epiC9repair · Targeting rogue DNA repair and genomic instability as novel toxicity mechanisms in C9orf72 ALS/FTD

Repeat expansions are a major cause of neurodegenerative diseases, but causal therapies are not available. A (G4C2)n repeat expansion in C9orf72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) in Europe. Despite extensive research, the mechanisms linking these expansions to selective neurodegeneration remain poorly understood. Our project, epiC9repair, explores the novel hypothesis that genomic instability at the C9orf72 locus, driven by aberrant DNA repair and repeat-induced chromatin changes, is a critical factor in ALS/FTD pathogenesis. This project builds on our recent observation that the C9orf72 repeat is also a hotspot of DNA synthesis in post-mitotic neurons, and on recent findings in Huntington’s disease that cell type-specific somatic expansion of the pathogenic (CAG)n repeat drives neurodegeneration by unknown mechanisms.Using advanced CRISPR screens and innovative chromatin mapping techniques, we aim to uncover the DNA repair pathways that drive genomic instability in C9orf72 ALS/FTD and how these pathways contribute to neurodegeneration. In addition, we will investigate the role of epigenetic modifications in cell culture models and patient tissues, with a focus on identifying biomarkers that correlate with disease progression and regional neurodegeneration. These findings will inform studies in mouse models to test the therapeutic potential of targeting genomic instability. This multidisciplinary approach has the potential to transform our understanding of C9orf72-related diseases and paves the way for targeted therapeutic strategies that address the root causes of genomic instability in neurodegeneration.