SNCA and Parkinson disease: EPS includes dystonias, tardive dyskinesia, and, importantly, Parkinsonism [4,7,8].Parkinson's disease (PD) itself is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta and the accumulation of misfolded α-synuclein aggregates (Lewy bodies and neurites) that disrupt neuronal and synaptic function [9,10].