α-syn, α-Synuclein; Apo, apolipoproteins; BBB, blood-brain barrier; CNS, central nervous system; CSF, cerebrospinal fluid; ELISA, enzyme-linked immunosorbent assay; LB, Lewy bodies; LRP1, low-density lipoprotein receptor-related protein-1; PD, Parkinson’s disease; SN, substantia nigra. Here, SNCA is linked to Parkinson disease.