Jia et al. found that concentrations of the growth-associated protein 43 (GAP43), neurogranin, synaptosome-associated protein 25 (SNAP25), and synaptotagmin 1 from neuronal-derived exosomes were lower in AD patients' blood, with which researchers may predict AD at the asymptomatic stage [73]. Here, NRGN is linked to Alzheimer disease.