While first-generation tau tracers suffered from substantial off-target binding, the next generation tau tracer [18F]PI-2620 proved absent off-target binding to monoamine oxidases, high affinity to 3R/4R tau in AD and also revealed binding in the 4R tauopathies PSP (Brendel et al., 2020, Franzmeier et al., 2022) and CBS (Franzmeier et al., 2022, Palleis et al., 2021). Here, MAPT is linked to Alzheimer disease.