The underlying pathological change in PD is the denaturation and necrosis of dopaminergic neurons in substantia nigra compacta (Xu et al., 2002), leading to a serious loss of tyrosine hydroxylase (TH) and dopamine (DA) (Kawahata and Fukunaga, 2020; Miller and O’callaghan, 2015). The gene discussed is TH; the disease is Parkinson disease.