SNCA and synucleinopathy: Aggregation of the protein α-synuclein (α-syn) is a histological hallmark of multiple neurodegenerative diseases collectively known as synucleinopathies, including Parkinson’s disease (PD), PD with dementia (PDD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA)4,10,11.