MAPT and Alzheimer disease: Third, although autoradiographic studies have shown that (18F)‐MK6240 does not bind to TDP‐43 or tau aggregates other than AD‐type neurofibrillary tangles [4], and clinical studies so far have not reported false positive results other than low tracer retention in MAPT mutation carriers (R406W and P301L) [19] that are distinguishable from high retention in AD, autopsy‐validation studies are needed to further confirm the specificity of in vivo (18F)‐MK6240 PET.