Electron cryo-microscopy (cryo-EM) imaging has allowed atomic structure determination of tau filaments from postmortem brain of patients in recent years.2–7 Distinct conformers of tau (or tau folds) define different diseases and provide a structure-based classification of tauopathies.7 In adult human brain, six tau isoforms are expressed.8 Three tau isoforms have 3 microtubule-binding repeats (3R), whereas the other three have 4 microtubule-binding repeats (4R). The gene discussed is MAPT; the disease is tauopathy.