C9orf72 and behavioral variant of frontotemporal dementia: To further study whether 18F-Flortaucipir binds to TDP-43 related pathology we recruited a group of svPPA patients along with a group of patients with bvFTD due to hexanucleotide expansions in the C9orf72-gene, known to be strongly related to TDP-43 pathology of type A and B4,5.