SNCA and Parkinson disease: Alpha-synuclein is a neuronal protein found at synapses and is abundantly found in the brain (Figure 1A) and is associated with the neuropathology observed in PD and related neurodegenerative disorders (e.g., Lewy Body Disease and Multiple System Atrophy), predominantly through the formation of aberrant aggregates that may disrupt cellular homeostasis, synaptic function, and induce neuronal degeneration (Spillantini et al., 1997, 1998; Trojanowski and Lee, 1998; Stefanis, 2012).