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Rudaks LI, Yeow D, Ng K, Deveson IW, Kennerson ML, Kumar KR. An Update on the Adult-Onset Hereditary Cerebellar Ataxias: Novel Genetic Causes and New Diagnostic Approaches. CEREBELLUM (LONDON, ENGLAND) 2024:10.1007/s12311-024-01703-z. [PMID: 38760634 DOI: 10.1007/s12311-024-01703-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/07/2024] [Indexed: 05/19/2024]
Abstract
The hereditary cerebellar ataxias (HCAs) are rare, progressive neurologic disorders caused by variants in many different genes. Inheritance may follow autosomal dominant, autosomal recessive, X-linked or mitochondrial patterns. The list of genes associated with adult-onset cerebellar ataxia is continuously growing, with several new genes discovered in the last few years. This includes short-tandem repeat (STR) expansions in RFC1, causing cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS), FGF14-GAA causing spinocerebellar ataxia type 27B (SCA27B), and THAP11. In addition, the genetic basis for SCA4, has recently been identified as a STR expansion in ZFHX3. Given the large and growing number of genes, and different gene variant types, the approach to diagnostic testing for adult-onset HCA can be complex. Testing methods include targeted evaluation of STR expansions (e.g. SCAs, Friedreich ataxia, fragile X-associated tremor/ataxia syndrome, dentatorubral-pallidoluysian atrophy), next generation sequencing for conventional variants, which may include targeted gene panels, whole exome, or whole genome sequencing, followed by various potential additional tests. This review proposes a diagnostic approach for clinical testing, highlights the challenges with current testing technologies, and discusses future advances which may overcome these limitations. Implementing long-read sequencing has the potential to transform the diagnostic approach in HCA, with the overall aim to improve the diagnostic yield.
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Affiliation(s)
- Laura Ivete Rudaks
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Sydney, Australia.
- Faculty of Medicine and Health, The University of Sydney, Sydney, Australia.
- Genomics and Inherited Disease Program, The Garvan Institute of Medical Research, Sydney, Australia.
- Clinical Genetics Unit, Royal North Shore Hospital, Sydney, Australia.
| | - Dennis Yeow
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Sydney, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Genomics and Inherited Disease Program, The Garvan Institute of Medical Research, Sydney, Australia
- Neurodegenerative Service, Prince of Wales Hospital, Sydney, Australia
- Neuroscience Research Australia, Sydney, Australia
| | - Karl Ng
- Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Neurology Department, Royal North Shore Hospital, Sydney, Australia
| | - Ira W Deveson
- Genomics and Inherited Disease Program, The Garvan Institute of Medical Research, Sydney, Australia
- Faculty of Medicine, University of New South Wales, Sydney, Australia
| | - Marina L Kennerson
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Sydney, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- The Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney Local Health District, Sydney, Australia
| | - Kishore Raj Kumar
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Sydney, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Genomics and Inherited Disease Program, The Garvan Institute of Medical Research, Sydney, Australia
- Faculty of Medicine, University of New South Wales, Sydney, Australia
- Faculty of Medicine, St Vincent's Healthcare Campus, UNSW Sydney, Sydney, Australia
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Conti F, Di Martino S, Drago F, Bucolo C, Micale V, Montano V, Siciliano G, Mancuso M, Lopriore P. Red Flags in Primary Mitochondrial Diseases: What Should We Recognize? Int J Mol Sci 2023; 24:16746. [PMID: 38069070 PMCID: PMC10706469 DOI: 10.3390/ijms242316746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/22/2023] [Accepted: 11/23/2023] [Indexed: 12/18/2023] Open
Abstract
Primary mitochondrial diseases (PMDs) are complex group of metabolic disorders caused by genetically determined impairment of the mitochondrial oxidative phosphorylation (OXPHOS). The unique features of mitochondrial genetics and the pivotal role of mitochondria in cell biology explain the phenotypical heterogeneity of primary mitochondrial diseases and the resulting diagnostic challenges that follow. Some peculiar features ("red flags") may indicate a primary mitochondrial disease, helping the physician to orient in this diagnostic maze. In this narrative review, we aimed to outline the features of the most common mitochondrial red flags offering a general overview on the topic that could help physicians to untangle mitochondrial medicine complexity.
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Affiliation(s)
- Federica Conti
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
| | - Serena Di Martino
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
| | - Filippo Drago
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
| | - Claudio Bucolo
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
- Center for Research in Ocular Pharmacology-CERFO, University of Catania, 95213 Catania, Italy
| | - Vincenzo Micale
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
| | - Vincenzo Montano
- Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy (P.L.)
| | - Gabriele Siciliano
- Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy (P.L.)
| | - Michelangelo Mancuso
- Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy (P.L.)
| | - Piervito Lopriore
- Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy (P.L.)
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Roberts LJ, Szmulewicz DJ. A patient with neuropathy and ataxia: what do I have to consider? Curr Opin Neurol 2023; 36:382-387. [PMID: 37639448 DOI: 10.1097/wco.0000000000001200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
PURPOSE OF REVIEW An increasing number of peripheral neuro(no)pathies are identified as involving other components of the neurological system, particularly those that further impair balance. Here we aim to outline an evidence-based approach to the diagnosis of patients who present with a somatosensory disorder which also involves at least one other area of neurological impairment such as the vestibular, auditory, or cerebellar systems. RECENT FINDINGS Detailed objective investigation of patients who present with sensory impairment, particularly where the degree of imbalance is greater than would be expected, aids the accurate diagnosis of genetic, autoimmune, metabolic, and toxic neurological disease. SUMMARY Diagnosis and management of complex somatosensory disorders benefit from investigation which extends beyond the presenting sensory impairment.
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Affiliation(s)
- Leslie J Roberts
- Neurophysiology Department, Department of Neurology & Neurological Research, St Vincent's Hospital, Department of Medicine, the University of Melbourne
| | - David J Szmulewicz
- Balance Disorders and Ataxia Service, Eye and Ear Hospital
- Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria, Australia
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Liao NY, Lai KL, Liao YC, Hsiao CT, Lee YC. Identification of m.3243A>G mitochondrial DNA mutation in patients with cerebellar ataxia. J Formos Med Assoc 2023; 122:1028-1034. [PMID: 37311680 DOI: 10.1016/j.jfma.2023.05.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 03/24/2023] [Accepted: 05/28/2023] [Indexed: 06/15/2023] Open
Abstract
BACKGROUND The mitochondrial DNA m.3243A>G mutation can affect mitochondrial function and lead to a wide phenotypic spectrum, including mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome, diabetes mellitus, hearing impairment, cardiac involvement, epilepsy, migraine, myopathy, and cerebellar ataxia. However, m.3243A>G has been rarely reported in patients with cerebellar ataxia as their predominant manifestation. The aim of this study is to investigate the prevalence and clinical features of m.3243A>G in a Taiwanese cohort of cerebellar ataxia with unknown genetic diagnosis. METHODS This retrospective cohort study conducted the mutation analysis of m.3243A>G by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) in 232 unrelated Han Chinese patients with genetically-undetermined cerebellar ataxia. The clinical presentation and neuroimaging features of patients with m.3243A>G mutation-related cerebellar ataxia were characterized. RESULTS We identified two patients harboring m.3243A>G mutation. These patients have suffered from apparently sporadic and slowly progressive cerebellar ataxia since age 52 and 35 years, respectively. Both patients had diabetes mellitus and/or hearing impairment. The neuroimaging studies revealed generalized brain atrophy with predominantly cerebellar involvement in both individuals and bilateral basal ganglia calcifications in one of the patients. CONCLUSION Mitochondrial m.3243A>G mutation accounted for 0.9% (2/232) of genetically-undetermined cerebellar ataxia in the Han Chinese cohort in Taiwan. These findings highlight the importance of investigating m.3243A>G in patients with genetically-undetermined cerebellar ataxia.
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Affiliation(s)
- Nai-Yi Liao
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Kuan-Lin Lai
- Department of Neurology, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan
| | - Yi-Chu Liao
- Department of Neurology, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan
| | - Cheng-Tsung Hsiao
- Department of Neurology, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan.
| | - Yi-Chung Lee
- Department of Neurology, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan.
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Moos WH, Faller DV, Glavas IP, Kanara I, Kodukula K, Pernokas J, Pernokas M, Pinkert CA, Powers WR, Sampani K, Steliou K, Vavvas DG. Epilepsy: Mitochondrial connections to the 'Sacred' disease. Mitochondrion 2023; 72:84-101. [PMID: 37582467 DOI: 10.1016/j.mito.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/03/2023] [Accepted: 08/12/2023] [Indexed: 08/17/2023]
Abstract
Over 65 million people suffer from recurrent, unprovoked seizures. The lack of validated biomarkers specific for myriad forms of epilepsy makes diagnosis challenging. Diagnosis and monitoring of childhood epilepsy add to the need for non-invasive biomarkers, especially when evaluating antiseizure medications. Although underlying mechanisms of epileptogenesis are not fully understood, evidence for mitochondrial involvement is substantial. Seizures affect 35%-60% of patients diagnosed with mitochondrial diseases. Mitochondrial dysfunction is pathophysiological in various epilepsies, including those of non-mitochondrial origin. Decreased ATP production caused by malfunctioning brain cell mitochondria leads to altered neuronal bioenergetics, metabolism and neurological complications, including seizures. Iron-dependent lipid peroxidation initiates ferroptosis, a cell death pathway that aligns with altered mitochondrial bioenergetics, metabolism and morphology found in neurodegenerative diseases (NDDs). Studies in mouse genetic models with seizure phenotypes where the function of an essential selenoprotein (GPX4) is targeted suggest roles for ferroptosis in epilepsy. GPX4 is pivotal in NDDs, where selenium protects interneurons from ferroptosis. Selenium is an essential central nervous system micronutrient and trace element. Low serum concentrations of selenium and other trace elements and minerals, including iron, are noted in diagnosing childhood epilepsy. Selenium supplements alleviate intractable seizures in children with reduced GPX activity. Copper and cuproptosis, like iron and ferroptosis, link to mitochondria and NDDs. Connecting these mechanistic pathways to selenoproteins provides new insights into treating seizures, pointing to using medicines including prodrugs of lipoic acid to treat epilepsy and to potential alternative therapeutic approaches including transcranial magnetic stimulation (transcranial), photobiomodulation and vagus nerve stimulation.
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Affiliation(s)
- Walter H Moos
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of California San Francisco, San Francisco, CA, USA.
| | - Douglas V Faller
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA; Cancer Research Center, Boston University School of Medicine, Boston, MA, USA
| | - Ioannis P Glavas
- Department of Ophthalmology, New York University School of Medicine, New York, NY, USA
| | | | | | - Julie Pernokas
- Advanced Dental Associates of New England, Woburn, MA, USA
| | - Mark Pernokas
- Advanced Dental Associates of New England, Woburn, MA, USA
| | - Carl A Pinkert
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL, USA
| | - Whitney R Powers
- Department of Health Sciences, Boston University, Boston, MA, USA; Department of Anatomy, Boston University School of Medicine, Boston, MA, USA
| | - Konstantina Sampani
- Beetham Eye Institute, Joslin Diabetes Center, Boston, MA, USA; Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Kosta Steliou
- Cancer Research Center, Boston University School of Medicine, Boston, MA, USA; PhenoMatriX, Inc., Natick, MA, USA
| | - Demetrios G Vavvas
- Department of Ophthalmology, Harvard Medical School, Boston, MA, USA; Retina Service, Angiogenesis Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA, USA
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Fluctuating ataxia caused by mitochondrial tRNA (Lys) gene m.8363G > A variant. Neurol Sci 2022; 43:6589-6591. [DOI: 10.1007/s10072-022-06246-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 06/21/2022] [Indexed: 11/25/2022]
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