PD is pathologically characterized by degeneration of nigrostriatal dopaminergic neurons and the presence of Lewy bodies (LBs), which mainly consist of misfolded α-synuclein, ubiquitin, Parkin, PTEN-induced kinase-1 (PINK1), and other proteins in the surviving neurons (Rai et al., 2017, 2019a; Zahra et al., 2020; Oliveira et al., 2021). The gene discussed is SNCA; the disease is Parkinson disease.