SNCA and Parkinson disease: The key pathological characteristics of PD are the accumulation of the protein alpha-synuclein (α-synuclein [α-syn]), also called Lewy bodies and Lewy neurites, and cell death in the brain's basal ganglia, where up to 70% of the dopamine-secreting neurons in the substantia nigra pars compacta are affected by the end of life (12, 13).