Diseases of Unstable Repeat Expansion: Mechanisms and Common Principles

2005 ◽  
Vol 6 (10) ◽  
pp. 743-755 ◽  
Author(s):  
Jennifer R. Gatchel ◽  
Huda Y. Zoghbi
Keyword(s):  
Repeat Expansion

CANVAS is a common form of late-onset hereditary ataxia

2020 ◽  
pp. 51-52
Author(s):  
Е.П. Нужный ◽  
Н.Ю. Абрамычева ◽  
Е.Г. Воробьева ◽  
Е.О. Иванова ◽  
Ю.А. Шпилюкова ◽  
...  
Keyword(s):  
Cerebellar Ataxia ◽  
Clinical Picture ◽  
Autosomal Recessive ◽  
Late Onset ◽  
Repeat Expansion ◽  
Hereditary Ataxia ◽  
Recessive Ataxia ◽  
Autosomal Recessive Ataxia

Синдром CANVAS (мозжечковая атаксия, невропатия и вестибулярная арефлексия) - аутосомно-рецессивная атаксия с поздним дебютом, обусловленная носительством биаллельной экспансии (AAGGG)n во 2-м интроне гена RFC1. До настоящего момента отсутствуют сведения о распространенности данного заболевания в российских семьях. Нами был проведен поиск биаллельной экспансии AAGGG-повторов у 35 российских пациентов с поздней мозжечковой атаксией. Верифицированы 5 пациентов (14,3%) с синдромом CANVAS и характерной клинической картиной. CANVAS (cerebellar ataxia, neuropathy and vestibular areflexia) is a late-onset autosomal recessive ataxia due to biallelic (AAGGG)n repeat expansion in the 2nd intron of the RFC1 gene. There is no information on the CANVAS prevalence in Russian families. We searched for biallelic expansion of AAGGG repeats in 35 Russian patients with late-onset cerebellar ataxia. Five patients (14.3%) with CANVAS syndrome and a characteristic clinical picture were verified.

scholarly journals C9orf72-derived arginine-containing dipeptide repeats associate with axonal transport machinery and impede microtubule-based motility

2021 ◽  
Vol 7 (15) ◽  
pp. eabg3013
Author(s):  
Laura Fumagalli ◽  
Florence L. Young ◽  
Steven Boeynaems ◽  
Mathias De Decker ◽  
Arpan R. Mehta ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Motor Neurons ◽  
Single Molecule ◽  
Repeat Expansion ◽  
Physical Interaction ◽  
Hexanucleotide Repeat ◽  
Hexanucleotide Repeat Expansion ◽  
Axonal Trafficking ◽  
Inhibitory Interactions

A hexanucleotide repeat expansion in the C9orf72 gene is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). How this mutation leads to these neurodegenerative diseases remains unclear. Here, we show using patient stem cell–derived motor neurons that the repeat expansion impairs microtubule-based transport, a process critical for neuronal survival. Cargo transport defects are recapitulated by treating neurons from healthy individuals with proline-arginine and glycine-arginine dipeptide repeats (DPRs) produced from the repeat expansion. Both arginine-rich DPRs similarly inhibit axonal trafficking in adult Drosophila neurons in vivo. Physical interaction studies demonstrate that arginine-rich DPRs associate with motor complexes and the unstructured tubulin tails of microtubules. Single-molecule imaging reveals that microtubule-bound arginine-rich DPRs directly impede translocation of purified dynein and kinesin-1 motor complexes. Collectively, our study implicates inhibitory interactions of arginine-rich DPRs with axonal transport machinery in C9orf72-associated ALS/FTD and thereby points to potential therapeutic strategies.

scholarly journals Special Issue: DNA Repair and Somatic Repeat Expansion in Huntington’s Disease

2021 ◽  
Vol 10 (1) ◽  
pp. 3-5
Author(s):  
Lesley Jones ◽  
Vanessa C. Wheeler ◽  
Christopher E. Pearson
Keyword(s):  
Dna Repair ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Repeat Expansion ◽  
Special Issue

scholarly journals Altered network properties in C9ORF72 repeat expansion cortical neurons are due to synaptic dysfunction

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Emma M. Perkins ◽  
Karen Burr ◽  
Poulomi Banerjee ◽  
Arpan R. Mehta ◽  
Owen Dando ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Synaptic Vesicle ◽  
Cortical Neurons ◽  
Electrode Array ◽  
Repeat Expansion ◽  
Cortical Network ◽  
Synaptic Function ◽  
Network Activity ◽  
Cortical Function ◽  
Network Function

Abstract Background Physiological disturbances in cortical network excitability and plasticity are established and widespread in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) patients, including those harbouring the C9ORF72 repeat expansion (C9ORF72RE) mutation – the most common genetic impairment causal to ALS and FTD. Noting that perturbations in cortical function are evidenced pre-symptomatically, and that the cortex is associated with widespread pathology, cortical dysfunction is thought to be an early driver of neurodegenerative disease progression. However, our understanding of how altered network function manifests at the cellular and molecular level is not clear. Methods To address this we have generated cortical neurons from patient-derived iPSCs harbouring C9ORF72RE mutations, as well as from their isogenic expansion-corrected controls. We have established a model of network activity in these neurons using multi-electrode array electrophysiology. We have then mechanistically examined the physiological processes underpinning network dysfunction using a combination of patch-clamp electrophysiology, immunocytochemistry, pharmacology and transcriptomic profiling. Results We find that C9ORF72RE causes elevated network burst activity, associated with enhanced synaptic input, yet lower burst duration, attributable to impaired pre-synaptic vesicle dynamics. We also show that the C9ORF72RE is associated with impaired synaptic plasticity. Moreover, RNA-seq analysis revealed dysregulated molecular pathways impacting on synaptic function. All molecular, cellular and network deficits are rescued by CRISPR/Cas9 correction of C9ORF72RE. Our study provides a mechanistic view of the early dysregulated processes that underpin cortical network dysfunction in ALS-FTD. Conclusion These findings suggest synaptic pathophysiology is widespread in ALS-FTD and has an early and fundamental role in driving altered network function that is thought to contribute to neurodegenerative processes in these patients. The overall importance is the identification of previously unidentified defects in pre and postsynaptic compartments affecting synaptic plasticity, synaptic vesicle stores, and network propagation, which directly impact upon cortical function.

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