GFAP and early-onset autosomal dominant Alzheimer disease: Plasma GFAP has demonstrated superior performance compared with its CSF counterpart in diagnosing Alzheimer’s disease, particularly in distinguishing Aβ-positive from Aβ-negative individuals, providing prognostic information in at-risk populations and differentiating Alzheimer’s disease from other neurodegenerative disorders such as frontotemporal dementia.