SNCA and Alzheimer disease: They are typically grouped by their predominant neuropathological protein deposit (e.g. synucleinopathies, like Parkinson’s disease and Lewy body dementia, by α-synuclein deposition and Alzheimer’s disease by deposition of amyloid), but more often than not, they present with co-pathologies, suggesting that they might share common pathogenic pathways1,2.