenergetic and morphogenetic mitochondrial modulator. Hum Mol Genet 2009; 19:1098-107. [DOI: 10.1093/hmg/ddp581] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Collated mutations in mitochondrial DNA (mtDNA) depletion syndrome (excluding the mitochondrial gamma polymerase, POLG1). Biochim Biophys Acta Mol Basis Dis 2009; 1792:1109-12. [DOI: 10.1016/j.bbadis.2009.08.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Accepted: 08/27/2009] [Indexed: 01/09/2023]
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Parini R, Furlan F, Notarangelo L, Spinazzola A, Uziel G, Strisciuglio P, Concolino D, Corbetta C, Nebbia G, Menni F, Rossi G, Maggioni M, Zeviani M. Glucose metabolism and diet-based prevention of liver dysfunction in MPV17 mutant patients. J Hepatol 2009; 50:215-21. [PMID: 19012992 DOI: 10.1016/j.jhep.2008.08.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2008] [Revised: 08/04/2008] [Accepted: 08/16/2008] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS To describe in detail the specific clinical and biological characteristics of three patients with MPV17 gene mutations, a rare hepatocerebral mitochondrial DNA depletion syndrome (MDS) and the positive effects of a novel dietetic treatment based on avoidance of fasting. METHODS We describe the case histories of three members of the same family with MPV17 mutations. RESULTS Two patients had a very severe and progressive liver disease: 1 died in the first year of life and the other underwent liver transplantation. The third patient, now 13 years of age, had a milder form of liver disease and developed progressive ataxia. Psychomotor involvement at onset of disease was mild or absent. No patient had severe hyperlactataemia. In vivo functional studies on two patients showed no hyperlactataemia even after intravenous and oral glucose loading, regular fasting hypoglycemia 3-4h after meals and no response to glucagon. Liver function tests improved when patients received continuous iv glucose infusion or were regularly fed every 3h. CONCLUSIONS These clinical and biochemical features allow us to differentiate patients with MPV17 mutations from other liver MDS and suggest that regular glucose intake at short intervals may be beneficial in slowing the progression of the disease.
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Affiliation(s)
- Rossella Parini
- Rare Metabolic Diseases Unit Fondazione Mariani, Pediatric Unit, San Gerardo Hospital, Via Pergolesi 33, 20052 Monza, Italy.
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Viscomi C, Spinazzola A, Maggioni M, Fernandez-Vizarra E, Massa V, Pagano C, Vettor R, Mora M, Zeviani M. Early-onset liver mtDNA depletion and late-onset proteinuric nephropathy in Mpv17 knockout mice. Hum Mol Genet 2008; 18:12-26. [PMID: 18818194 PMCID: PMC2644642 DOI: 10.1093/hmg/ddn309] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In humans, MPV17 mutations are responsible for severe mitochondrial depletion syndrome, mainly affecting the liver and the nervous system. To gain insight into physiopathology of MPV17-related disease, we investigated an available Mpv17 knockout animal model. We found severe mtDNA depletion in liver and, albeit to a lesser extent, in skeletal muscle, whereas hardly any depletion was detected in brain and kidney, up to 1 year after birth. Mouse embryonic fibroblasts did show mtDNA depletion, but only after several culturing passages, or in a serumless culturing medium. In spite of severe mtDNA depletion, only moderate decrease in respiratory chain enzymatic activities, and mild cytoarchitectural alterations, were observed in the Mpv17−/− livers, but neither cirrhosis nor failure ever occurred in this organ at any age. The mtDNA transcription rate was markedly increased in liver, which could contribute to compensate the severe mtDNA depletion. This phenomenon was associated with specific downregulation of Mterf1, a negative modulator of mtDNA transcription. The most relevant clinical features involved skin, inner ear and kidney. The coat of the Mpv17−/− mice turned gray early in adulthood, and 18-month or older mice developed focal segmental glomerulosclerosis (FSGS) with massive proteinuria. Concomitant degeneration of cochlear sensory epithelia was reported as well. These symptoms were associated with significantly shorter lifespan. Coincidental with the onset of FSGS, there was hardly any mtDNA left in the glomerular tufts. These results demonstrate that Mpv17 controls mtDNA copy number by a highly tissue- and possibly cytotype-specific mechanism.
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Affiliation(s)
- Carlo Viscomi
- Unit of Molecular Neurogenetics - Pierfranco and Luisa Mariani Center for the Study of Mitochondrial Disorders in Children, IRCCS Foundation Neurological Institute C. Besta, Milan, Italy
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