Table 1. [C9orf72-FTD/ALS: Frequency of Diagnoses Based on Clinical Findings Alone]. - GeneReviews®

Diagnosis	Frequency	Comments (Frequency)
FTD	34.8%	Behavioral variant FTD (31.4%) Nonfluent/agrammatic variant PPA (1.8%) Semantic variant PPA (0.9%) Other tauopathy: corticobasal degeneration, progressive supranuclear palsy, other PPA (0.7%)
ALS	19.3%
FTD-ALS	11.0%
Atypical presentations mimicking other kinds of neurodegenerative brain diseases	35.0%	Alzheimer disease, Parkinson disease, Huntington disease, & dementia w/Lewy bodies are common. Also incl vascular dementia & dementia not otherwise specified Atypical parkinsonian syndromes ¹

From: C9orf72 Frontotemporal Dementia and/or Amyotrophic Lateral Sclerosis

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