BDNF and Parkinson disease: These genes include Fez1, which is involved in oligodendrocyte and myelin formation (Chen et al., 2017); Nf2, which is involved in axonal regeneration in peripheral neurogenic injury (Mindos et al., 2017); Slc39s12, which is required for neurite outgrowth (Davis et al., 2021); brain-derived neurotrophic factor (BDNF), which is important for neural activity and synaptic plasticity (Oh et al., 2019; Wang et al., 2019), and the cholecystokinin gene (Cck), which has neuroprotective effects in Alzheimer’s disease and Parkinson’s disease (Reich and Holscher, 2024).