SNCA and Parkinson disease: α-synuclein has been implicated in Lewy body diseases as duplications/triplications in its gene, SNCA, are associated with autosomal dominant PD, variants in SNCA increase risk of idiopathic and familial PD, drugs that repress α-synuclein transcription are associated with reduced risk of PD and α-synuclein is a major component of Lewy bodies [57–60].