IAPP and neurodegenerative disease: Although most amyloid species were initially identified within the context of neurodegenerative diseases and their transmission (see Peng et al., 2020 for a recent review), several proteins have also been found to form amyloid-like fibrils [e.g., islet amyloid polypeptide (amylin) (Zheng et al., 2020) or insulin (Zheng et al., 2020)] outside the nervous system.