SNCA and Parkinson disease: Since the discovery of a linkage of missense mutations in the α-synuclein (αS) gene to a rare familial dominant Parkinson’s disease (PD) in 1995 [1], numerous studies have established that aggregation of α-synuclein, a presynaptic protein with unknown functions, may play a central role in the pathogenesis of α-synucleinopathies [2].