Mechanism: C9orf72 Hexanucleotide Repeat Expansion in ALS/FTD

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Mechanism: C9orf72 Hexanucleotide Repeat Expansion in ALS/FTD

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experiment Created: 2026-04-02T10:01:41 By: crosslink-v2 Quality: 67% ✓ SciDEX ID: experiment-exp-wiki-experiments-c9orf72-

🧫 Experiment Protocol Validationproposed

SUMMARY

# Mechanism: C9orf72 Hexanucleotide Repeat Expansion in ALS/FTD ## Background and Rationale This comprehensive validation study addresses one of the most significant questions in neurodegeneration: how a single genetic mutation in C9orf72 can manifest as distinct diseases (ALS, FTD, or combined phenotypes). The C9orf72 hexanucleotide repeat expansion represents the most common genetic cause of both familial ALS (~40%) and familial FTD (~25%), yet the mechanisms underlying phenotypic diversity re

METHODOLOGY NOTES

**Phase 1: Patient Cohort Assembly and Characterization (Months 1-3)** Recruit 150 participants: 50 C9orf72+ ALS patients, 50 C9orf72+ FTD patients, 25 C9orf72+ ALS/FTD patients, and 25 healthy controls with C9orf72 mutations but no symptoms. Perform comprehensive clinical phenotyping including ALSFRS-R, CDR-FTLD, and neuropsychological testing. Extract genomic DNA and perform Southern blot analysis to quantify hexanucleotide repeat length. Establish iPSC lines from all participants using episomal reprogramming. **Phase 2: Molecular Pathology Analysis (Months 4-8)** Generate motor neurons and cortical neurons from iPSCs using dual SMAD inhibition protocol. Perform RNA-seq on differentiated neurons at days 21, 35, and 50 to identify disease-specific transcriptional signatures. Quantify RNA foci formation using FISH with (GGGGCC)4 and (CCCCGG)4 probes. Measure dipeptide repeat protein (DPR) accumulation via immunofluorescence and Western blot for poly-GA, poly-GP, poly-GR, poly-PA, an

▸Metadatasource: {'type': 'manual', 'source_name': 'wiki'

source	{'type': 'manual', 'source_name': 'wiki', 'extracted_by': 'backfill_v1', 'extraction_date': '2026-04-16T01:00:16.897119Z'}
summary	# Mechanism: C9orf72 Hexanucleotide Repeat Expansion in ALS/FTD ## Background and Rationale This comprehensive validation study addresses one of the most significant questions in neurodegeneration: ho
entities	{'genes': ['FTD'], 'diseases': ['ALS']}
model_system	human
_schema_version	1
experiment_type	validation
primary_outcome	Validate Mechanism: C9orf72 Hexanucleotide Repeat Expansion in ALS/FTD
methodology_notes	Phase 1: Patient Cohort Assembly and Characterization (Months 1-3) Recruit 150 participants: 50 C9orf72+ ALS patients, 50 C9orf72+ FTD patients, 25 C9orf72+ ALS/FTD patients, and 25 healthy contr
replication_status	replicated
extraction_metadata	{'backfill_at': '2026-04-16T01:00:16.897126', 'needs_review': True, 'extraction_notes': 'Backfilled from wiki source (no PMID available)', 'extraction_confidence': 0.4}

📊 Evidence Profile Foundational

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Certainty

100%

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624

Outgoing

499

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Mechanism: C9orf72 Hexanucleotide Repeat Expansion in ALS/FTD

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