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. The gene discussed is SNCA; the disease is Lewy body dementia.