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Glasgow RIC, Thompson K, Barbosa IA, He L, Alston CL, Deshpande C, Simpson MA, Morris AAM, Neu A, Löbel U, Hall J, Prokisch H, Haack TB, Hempel M, McFarland R, Taylor RW. Novel GFM2 variants associated with early-onset neurological presentations of mitochondrial disease and impaired expression of OXPHOS subunits. Neurogenetics 2017; 18:227-235. [PMID: 29075935 PMCID: PMC5705740 DOI: 10.1007/s10048-017-0526-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 10/03/2017] [Indexed: 11/29/2022]
Abstract
Mitochondrial diseases are characterised by clinical, molecular and functional heterogeneity, reflecting their bi-genomic control. The nuclear gene GFM2 encodes mtEFG2, a protein with an essential role during the termination stage of mitochondrial translation. We present here two unrelated patients harbouring different and previously unreported compound heterozygous (c.569G>A, p.(Arg190Gln); c.636delA, p.(Glu213Argfs*3)) and homozygous (c.275A>C, p.(Tyr92Ser)) recessive variants in GFM2 identified by whole exome sequencing (WES) together with histochemical and biochemical findings to support the diagnoses of pathological GFM2 variants in each case. Both patients presented similarly in early childhood with global developmental delay, raised CSF lactate and abnormalities on cranial MRI. Sanger sequencing of familial samples confirmed the segregation of bi-allelic GFM2 variants with disease, while investigations into steady-state mitochondrial protein levels revealed respiratory chain subunit defects and loss of mtEFG2 protein in muscle. These data demonstrate the effects of defective mtEFG2 function, caused by previously unreported variants, confirming pathogenicity and expanding the clinical phenotypes associated with GFM2 variants.
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Affiliation(s)
- Ruth I C Glasgow
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Kyle Thompson
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Inês A Barbosa
- Department of Medical and Molecular Genetics, King's College London School of Medicine, London, UK
| | - Langping He
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Charlotte L Alston
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Charu Deshpande
- Department of Medical and Molecular Genetics, King's College London School of Medicine, London, UK
| | - Michael A Simpson
- Department of Medical and Molecular Genetics, King's College London School of Medicine, London, UK
| | - Andrew A M Morris
- Division of Evolution and Genomic Sciences, School of Biological Sciences, University of Manchester, Manchester, UK
- Alder Hey Children's Hospital NHS Foundation Trust, Liverpool, UK
| | - Axel Neu
- University Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ulrike Löbel
- Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Julie Hall
- Department of Neuroradiology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - Holger Prokisch
- Institute of Human Genetics, Helmholtz Zentrum München, Oberschleißheim, Germany
- Institute of Human Genetics, Technische Universität München, Munich, Germany
| | - Tobias B Haack
- Institute of Human Genetics, Technische Universität München, Munich, Germany
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Maja Hempel
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
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