MAPT and multiple system atrophy: Fibrils can be composed of many protofilaments and vary with disease [84], as reported for Alzheimer’s-derived Aβ fibrils [53], AA amyloidosis from human kidney [85] or mouse models [51], tau fibrils from Alzheimer’s disease patients [86], multiple system atrophy (MSA) α-syn fibrils [50], and RML PrPSc fibrils isolated from mouse models expressing PrP with or without the GPI anchor [41,49,87].