SNCA and Parkinson disease: PD is the second most common neurodegenerative disease after AD, characterized by the progressive degeneration of dopaminergic (DA) neurons within the substantia nigra pars compacta (SNpc) in the midbrain, the formation of Lewy bodies with aggregated a-synuclein in intracellular inclusions, and the presence of neuroinflammation [104–109].