Over 70 mutations have been reported in the literature.15 In FTD cohorts with more than 100 patients,mutations in GRN were found in 4-12% of cases (7-28% among familialand 1-4% among sporadic FTD cases).12,16-20,31Mutations have an autosomal dominant pattern of inheritance, with an estimatedpenetrance in 50-60% at 60 years and greater than 90% at age 70.20,31,32. This evidence concerns the gene GRN and frontotemporal dementia.