In electron micrographs, the filaments appear to be surrounded by a fuzzy outer coat.[12, 13, 14] A recent breakthrough discovery using cryo‐EM on patient‐derived material revealed that the rigid core of AD paired helical and straight filaments is formed by the V306‐F378 fragment.[4] This region largely overlaps with the I297‐E391 (dGAE) fragment (Figure 1a), previously found to be the main component of AD patient‐derived material.[12] dGAE covers the end of R2, whole R3 and R4 repeats, and the major part of R′ repeat of the full‐length (2N4R) tau protein. The gene discussed is MAPT; the disease is Alzheimer disease.