MAPT and frontotemporal dementia: Mutations in the genes that encode tau (MAPT), progranulin (GRN) and C9orf72 are the most common causes of FTD, whilst rare mutations have been identified in valosin-containing protein (VCP), TDP-43 (TARDBP), fused in sarcoma (FUS) and charged multivesicular body protein 2B (CHMP2B) [33].