SNCA and Parkinson disease: These essential functions include trophic support delivery to neurons, clearing away cellular debris and abnormally folded proteins (such as alpha-synuclein in PD and amyloid-beta in AD), regulating neuronal excitability, and pruning synapses during development and plasticity (Miao et al. 2023a; Badawi et al. 2024; Khowdiary et al. 2025).