GRN and frontotemporal dementia: Given that SD is consistently associated with FTLD-TDP type C pathology, the rarity of mutations identified in this syndrome is consistent with other recognized geno-pathological associations within the frontotemporal dementia spectrum (e.g. GRN with FTLD-TDP subtype A; C9ORF72 with FTLD-TDP subtype B; and MAPT with FTLD-tau) [62].