GFAP and supranuclear palsy, progressive, 1: More recently, other CSF biomarkers, such as YKL-40, the soluble β fragment of amyloid precursor protein (sAPPβ), neurogranin, glial fibrillary acidic protein (GFAP) or Neurofilament Light (NfL), have been described to be potentially informative for the discrimination of various neurodegenerative conditions, such as AD, FTD, progressive supranuclear palsy (PSP), corticobasal syndrome (CBS), or DLB4–8.