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Rydning SL, Koht J, Sheng Y, Sowa P, Hjorthaug HS, Wedding IM, Erichsen AK, Hovden IA, Backe PH, Tallaksen CME, Vigeland MD, Selmer KK. Biallelic POLR3A variants confirmed as a frequent cause of hereditary ataxia and spastic paraparesis. Brain 2019; 142:e12. [PMID: 30847471 PMCID: PMC6439323 DOI: 10.1093/brain/awz041] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Siri L Rydning
- Institute of Clinical Medicine, University of Oslo, Norway.,Department of Neurology, Oslo University Hospital, Norway
| | - Jeanette Koht
- Institute of Clinical Medicine, University of Oslo, Norway.,Department of Neurology, Vestre Viken Hospital, Norway
| | - Ying Sheng
- Department of Medical Genetics, Oslo University Hospital, Norway
| | - Piotr Sowa
- Department of Radiology and Nuclear Medicine, Oslo University Hospital, Norway
| | | | | | | | | | - Paul H Backe
- Department of Medical Biochemistry, University of Oslo, Norway.,Department of Microbiology, Oslo University Hospital, Norway
| | | | - Magnus D Vigeland
- Institute of Clinical Medicine, University of Oslo, Norway.,Department of Medical Genetics, Oslo University Hospital, Norway
| | - Kaja K Selmer
- Department of Research and Development, Division of Neuroscience, Oslo University Hospital and the University of Oslo, Norway.,National Centre for Epilepsy, Oslo University Hospital, Norway
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Iqbal Z, Rydning SL, Wedding IM, Koht J, Pihlstrøm L, Rengmark AH, Henriksen SP, Tallaksen CME, Toft M. Correction: Targeted high throughput sequencing in hereditary ataxia and spastic paraplegia. PLoS One 2017; 12:e0186571. [PMID: 29023604 PMCID: PMC5638532 DOI: 10.1371/journal.pone.0186571] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Rydning SL, Backe PH, Sousa MML, Iqbal Z, Øye AM, Sheng Y, Yang M, Lin X, Slupphaug G, Nordenmark TH, Vigeland MD, Bjørås M, Tallaksen CM, Selmer KK. Novel UCHL1 mutations reveal new insights into ubiquitin processing. Hum Mol Genet 2017; 26:1031-1040. [PMID: 28007905 DOI: 10.1093/hmg/ddw391] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 11/08/2016] [Indexed: 12/30/2022] Open
Abstract
Recessive loss of function of the neuronal ubiquitin hydrolase UCHL1 has been implicated in early-onset progressive neurodegeneration (MIM no. 615491), so far only in one family. In this study a second family is characterized, and the functional consequences of the identified mutations in UCHL1 are explored. Three siblings developed childhood-onset optic atrophy, followed by spasticity and ataxia. Whole exome sequencing identified compound heterozygous variants in UCHL1, c.533G > A (p.Arg178Gln) and c.647C > A (p.Ala216Asp), cosegregating with the phenotype. Enzymatic activity of purified recombinant proteins analysed by ubiquitin hydrolase assays showed a 4-fold increased hydrolytic activity of the recombinant UCHL1 mutant Arg178Gln compared to wild type, whereas the Ala216Asp protein was insoluble. Structural 3D analysis of UCHL1 by computer modelling suggests that Arg178 is a rate-controlling residue in catalysis which is partly abolished in the Arg178Gln mutant and, consequently, the Arg178Gln mutant increases the enzymatic turnover. UCHL1 protein levels in fibroblasts measured by targeted mass spectrometry showed a total amount of UCHL1 in control fibroblasts about 4-fold higher than in the patients. Hence, studies of the identified missense variants reveal surprisingly different functional consequences as the insoluble Ala216Asp variant leads to loss of function, whereas the Arg178Gln leads to increased enzyme activity. The reported patients have remarkably preserved cognition, and we propose that the increased enzyme activity of the Arg178Gln variant offers a protective effect on cognitive function. This study establishes the importance of UCHL1 in neurodegeneration, provides new mechanistic insight about ubiquitin processing, and underlines the complexity of the different roles of UCHL1.
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Affiliation(s)
- Siri L Rydning
- Department of Neurology, Oslo University Hospital, Norway.,Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Norway
| | - Paul H Backe
- Department of Microbiology, Oslo University Hospital, Norway.,Department of Medical Biochemistry, University of Oslo, Norway
| | - Mirta M L Sousa
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Zafar Iqbal
- Department of Neurology, Oslo University Hospital, Norway
| | - Ane-Marte Øye
- Department of Medical Genetics, Oslo University Hospital and University of Oslo, Norway
| | - Ying Sheng
- Department of Medical Genetics, Oslo University Hospital and University of Oslo, Norway
| | - Mingyi Yang
- Department of Microbiology, Oslo University Hospital, Norway.,Department of Medical Biochemistry, University of Oslo, Norway
| | - Xiaolin Lin
- Department of Microbiology, Oslo University Hospital, Norway.,Department of Medical Biochemistry, University of Oslo, Norway
| | - Geir Slupphaug
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,Proteomics and Metabolomics Core Facility (PROMEC), NTNU, Trondheim, Norway
| | - Tonje H Nordenmark
- Department of Physical Medicine and Rehabilitation, Oslo University Hospital, Norway
| | - Magnus D Vigeland
- Department of Medical Genetics, Oslo University Hospital and University of Oslo, Norway
| | - Magnar Bjørås
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Norway.,Department of Microbiology, Oslo University Hospital, Norway.,Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Chantal M Tallaksen
- Department of Neurology, Oslo University Hospital, Norway.,Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Norway
| | - Kaja K Selmer
- Department of Medical Genetics, Oslo University Hospital and University of Oslo, Norway
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Rydning SL, Backe PH, Sousa MML, Iqbal Z, Øye AM, Sheng Y, Yang M, Lin X, Slupphaug G, Nordenmark TH, Vigeland MD, Bjørås M, Tallaksen CM, Selmer KK. Novel UCHL1 mutations reveal new insights into ubiquitin processing. Hum Mol Genet 2017; 26:1217-1218. [DOI: 10.1093/hmg/ddx072] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Iqbal Z, Rydning SL, Wedding IM, Koht J, Pihlstrøm L, Rengmark AH, Henriksen SP, Tallaksen CME, Toft M. Targeted high throughput sequencing in hereditary ataxia and spastic paraplegia. PLoS One 2017; 12:e0174667. [PMID: 28362824 PMCID: PMC5375131 DOI: 10.1371/journal.pone.0174667] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 03/13/2017] [Indexed: 12/24/2022] Open
Abstract
Hereditary ataxia and spastic paraplegia are heterogeneous monogenic neurodegenerative disorders. To date, a large number of individuals with such disorders remain undiagnosed. Here, we have assessed molecular diagnosis by gene panel sequencing in 105 early and late-onset hereditary ataxia and spastic paraplegia probands, in whom extensive previous investigations had failed to identify the genetic cause of disease. Pathogenic and likely-pathogenic variants were identified in 20 probands (19%) and variants of uncertain significance in ten probands (10%). Together these accounted for 30 probands (29%) and involved 18 different genes. Among several interesting findings, dominantly inherited KIF1A variants, p.(Val8Met) and p.(Ile27Thr) segregated in two independent families, both presenting with a pure spastic paraplegia phenotype. Two homozygous missense variants, p.(Gly4230Ser) and p.(Leu4221Val) were found in SACS in one consanguineous family, presenting with spastic ataxia and isolated cerebellar atrophy. The average disease duration in probands with pathogenic and likely-pathogenic variants was 31 years, ranging from 4 to 51 years. In conclusion, this study confirmed and expanded the clinical phenotypes associated with known disease genes. The results demonstrate that gene panel sequencing and similar sequencing approaches can serve as efficient diagnostic tools for different heterogeneous disorders. Early use of such strategies may help to reduce both costs and time of the diagnostic process.
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Affiliation(s)
- Zafar Iqbal
- Department of Neurology, Oslo University Hospital, Oslo, Norway
- * E-mail:
| | - Siri L. Rydning
- Department of Neurology, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Iselin M. Wedding
- Department of Neurology, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Jeanette Koht
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Neurology, Drammen Hospital, Vestre Viken Hospital Trust, Drammen, Norway
| | - Lasse Pihlstrøm
- Department of Neurology, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | | | | | - Chantal M. E. Tallaksen
- Department of Neurology, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Mathias Toft
- Department of Neurology, Oslo University Hospital, Oslo, Norway
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Rydning SL, Wedding IM, Koht J, Chawla M, Øye AM, Sheng Y, Vigeland MD, Selmer KK, Tallaksen CME. A founder mutation p.H701P identified as a major cause of SPG7 in Norway. Eur J Neurol 2016; 23:763-71. [PMID: 26756429 DOI: 10.1111/ene.12937] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 11/04/2015] [Indexed: 12/14/2022]
Abstract
BACKGROUND AND PURPOSE SPG7 is one of the most common forms of autosomal recessive hereditary spastic paraplegia. The phenotype has been shown to be heterogeneous, varying from a complex spastic ataxia to pure spastic paraplegia or pure ataxia. The aim of this study was to clinically and genetically characterize patients with SPG7 in Norway. METHODS Six Norwegian families with a clinical diagnosis of hereditary spastic paraplegia were diagnosed with SPG7 through Sanger sequencing and whole-exome sequencing. Haplotypes were established to identify a possible founder mutation. All patients were thoroughly examined and the clinical and molecular findings are described. RESULTS The core phenotype was spastic paraparesis with ataxia, bladder disturbances and progressive external ophthalmoplegia. The variant p.H701P was identified in homozygous state in one family and in compound heterozygous state in three families. Haplotype analysis of seven surrounding single nucleotide polymorphisms supports that this variant resides on a founder haplotype. Four of the families were compound heterozygous for the previously well-described p.A510V variant. CONCLUSION SPG7 is a common subgroup of hereditary spinocerebellar disorders in Norway. The broad phenotype in the Norwegian SPG7 population illustrates the challenges with the traditional dichotomous classification of hereditary spinocerebellar disorders into hereditary spastic paraplegia or hereditary ataxia. A Norwegian founder mutation p.H701P was identified in four out of six families, making it a major cause of SPG7 in Norway.
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Affiliation(s)
- S L Rydning
- Department of Neurology, Oslo University Hospital, Norway.,Institute of Clinical Medicine, University of Oslo, Norway
| | - I M Wedding
- Department of Neurology, Oslo University Hospital, Norway.,Institute of Clinical Medicine, University of Oslo, Norway
| | - J Koht
- Department of Neurology, Drammen Hospital, Vestre Viken Health Trust, Norway
| | - M Chawla
- Department of Radiology and Nuclear Medicine, Oslo University Hospital, Norway
| | - A-M Øye
- Department of Medical Genetics, Oslo University Hospital and University of Oslo, Norway
| | - Y Sheng
- Department of Medical Genetics, Oslo University Hospital and University of Oslo, Norway
| | - M D Vigeland
- Department of Medical Genetics, Oslo University Hospital and University of Oslo, Norway
| | - K K Selmer
- Department of Medical Genetics, Oslo University Hospital and University of Oslo, Norway
| | - C M E Tallaksen
- Department of Neurology, Oslo University Hospital, Norway.,Institute of Clinical Medicine, University of Oslo, Norway
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