Presenillin (PSEN1, PSEN2), β-site APP-cleaving enzyme 1 (BACE1), alpha-1-antitrypsin (SERPINA1), apolipoprotein E (APOE), neurosecretory VGF (VGF), and complement components were identified as biomarkers for AD (Wattamwar and Mathuranath, 2010; Sathe et al., 2019). Here, VGF is linked to Alzheimer disease.