The selective and progressive degeneration of midbrain dopaminergic (mDAergic) neurons of the substantia nigra pars compacta (SNpc) and their projections into the caudate–putamen (striatum) leading to substantial decrease in dopamine levels, the accumulation of pathological α-synuclein, which is a major component of Lewy bodies (LBs), and gliosis as the major hallmarks of PD [1,2]. Here, SNCA is linked to Parkinson disease.