In AD patients, significant elevations of amyloid-β-peptide (Aβ)42 and phosphorylated tau as well as differential levels of lysosomal and synaptic proteins were reported in blood-derived L1CAM-positive exosomes compared to healthy controls, with high predictive power for development of AD and correlation with CSF levels (Fiandaca et al., 2015; Goetzl et al., 2015a,b, 2016a; Winston et al., 2016; Jia et al., 2019). This evidence concerns the gene L1CAM and Alzheimer disease.