SNCA and Parkinson disease: Immune dysfunction is associated with genetic forms of the disease and genetic risk factors, such as HLA and α-synuclein (SNCA).[8,9] The pathological process of PD can destroy the blood-brain barrier, and the destruction of the blood-brain barrier leads to increased infiltration of peripheral immune cells into the central nervous system, which has been identified as one of the main contributing factors of PD.[10] Increased peripheral immune cell infiltration may cause excessive microglial inflammation, oxidative stress, and cytotoxicity, thereby exacerbating neurodegeneration in PD.