In the backdrop of clinical scenarios, the neuropathological diagnosis of PD requires two features: (i) depigmentation/demelanization of the substantia nigra-pars compacta (SNpc) due to the pathological loss of dopaminergic neurons and (ii) the presence of Lewy related α-synuclein (α-syn; gene symbol SNCA/PARK1) pathology (LRP), e.g., Lewy bodies (LBs) and Lewy neurites (LNs), across several brain regions, primarily in the brainstem nuclei [1,11,12]. Here, SNCA is linked to Parkinson disease.