Finally, glial fibrillary acid protein (GFAP), a marker of astrocytosis, has attracted recent attention because of preliminary evidence indicating a better performance of the plasma biomarker than the CSF counterpart in detecting AD pathology [16, 17], even in the preclinical or mild cognitive impairment (MCI)-AD stages [14, 17–20]. The gene discussed is GFAP; the disease is Alzheimer disease.