Neurodegeneration in PD may be related to neuroinflammation, abnormal aggregation of α-synuclein, oxidative stress, mitochondrial dysfunction, abnormal iron metabolism, abnormal brain structure and metabolism, changes in intestinal microbial composition, excitotoxicity, protein degradation disorders and other factors (Si et al., 2020; Shrestha et al., 2021). This evidence concerns the gene SNCA and Parkinson disease.