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Analyzing Mitochondrial Transport and Morphology in Human Induced Pluripotent Stem Cell-Derived Neurons in Hereditary Spastic Paraplegia
Published on: February 9, 2020
MDSGene Systematic Review of Common Forms of Dominant Hereditary Spastic Paraplegia: Novel Insights
Ce Kang1, Rajasumi Rajalingam2,3, Zachary Walls4
1Sydney Medical School, Faculty of Medicine and Health, University of Sydney, Camperdown, NSW, Australia.
Background:
Hereditary spastic paraplegia (HSP) is a neurodegenerative disorder characterized by progressive spasticity and lower limb weakness. The most common forms of autosomal dominant HSP are caused by pathogenic variants in SPAST (SPG4 or HSP-SPAST), ATL1 (SPG3A or HSP-ATL1), and REEP1 (SPG31 or HSP-REEP1).
Objectives:
We performed an MDSGene Systematic Review to determine in-depth genotype-phenotype associations and to estimate longitudinal progression, to inform prognostication and clinical trial stratification.
Methods:
We systematically collected demographic, phenotypic, and genetic data from published reports of individuals affected by these forms of HSP using the MDSGene protocol.
Results:
We reviewed 2177 affected individuals, including 1670 individuals with HSP-SPAST, 356 with HSP-ATL1 and 151 with HSP-REEP1. HSP-ATL1 was associated with an earlier age at onset compared to HSP-SPAST and HSP-REEP1. Toe-walking was more frequently reported in HSP-ATL1 (10.4%) and HSP-REEP1 (3.3%) than HSP-SPAST (0.3%). Upper limb hyperreflexia and abnormalities of bladder function were more frequent in HSP-SPAST than HSP-ATL1 or HSP-REEP1. Sufficient data was available to estimate disease progression for HSP-SPAST; this showed that Spastic Paraplegia Rating Scale (SPRS) scores increased with increasing age at examination after the age of 40 years. Truncating variants were more frequent in HSP-SPAST and HSP-REEP1 than HSP-ATL1.
Conclusion:
Overall, HSP-ATL1, HSP-SPAST and HSP-REEP1 demonstrated differences in clinical phenotypes. To our knowledge, this is the first systematic review to model longitudinal progression using SPRS scores in HSP. Missing data is a limiting factor in all these comparisons, highlighting the need for uniform data collection. Online resources can be found at https://www.mdsgene.org/.
