C9orf72 and frontotemporal dementia: In their fundamental study, van der Ende et al. (2019) from the GENFI analyzed serum NFL in a large cohort (n = 140) of presymptomatic carriers of MAPT and GRN mutations and the C9orf72 HRE, 59 symptomatic carriers with FTD, and 127 neurologically healthy non-carriers belonging to the same families.