GRN and frontotemporal dementia: Previous studies have also identified glial fibrillary acidic protein (GFAP), tau and NEFL as possible plasma-based biomarkers, where GFAP is elevated in symptomatic GRN mutation carriers, tau is elevated in sporadic FTD and in symptomatic MAPT mutation carriers, and NEFL is elevated in both genetic and sporadic FTD [5–7].