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Neuhofer CM, Prokisch H. Digenic Inheritance in Rare Disorders and Mitochondrial Disease-Crossing the Frontier to a More Comprehensive Understanding of Etiology. Int J Mol Sci 2024; 25:4602. [PMID: 38731822 PMCID: PMC11083678 DOI: 10.3390/ijms25094602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 04/10/2024] [Accepted: 04/12/2024] [Indexed: 05/13/2024] Open
Abstract
Our understanding of rare disease genetics has been shaped by a monogenic disease model. While the traditional monogenic disease model has been successful in identifying numerous disease-associated genes and significantly enlarged our knowledge in the field of human genetics, it has limitations in explaining phenomena like phenotypic variability and reduced penetrance. Widening the perspective beyond Mendelian inheritance has the potential to enable a better understanding of disease complexity in rare disorders. Digenic inheritance is the simplest instance of a non-Mendelian disorder, characterized by the functional interplay of variants in two disease-contributing genes. Known digenic disease causes show a range of pathomechanisms underlying digenic interplay, including direct and indirect gene product interactions as well as epigenetic modifications. This review aims to systematically explore the background of digenic inheritance in rare disorders, the approaches and challenges when investigating digenic inheritance, and the current evidence for digenic inheritance in mitochondrial disorders.
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Affiliation(s)
- Christiane M. Neuhofer
- Institute of Human Genetics, University Medical Center, Technical University of Munich, Trogerstr. 32, 81675 Munich, Germany
- Institute of Neurogenomics, Computational Health Center, Helmholtz Centre Munich Neuherberg, Ingolstädter Landstraße 1, 85764 Oberschleißheim, Germany
- Institute of Human Genetics, Salzburger Landeskliniken, University Hospital of the Paracelsus Medical University, Müllner Hauptstraße 48, 5020 Salzburg, Austria
| | - Holger Prokisch
- Institute of Human Genetics, University Medical Center, Technical University of Munich, Trogerstr. 32, 81675 Munich, Germany
- Institute of Neurogenomics, Computational Health Center, Helmholtz Centre Munich Neuherberg, Ingolstädter Landstraße 1, 85764 Oberschleißheim, Germany
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Skorczyk-Werner A, Tońska K, Maciejczuk A, Nowomiejska K, Korwin M, Ołdak M, Wawrocka A, Krawczyński MR. DNAJC30 Gene Variants Are a Frequent Cause of a Rare Disease: Leber Hereditary Optic Neuropathy in Polish Patients. Int J Mol Sci 2023; 24:17496. [PMID: 38139324 PMCID: PMC10743999 DOI: 10.3390/ijms242417496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/05/2023] [Accepted: 12/06/2023] [Indexed: 12/24/2023] Open
Abstract
Leber hereditary optic neuropathy (LHON) is a rare disorder causing a sudden painless loss of visual acuity in one or both eyes, affecting young males in their second to third decade of life. The molecular background of the LHON is up to 90%, genetically defined by a point mutation in mitochondrial DNA. Recently, an autosomal recessive form of LHON (LHONAR1, arLHON) has been discovered, caused by biallelic variants in the DNAJC30 gene. This study provides the results of the DNAJC30 gene analysis in a large group of 46 Polish patients diagnosed with LHON, together with the clinical characterization of the disease. The c.152A>G (p.Tyr51Cys) substitution in the DNAJC30 gene was detected in all the patients as homozygote or compound heterozygote. Moreover, we identified one novel variant, c.293A>G, p.(Tyr98Cys), as well as two ultra-rare DNAJC30 variants: c.293A>C, p.(Tyr98Ser), identified to date only in one individual affected with LHONAR1, and c.130_131delTC (p.Ser44ValfsTer8), previously described only in two patients with Leigh syndrome. The patients presented here represent the largest group of subjects with DNAJC30 gene mutations described to date. Based on our data, the autosomal recessive form of LHON caused by DNAJC30 gene mutations is more frequent than the mitochondrial form in Polish patients. The results of our study suggest that Sanger sequencing of the single-exon DNAJC30 gene should be a method of choice applied to identify a molecular background of clinically confirmed LHON in Polish patients. This approach will help to reduce the costs of molecular testing.
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Affiliation(s)
- Anna Skorczyk-Werner
- Department of Medical Genetics, Poznan University of Medical Sciences, 60-806 Poznan, Poland; (A.W.); (M.R.K.)
| | - Katarzyna Tońska
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland; (K.T.); (A.M.)
| | - Aleksandra Maciejczuk
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland; (K.T.); (A.M.)
| | - Katarzyna Nowomiejska
- Department of General and Pediatric Ophthalmology, Medical University of Lublin, 20-079 Lublin, Poland;
| | - Magdalena Korwin
- Department of Ophthalmology, Medical University of Warsaw, 02-005 Warsaw, Poland;
| | - Monika Ołdak
- Department of Genetics, Institute of Physiology and Pathology of Hearing, 02-042 Warsaw, Poland;
- Department of Histology and Embryology, Center of Biostructure Research, Medical University of Warsaw, 02-004 Warsaw, Poland
| | - Anna Wawrocka
- Department of Medical Genetics, Poznan University of Medical Sciences, 60-806 Poznan, Poland; (A.W.); (M.R.K.)
| | - Maciej R. Krawczyński
- Department of Medical Genetics, Poznan University of Medical Sciences, 60-806 Poznan, Poland; (A.W.); (M.R.K.)
- Center for Medical Genetics GENESIS, 60-529 Poznan, Poland
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Major TC, Arany ES, Schon K, Simo M, Karcagi V, van den Ameele J, Yu Wai Man P, Chinnery PF, Olimpio C, Horvath R. Case report: Mutations in DNAJC30 causing autosomal recessive Leber hereditary optic neuropathy are common amongst Eastern European individuals. Front Neurol 2023; 14:1292320. [PMID: 38107630 PMCID: PMC10722306 DOI: 10.3389/fneur.2023.1292320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 11/03/2023] [Indexed: 12/19/2023] Open
Abstract
Background Leber Hereditary Optic Neuropathy (LHON) is the most common inherited mitochondrial disease characterized by bilateral, painless, subacute visual loss with a peak age of onset in the second to third decade. Historically, LHON was thought to be exclusively maternally inherited due to mutations in mitochondrial DNA (mtDNA); however, recent studies have identified an autosomal recessive form of LHON (arLHON) caused by point mutations in the nuclear gene, DNAJC30. Case Presentations In this study, we report the cases of three Eastern European individuals presenting with bilateral painless visual loss, one of whom was also exhibiting motor symptoms. After a several-year-long diagnostic journey, all three patients were found to carry the homozygous c.152A>G (p.Tyr51Cys) mutation in DNAJC30. This has been identified as the most common arLHON pathogenic variant and has been shown to exhibit a significant founder effect amongst Eastern European individuals. Conclusion This finding adds to the growing cohort of patients with arLHON and demonstrates the importance of DNAJC30 screening in patients with molecularly undiagnosed LHON, particularly in Eastern European individuals. It is of heightened translational significance as patients diagnosed with arLHON exhibit a better prognosis and response to therapeutic treatment with the co-enzyme Q10 analog idebenone.
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Affiliation(s)
- Toby Charles Major
- School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Eszter Sara Arany
- School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Katherine Schon
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Department of Clinical Genetics, East Anglian Medical Genetics Service, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Magdolna Simo
- University Clinic of Neurology, Semmelweis University, Budapest, Hungary
| | | | - Jelle van den Ameele
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Patrick Yu Wai Man
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- NIHR Biomedical Research Centre, Moorfields Eye Hospital & UCL Institute of Ophthalmology, London, United Kingdom
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, United Kingdom
| | - Patrick F. Chinnery
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Catarina Olimpio
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Department of Clinical Genetics, East Anglian Medical Genetics Service, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Rita Horvath
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
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