In cerebrospinal fluid (CSF), levels of the Aβ42 and Aβ40 peptides, total or hyperphosphorylated tau (tTau or pTau), neurofilament light (NfL; nonspecific marker of neuronal damage) and glial fibrillary acidic protein (GFAP; marker of astrocytic reactivity) collectively establish the AT(N) (amyloid/tau/neurodegeneration) diagnostic framework for AD, currently the best predictive biomarker set [4]. This evidence concerns the gene GFAP and Alzheimer disease.