We studied tissue of clinically diagnosed and neuropathologically verified PD patients (Braak PD stage 4–6) [50], age- and gender-matched control subjects (Braak PD stage 0) and incidental Lewy body disease (iLBD) cases (Braak PD 1–3), that did not have clinical PD symptoms but displayed α-synuclein deposition at autopsy and can therefore be considered a prodromal state of PD [51]. Here, SNCA is linked to Parkinson disease.