C9orf72 and frontotemporal dementia: Moreover, no subject showed rare variants in the known FTD-causing genes (i.e., CHMP2B, TARDBP, VCP, along with MAPT, GRN and C9orf72), and 50% of sFTD patients did not carry any variants in the screened genes (Patients 2, 3, 4, 8).