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Ververis A, Dajani R, Koutsou P, Aloqaily A, Nelson-Williams C, Loring E, Arafat A, Mubaidin AF, Horany K, Bader MB, Al-Baho Y, Ali B, Muhtaseb A, DeSpenza T, Al-Qudah AA, Middleton LT, Zamba-Papanicolaou E, Lifton R, Christodoulou K. Distal hereditary motor neuronopathy of the Jerash type is caused by a novel SIGMAR1 c.500A>T missense mutation. J Med Genet 2020; 57:178-186. [PMID: 31511340 PMCID: PMC7042970 DOI: 10.1136/jmedgenet-2019-106108] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [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: 02/25/2019] [Revised: 08/06/2019] [Accepted: 08/10/2019] [Indexed: 12/11/2022]
Abstract
BACKGROUND Distal hereditary motor neuronopathies (dHMN) are a group of genetic disorders characterised by motor neuron degeneration leading to muscle weakness that are caused by mutations in various genes. HMNJ is a distinct form of the disease that has been identified in patients from the Jerash region of Jordan. Our aim was to identify and characterise the genetic cause of HMNJ. METHODS We used whole exome and Sanger sequencing to identify a novel genetic variant associated with the disease and then carried out immunoblot, immunofluorescence and apoptosis assays to extract functional data and clarify the effect of this novel SIGMAR1 mutation. Physical and neurological examinations were performed on selected patients and unaffected individuals in order to re-evaluate clinical status of patients 20 years after the initial description of HMNJ as well as to evaluate new and previously undescribed patients with HMNJ. RESULTS A homozygous missense mutation (c.500A>T, N167I) in exon 4 of the SIGMAR1 gene was identified, cosegregating with HMNJ in the 27 patients from 7 previously described consanguineous families and 3 newly ascertained patients. The mutant SIGMAR1 exhibits reduced expression, altered subcellular distribution and elevates cell death when expressed. CONCLUSION In conclusion, the homozygous SIGMAR1 c.500A>T mutation causes dHMN of the Jerash type, possibly due to a significant drop of protein levels. This finding is in agreement with other SIGMAR1 mutations that have been associated with autosomal recessive dHMN with pyramidal signs; thus, our findings further support that SIGMAR1 be added to the dHMN genes diagnostic panel.
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Affiliation(s)
- Antonis Ververis
- Neurogenetics Department, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
- Cyprus School of Molecular Medicine, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Rana Dajani
- Department of Biology and Biotechnology, Hashemite University, Zarqa, Jordan
| | - Pantelitsa Koutsou
- Neurogenetics Department, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Ahmad Aloqaily
- Department of Computer Science, Hashemite University, Zarqa, Jordan
| | | | - Erin Loring
- Department of Genetics, Yale University, New Haven, Connecticut, USA
| | - Ala Arafat
- Department of Biology and Biotechnology, Hashemite University, Zarqa, Jordan
| | | | - Khalid Horany
- Neurology Department, King Hussein Medical Centre, Amman, Jordan
| | - Mai B Bader
- College of Medicine, University of Jordan, Amman, Jordan
| | - Yaqoub Al-Baho
- College of Medicine, University of Jordan, Amman, Jordan
| | - Bushra Ali
- College of Medicine, University of Jordan, Amman, Jordan
| | - Abdurrahman Muhtaseb
- Keck School of Medicine, University of Southern California, Los Angeles, Connecticut, USA
| | - Tyrone DeSpenza
- Department of Genetics, Yale University, New Haven, Connecticut, USA
| | | | - Lefkos T Middleton
- Ageing Epidemiology (AGE) Research Unit, School of Public Health, Imperial College London, London, UK
| | - Eleni Zamba-Papanicolaou
- Cyprus School of Molecular Medicine, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
- Neurology Clinic D, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Richard Lifton
- Department of Genetics, Yale University, New Haven, Connecticut, USA
| | - Kyproula Christodoulou
- Neurogenetics Department, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
- Cyprus School of Molecular Medicine, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
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