Despite possessing conserved macroscopic featuresand hallmarkedproperties, the atomic structures of fibrils can vary considerablydepending on the amyloidogenic protein undergoing fibril formation.This has been shown by cryo-EM-derived atomic structures for fibrilsof Aβ40 (Figure a) and Aβ42 in AD (Figure b), tau in AD (Figure c), α-synuclein in PD, Parkinson’sdisease dementia (PDD), and Dementia with Lewy Bodies (DLB) (Figure d), Serum amyloid A1 in vascular AA amyloidosis (Figure e), and transthyretin in hereditary Val30Met ATTR amyloidosis (Figure f). The gene discussed is SAA1; the disease is Alzheimer disease.