Over 80% of patients with FTD caused by genetic mutations harbor heterozygous mutations in one of three genes: microtubule-associated protein tau (MAPT) [37, 38], chromosome 9 open reading frame 72 (C9orf72) [39–42], and progranulin (GRN) [2, 43, 44]. This evidence concerns the gene GRN and frontotemporal dementia.