A positive family history for FTD was present in one nfvPPA patient who had a hexanucleotide repeat expansion in chromosome 9 open-reading frame 72 (C9orf72) gene, and for AD in 2 lvPPA patients, whereas none of the svPPA patients had a clear autosomal dominant inheritance of any type of dementia. This evidence concerns the gene C9orf72 and Alzheimer disease.