SNCA and Parkinson disease: Among the factors implicated in PD pathogenesis, upregulations were found for FOXO3 (Forkhead box O3) as the mediator of toxicity of the ferrireductase alpha-synuclein (SNCA) toxicity, and for beta-synuclein (SNCB) as an antagonist of SNCA [62,63,64,65,66].