A2M and Alzheimer disease: Among these, several ligands and receptors are genetically associated with neurodegenerative diseases (Fig. 5E), for instance, Alpha-2-macroglobulin (A2M) is genetically associated with Alzheimer’s disease (32), low-density lipoprotein receptor-related protein 1 (LRP1) is a master regulator of tau uptake and spread (33), and neurexin (NRXN1/3) is implicated in Autism (34).