SNCA and Parkinson disease: Intracellular accumulation of α‐synuclein (SNCA) into amyloid fibrils is a common pathological hallmark of Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), collectively known as synucleinopathies (Spillantini et al. 1998; Wakabayashi et al. 1998).