The α-Syn protein plays critical roles in both sporadic and familial PD as (1) mutations or multiplications of the SNCA gene cause autosomal-dominant PD [25], (2) genome-wide association studies show a correlation between single-nucleotide polymorphisms in the SNCA locus and the risk of developing sporadic PD [26,27], (3) levels of phosphorylated α-Syn are increased in post-mortem brains of PD patients and patient-derived dopaminergic neurons [28], (4) DA neurons that lack α-Syn are protected in neurotoxin and genetic models of PD [29,30,31]. The gene discussed is SNCA; the disease is Parkinson disease.