1
|
Ricci FS, Stanga S, Mezzanotte M, Marinaccio C, D'Alessandro R, Somà A, Sottemano S, Conio A, Morana G, Spada M, Boido M, Mongini TE. Biochemical characterization on muscle tissue of a novel biallelic ACO2 mutation in an infant with progressive encephalopathy. JIMD Rep 2024; 65:3-9. [PMID: 38186851 PMCID: PMC10764196 DOI: 10.1002/jmd2.12400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 10/06/2023] [Accepted: 10/10/2023] [Indexed: 01/09/2024] Open
Abstract
The ACO2 gene encodes the mitochondrial protein aconitate hydratase, which is responsible for catalyzing the interconversion of citrate into isocitrate in the tricarboxylic acid (TCA) cycle. Mitochondrial aconitase is expressed ubiquitously, and deficiencies in TCA-cycle enzymes have been reported to cause various neurodegenerative diseases due to disruption of cellular energy metabolism and development of oxidative stress. We investigated a severe early infantile-onset neurometabolic syndrome due to a homozygous novel variant in exon 13 of the ACO2 gene. The in vitro pathogenicity of this variant of unknown significance was demonstrated by the loss of both protein expression and its enzymatic activity on muscle tissue sample taken from the patient. The patient presented with progressive encephalopathy soon after birth, characterized by hypotonia, progressive severe muscle atrophy, and respiratory failure. Serial brain magnetic resonance imaging showed progressive abnormalities compatible with a metabolic disorder, possibly mitochondrial. Muscle biopsy disclosed moderate myopathic alterations and features consistent with a mitochondriopathy albeit nonspecific. The course was characterized by progressive worsening of the clinical and neurological picture, and the patient died at 5 months of age. This study provides the first report on the validation in muscle from human subjects regarding in vitro analysis for mitochondrial aconitase activity. To our knowledge, no prior reports have demonstrated a correlation of phenotypic and diagnostic characteristics with in vitro muscle enzymatic activity of mitochondrial aconitase in humans. In conclusion, this case further expands the genetic spectrum of ACO2 variants and defines a complex case of severe neonatal neurometabolic disorder.
Collapse
Affiliation(s)
- Federica Silvia Ricci
- Division of Child and Adolescent Neuropsychiatry, Department of Public Health and Pediatric SciencesUniversity of TurinTurinItaly
| | - Serena Stanga
- Department of Neuroscience “Rita Levi Montalcini”Neuroscience Institute Cavalieri Ottolenghi, University of TurinTurinItaly
| | - Mariarosa Mezzanotte
- Department of Neuroscience “Rita Levi Montalcini”Neuroscience Institute Cavalieri Ottolenghi, University of TurinTurinItaly
| | - Cristina Marinaccio
- Division of Child and Adolescent Neuropsychiatry, Department of Child Care and PathologyChildren Hospital “Regina Margherita”TurinItaly
| | - Rossella D'Alessandro
- Division of Child and Adolescent Neuropsychiatry, Department of Child Care and PathologyChildren Hospital “Regina Margherita”TurinItaly
| | - Alessandra Somà
- Division of Child and Adolescent Neuropsychiatry, Department of Public Health and Pediatric SciencesUniversity of TurinTurinItaly
| | - Stefano Sottemano
- Division of Child and Adolescent Neuropsychiatry, Department of Public Health and Pediatric SciencesUniversity of TurinTurinItaly
| | - Alessandra Conio
- Pediatric Intensive Care Unit, Anesthesia, Resuscitation and Emergency DepartmentUniversity of TurinTurinItaly
| | - Giovanni Morana
- Neuroradiology Unit, Department of Neuroscience “Rita Levi Montalcini”University of TurinTurinItaly
| | - Marco Spada
- Division of Child and Adolescent Neuropsychiatry, Department of Child Care and PathologyChildren Hospital “Regina Margherita”TurinItaly
| | - Marina Boido
- Department of Neuroscience “Rita Levi Montalcini”Neuroscience Institute Cavalieri Ottolenghi, University of TurinTurinItaly
| | - Tiziana E. Mongini
- Division of Neurology 1, Department of Neuroscience “Rita Levi Montalcini”University of TurinTurinItaly
| |
Collapse
|
2
|
Ha DJ, Park J, Seo GH, Lee K, Kwon YS, Lee JE, Kim SJ. Case Report: Infantile Cerebellar-Retinal Degeneration With Compound Heterozygous Variants in ACO2 Gene-Long-Term Follow-Up of a Sibling. Front Genet 2022; 13:729980. [PMID: 35368710 PMCID: PMC8965713 DOI: 10.3389/fgene.2022.729980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 02/09/2022] [Indexed: 11/13/2022] Open
Abstract
Infantile cerebellar-retinal degeneration (ICRD) is an extremely rare, infantile-onset neuro-degenerative disease, characterized by autosomal recessive inherited, global developmental delay (GDD), progressive cerebellar and cortical atrophy, and retinal degeneration. In 2012, a biallelic pathogenic variant in ACO2 gene (NM_001098.3) was found to be causative of this disease. To date, approximately 44 variants displaying various clinical features have been reported. Here, we report a case of two siblings with compound heterozygous variants in the ACO2 gene. Two siblings without perinatal problems were born to healthy non-consanguineous Korean parents. They showed GDD and seizures since infancy. Their first brain magnetic resonance imaging (MRI), electroencephalography, and metabolic workup revealed no abnormal findings. As they grew, they developed symptoms including ataxia, dysmetria, poor sitting balance, and myopia. Follow-up brain MRI findings revealed atrophy of the cerebellum and optic nerve. Through exome sequencing of both siblings and their parents, we identified the following compound heterozygous variants in the ACO2: c.85C > T (p.Arg29Trp) and c.2303C > A (p.Ala768Asp). These two variants were categorized as likely pathogenic based on ACMG/AMP guidelines. In conclusion, this case help to broaden the genetic and clinical spectrum of the ACO2 variants associated with ICRD. We have also documented the long-term clinical course and serial brain MRI findings for two patients with this extremely rare disease.
Collapse
Affiliation(s)
- Dong Jun Ha
- Department of Pediatrics, Inha University Hospital, Inha University College of Medicine, Incheon, South Korea
| | - Jisun Park
- Department of Pediatrics, Inha University Hospital, Inha University College of Medicine, Incheon, South Korea.,Northwest Gyeonggi Regional Center for Rare Disease, Inha University Hospital, Incheon, Korea
| | | | | | - Young Se Kwon
- Department of Pediatrics, Inha University Hospital, Inha University College of Medicine, Incheon, South Korea.,Northwest Gyeonggi Regional Center for Rare Disease, Inha University Hospital, Incheon, Korea
| | - Ji Eun Lee
- Department of Pediatrics, Inha University Hospital, Inha University College of Medicine, Incheon, South Korea.,Northwest Gyeonggi Regional Center for Rare Disease, Inha University Hospital, Incheon, Korea
| | - Su Jin Kim
- Department of Pediatrics, Inha University Hospital, Inha University College of Medicine, Incheon, South Korea.,Northwest Gyeonggi Regional Center for Rare Disease, Inha University Hospital, Incheon, Korea
| |
Collapse
|
3
|
Murakhovskaya YK, Sheremet NL, Shmelkova MS, Krylova TD, Tsygankova PG. [Autosomal recessive optic neuropathies: genetic variants, clinical manifestations]. Vestn Oftalmol 2022; 138:116-122. [PMID: 36573955 DOI: 10.17116/oftalma2022138061116] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Hereditary optic neuropathies (HON) - a group of neurodegenerative diseases characterized by primary loss of structure and function of the retinal ganglion cells and subsequent death of their axons, development of partial optic nerve atrophy. Autosomal dominant optic neuropathy and Leber`s hereditary optic neuropathy until recently were considered the most common genetic hereditary optic neuropathies, while autosomal recessive optic neuropathies (ARON) were described as rare types of HON, usually accompanying severe syndromic pathologies. In the 2000s it has become clear that ARON occur significantly more often, are underestimated, and their clinical variability is poorly studied. Despite the fact that non-syndromic ARON are less common than syndromic optic neuropathies, their contribution to the development of isolated hereditary optic neuropathies should be considered. This article presents a literature review on non-syndromic ARON developing as a result of mutations in the ACO2, MCAT, WFS1, RTN4IP1, TMEM126A, NDUFS2, DNAJC30 genes.
Collapse
Affiliation(s)
- Yu K Murakhovskaya
- Krasnov Research Institute of Eye Diseases, Moscow, Russia.,I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | - N L Sheremet
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
| | - M S Shmelkova
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
| | - T D Krylova
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | | |
Collapse
|
4
|
Strachan EL, Mac White-Begg D, Crean J, Reynolds AL, Kennedy BN, O’Sullivan NC. The Role of Mitochondria in Optic Atrophy With Autosomal Inheritance. Front Neurosci 2021; 15:784987. [PMID: 34867178 PMCID: PMC8634724 DOI: 10.3389/fnins.2021.784987] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 10/22/2021] [Indexed: 11/13/2022] Open
Abstract
Optic atrophy (OA) with autosomal inheritance is a form of optic neuropathy characterized by the progressive and irreversible loss of vision. In some cases, this is accompanied by additional, typically neurological, extra-ocular symptoms. Underlying the loss of vision is the specific degeneration of the retinal ganglion cells (RGCs) which form the optic nerve. Whilst autosomal OA is genetically heterogenous, all currently identified causative genes appear to be associated with mitochondrial organization and function. However, it is unclear why RGCs are particularly vulnerable to mitochondrial aberration. Despite the relatively high prevalence of this disorder, there are currently no approved treatments. Combined with the lack of knowledge concerning the mechanisms through which aberrant mitochondrial function leads to RGC death, there remains a clear need for further research to identify the underlying mechanisms and develop treatments for this condition. This review summarizes the genes known to be causative of autosomal OA and the mitochondrial dysfunction caused by pathogenic mutations. Furthermore, we discuss the suitability of available in vivo models for autosomal OA with regards to both treatment development and furthering the understanding of autosomal OA pathology.
Collapse
Affiliation(s)
- Elin L. Strachan
- UCD Conway Institute, University College Dublin, Dublin, Ireland
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Delphi Mac White-Begg
- UCD Conway Institute, University College Dublin, Dublin, Ireland
- UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - John Crean
- UCD Conway Institute, University College Dublin, Dublin, Ireland
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- UCD Diabetes Complications Research Centre, Conway Institute of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Alison L. Reynolds
- UCD Conway Institute, University College Dublin, Dublin, Ireland
- UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - Breandán N. Kennedy
- UCD Conway Institute, University College Dublin, Dublin, Ireland
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Niamh C. O’Sullivan
- UCD Conway Institute, University College Dublin, Dublin, Ireland
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| |
Collapse
|
5
|
Guehlouz K, Foulonneau T, Amati-Bonneau P, Charif M, Colin E, Bris C, Desquiret-Dumas V, Milea D, Gohier P, Procaccio V, Bonneau D, den Dunnen JT, Lenaers G, Reynier P, Ferré M. ACO2 clinicobiological dataset with extensive phenotype ontology annotation. Sci Data 2021; 8:205. [PMID: 34354088 PMCID: PMC8342444 DOI: 10.1038/s41597-021-00984-x] [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] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 06/22/2021] [Indexed: 11/08/2022] Open
Abstract
Pathogenic variants of the aconitase 2 gene (ACO2) are responsible for a broad clinical spectrum involving optic nerve degeneration, ranging from isolated optic neuropathy with recessive or dominant inheritance, to complex neurodegenerative syndromes with recessive transmission. We created the first public locus-specific database (LSDB) dedicated to ACO2 within the "Global Variome shared LOVD" using exclusively the Human Phenotype Ontology (HPO), a standard vocabulary for describing phenotypic abnormalities. All the variants and clinical cases listed in the literature were incorporated into the database, from which we produced a dataset. We followed a rational and comprehensive approach based on the HPO thesaurus, demonstrating that ACO2 patients should not be classified separately between isolated and syndromic cases. Our data highlight that certain syndromic patients do not have optic neuropathy and provide support for the classification of the recurrent pathogenic variants c.220C>G and c.336C>G as likely pathogenic. Overall, our data records demonstrate that the clinical spectrum of ACO2 should be considered as a continuum of symptoms and refines the classification of some common variants.
Collapse
Affiliation(s)
- Khadidja Guehlouz
- Département d'Ophtalmologie, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Thomas Foulonneau
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France
| | - Patrizia Amati-Bonneau
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France
- Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Majida Charif
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France
- Genetics, and immuno-cell therapy Team, Mohammed First University, Oujda, Morocco
| | - Estelle Colin
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France
- Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Céline Bris
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France
- Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Valérie Desquiret-Dumas
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France
- Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Dan Milea
- Singapore National Eye Centre, Singapore Eye Research Institute, Duke-NUS, Singapore
| | - Philippe Gohier
- Département d'Ophtalmologie, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Vincent Procaccio
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France
- Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Dominique Bonneau
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France
- Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Johan T den Dunnen
- Human Genetics and Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Guy Lenaers
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France
| | - Pascal Reynier
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France
- Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Marc Ferré
- Unité Mixte de Recherche MITOVASC, CNRS 6015/INSERM 1083, Université d'Angers, Angers, France.
| |
Collapse
|
6
|
Charif M, Gueguen N, Ferré M, Elkarhat Z, Khiati S, LeMao M, Chevrollier A, Desquiret-Dumas V, Goudenège D, Bris C, Kane S, Alban J, Chupin S, Wetterwald C, Caporali L, Tagliavini F, LaMorgia C, Carbonelli M, Jurkute N, Barakat A, Gohier P, Verny C, Barth M, Procaccio V, Bonneau D, Zanlonghi X, Meunier I, Weisschuh N, Schimpf-Linzenbold S, Tonagel F, Kellner U, Yu-Wai-Man P, Carelli V, Wissinger B, Amati-Bonneau P, Reynier P, Lenaers G. Dominant ACO2 mutations are a frequent cause of isolated optic atrophy. Brain Commun 2021; 3:fcab063. [PMID: 34056600 PMCID: PMC8152918 DOI: 10.1093/braincomms/fcab063] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/11/2021] [Accepted: 02/12/2021] [Indexed: 12/24/2022] Open
Abstract
Biallelic mutations in ACO2, encoding the mitochondrial aconitase 2, have been identified in individuals with neurodegenerative syndromes, including infantile cerebellar retinal degeneration and recessive optic neuropathies (locus OPA9). By screening European cohorts of individuals with genetically unsolved inherited optic neuropathies, we identified 61 cases harbouring variants in ACO2, among whom 50 carried dominant mutations, emphasizing for the first time the important contribution of ACO2 monoallelic pathogenic variants to dominant optic atrophy. Analysis of the ophthalmological and clinical data revealed that recessive cases are affected more severely than dominant cases, while not significantly earlier. In addition, 27% of the recessive cases and 11% of the dominant cases manifested with extraocular features in addition to optic atrophy. In silico analyses of ACO2 variants predicted their deleterious impacts on ACO2 biophysical properties. Skin derived fibroblasts from patients harbouring dominant and recessive ACO2 mutations revealed a reduction of ACO2 abundance and enzymatic activity, and the impairment of the mitochondrial respiration using citrate and pyruvate as substrates, while the addition of other Krebs cycle intermediates restored a normal respiration, suggesting a possible short-cut adaptation of the tricarboxylic citric acid cycle. Analysis of the mitochondrial genome abundance disclosed a significant reduction of the mitochondrial DNA amount in all ACO2 fibroblasts. Overall, our data position ACO2 as the third most frequently mutated gene in autosomal inherited optic neuropathies, after OPA1 and WFS1, and emphasize the crucial involvement of the first steps of the Krebs cycle in the maintenance and survival of retinal ganglion cells.
Collapse
Affiliation(s)
- Majida Charif
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Genetics and Immuno-Cell Therapy Team, Mohammed First University, Oujda, Morocco
| | - Naïg Gueguen
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | - Marc Ferré
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Zouhair Elkarhat
- Laboratory of Genomics and Human Genetics, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Salim Khiati
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Morgane LeMao
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Arnaud Chevrollier
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Valerie Desquiret-Dumas
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | - David Goudenège
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | - Céline Bris
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | - Selma Kane
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Jennifer Alban
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Stéphanie Chupin
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | | | - Leonardo Caporali
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Francesca Tagliavini
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Chiara LaMorgia
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | - Michele Carbonelli
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Neringa Jurkute
- Moorfields Eye Hospital, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
- Cambridge Eye Unit, Addenbrooke’s Hospital, Cambridge University Hospitals, Cambridge, UK
- Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Abdelhamid Barakat
- Laboratory of Genomics and Human Genetics, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Philippe Gohier
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
| | - Christophe Verny
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Centre de référence des Maladies Neurogénétiques, Département de Neurologie, CHU d’Angers, Angers, France
| | - Magalie Barth
- Department of Pediatrics, Competence Center of Inherited Metabolic Disorders, Angers Hospital, Angers, France
| | - Vincent Procaccio
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | - Dominique Bonneau
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | | | - Isabelle Meunier
- National Center for Rare Diseases, Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Nicole Weisschuh
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | | | - Felix Tonagel
- Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Ulrich Kellner
- Rare Retinal Disease Center, AugenZentrum Siegburg, MVZ ADTC Siegburg GmbH, Siegburg, Germany
- RetinaScience, 53113 Bonn, Germany
| | - Patrick Yu-Wai-Man
- Moorfields Eye Hospital, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
- Cambridge Eye Unit, Addenbrooke’s Hospital, Cambridge University Hospitals, Cambridge, UK
- Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Valerio Carelli
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | - Bernd Wissinger
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Patrizia Amati-Bonneau
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | - Pascal Reynier
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Département de Biochimie et Génétique, CHU d'Angers, Angers, France
| | | | - Guy Lenaers
- Université Angers, MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, SFR ICAT, Angers, France
- Correspondence to: Guy Lenaers MitoLab Team, Mitochondrial Medicine Research Centre, MitoVasc Unit, Université d'Angers UMR CNRS 6015, INSERM U1083, CHU Bât IRIS/IBS, Rue des Capucins 49933 Angers cedex 9, France E-mail:
| |
Collapse
|
7
|
Haploinsufficiency due to a novel ACO2 deletion causes mitochondrial dysfunction in fibroblasts from a patient with dominant optic nerve atrophy. Sci Rep 2020; 10:16736. [PMID: 33028849 PMCID: PMC7541502 DOI: 10.1038/s41598-020-73557-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 09/02/2020] [Indexed: 01/20/2023] Open
Abstract
ACO2 is a mitochondrial protein, which is critically involved in the function of the tricarboxylic acid cycle (TCA), the maintenance of iron homeostasis, oxidative stress defense and the integrity of mitochondrial DNA (mtDNA). Mutations in the ACO2 gene were identified in patients suffering from a broad range of symptoms, including optic nerve atrophy, cortical atrophy, cerebellar atrophy, hypotonia, seizures and intellectual disabilities. In the present study, we identified a heterozygous 51 bp deletion (c.1699_1749del51) in ACO2 in a family with autosomal dominant inherited isolated optic atrophy. A complementation assay using aco1-deficient yeast revealed a growth defect for the mutant ACO2 variant substantiating a pathogenic effect of the deletion. We used patient-derived fibroblasts to characterize cellular phenotypes and found a decrease of ACO2 protein levels, while ACO2 enzyme activity was not affected compared to two age- and gender-matched control lines. Several parameters of mitochondrial function, including mitochondrial morphology, mitochondrial membrane potential or mitochondrial superoxide production, were not changed under baseline conditions. However, basal respiration, maximal respiration, and spare respiratory capacity were reduced in mutant cells. Furthermore, we observed a reduction of mtDNA copy number and reduced mtDNA transcription levels in ACO2-mutant fibroblasts. Inducing oxidative stress led to an increased susceptibility for cell death in ACO2-mutant fibroblasts compared to controls. Our study reveals that a monoallelic mutation in ACO2 is sufficient to promote mitochondrial dysfunction and increased vulnerability to oxidative stress as main drivers of cell death related to optic nerve atrophy.
Collapse
|
8
|
Park JS, Kim MJ, Kim SY, Lim BC, Kim KJ, Seong MW, Lee JS, Chae JH. Novel compound heterozygous ACO2 mutations in an infant with progressive encephalopathy: A newly identified neurometabolic syndrome. Brain Dev 2020; 42:680-685. [PMID: 32713659 DOI: 10.1016/j.braindev.2020.07.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 06/18/2020] [Accepted: 07/06/2020] [Indexed: 11/17/2022]
Abstract
BACKGROUND The ACO2 gene encodes mitochondrial aconitase, the enzyme involved in the second step of the tricarboxylic acid cycle, catalyzing the interconversion of citrate into isocitrate. To date, fewer than 20 families harboring ACO2 mutations have been identified since the first report of a neurodegenerative disorder such as infantile cerebellar retinal degeneration in 2012. Subsequently, various phenotypes, from isolated optic atrophy to spastic paraplegia, have been recognized. Here, we report a case of a newly identified neurometabolic syndrome resulting from novel ACO2 mutations, which expands the genetic spectrum and increases clinical awareness in real-world clinical practice. CASE REPORT A 2-month-old boy presented with hypotonia, cyanosis, and abnormal eye movements. He had severe psychomotor retardation and intractable seizures manifesting with cyanotic episodes. Diffuse cerebral atrophy and bilateral optic atrophy were noted without cerebellar atrophy. With unremarkable results on comprehensive diagnostic work-up and targeted genetic tests, whole exome sequencing revealed novel compound heterozygous variants in ACO2 (p.Met393Ile and p.Cys448Ser), which were confirmed by Sanger sequencing. Although no definitive signs suggestive of metabolic disturbances or mitochondrial dysfunction have been noted in patients with ACO2 mutations to date, elevated plasma glutamate levels were noted in our case. CONCLUSION A high index of clinical suspicion and awareness of this disease may aid in the diagnosis of cases with unknown neurodegenerative diseases, facilitated by deep sequencing.
Collapse
Affiliation(s)
- Ji Soo Park
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, Republic of Korea
| | - Man Jin Kim
- Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Republic of Korea; Rare Disease Center, Seoul National University Hospital, Seoul, Republic of Korea
| | - Soo Yeon Kim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, Republic of Korea; Pediatric Clinical Neuroscience Center, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, Republic of Korea
| | - Byung Chan Lim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, Republic of Korea; Pediatric Clinical Neuroscience Center, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, Republic of Korea
| | - Ki Joong Kim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, Republic of Korea; Pediatric Clinical Neuroscience Center, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, Republic of Korea
| | - Moon-Woo Seong
- Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Republic of Korea; Rare Disease Center, Seoul National University Hospital, Seoul, Republic of Korea
| | - Jin Sook Lee
- Department of Pediatrics, Department of Genome Medicine and Science, Gil Medical Center, Gachon University College of Medicine, Incheon, Republic of Korea.
| | - Jong-Hee Chae
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, Republic of Korea; Rare Disease Center, Seoul National University Hospital, Seoul, Republic of Korea; Pediatric Clinical Neuroscience Center, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, Republic of Korea.
| |
Collapse
|
9
|
Gibson S, Azamian MS, Lalani SR, Yen KG, Sutton VR, Scott DA. Recessive ACO2 variants as a cause of isolated ophthalmologic phenotypes. Am J Med Genet A 2020; 182:1960-1966. [PMID: 32449285 DOI: 10.1002/ajmg.a.61634] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 04/15/2020] [Accepted: 05/04/2020] [Indexed: 12/20/2022]
Abstract
The mitochondrial aconitase gene (ACO2) encodes an enzyme that catalyzes the conversion of citrate to isocitrate in the tricarboxylic acid cycle. Biallelic variants in ACO2 are purported to cause two distinct disorders: infantile cerebellar-retinal degeneration (ICRD) which is characterized by CNS abnormalities, neurodevelopmental phenotypes, optic atrophy and retinal degeneration; and optic atrophy 9 (OPA9), characterized by isolated ophthalmologic phenotypes including optic atrophy and low vision. However, some doubt remains as to whether biallelic ACO2 variants can cause isolated ophthalmologic phenotypes. A review of the literature revealed five individuals from three families who carry biallelic ACO2 variants whose phenotypes are consistent with OPA9. Here, we describe a brother and sister with OPA9 who are compound heterozygous for novel missense variants in ACO2; c.[487G>T];[1894G>A], p.[(Val163Leu)];[(Val632Met)]. A review of pathogenic ACO2 variants revealed that those associated with OPA9 are distinct from those associated with ICRD. Missense variants associated with either OPA9 or ICRD do not cluster in distinct ACO2 domains, making it difficult to predict the severity of a variant based on position alone. We conclude that biallelic variants in ACO2 can cause the milder OPA9 phenotype, and that the OPA9-related ACO2 variants identified to date are distinct from those that cause ICRD.
Collapse
Affiliation(s)
- Shelley Gibson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Mahshid S Azamian
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Texas Children's Hospital, Houston, Texas, USA
| | - Seema R Lalani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Texas Children's Hospital, Houston, Texas, USA
| | - Kimberly G Yen
- Texas Children's Hospital, Houston, Texas, USA
- Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, USA
| | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Texas Children's Hospital, Houston, Texas, USA
| | - Daryl A Scott
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Texas Children's Hospital, Houston, Texas, USA
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, USA
| |
Collapse
|
10
|
An evaluation of genetic causes and environmental risks for bilateral optic atrophy. PLoS One 2019; 14:e0225656. [PMID: 31765440 PMCID: PMC6876833 DOI: 10.1371/journal.pone.0225656] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 11/08/2019] [Indexed: 12/15/2022] Open
Abstract
Purpose To assess the clinical utility of next-generation sequencing (NGS) for the diagnosis of patients with optic atrophy (OA). Design Retrospective cohort study. Methods 97 patients were referred to the McMaster University Medical Center (Hamilton, Ontario) for evaluation of bilateral OA. All patients were sent for NGS including a 22 nuclear gene panel and/or complete mitochondrial DNA (mtDNA) sequencing. Positive genetic test results and abnormal vibration sensation were compared in patients +/- environmental exposures or a family history. Results 19/94 (20.2%) had a positive nuclear variant, of which 15/19 (78.9%) were in the OPA1 gene. No positive mtDNA variants were identified. The detection of a positive genetic variant was significantly different in patients who reported excessive ethanol use, but not in patients who smoke (0/19 (0%) vs. 19/78 (24.4%), P = 0.0164 and 4/22 (18.2%) vs. 15/74 (20.3%), P = 0.829, respectively). Patients with a positive family history were more likely to have a positive genetic variant compared to patients with a negative family history (P = 0.0112). There were significantly more excessive drinkers with an abnormal vibration sensation (P = 0.026), and with a similar trend in smokers (P = 0.074). Conclusions All positive genetic variants were identified in nuclear genes. We identified a potential independent pathophysiological link between a history of excessive ethanol consumption and bilateral OA. Further investigations should evaluate and identify potential environmental risk factors for OA.
Collapse
|
11
|
Sharkia R, Wierenga KJ, Kessel A, Azem A, Bertini E, Carrozzo R, Torraco A, Goffrini P, Ceccatelli Berti C, McCormick ME, Plecko B, Klein A, Abela L, Hengel H, Schöls L, Shalev S, Khayat M, Mahajnah M, Spiegel R. Clinical, radiological, and genetic characteristics of 16 patients with ACO2 gene defects: Delineation of an emerging neurometabolic syndrome. J Inherit Metab Dis 2019; 42:264-275. [PMID: 30689204 DOI: 10.1002/jimd.12022] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 12/07/2018] [Indexed: 12/26/2022]
Abstract
Mitochondrial aconitase is the second enzyme in the tricarboxylic acid (TCA) cycle catalyzing the interconversion of citrate into isocitrate and encoded by the nuclear gene ACO2. A homozygous pathogenic variant in the ACO2 gene was initially described in 2012 resulting in a novel disorder termed "infantile cerebellar retinal degeneration" (ICRD, OMIM#614559). Subsequently, additional studies reported patients with pathogenic ACO2 variants, further expanding the genetic and clinical spectrum of this disorder to include milder and later onset manifestations. Here, we report an international multicenter cohort of 16 patients (of whom 7 are newly diagnosed) with biallelic pathogenic variants in ACO2 gene. Most patients present in early infancy with severe truncal hypotonia, truncal ataxia, variable seizures, evolving microcephaly, and ophthalmological abnormalities of which the most dominant are esotropia and optic atrophy with later development of retinal dystrophy. Most patients remain nonambulatory and do no acquire any language, but a subgroup of patients share a more favorable course. Brain magnetic resonance imaging (MRI) is typically normal within the first months but global atrophy gradually develops affecting predominantly the cerebellum. Ten of our patients were homozygous to the previously reported c.336C>G founder mutation while the other six patients were all compound heterozygotes displaying 10 novel mutations of whom 2 were nonsense predicting a deleterious effect on enzyme function. Structural protein modeling predicted significant impairment in aconitase substrate binding in the additional missense mutations. This study provides the most extensive cohort of patients and further delineates the clinical, radiological, biochemical, and molecular features of ACO2 deficiency.
Collapse
Affiliation(s)
- Rajech Sharkia
- Unit of Human Biology and Genetics, The Triangle Regional Research and Development Center, Kafr Qari, Israel
- Unit of Nature Science, Beit-Berl Academic College, Beit-Berl, Israel
| | - Klaas J Wierenga
- Department of Pediatrics, Oklahoma University Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Amit Kessel
- Department of Biochemistry and Molecular Biology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Abdussalam Azem
- Department of Biochemistry and Molecular Biology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Enrico Bertini
- Unit of Muscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesu' Children's Research Hospital, Rome, Italy
| | - Rosalba Carrozzo
- Unit of Muscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesu' Children's Research Hospital, Rome, Italy
| | - Alessandra Torraco
- Unit of Muscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesu' Children's Research Hospital, Rome, Italy
| | - Paola Goffrini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Camilla Ceccatelli Berti
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - M Eileen McCormick
- Department of Pediatrics, Oakland University William Beaumont School of Medicine, Rochester, Michigan
| | - Barbara Plecko
- Division of Child Neurology, University Children's Hospital Zurich, Zurich, Switzerland
- Department of Pediatrics, Medical University of Graz, Graz, Austria
| | - Andrea Klein
- Department of Pediatric Neurology, University Children's Hospital Basel and University Children's Hospital, Bern, Switzerland
| | - Lucia Abela
- Molecular Neurosciences, Developmental Neuroscience, UCL Institute of Child Health, London, UK
| | - Holger Hengel
- German Research Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
- Department of Neurodegenerative Diseases and Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Ludger Schöls
- German Research Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
- Department of Neurodegenerative Diseases and Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Stavit Shalev
- Rappaport Faculty of Medicine, Technion- Israel Institute of Technology, Haifa, Israel
- Institute of Medical Genetics, Emek Medical Center, Afula, Israel
| | - Morad Khayat
- Institute of Medical Genetics, Emek Medical Center, Afula, Israel
| | - Muhammad Mahajnah
- Rappaport Faculty of Medicine, Technion- Israel Institute of Technology, Haifa, Israel
- Child Neurology and Development Center, Hillel-Yaffe Medical Center, Hadera, Israel
| | - Ronen Spiegel
- Rappaport Faculty of Medicine, Technion- Israel Institute of Technology, Haifa, Israel
- Department of Pediatrics B, Emek Medical Center, Afula, Israel
| |
Collapse
|