Starting with the determination of the tau fibril structure from AD patient samples in 2017 (Fitzpatrick et al., 2017), advancements in cryo-EM have enabled the structural categorization of tau strains by fibril arrangement (Shi et al., 2021), greatly extending beyond our previous studies investigating the specific isoform involvement in each strain (Woerman et al., 2016). The gene discussed is MAPT; the disease is Alzheimer disease.