Ninety-four percent of suspected prion disease cases with DVs were linked to a single gene, PRNP; 93.5% of FTD patients with DVs were linked to three major, and two additional genes associated with FTD syndromes (C9orf72, GRN, MAPT, SQSTM1, VCP); however, in only 63% of clinically diagnosed AD patients were the DVs in genes linked to AD pathologies (APP, PSEN1 or PSEN2). The gene discussed is C9orf72; the disease is Alzheimer disease.