SNCA and Parkinson disease: Furthermore, the filamentous Lewy body formation could be observed in early onset of PDD carrying SNCA mutations and Dementia with Lewy bodies (DLB) [42, 55], and the aggregation of α-synuclein could be detected in substantia nigra as well as cortex in idiopathic PD patients, which suggests that the accumulation of α-synuclein could be the presynaptic dysfunction attributed to neuronal toxicity caused by various genetic or nongenetic risk factors.