GFAP and early-onset autosomal dominant Alzheimer disease: Abbreviations: Ab40: 40-amino-acid form of beta-amyloid, Ab42: 42-amino-acid form of beta-amyloid, AD: Alzheimer’s disease, CNS: central nervous system, CSF: cerebrospinal fluid, DM1: myotonic dystrophy type 1, ELISA: enzyme-linked immunosorbent assay, GFAP: Glial Fibrillary Acidic Protein, MA: mean age, MDD: mean disease duration, NfL: Neurofilament Light Chain, P-tau: phosphorylated tau, pts: patients, SiMoA: single molecule array, T-tau: total tau, y: years.