While there has been significant debate about the specificity of this ligand for tau, especially in the non-Alzheimer’s dementias (Bevan-Jones et al., 2017a; Xia and Dickerson, 2017), the distribution of 18F-AV-1451 binding recapitulates Braak staging in Alzheimer’s disease (Schwarz et al., 2016) and correlates with post-mortem neuropathology in primary tauopathies (Smith et al., 2016; Passamonti et al., 2017). Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.