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Dellatte J, Lievens I, Wang FC. Could some mutations of the KIF5A gene be responsible for a dominant CMT2 phenotype? (Case report). Acta Neurol Belg 2023; 123:2435-2438. [PMID: 37084037 DOI: 10.1007/s13760-023-02248-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 03/20/2023] [Indexed: 04/22/2023]
Affiliation(s)
- Julien Dellatte
- Department of Neurophysiology, CHU Liège, Sart-Tilman B35, 4000, Liege, Belgium.
| | - Isabelle Lievens
- Department of Neurology, CHU Liège, Sart-Tilman B35, 4000, Liege, Belgium
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2
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Higuchi Y, Takashima H. Clinical genetics of Charcot-Marie-Tooth disease. J Hum Genet 2023; 68:199-214. [PMID: 35304567 DOI: 10.1038/s10038-022-01031-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/02/2022] [Accepted: 03/06/2022] [Indexed: 02/08/2023]
Abstract
Recent research in the field of inherited peripheral neuropathies (IPNs) such as Charcot-Marie-Tooth (CMT) disease has helped identify the causative genes provided better understanding of the pathogenesis, and unraveled potential novel therapeutic targets. Several reports have described the epidemiology, clinical characteristics, molecular pathogenesis, and novel causative genes for CMT/IPNs in Japan. Based on the functions of the causative genes identified so far, the following molecular and cellular mechanisms are believed to be involved in the causation of CMTs/IPNs: myelin assembly, cytoskeletal structure, myelin-specific transcription factor, nuclear related, endosomal sorting and cell signaling, proteasome and protein aggregation, mitochondria-related, motor proteins and axonal transport, tRNA synthetases and RNA metabolism, and ion channel-related mechanisms. In this article, we review the epidemiology, genetic diagnosis, and clinicogenetic characteristics of CMT in Japan. In addition, we discuss the newly identified novel causative genes for CMT/IPNs in Japan, namely MME and COA7. Identification of the new causes of CMT will facilitate in-depth characterization of the underlying molecular mechanisms of CMT, leading to the establishment of therapeutic approaches such as drug development and gene therapy.
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Affiliation(s)
- Yujiro Higuchi
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Hiroshi Takashima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
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3
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Zanfardino P, Longo G, Amati A, Morani F, Picardi E, Girolamo F, Pafundi M, Cox SN, Manzari C, Tullo A, Doccini S, Santorelli FM, Petruzzella V. Mitofusin 2 mutation drives cell proliferation in Charcot-Marie-Tooth 2A fibroblasts. Hum Mol Genet 2023; 32:333-350. [PMID: 35994048 DOI: 10.1093/hmg/ddac201] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 08/12/2022] [Accepted: 08/16/2022] [Indexed: 01/20/2023] Open
Abstract
Dominant mutations in ubiquitously expressed mitofusin 2 gene (MFN2) cause Charcot-Marie-Tooth type 2A (CMT2A; OMIM 609260), an inherited sensory-motor neuropathy that affects peripheral nerve axons. Mitofusin 2 protein has been found to take part in mitochondrial fusion, mitochondria-endoplasmic reticulum tethering, mitochondrial trafficking along axons, mitochondrial quality control and various types of cancer, in which MFN2 has been indicated as a tumor suppressor gene. Discordant data on the mitochondrial altered phenotypes in patient-derived fibroblasts harboring MFN2 mutations and in animal models have been reported. We addressed some of these issues by focusing on mitochondria behavior during autophagy and mitophagy in fibroblasts derived from a CMT2AMFN2 patient with an MFN2650G > T/C217F mutation in the GTPase domain. This study investigated mitochondrial dynamics, respiratory capacity and autophagy/mitophagy, to tackle the multifaceted MFN2 contribution to CMT2A pathogenesis. We found that MFN2 mutated fibroblasts showed impairment of mitochondrial morphology, bioenergetics capacity, and impairment of the early stages of autophagy, but not mitophagy. Unexpectedly, transcriptomic analysis of mutated fibroblasts highlighted marked differentially expressed pathways related to cell population proliferation and extracellular matrix organization. We consistently found the activation of mTORC2/AKT signaling and accelerated proliferation in the CMT2AMFN2 fibroblasts. In conclusion, our evidence indicates that MFN2 mutation can positively drive cell proliferation in CMT2AMFN2 fibroblasts.
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Affiliation(s)
- Paola Zanfardino
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Giovanna Longo
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Alessandro Amati
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Federica Morani
- Department of Biology, University of Pisa, 56126 Pisa, Italy
| | - Ernesto Picardi
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70125 Bari, Italy.,Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, 70125 Bari, Italy
| | - Francesco Girolamo
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Mariella Pafundi
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Sharon N Cox
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70125 Bari, Italy
| | - Caterina Manzari
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70125 Bari, Italy
| | - Apollonia Tullo
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, 70125 Bari, Italy
| | - Stefano Doccini
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, 56128 Pisa, Italy
| | - Filippo M Santorelli
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, 56128 Pisa, Italy
| | - Vittoria Petruzzella
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
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4
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Evaluation of optical coherence tomography findings and visual evoked potentials in Charcot-Marie-Tooth disease. Int Ophthalmol 2023; 43:333-341. [PMID: 35953577 DOI: 10.1007/s10792-022-02452-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 07/31/2022] [Indexed: 02/07/2023]
Abstract
PURPOSE To evaluate the spectral-domain optical coherence tomography (SD-OCT) findings and pattern visual evoked potential (VEP) in Charcot-Marie-Tooth (CMT) disease. METHODS Seventeen patients with CMT disease and 17 control subjects were included in the study. The patients were divided into two groups according to conduction velocity and inheritance pattern as demyelinating type (CMT 1) and axonal type (CMT 2). The average retinal nerve fiber layer (RNFL) thickness, RNFL thicknesses of all quadrants, and thicknesses of the ganglion cell layer complex (GCC) were measured using SD-OCT. Pattern VEP recordings were evaluated in both groups. RESULTS The average and four quadrants of RNFL thicknesses, and superior and inferior GCC thicknesses were significantly thinner in the CMT patients compared with healthy individuals, but there were no statistically significant differences between the CMT groups. There was a significant positive correlation between age and all RNFL and GCC thicknesses in the CMT 2 group and between age and RNFL thickness of the temporal quadrant in the CMT 1 group. P100 latencies were significantly delayed in the CMT groups compared with controls, and there were no significant differences in P100 latencies between the CMT groups (p < 0.001). VEP amplitudes were in normal ranges in the CMT groups. CONCLUSION This study showed that RNFL and GCC thicknesses were significantly reduced and VEP latencies were prolonged in patients with CMT with normal clinical examinations. Our results suggest that optic nerves may be affected more frequently in patients with CMT that is detected in clinical examinations.
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5
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Kimura Y, Nishikawa A, Hashiguchi A, Etoh M, Yoshimura A, Asai K, Miyashita N, Takashima H, Sumi H, Naka T. An MFN2-related Charcot-Marie-Tooth Disease Patient with Optic Nerve Atrophy, Neurogenic Bladder Dysfunction, and Diaphragmatic Weakness. Intern Med 2022; 61:1743-1747. [PMID: 34803088 PMCID: PMC9259307 DOI: 10.2169/internalmedicine.6487-20] [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: 11/06/2022] Open
Abstract
Charcot-Marie-Tooth disease (CMT) is a common hereditary peripheral polyneuropathy encompassing distinct monogenetic disorders. Pathogenic mutations in mitofusin 2 (MFN2) are the most frequent cause of its axonal type, CMT type 2A, with diverse phenotypes. We herein report a Japanese patient with a novel heterozygous MFN2 pathogenic variant (c.740 G>C, p.R247P) and severe CMT phenotypes, including progressive muscle weakness, optic atrophy, urinary inconsistency, and restrictive pulmonary dysfunction with eventration of the diaphragm that developed over her 60-year disease course. Our case expands the clinico-genetic features of MFN2-related CMT and highlights the need to evaluate infrequent manifestations during long-term care of CMT patients.
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Affiliation(s)
- Yasuyoshi Kimura
- Department of Neurology, Higashiosaka City Medical Center, Japan
- Department of Neurology, Osaka University Graduate School of Medicine, Japan
| | - Akira Nishikawa
- Department of Neurology, Higashiosaka City Medical Center, Japan
| | - Akihiro Hashiguchi
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Japan
| | | | - Akiko Yoshimura
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Japan
| | - Kanako Asai
- Department of Neurology, Higashiosaka City Medical Center, Japan
| | - Noriko Miyashita
- Department of Neurology, Higashiosaka City Medical Center, Japan
| | - Hiroshi Takashima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Japan
| | - Hisae Sumi
- Department of Neurology, Higashiosaka City Medical Center, Japan
| | - Takashi Naka
- Department of Neurology, Higashiosaka City Medical Center, Japan
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6
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Ando M, Higuchi Y, Okamoto Y, Yuan J, Yoshimura A, Takei J, Taniguchi T, Hiramatsu Y, Sakiyama Y, Hashiguchi A, Matsuura E, Nakagawa H, Sonoda K, Yamashita T, Tamura A, Terasawa H, Mitsui J, Ishiura H, Tsuji S, Takashima H. An NEFH founder mutation causes broad phenotypic spectrum in multiple Japanese families. J Hum Genet 2022; 67:399-403. [DOI: 10.1038/s10038-022-01019-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/28/2021] [Accepted: 01/16/2022] [Indexed: 12/28/2022]
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Elderly patients with suspected Charcot-Marie-Tooth disease should be tested for the TTR gene for effective treatments. J Hum Genet 2022; 67:353-362. [PMID: 35027655 DOI: 10.1038/s10038-021-01005-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/30/2021] [Accepted: 12/03/2021] [Indexed: 01/23/2023]
Abstract
BACKGROUND AND AIMS Some hereditary transthyretin (ATTRv) amyloidosis patients are misdiagnosed as Charcot-Marie-Tooth disease (CMT) at onset. We assess the findings to identify ATTRv amyloidosis among patients with suspected CMT to screen transthyretin gene variants for treatments. METHODS We assessed clinical, cerebrospinal fluid, and electrophysiological findings by comparing ATTRv amyloidosis patients with suspected CMT (n = 10) and CMT patients (n = 489). RESULTS The median (interquartile range) age at onset of neurological symptoms was 69 (64.2-70) years in the ATTRv amyloidosis vs 12 (5-37.2) years in CMT group (Mann-Whitney U, p < 0.01). The proportion of patients with initial sensory symptoms was 70% in the ATTRv amyloidosis group vs 7.1% in CMT group (Fisher's exact, p < 0.01). The proportion of patients with histories of suspected chronic inflammatory demyelinating polyneuropathy (CIDP) were 50% in the ATTRv amyloidosis group vs 8.7% in CMT group (Fisher's exact, p < .01). Other measures and outcomes were not different between the two groups. Five of the six patients with ATTRv amyloidosis received treatment and survived. INTERPRETATION For effective treatments, the transthyretin gene should be screened in patients with suspected CMT with old age at onset of neurological symptoms, initial sensory symptoms, and histories of suspected CIDP.
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8
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Nan H, Hata T, Fukao T, Fukao T, Chen W, Kurita T, Natori T, Takiyama Y. MFN2-related Charcot-Marie-Tooth Disease with Atypical Ocular Manifestations. Intern Med 2021; 60:3969-3974. [PMID: 34121014 PMCID: PMC8758439 DOI: 10.2169/internalmedicine.7463-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We herein describe a Charcot-Marie-Tooth disease (CMT) family with a MFN2 mutation with atypical ocular manifestations. The proband, his mother, his third daughter, and his deceased maternal grandfather all had symptoms of CMT and a visual impairment (either cataracts or severe astigmatism). On whole-exome sequencing for the proband having CMT and congenital cataracts, we identified a c.314C>T (p.Thr105Met) mutation in MFN2, but no mutation in the causative genes associated with cataracts. This missense mutation in MFN2 co-segregated with CMT and the atypical ocular manifestations in this family. The findings of this study might help to expand the clinical phenotype of heterogeneous MFN2-related CMT.
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Affiliation(s)
- Haitian Nan
- Department of Neurology, University of Yamanashi, Japan
| | - Takanori Hata
- Department of Neurology, University of Yamanashi, Japan
| | - Toko Fukao
- Department of Neurology, University of Yamanashi, Japan
| | | | - Wanjing Chen
- Department of Ophthalmology, University of Yamanashi, Japan
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9
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Ma Y, Sun A, Zhang Y, Fan D, Liu X. The Genotype and Phenotype Features in a Large Chinese MFN2 Mutation Cohort. Front Neurol 2021; 12:757518. [PMID: 34721278 PMCID: PMC8548668 DOI: 10.3389/fneur.2021.757518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 09/09/2021] [Indexed: 12/24/2022] Open
Abstract
Introduction: Charcot–Marie–Tooth disease type 2A (CMT2A) is a group of clinically and genetically heterogeneous disorders, which is mostly caused by mutations of the mitofusin2 (MFN2) gene. As the genotype–phenotype characteristics of CMT2A were still incompletely understood, we further explored the spectrum of CMT2A variants in China and demonstrated their phenotypic diversities. Methods: A total of 402 index patients/families with CMT throughout Mainland China were enrolled in this study. Among them, we analyzed 20 unrelated index cases with CMT2A by Sanger sequencing, next-generation sequencing, or whole-exome sequencing. Detailed clinical and genetic features of CMT2A patients were collected and analyzed. Of note, de novo mutations were not rare in MFN2 gene; we compared the clinical features of patients from the de novo group with those from the non-de novo group. Results: We identified 20 MFN2 variants, occupying 5.0% of CMT. Most patients presented with early onset and moderate phenotype with abnormal gait and foot drop as the main complaints at onset. Pyramidal signs accounts for 31.6% (6/19) in all patients, which is not uncommon. Four novel variants (p.Tyr752*, c.475-2A>G, p.Val99Met, and p.Arg275_Gln276insArg) were identified in the cohort. Besides, de novo variants occupied 35.0% (7/20) in our study with a much earlier age at onset compared with those in the non-de novo group (p = 0.021). Conclusion: Chinese CMT2A is a predominant typical pure CMT2A, with early onset and mild to moderate phenotype. Given the high frequency of de novo MFN2 mutations, genetic study should be considered for patients with early onset and severe idiopathic axonal neuropathy.
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Affiliation(s)
- Yan Ma
- Department of Neurology, Peking University Third Hospital, Beijing, China.,Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, China
| | - Aping Sun
- Department of Neurology, Peking University Third Hospital, Beijing, China.,Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, China
| | - Yingshuang Zhang
- Department of Neurology, Peking University Third Hospital, Beijing, China.,Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, China
| | - Dongsheng Fan
- Department of Neurology, Peking University Third Hospital, Beijing, China.,Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, China
| | - Xiaoxuan Liu
- Department of Neurology, Peking University Third Hospital, Beijing, China.,Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, China
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10
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Aberrant Mitochondrial Dynamics and Exacerbated Response to Neuroinflammation in a Novel Mouse Model of CMT2A. Int J Mol Sci 2021; 22:ijms222111569. [PMID: 34769001 PMCID: PMC8584238 DOI: 10.3390/ijms222111569] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/06/2021] [Accepted: 10/20/2021] [Indexed: 01/09/2023] Open
Abstract
Charcot-Marie-Tooth disease type 2A (CMT2A) is the most common hereditary axonal neuropathy caused by mutations in MFN2 encoding Mitofusin-2, a multifunctional protein located in the outer mitochondrial membrane. In order to study the effects of a novel MFN2K357T mutation associated with early onset, autosomal dominant severe CMT2A, we generated a knock-in mouse model. While Mfn2K357T/K357T mouse pups were postnatally lethal, Mfn2+/K357T heterozygous mice were asymptomatic and had no histopathological changes in their sciatic nerves up to 10 months of age. However, immunofluorescence analysis of Mfn2+/K357T mice revealed aberrant mitochondrial clustering in the sciatic nerves from 6 months of age, in optic nerves from 8 months, and in lumbar spinal cord white matter at 10 months, along with microglia activation. Ultrastructural analyses confirmed dysmorphic mitochondrial aggregates in sciatic and optic nerves. After exposure of 6-month-old mice to lipopolysaccharide, Mfn2+/K357T mice displayed a higher immune response, a more severe motor impairment, and increased CNS inflammation, microglia activation, and macrophage infiltrates. Overall, ubiquitous Mfn2K357T expression renders the CNS and peripheral nerves of Mfn2+/K357T mice more susceptible to mitochondrial clustering, and augments their response to inflammation, modeling some cellular mechanisms that may be relevant for the development of neuropathy in patients with CMT2A.
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11
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Majorel-Beraud C, Baudou E, Walther-Louvier U, Espil-Taris C, Beze-Beyrie P, Cintas P, Rivier F, Cances C. Clinical Phenotype in an Early-Onset French Pediatric Population: Charcot-Marie-Tooth's Disease Type 2A. Neuropediatrics 2021; 52:351-357. [PMID: 33578441 DOI: 10.1055/s-0041-1723759] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Charcot-Marie-Tooth's disease type 2A (MCT2A), induced by mutation of the mitofusin 2 (MFN2) gene represents the main cause of MCT2. The aim of this study is to provide details of the clinical and electromyographic phenotype of MCT2A in a pediatric population. We conducted a French multicenter retrospective study, including all children with a genetic diagnosis of MCT2A. Thirteen MCT2A children were included with a beginning of symptoms before the age of 10 years ("early-onset group"). We report two new mutations: c.1070 A → T (p.Lys357.Met) and c.280 C → G (p.Arg94Gly). The evolution of the disease is marked by a fast worsening for three patients with loss of motor autonomy, while the evolution is relatively stable for eight patients. The group of early-onset MCT2A seems more heterogeneous than previously described, with a nonconstant severe phenotype.
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Affiliation(s)
- C Majorel-Beraud
- Unit of Pediatric Neurology, French Greater South-West Reference Center for Neuromuscular Diseases, Hôpital des Enfants, Toulouse University Hospital Center, Toulouse, France
| | - E Baudou
- Unit of Pediatric Neurology, French Greater South-West Reference Center for Neuromuscular Diseases, Hôpital des Enfants, Toulouse University Hospital Center, Toulouse, France
| | - U Walther-Louvier
- Unit of Pediatric Neurology, French Greater South-West Reference Center for Neuromuscular Diseases, Hôpital Gui de Chauliac, Montpellier University Hospital Center, Montpellier, France
| | - C Espil-Taris
- Unit of Pediatric Neurology, French Greater South-West Reference Center for Neuromuscular Diseases, Hôpital des Enfants, University Hospital Center Pellegrin, Bordeaux, France
| | - P Beze-Beyrie
- Unit of Pediatrics, Centre Hospitalier de Pau, Pau, France
| | - P Cintas
- Department of Neurology, Pierre Paul Riquet Hospital, University Hospital Center Purpan, Toulouse, France
| | - F Rivier
- Unit of Pediatric Neurology, French Greater South-West Reference Center for Neuromuscular Diseases, Hôpital Gui de Chauliac, Montpellier University Hospital Center, Montpellier, France
| | - C Cances
- Unit of Pediatric Neurology, French Greater South-West Reference Center for Neuromuscular Diseases, Hôpital des Enfants, Toulouse University Hospital Center, Toulouse, France
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12
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Wu R, Lv H, Wang H, Wang Z, Yuan Y. The Pathological Features of Common Hereditary Mitochondrial Dynamics Neuropathy. Front Neurosci 2021; 15:705277. [PMID: 34366782 PMCID: PMC8341155 DOI: 10.3389/fnins.2021.705277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 06/28/2021] [Indexed: 01/02/2023] Open
Abstract
Objectives Mitofusin 2 and ganglioside-induced differentiation-associated protein 1 are two main mitochondrial dynamics-related proteins. Dysfunction of these two proteins leads to different subtypes of Charcot–Marie–Tooth disease type 2A (CMT2A) and CMT2K. This study aims to report the pathological difference between CMT2A and CMT2K in a large cohort. Methods Thirty patients with molecularly confirmed CMT2A and nine with CMT2K were identified by next-generation sequencing. Sural nerve biopsies were performed in 29 patients. Results The patients with both diseases showed length-dependent neuropathy with distal weakness, sensory loss, and no deep tendon reflex. Optic neuropathy appeared in 3/30 (10%) patients with CMT2A. Tendon contracture appeared in 4/9 (50.0%) patients with CMT2K. Sural biopsy revealed the loss of both myelinated and unmyelinated nerve fibers. Closely packed, irregularly oriented neurofilaments were observed in axons of unmyelinated nerve fibers in both diseases. Another important finding was the ubiquitous presence of smaller, rounded, and fragmented mitochondria in CMT2A and elongated mitochondria in CMT2K in the myelinated and unmyelinated axons. Conclusion This study confirmed large diversity in phenotypes between CMT2A and CMT2K. Mitochondrial dynamics-related variations can induce different mitochondrial morphological changes and neurofilament accumulation in axons.
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Affiliation(s)
- Rui Wu
- Department of Neurology, Peking University First Hospital, Beijing, China.,Department of Neurology, Shandong Provincial Hospital, Shandong University, Jinan, China
| | - He Lv
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Hui Wang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, Beijing, China
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13
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Ferese R, Campopiano R, Scala S, D'Alessio C, Storto M, Buttari F, Centonze D, Logroscino G, Zecca C, Zampatti S, Fornai F, Cianci V, Manfroi E, Giardina E, Magnani M, Suppa A, Novelli G, Gambardella S. Cohort Analysis of 67 Charcot-Marie-Tooth Italian Patients: Identification of New Mutations and Broadening of Phenotype Expression Produced by Rare Variants. Front Genet 2021; 12:682050. [PMID: 34354735 PMCID: PMC8329958 DOI: 10.3389/fgene.2021.682050] [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: 03/17/2021] [Accepted: 06/17/2021] [Indexed: 11/13/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) disease is the most prevalent inherited motor sensory neuropathy, which clusters a clinically and genetically heterogeneous group of disorders with more than 90 genes associated with different phenotypes. The goal of this study is to identify the genetic features in the recruited cohort of patients, highlighting the role of rare variants in the genotype-phenotype correlation. We enrolled 67 patients and applied a diagnostic protocol including multiple ligation-dependent probe amplification for copy number variation (CNV) detection of PMP22 locus, and next-generation sequencing (NGS) for sequencing of 47 genes known to be associated with CMT and routinely screened in medical genetics. This approach allowed the identification of 26 patients carrying a whole gene CNV of PMP22. In the remaining 41 patients, NGS identified the causative variants in eight patients in the genes HSPB1, MFN2, KIF1A, GDAP1, MTMR2, SH3TC2, KIF5A, and MPZ (five new vs. three previously reported variants; three sporadic vs. five familial variants). Familial segregation analysis allowed to correctly interpret two variants, initially reported as "variants of uncertain significance" but re-classified as pathological. In this cohort is reported a patient carrying a novel familial mutation in the tail domain of KIF5A [a protein domain previously associated with familial amyotrophic lateral sclerosis (ALS)], and a CMT patient carrying a HSPB1 mutation, previously reported in ALS. These data indicate that combined tools for gene association in medical genetics allow dissecting unexpected phenotypes associated with previously known or unknown genotypes, thus broadening the phenotype expression produced by either pathogenic or undefined variants. Clinical trial registration: ClinicalTrials.gov (NCT03084224).
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Affiliation(s)
| | | | | | | | | | | | - Diego Centonze
- IRCCS Neuromed, Pozzilli, Italy.,Laboratory of Synaptic Immunopathology, Department of Systems Medicine, Tor Vergata University, Rome, Italy
| | - Giancarlo Logroscino
- Center for Neurodegenerative Diseases and the Aging Brain, Department of Clinical Research in Neurology, The University of Bari "Aldo Moro," "Pia Fondazione Card G. Panico" Hospital Tricase, Lecce, Italy.,Department of Basic Medicine Neuroscience and Sense Organs, University "Aldo Moro" Bari, Bari, Italy
| | - Chiara Zecca
- Center for Neurodegenerative Diseases and the Aging Brain, Department of Clinical Research in Neurology, The University of Bari "Aldo Moro," "Pia Fondazione Card G. Panico" Hospital Tricase, Lecce, Italy
| | - Stefania Zampatti
- IRCCS Neuromed, Pozzilli, Italy.,Genomic Medicine Laboratory, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Francesco Fornai
- IRCCS Neuromed, Pozzilli, Italy.,Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Vittoria Cianci
- Regional Epilepsy Centre, Great Metropolitan Hospital Bianchi-Melacrino-Morelli, Reggio Calabria, Italy
| | - Elisabetta Manfroi
- Department of Neuroscience- Neurogenetics, Santa Maria Hospital, Terni, Italy
| | - Emiliano Giardina
- Genomic Medicine Laboratory, IRCCS Fondazione Santa Lucia, Rome, Italy.,Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Rome, Italy
| | - Mauro Magnani
- Department of Biomolecular Sciences, University of Urbino "Carlo Bo," Urbino, Italy
| | - Antonio Suppa
- IRCCS Neuromed, Pozzilli, Italy.,Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Giuseppe Novelli
- IRCCS Neuromed, Pozzilli, Italy.,Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Rome, Italy
| | - Stefano Gambardella
- IRCCS Neuromed, Pozzilli, Italy.,Department of Biomolecular Sciences, University of Urbino "Carlo Bo," Urbino, Italy
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14
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Kanwal S, Choi YJI, Lim SO, Choi HJ, Park JH, Nuzhat R, Khan A, Perveen S, Choi BO, Chung KW. Novel homozygous mutations in Pakistani families with Charcot-Marie-Tooth disease. BMC Med Genomics 2021; 14:174. [PMID: 34193129 PMCID: PMC8247155 DOI: 10.1186/s12920-021-01019-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 06/18/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Charcot-Marie-Tooth disease (CMT) is a group of genetically and clinically heterogeneous peripheral nervous system disorders. Few studies have identified genetic causes of CMT in the Pakistani patients. METHODS This study was performed to identify pathogenic mutations in five consanguineous Pakistani CMT families negative for PMP22 duplication. Genomic screening was performed by application of whole exome sequencing. RESULTS We identified five pathogenic or likely pathogenic homozygous mutations in four genes: c.2599C > T (p.Gln867*) and c.3650G > A (p.Gly1217Asp) in SH3TC2, c.19C > T (p.Arg7*) in HK1, c.247delG (p.Gly83Alafs*44) in REEP1, and c.334G > A (p.Val112Met) in MFN2. These mutations have not been reported in CMT patients. Mutations in SH3TC2, HK1, REEP1, and MFN2 have been reported to be associated with CMT4C, CMT4G, dHMN5B (DSMA5B), and CMT2A, respectively. The genotype-phenotype correlations were confirmed in all the examined families. We also confirmed that both alleles from the homozygous variants originated from a single ancestor using homozygosity mapping. CONCLUSIONS This study found five novel mutations as the underlying causes of CMT. Pathogenic mutations in SH3TC2, HK1, and REEP1 have been reported rarely in other populations, suggesting ethnic-specific distribution. This study would be useful for the exact molecular diagnosis and treatment of CMT in Pakistani patients.
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Affiliation(s)
- Sumaira Kanwal
- Department of Biosciences, COMSATS University Islamabad, Sahiwal, Pakistan
| | - Yu JIn Choi
- Department of Biological Sciences, Kongju National University, 56 Gongjudaehakro, Gongju, 32588, Korea
| | - Si On Lim
- Department of Biological Sciences, Kongju National University, 56 Gongjudaehakro, Gongju, 32588, Korea
| | - Hee Ji Choi
- Department of Biological Sciences, Kongju National University, 56 Gongjudaehakro, Gongju, 32588, Korea
| | - Jin Hee Park
- Department of Biological Sciences, Kongju National University, 56 Gongjudaehakro, Gongju, 32588, Korea
| | - Rana Nuzhat
- Department of Pediatric Neurology, The Children Hospital and Institute of Child Health, Multan, Pakistan
| | - Aneela Khan
- Department of Pediatric Neurology, The Children Hospital and Institute of Child Health, Multan, Pakistan
| | - Shazia Perveen
- Department of Zoology, The Women University, Multan, Pakistan
| | - Byung-Ok Choi
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul, 06351, Korea.
| | - Ki Wha Chung
- Department of Biological Sciences, Kongju National University, 56 Gongjudaehakro, Gongju, 32588, Korea.
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15
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Stavrou M, Sargiannidou I, Georgiou E, Kagiava A, Kleopa KA. Emerging Therapies for Charcot-Marie-Tooth Inherited Neuropathies. Int J Mol Sci 2021; 22:6048. [PMID: 34205075 PMCID: PMC8199910 DOI: 10.3390/ijms22116048] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/29/2021] [Accepted: 05/31/2021] [Indexed: 12/12/2022] Open
Abstract
Inherited neuropathies known as Charcot-Marie-Tooth (CMT) disease are genetically heterogeneous disorders affecting the peripheral nerves, causing significant and slowly progressive disability over the lifespan. The discovery of their diverse molecular genetic mechanisms over the past three decades has provided the basis for developing a wide range of therapeutics, leading to an exciting era of finding treatments for this, until now, incurable group of diseases. Many treatment approaches, including gene silencing and gene replacement therapies, as well as small molecule treatments are currently in preclinical testing while several have also reached clinical trial stage. Some of the treatment approaches are disease-specific targeted to the unique disease mechanism of each CMT form, while other therapeutics target common pathways shared by several or all CMT types. As promising treatments reach the stage of clinical translation, optimal outcome measures, novel biomarkers and appropriate trial designs are crucial in order to facilitate successful testing and validation of novel treatments for CMT patients.
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Affiliation(s)
- Marina Stavrou
- Neuroscience Department, The Cyprus Institute of Neurology and Genetics, Cyprus School of Molecular Medicine, Nicosia 2371, Cyprus; (M.S.); (I.S.); (E.G.); (A.K.)
| | - Irene Sargiannidou
- Neuroscience Department, The Cyprus Institute of Neurology and Genetics, Cyprus School of Molecular Medicine, Nicosia 2371, Cyprus; (M.S.); (I.S.); (E.G.); (A.K.)
| | - Elena Georgiou
- Neuroscience Department, The Cyprus Institute of Neurology and Genetics, Cyprus School of Molecular Medicine, Nicosia 2371, Cyprus; (M.S.); (I.S.); (E.G.); (A.K.)
| | - Alexia Kagiava
- Neuroscience Department, The Cyprus Institute of Neurology and Genetics, Cyprus School of Molecular Medicine, Nicosia 2371, Cyprus; (M.S.); (I.S.); (E.G.); (A.K.)
| | - Kleopas A. Kleopa
- Neuroscience Department, The Cyprus Institute of Neurology and Genetics, Cyprus School of Molecular Medicine, Nicosia 2371, Cyprus; (M.S.); (I.S.); (E.G.); (A.K.)
- Center for Neuromuscular Diseases, The Cyprus Institute of Neurology and Genetics, Cyprus School of Molecular Medicine, Nicosia 2371, Cyprus
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16
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Mitochondrial hyperfusion: a friend or a foe. Biochem Soc Trans 2021; 48:631-644. [PMID: 32219382 DOI: 10.1042/bst20190987] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 02/24/2020] [Accepted: 03/04/2020] [Indexed: 12/13/2022]
Abstract
The cellular mitochondrial population undergoes repeated cycles of fission and fusion to maintain its integrity, as well as overall cellular homeostasis. While equilibrium usually exists between the fission-fusion dynamics, their rates are influenced by organellar and cellular metabolic and pathogenic conditions. Under conditions of cellular stress, there is a disruption of this fission and fusion balance and mitochondria undergo either increased fusion, forming a hyperfused meshwork or excessive fission to counteract stress and remove damaged mitochondria via mitophagy. While some previous reports suggest that hyperfusion is initiated to ameliorate cellular stress, recent studies show its negative impact on cellular health in disease conditions. The exact mechanism of mitochondrial hyperfusion and its role in maintaining cellular health and homeostasis, however, remain unclear. In this review, we aim to highlight the different aspects of mitochondrial hyperfusion in either promoting or mitigating stress and also its role in immunity and diseases.
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17
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Di Nottia M, Verrigni D, Torraco A, Rizza T, Bertini E, Carrozzo R. Mitochondrial Dynamics: Molecular Mechanisms, Related Primary Mitochondrial Disorders and Therapeutic Approaches. Genes (Basel) 2021; 12:247. [PMID: 33578638 PMCID: PMC7916359 DOI: 10.3390/genes12020247] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/02/2021] [Accepted: 02/04/2021] [Indexed: 02/06/2023] Open
Abstract
Mitochondria do not exist as individual entities in the cell-conversely, they constitute an interconnected community governed by the constant and opposite process of fission and fusion. The mitochondrial fission leads to the formation of smaller mitochondria, promoting the biogenesis of new organelles. On the other hand, following the fusion process, mitochondria appear as longer and interconnected tubules, which enhance the communication with other organelles. Both fission and fusion are carried out by a small number of highly conserved guanosine triphosphatase proteins and their interactors. Disruption of this equilibrium has been associated with several pathological conditions, ranging from cancer to neurodegeneration, and mutations in genes involved in mitochondrial fission and fusion have been reported to be the cause of a subset of neurogenetic disorders.
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Affiliation(s)
| | | | | | | | | | - Rosalba Carrozzo
- Laboratory of Molecular Medicine, Unit of Muscular and Neurodegenerative Disorders, Bambino Gesù Children’s Hospital, IRCCS, 00146 Rome, Italy; (M.D.N.); (D.V.); (A.T.); (T.R.); (E.B.)
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18
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Schiavon CR, Shadel GS, Manor U. Impaired Mitochondrial Mobility in Charcot-Marie-Tooth Disease. Front Cell Dev Biol 2021; 9:624823. [PMID: 33598463 PMCID: PMC7882694 DOI: 10.3389/fcell.2021.624823] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 01/05/2021] [Indexed: 12/13/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) disease is a progressive, peripheral neuropathy and the most commonly inherited neurological disorder. Clinical manifestations of CMT mutations are typically limited to peripheral neurons, the longest cells in the body. Currently, mutations in at least 80 different genes are associated with CMT and new mutations are regularly being discovered. A large portion of the proteins mutated in axonal CMT have documented roles in mitochondrial mobility, suggesting that organelle trafficking defects may be a common underlying disease mechanism. This review will focus on the potential role of altered mitochondrial mobility in the pathogenesis of axonal CMT, highlighting the conceptional challenges and potential experimental and therapeutic opportunities presented by this "impaired mobility" model of the disease.
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Affiliation(s)
- Cara R. Schiavon
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, United States
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, United States
| | - Gerald S. Shadel
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, United States
| | - Uri Manor
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, United States
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19
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Barreda Fierro R, Herrera Mora P, Zenteno JC, Villarroel Cortés CE. Clinical and molecular evidence of possible digenic inheritance for MFN2/GDAP1 genes in Charcot-Marie-Tooth disease. Neuromuscul Disord 2020; 30:986-990. [PMID: 33187793 DOI: 10.1016/j.nmd.2020.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 10/14/2020] [Indexed: 10/23/2022]
Abstract
Charcot Marie Tooth disease (CMT) is a progressive motor and sensory polyneuropathy, it is characterized by a very heterogeneous molecular basis and phenotype. MFN2 and GDAP1 participate in mitochondrial energy metabolism and the rare coinheritance of its pathogenic variants has been associated with a cumulative effect in the observed phenotype. We describe a patient with a severe axonal CMT and inherited heterozygous MFN2 (p.Leu741Val) and GDAP1 (p.Gln163*) variants. In accordance with a possible digenic inheritance, none of the heterozygous carriers in his family were symptomatic or exhibited electrophysiological abnormalities. We also review all of the previously reported patients with coinheritance of variants in these two genes; similar to our patient, all exhibit a predominantly axonal severe CMT phenotype. Our findings expand the genotypic spectrum of CMT and further support that digenic inheritance should be considered for analyzing and counseling CMT patients.
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Affiliation(s)
- Renée Barreda Fierro
- Human Genetics Department, National Institute of Pediatrics, Mexico City, Mexico
| | | | - Juan Carlos Zenteno
- Genetics Department-Research Unit, Institute of Ophthalmology "Conde de Valenciana", Mexico City, Mexico; Biochemistry Department, Faculty of Medicine, UNAM, Mexico City, Mexico
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20
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Sanford E, Jones MC, Brigger M, Hammer M, Giudugli L, Kingsmore SF, Dimmock D, Bainbridge MN. Postmortem diagnosis of PPA2-associated sudden cardiac death from dried blood spot in a neonate presenting with vocal cord paralysis. Cold Spring Harb Mol Case Stud 2020; 6:mcs.a005611. [PMID: 33028643 PMCID: PMC7552926 DOI: 10.1101/mcs.a005611] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/12/2020] [Indexed: 01/16/2023] Open
Abstract
Biallelic variants in inorganic pyrophosphatase 2 (PPA2) are known to cause infantile sudden cardiac failure (OMIM #617222), but relatively little is known about phenotypic variability of these patients prior to their death. We report a 5-wk-old male with bilateral vocal cord paralysis and hypertension who had a sudden unexpected cardiac death. Subsequently, molecular autopsy via whole-genome sequencing from newborn dried blood spot identified compound heterozygous mutations in PPA2, with a paternally inherited, pathogenic missense variant (c.514G > A; p.Glu172Lys) and a novel, maternally inherited missense variant of uncertain significance (c.442A > T; p.Thr148Ser). This report expands the presenting phenotype of patients with PPA2 variants. It also highlights the utility of dried blood spots for postmortem molecular diagnosis.
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Affiliation(s)
- Erica Sanford
- Rady Children's Institute of Genomic Medicine, University of California San Diego, La Jolla, California 92093, USA.,Division of Pediatric Critical Care Medicine, Department of Pediatrics, University of California San Diego, La Jolla, California 92093, USA
| | - Marilyn C Jones
- Division of Genetics, Department of Pediatrics, University of California San Diego, La Jolla, California 92093, USA
| | - Matthew Brigger
- Department of Otolaryngology, Rady Children's Hospital, San Diego, California 92123, USA
| | - Monia Hammer
- Rady Children's Institute of Genomic Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Lucia Giudugli
- Rady Children's Institute of Genomic Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Stephen F Kingsmore
- Rady Children's Institute of Genomic Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - David Dimmock
- Rady Children's Institute of Genomic Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Matthew N Bainbridge
- Rady Children's Institute of Genomic Medicine, University of California San Diego, La Jolla, California 92093, USA
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21
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Rickman OJ, Baple EL, Crosby AH. Lipid metabolic pathways converge in motor neuron degenerative diseases. Brain 2020; 143:1073-1087. [PMID: 31848577 PMCID: PMC7174042 DOI: 10.1093/brain/awz382] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 09/11/2019] [Accepted: 10/01/2019] [Indexed: 12/11/2022] Open
Abstract
Motor neuron diseases (MNDs) encompass an extensive and heterogeneous group of upper and/or lower motor neuron degenerative disorders, in which the particular clinical outcomes stem from the specific neuronal component involved in each condition. While mutations in a large number of molecules associated with lipid metabolism are known to be implicated in MNDs, there remains a lack of clarity regarding the key functional pathways involved, and their inter-relationships. This review highlights evidence that defines defects within two specific lipid (cholesterol/oxysterol and phosphatidylethanolamine) biosynthetic cascades as being centrally involved in MND, particularly hereditary spastic paraplegia. We also identify how other MND-associated molecules may impact these cascades, in particular through impaired organellar interfacing, to propose ‘subcellular lipidome imbalance’ as a likely common pathomolecular theme in MND. Further exploration of this mechanism has the potential to identify new therapeutic targets and management strategies for modulation of disease progression in hereditary spastic paraplegias and other MNDs.
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Affiliation(s)
- Olivia J Rickman
- Medical Research (Level 4), RILD Wellcome Wolfson Centre, University of Exeter Medical School, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, UK
| | - Emma L Baple
- Medical Research (Level 4), RILD Wellcome Wolfson Centre, University of Exeter Medical School, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, UK
| | - Andrew H Crosby
- Medical Research (Level 4), RILD Wellcome Wolfson Centre, University of Exeter Medical School, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, UK
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22
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Dorn GW. Mitofusin 2 Dysfunction and Disease in Mice and Men. Front Physiol 2020; 11:782. [PMID: 32733278 PMCID: PMC7363930 DOI: 10.3389/fphys.2020.00782] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 06/15/2020] [Indexed: 01/30/2023] Open
Abstract
A causal relationship between Mitofusin (MFN) 2 gene mutations and the hereditary axonal neuropathy Charcot-Marie-Tooth disease type 2A (CMT2A) was described over 15 years ago. During the intervening period much has been learned about MFN2 functioning in mitochondrial fusion, calcium signaling, and quality control, and the consequences of these MFN2 activities on cell metabolism, fitness, and development. Nevertheless, the challenge of defining the central underlying mechanism(s) linking mitochondrial abnormalities to progressive dying-back of peripheral arm and leg nerves in CMT2A is largely unmet. Here, a different perspective of why, in humans, MFN2 dysfunction preferentially impacts peripheral nerves is provided based on recent insights into its role in determining whether individual mitochondria will be fusion-competent and retained within the cell, or are fusion-impaired, sequestered, and eliminated by mitophagy. Evidence for and against a regulatory role of mitofusins in mitochondrial transport is reviewed, nagging questions defined, and implications on mitochondrial fusion, quality control, and neuronal degeneration discussed. Finally, in the context of recently described mitofusin activating peptides and small molecules, an overview is provided of potential therapeutic applications for pharmacological enhancement of mitochondrial fusion and motility in CMT2A and other neurodegenerative conditions.
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Affiliation(s)
- Gerald W Dorn
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States
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23
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Guerriero S, D'Oria F, Rossetti G, Favale RA, Zoccolella S, Alessio G, Petruzzella V. CMT2A Harboring Mitofusin 2 Mutation with Optic Nerve Atrophy and Normal Visual Acuity. Int Med Case Rep J 2020; 13:41-45. [PMID: 32110117 PMCID: PMC7039061 DOI: 10.2147/imcrj.s237620] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 01/17/2020] [Indexed: 01/20/2023] Open
Abstract
Charcot-Marie-Tooth (CMT) constitutes a group of heterogeneous hereditary motor and sensor neuropathies. Mutations in mitofusin-2 (MFN2) cause CMT type 2A by altering mitochondrial fusion and trafficking along with the axonal microtubule system. In literature patients presenting with CMT2A are reported as having a subacute onset of optic atrophy associated with central scotoma and color vision defects. We report on the clinical and genetic findings in a 40 years-old Caucasian woman presenting with CMT type 2A and MFN2 mutation (c.2258duplT/p.Leu753fs) who presented bilateral progressive optic atrophy with bilateral severe concentric narrowing of the visual field but normal visual acuity and color vision. This is the first report that describes such phenotypical manifestation of an MFN2 mutation suggesting that the molecular mechanisms underlying the mitofusin-2 function alteration at optic nerve need to be investigated further.
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Affiliation(s)
- Silvana Guerriero
- Department of Medical Science, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Francesco D'Oria
- Department of Medical Science, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Giacomo Rossetti
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Rosa Anna Favale
- Department of Medical Science, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Stefano Zoccolella
- Department of Medical Science, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Giovanni Alessio
- Department of Medical Science, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Vittoria Petruzzella
- Department of Medical Science, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy
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24
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Roggenbuck J, Doyle C, Lincoln T, Glass J. Theme 2 Genetics and genomics. Amyotroph Lateral Scler Frontotemporal Degener 2019; 20:114-134. [PMID: 31702465 DOI: 10.1080/21678421.2019.1646990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Background: A genetic basis is found in ∼70% of familial and ∼15% of sporadic ALS, in research cohorts. Clinical trials of gene-targeted therapies are underway, heralding a new era of personalized medicine in ALS treatment. However, ALS management guidelines do not include recommendations for the offer of genetic testing. Many persons with ALS who desire genetic testing are not currently offered it, and the yield of genetic testing in clinic-based ALS populations is unknown. The ALS GAP program, sponsored by the Northeast ALS (NEALS) Consortium, provides free genetic testing for patients with ALS who have a family history of ALS or dementia. We report genetic testing outcomes in the first 142 patients tested in the
program.Objectives: 1) To create a pilot ALS genetic testing program for NEALS clinics, 2) To study the rate of ALS gene identification in a US clinic-based populationMethods: Persons with ALS and a family history of ALS (fALS) or dementia (dALS) who receive care at a US NEALS clinic are eligible for testing. Patients classified as fALS (having a positive family history of ALS in a 1st, 2nd, or 3rd degree relative) are eligible for C9orf72 testing, with the option to reflex to a 5 gene (SOD1, FUS, TARDBP, TBK1, VCP) panel. Patients classified as dALS (having a positive family history of dementia of any type in a 1st or 2nd degree relative) are eligible for C9orf72 testing only.Results: Currently, 29.5% (34/115) of US NEALS clinics have participated in the program. Of 142 patients who have completed testing to date, 78 (54.9%) were classified as fALS and 64 (45.1%) as dALS. Among fALS cases, 42/78 (53.9%) tested positive, including 32/78 (41%) with a C9orf72 repeat expansion, and 10/78 (12.8%) with other pathogenic or likely pathogenic variants in SOD, FUS, TARDP or VCP. Variants of uncertain significance (VUS) in FUS were identified in 2/78 (2.6%). Among dALS cases, 12/60 (20%) tested positive for C9orf72.Discussion and conclusions: Participation in ALS-GAP indicates significant clinician and patient interest in ALS genetic testing. This program addresses several current barriers to testing access, including cost, identifying appropriate candidates for testing, and appropriate test selection. Although 38% of patients who participated in the program have thus far received a genetic diagnosis, our testing outcome data suggests that the gene identification rate in fALS cases may be lower in clinic-based patients than in research cohorts, particularly for genes other than C9orf72. This program may serve as a model for the practice of ALS genetic testing in the clinic setting. Consistent, equitable testing policies, as well as an accurate understanding of the genetic profile of clinic-based ALS populations, are needed as gene-targeted therapies reach patient care.
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25
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Kanemaru K, Ogawa G, Mochizuki H, Nakazato M, Shiomi K. A Sporadic Case of Charcot-Marie-Tooth Disease Type 2 with Left Vocal Fold Palsy due to Mitofusin 2 Mutation. Intern Med 2019; 58:2091-2093. [PMID: 30996168 PMCID: PMC6701995 DOI: 10.2169/internalmedicine.2318-18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
A 33-year-old Japanese woman was referred for hoarseness. She had been diagnosed with Charcot-Marie-Tooth disease at age 3 and bilateral optic atrophy at age 15. Laryngoscopy revealed left vocal fold palsy. These findings suggested Charcot-Marie-Tooth disease type 2; the diagnosis was confirmed by a mitofusin 2 mutation analysis. Her symptoms remained stable for almost 10 years. Although vocal fold palsy and optic atrophy have been previously reported in patients with mitofusin 2 mutations, detailed clinical information and clinical course have never been documented. These data might contribute to the elucidation of the pathological conditions associated with mitofusin 2 mutations.
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Affiliation(s)
- Kazuki Kanemaru
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Japan
| | - Go Ogawa
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Japan
| | - Hitoshi Mochizuki
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Japan
| | - Masamitsu Nakazato
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Japan
| | - Kazutake Shiomi
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Japan
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26
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Zhou Y, Carmona S, Muhammad AKMG, Bell S, Landeros J, Vazquez M, Ho R, Franco A, Lu B, Dorn GW, Wang S, Lutz CM, Baloh RH. Restoring mitofusin balance prevents axonal degeneration in a Charcot-Marie-Tooth type 2A model. J Clin Invest 2019; 129:1756-1771. [PMID: 30882371 DOI: 10.1172/jci124194] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 01/29/2019] [Indexed: 01/08/2023] Open
Abstract
Mitofusin-2 (MFN2) is a mitochondrial outer-membrane protein that plays a pivotal role in mitochondrial dynamics in most tissues, yet mutations in MFN2, which cause Charcot-Marie-Tooth disease type 2A (CMT2A), primarily affect the nervous system. We generated a transgenic mouse model of CMT2A that developed severe early onset vision loss and neurological deficits, axonal degeneration without cell body loss, and cytoplasmic and axonal accumulations of fragmented mitochondria. While mitochondrial aggregates were labeled for mitophagy, mutant MFN2 did not inhibit Parkin-mediated degradation, but instead had a dominant negative effect on mitochondrial fusion only when MFN1 was at low levels, as occurs in neurons. Finally, using a transgenic approach, we found that augmenting the level of MFN1 in the nervous system in vivo rescued all phenotypes in mutant MFN2R94Q-expressing mice. These data demonstrate that the MFN1/MFN2 ratio is a key determinant of tissue specificity in CMT2A and indicate that augmentation of MFN1 in the nervous system is a viable therapeutic strategy for the disease.
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Affiliation(s)
- Yueqin Zhou
- Center for Neural Science and Medicine, and.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Sharon Carmona
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - A K M G Muhammad
- Center for Neural Science and Medicine, and.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Shaughn Bell
- Center for Neural Science and Medicine, and.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Jesse Landeros
- Center for Neural Science and Medicine, and.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Michael Vazquez
- Center for Neural Science and Medicine, and.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Ritchie Ho
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Antonietta Franco
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Bin Lu
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Gerald W Dorn
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Shaomei Wang
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | | | - Robert H Baloh
- Center for Neural Science and Medicine, and.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.,Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, California, USA
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27
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Yuan JH, Sakiyama Y, Hashiguchi A, Ando M, Okamoto Y, Yoshimura A, Higuchi Y, Takashima H. Genetic and phenotypic profile of 112 patients with X-linked Charcot-Marie-Tooth disease type 1. Eur J Neurol 2018; 25:1454-1461. [PMID: 29998508 DOI: 10.1111/ene.13750] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 07/10/2018] [Indexed: 12/22/2022]
Abstract
BACKGROUND AND PURPOSE X-linked Charcot-Marie-Tooth disease type 1 (CMTX1), caused by mutations in gap junction protein beta 1 (GJB1), is characterized by various central nervous system symptoms and gender differences of clinical severity. The aim of this study was to identify the frequency and mutation spectrum of CMTX1 patients in Japan and to demonstrate their phenotypic diversities. METHODS Using three high-throughput sequencing systems, targeted gene panel sequencing on 1483 unrelated index patients with suspected Charcot-Marie-Tooth (CMT) disease was performed. The peripheral and central nervous system involvements of all patients with GJB1 variants were assessed retrospectively and a detailed gender comparison was conducted with the CMT examination score. RESULTS Twenty-three novel and 36 described GJB1 variants were identified from 88 pedigrees, in which 34 female and 78 male patients were enrolled. Mean age at onset of the male patients was much younger than the females, 21.56 ± 17.63 years vs. 35.53 ± 23.72 years (P = 0.007). Male patients presented with more severe phenotypes in every examination item, but statistical differences were observed only in motor dysfunctions of the lower extremities and vibration sensation. No significant sensory difference was identified between genders, either clinically or electrophysiologically. Central nervous system dysfunctions were found in 15 patients from 12 pedigrees. Therein, six patients developed stroke-like phenotypes, with dysarthria as the leading symptom. CONCLUSIONS A relatively lower frequency of CMTX1 (5.9%) was demonstrated and a broad mutation spectrum of GJB1 was described. Detailed clinical differences between genders and various central nervous system symptoms were also illustrated, even in the same pedigree.
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Affiliation(s)
- J-H Yuan
- Department of Neurology and Geriatrics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Y Sakiyama
- Department of Neurology and Geriatrics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - A Hashiguchi
- Department of Neurology and Geriatrics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - M Ando
- Department of Neurology and Geriatrics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Y Okamoto
- Department of Neurology and Geriatrics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - A Yoshimura
- Department of Neurology and Geriatrics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Y Higuchi
- Department of Neurology and Geriatrics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - H Takashima
- Department of Neurology and Geriatrics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
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28
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Clinical and genetic diversities of Charcot-Marie-Tooth disease with MFN2 mutations in a large case study. J Peripher Nerv Syst 2018; 23:149-150. [PMID: 29906321 DOI: 10.1111/jns.12263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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