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Modifiers of CAG/CTG Repeat Instability: Insights from Mammalian Models
Vanessa C Wheeler1,2, Vincent Dion3
1Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.
Journal of Huntington'S Disease
|February 13, 2021
Summary
CAG/CTG repeat expansion causes neurodegenerative diseases like Huntington's. Mammalian models reveal mismatch repair proteins drive repeat instability, offering therapeutic targets for preventing expansion.
Area of Science:
- Genetics
- Neuroscience
- Molecular Biology
Background:
- CAG/CTG repeat expansion at 15 genomic loci causes neurodegenerative/neuromuscular diseases.
- Huntington's disease and myotonic dystrophy type 1 are common examples.
- Germline and somatic instability of these repeats contribute to disease severity and progression.
Purpose of the Study:
- To review mammalian model systems for studying CAG/CTG repeat instability.
- To identify modifiers of repeat instability across different systems.
- To explore potential therapeutic strategies targeting repeat dynamics.
Main Methods:
- Review of mammalian (primarily mouse) model systems.
- Analysis of identified genetic modifiers of repeat instability.
- Integration of findings from model systems and human genetic studies.
Main Results:
- Mouse models highlight the critical role of mismatch repair pathway proteins in CAG/CTG instability.
- Genome-wide association studies in humans support the involvement of these proteins.
- A network of interacting modifiers suggests pathway crosstalk influencing repeat instability.
Conclusions:
- CAG/CTG repeat instability is influenced by DNA metabolic proteins, their regulation, chromatin interactions, and direct repeat tract perturbation.
- Understanding these mechanisms provides hypotheses for therapeutic interventions.
- Novel methodologies are needed for deeper mechanistic insight and therapy development.
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