MAPT and frontotemporal dementia: Additionally, plasma GFAP was significantly higher in patients with FTD with symptomatic GRN pathogenic variants compared to C9orf72 expansion carriers or patients with MAPT pathogenic variants.209 Finally, plasma tau concentrations were found to be higher in bvFTD (n = 71) and PPA (n = 83) compared to healthy controls (n = 22), as well as in patients with MAPT pathogenic variants compared to those with C9orf72 expansions or GRN pathogenic variants.210