C9orf72 and amyotrophic lateral sclerosis: FTLD, which shares some of the pathological and genetic mechanisms with ALS, is also a common form of dementia, with a prevalence ranging from 1 to 461 per 100,000 people.195 The majority of FTLD cases arise from mutations in genes encoding microtubule-associated protein tau (MAPT), progranulin (GRN), and C9orf72, whereas the remaining FTLD cases are caused primarily by mutations in genes encoding FUS, TDP-43, valosin-containing protein (VCP) and charged multivesicular body protein 2B (CHMP2B).