C9orf72 and behavioral variant of frontotemporal dementia: A fraction of the symptomatic mutation carriers had the behavioral variant of FTD (bvFTD; 46% in FTD‐GRN, 92% in FTD‐C9orf72, and 100% in FTD‐MAPT), with a lower percentage of patients showing primary progressive aphasia (PPA; 25% in FTD‐GRN, 7.2% in FTD‐C9orf72, and 0% in FTD‐MAPT).