An earlier first generation tracer, [11C]PBB3 and its derivatives, [18F]PBB3 and [18F]-PM-PBB3 ([18F]APN-1607), are also among tracers with acceptable non-AD tau binding affinity with some off-target binding in the basal ganglia, thalamus, and choroid plexus but not to monoamine oxidase (MAO) (237). The gene discussed is MAPT; the disease is Alzheimer disease.