GFAP and early-onset autosomal dominant Alzheimer disease: Aβ42, beta-amyloid 1–42 peptide; APOEe4, Apolipoprotein E epsilon 4; AD, Alzheimer’s disease; CDR, clinical dementia rating; CDR-SB, clinical dementia rating sum-of-boxes; GFAP, glial fibrillary acid protein; MMSE, mini mental status examination; n, number; NfL, neurofilament light chain; NPI-Q, neuropsychiatric inventory questionnaire; NPS, neuropsychiatric symptoms; pTau181, tau phosphorylated at threonine 181