The underacknowledged PPA-ALS: A unique clinicopathologic subtype with strong heritability.

The present study identified ALS in 12% of a large cohort of patients with nfvPPA and svPPA, which is comparable to the 10%-15% reported in FTD overall, indicating that a third of patients with FTD-ALS will have a predominant language profile. These findings highlight the importance of assessing for ALS in PPA, particularly since this is the only PPA phenotype in which a perfect clinicopathologic association has been reported in to date.