SNCA and Parkinson disease: The hypothesis according to which α-synuclein (α-Syn) plays a causative role in PD pathogenesis is strongly supported, since the major fibrillar protein component of LBs in both sporadic and familial PD is α-Syn, and three different α-Syn missense mutations (A30P, A53T and E46K) and the duplication and triplication of loci cause autosomal-dominant PD [5-9].