SNCA and Parkinson disease: Neuropathologically, PD is marked by the gradual degeneration of dopaminergic neurons within the pars compacta of the substantia nigra (SNpc), accompanied by the accumulation of α-synuclein aggregates called Lewy bodies (LBs) [85,86], which are mainly composed of misfolded and aggregated forms of the α-synuclein protein, which is a presynaptic protein [87].