PD is the second most common progressive ND after AD, and it is characterised by the loss of dopaminergic neurons in the substantia nigra pars compacta (DA SNc) and the accumulation of α-synuclein intracellular aggregates, forming Lewy bodies and Lewy neurites [72,73], which result in both in motor and nonmotor symptoms. The gene discussed is SNCA; the disease is Parkinson disease.