Glial fibrillary acidic protein (GFAP), the signature intermediate filament of astrocytes, has been proposed as a promising biomarker in various neurological conditions including traumatic brain and spinal cord injury, multiple sclerosis, neuromyelitis optica spectrum disorders, neurodegenerative diseases (e.g. Alzheimer’s disease) and brain tumors [1, 2]. The gene discussed is GFAP; the disease is early-onset autosomal dominant Alzheimer disease.