SV2A and red-green color blindness: This review focuses on PET tracers to detect synaptic vesicle glycoprotein 2 (SV2) protein family, with a particular emphasis on SV2A, as a tool in neurodegenerative diseases including Alzheimer’s disease (AD), frontotemporal dementia (FTD), Parkinson’s disease (PD), dementia with Lewy bodies (DLB), Huntington’s disease (HD), progressive supranuclear palsy/Richardson syndrome (PSP), and corticobasal syndrome (CBD).