Alpha-synuclein (α-syn) is a synapse-associated protein that can abnormally accumulate, forming Lewy bodies, and is linked to a group of neurodegenerative diseases called synucleinopathies, which includes Parkinson’s disease, multiple system atrophy, and dementia with Lewy bodies [158–161]. The gene discussed is SNCA; the disease is neurodegenerative disease.