BDNF and Parkinson disease: Among them, Neurotrophin signaling pathway (p = 5.70E-13), mTOR signaling pathway (p = 2.86E-12), Ubiquitin mediated proteolysis (p = 2.86E-12), Long-term potentiation (p = 3.68E-12), Axon guidance (p = 3.51E-11), Cholinergic synapse (p = 1.75E-10), Gap junction (p = 7.09E-10), Dopaminergic synapse (p = 3.43E-08), Glutamatergic synapse (p = 1.76E-05) were the most prominent pathways enriched in quantiles with differential exosomal miRNA patterns in PD (Table S1), suggesting that these biologic pathways were involved in development of PD.