C9orf72 and frontotemporal dementia: MAPT, GRN, and C9orf72 mutations, detected in up to 74% of patients with high family history, represent the most frequent genetic cause of FTD; nowadays 54 and 79 mutations have been described for MAPT and GRN, respectively.1,2 Of note, a compound heterozygosity of two MAPT mutations (transmitted by the unaffected parents) was found in a sporadic case, thus highlighting that mutations can be found also in sporadic cases (Anfossi et al., 2011).