Our results show that while pathogenic variants within the most common dementia genes were rarely associated with PPA, these were found almost exclusively in GRN and C9orf72, suggesting that PPA is more TDP43- than tau-related in our series.
Seven patients with behavioural variant FTD (bvFTD), 11 patients with non-fluent-variant primary progressive aphasia (nfvPPA), two patients with sematic-variant primary progressive aphasia(svPPA), 10 patients with amyotrophic lateral sclerosis and FTD carrying the C9orf72 hexanucleotide repeat (C9 + ALS-FTD), 10 patients with ALS-FTD without hexanucleotide repeats (C9-ALS-FTD), 20 ALS patients without behavioural or cognitive deficits (ALSnci) and 40 healthy controls (HC) were included in a prospective quantitative neuroimaging study.
GBA mutations were detected in one healthy control and four patients with a clinical diagnosis of PSP (n = 1), probable CBS (n = 2) and PPA (n = 1, with concomitant C9orf72 expansion).
The C9orf72 mutation should be analyzed in sporadic ALS patients after determining their family histories not only of frontotemporal dementia but also of primary progressive aphasia.
The hexanucleotide repeat expansion in C9orf72 is an important cause of frontotemporal dementia with and without amyotrophic lateral sclerosis, and is sometimes associated with primary progressive aphasia.