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Diarra S, Coulibaly T, Dembélé K, Ngouth N, Cissé L, Diallo SH, Ouologuem M, Diallo S, Coulibaly O, Bagayoko K, Coulibaly D, Simaga A, Sango HA, Traoré M, Jacobson S, Fischbeck KH, Landouré G, Guinto CO. Hereditary spastic paraplegia in Mali: epidemiological and clinical features. Acta Neurol Belg 2023; 123:2155-2165. [PMID: 36396882 DOI: 10.1007/s13760-022-02113-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 10/03/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND AND PURPOSE Hereditary spastic paraplegia (HSP) is a group of neurodegenerative diseases divided into pure and complex forms, with spasticity in lower limbs only, or associated with other neurologic and non-neurologic manifestations, respectively. Although widely reported in other populations, very little data exist in sub-Saharan Africa. METHODS Patients with neurodegenerative features were evaluated over a 19-month period at the Department of Neurology, Teaching Hospital of Point "G", Bamako, Mali. The diagnosis of HSP was considered based on family history and the absence of other known non-genetic causes. Genetic analysis including candidate gene and whole exome sequencing was performed and variant pathogenicity was tested using prediction tools and ACMG guidelines. RESULTS Of the 170 families with hereditary neurological disorders enrolled, 16 had features consistent with HSP, a frequency of 9%. The average age of onset was 14.7 years with 46% starting before age 6. The male/female ratio was 2.6:1. Complex forms were seen in 75% of cases, and pure forms in 25%. Pyramidal findings were present in all patients. Associated features included mental retardation, peripheral neuropathy, epilepsy, oculomotor impairment and urinary urgency. Most patients were treated with a muscle relaxant and physical therapy, and restorative surgery was done in one. Genetic testing identified novel variants in three families (19%). CONCLUSION This study confirms the clinical variability of HSPs and adds African data to the current literature.
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Affiliation(s)
- Salimata Diarra
- Faculté de Médecine et d'Odontostomatologie, USTTB, Bamako, Mali
- Neurogenetics Branch, NINDS, NIH, Bethesda, MD, USA
| | - Thomas Coulibaly
- Faculté de Médecine et d'Odontostomatologie, USTTB, Bamako, Mali
- Service de Neurologie, CHU du Point "G", Bamako, Mali
| | | | - Nyater Ngouth
- Neuroimmunology Division, NINDS, NIH, Bethesda, MD, USA
| | - Lassana Cissé
- Service de Neurologie, CHU du Point "G", Bamako, Mali
| | - Seybou H Diallo
- Faculté de Médecine et d'Odontostomatologie, USTTB, Bamako, Mali
- Service de Neurologie, CHU de Gabriel Touré, Bamako, Mali
| | | | | | - Oumar Coulibaly
- Service de Chirugie Pédiatrique, CHU de Gabriel Touré, Bamako, Mali
| | - Koumba Bagayoko
- Faculté de Médecine et d'Odontostomatologie, USTTB, Bamako, Mali
| | | | - Assiatou Simaga
- Institut d'Ophtalmologie Tropicale de l'Afrique (IOTA), Bamako, Mali
| | - Hammadoun A Sango
- DER de Santé Publique, Faculté de Médecine et d'Odontostomatologie, Bamako, Mali
| | - Mahamadou Traoré
- Service de Cytogénétique et de la Réproduction Biologique, INSP, Bamako, Mali
| | | | | | - Guida Landouré
- Faculté de Médecine et d'Odontostomatologie, USTTB, Bamako, Mali.
- Neurogenetics Branch, NINDS, NIH, Bethesda, MD, USA.
- Service de Neurologie, CHU du Point "G", Bamako, Mali.
| | - Cheick O Guinto
- Faculté de Médecine et d'Odontostomatologie, USTTB, Bamako, Mali
- Service de Neurologie, CHU du Point "G", Bamako, Mali
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A novel insertion mutation in atlastin 1 is associated with spastic quadriplegia, increased membrane tethering, and aberrant conformational switching. J Biol Chem 2021; 298:101438. [PMID: 34808209 PMCID: PMC8688574 DOI: 10.1016/j.jbc.2021.101438] [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: 07/06/2021] [Revised: 11/07/2021] [Accepted: 11/17/2021] [Indexed: 11/20/2022] Open
Abstract
Hereditary spastic paraplegia (HSP) comprises a heterogeneous group of neuropathies affecting upper motor neurons and causing progressive gait disorder. Mutations in the gene SPG3A/atlastin-1 (ATL1), encoding a dynamin superfamily member, which utilizes the energy from GTP hydrolysis for membrane tethering and fusion to promote the formation of a highly branched, smooth endoplasmic reticulum (ER), account for approximately 10% of all HSP cases. The continued discovery and characterization of novel disease mutations are crucial for our understanding of HSP pathogenesis and potential treatments. Here, we report a novel disease-causing, in-frame insertion in the ATL1 gene, leading to inclusion of an additional asparagine residue at position 417 (N417ins). This mutation correlates with complex, early-onset spastic quadriplegia affecting all four extremities, generalized dystonia, and a thinning of the corpus callosum. We show using limited proteolysis and FRET-based studies that this novel insertion affects a region in the protein central to intramolecular interactions and GTPase-driven conformational change, and that this insertion mutation is associated with an aberrant prehydrolysis state. While GTPase activity remains unaffected by the insertion, membrane tethering is increased, indicative of a gain-of-function disease mechanism uncommon for ATL1-associated pathologies. In conclusion, our results identify a novel insertion mutation with altered membrane tethering activity that is associated with spastic quadriplegia, potentially uncovering a broad spectrum of molecular mechanisms that may affect neuronal function.
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