Mechanistic description
Antisense oligonucleotides targeting C9orf72 hexanucleotide repeat expansion reduce toxic DPR proteins and RNA foci, restoring nuclear TDP-43 localization and splicing function. This is the strongest hypothesis based on genetic prevalence (~40% familial ALS, ~25% FTD), active clinical trial data (NCT04165729), and mechanistic link between repeat transcripts and downstream TDP-43 pathology. Key unresolved questions include the relative contribution of haploinsufficiency vs. gain-of-function and whether TDP-43 inclusions represent a reversible state.
Mechanism / pathway
- C9orf72
- neurodegeneration
Evidence for (8)
C9orf72 expansion accounts for ~40% familial ALS, ~25% FTD
C9-ASOs reduce toxic RNA foci and DPR proteins in patient-derived neurons
Single-dose C9-ASO trial shows safety and biomarker reduction in humans
ALS-linked mutant TDP-43 in oligodendrocytes induces oligodendrocyte damage and exacerbates motor dysfunction in mice.
ALS-associated TDP-43 aggregates drive innate and adaptive immune cell activation.
Towards a TDP-43-Based Biomarker for ALS and FTLD.
TDP-43 toxic gain of function links ALS, FTD and Alzheimer's Disease through splicing dysregulation.
Sephin1 reduces TDP-43 cytoplasmic mislocalization and improves motor neuron survival in ALS models.
Evidence against (2)
C9 haploinsufficiency vs. toxic gain-of-function contribution remains unresolved
TDP-43 pathology may represent a point-of-no-return beyond which nuclear TDP-43 localization is insufficient to restore splicing
Evidence matrix
Supporting
- C9orf72 expansion accounts for ~40% familial ALS, ~25% FTD PMID:21944792
- C9-ASOs reduce toxic RNA foci and DPR proteins in patient-derived neurons PMID:28960178
- Single-dose C9-ASO trial shows safety and biomarker reduction in humans PMID:NCT04165729
- ALS-linked mutant TDP-43 in oligodendrocytes induces oligodendrocyte damage and exacerbates motor dysfunction in mice. PMID:39605053 · 2024 · Acta Neuropathol Commun
- ALS-associated TDP-43 aggregates drive innate and adaptive immune cell activation. PMID:40520109 · 2025 · iScience
- Towards a TDP-43-Based Biomarker for ALS and FTLD. PMID:29460270 · 2018 · Mol Neurobiol
- TDP-43 toxic gain of function links ALS, FTD and Alzheimer's Disease through splicing dysregulation. PMID:40654715 · 2025 · bioRxiv
- Sephin1 reduces TDP-43 cytoplasmic mislocalization and improves motor neuron survival in ALS models. PMID:40602832 · 2025 · Life Sci Alliance
Contradicting
- C9 haploinsufficiency vs. toxic gain-of-function contribution remains unresolved PMID:26727886
- TDP-43 pathology may represent a point-of-no-return beyond which nuclear TDP-43 localization is insufficient to restore splicing PMID:28827163
Bayesian persona consensus
scidex.consensus.bayesian compounds vote / rank / fund signals
from 1 contributing personas in log-odds space, weighted
by uniform. Prior 50%.
Cite this hypothesis
Cite this hypothesis
etl-backfill (2026). C9orf72 ASO Treatment Reverses TDP-43 Pathology in ALS/FTD. SciDEX hypothesis. https://prism.scidex.ai/hypotheses/h-72c719461c
@misc{scidex_hypothesis_h72c7194,
title = {C9orf72 ASO Treatment Reverses TDP-43 Pathology in ALS/FTD},
author = {etl-backfill},
year = {2026},
howpublished = {SciDEX hypothesis},
url = {https://prism.scidex.ai/hypotheses/h-72c719461c},
note = {SciDEX artifact hypothesis:h-72c719461c}
}