The most frequent mutated genes involved in FTD with a dominant inheritance pattern are the C9orf72 (8.2%) (DeJesus-Hernandez et al., 2011; Renton et al., 2011; Gijselinck et al., 2012), the progranulin (GRN) (4.1%) (Baker et al., 2006; Cruts et al., 2006; Sieben et al., 2012) and the microtubule associated protein tau (MAPT) (5.6%) (Hutton et al., 1998). The gene discussed is C9orf72; the disease is frontotemporal dementia.