CXCL12 and Parkinson disease: Here, we reviewed the potential of exosomal proteins such as α-syn, amyloid-β (Aβ), tau, and C-X-C motif chemokine ligand 12 (CXCL12), as well as miRNAs (miR-24, miR-23b-3p, miR-29c, miR-195-3p, and miR-331-5p) as biomarkers for PD.