SNCA and Parkinson disease: Even though the exact cause of Parkinson's disease is still unknown, two main pathological indicators are observed in the post-mortem brain; namely (i) loss of dopamine-producing neurons in the substantia nigra pars compacta (SNc; Kordower et al., 2013) and (ii) the widespread deposition of amyloid-like Lewy bodies rich in α-synuclein both in the SNc and other brain regions where overt neurodegeneration is not observed (Surmeier et al., 2017).