GFAP and early-onset autosomal dominant Alzheimer disease: In the context of Alzheimer’s disease (AD), GFAP has been shown to increase concurrently with amyloid-PET signal in the brain7 and increase >10 years prior to estimated disease onset in genetically determined AD.8,9 While these advances are opening new diagnostic avenues in clinical disciplines ranging from internal medicine to psychiatry and neurosurgery, there remain logistical challenges which could potentially reduce clinical impact.