SAA1 and primary systemic amyloidosis: Furthermore, the same topology is described in a recently reported Cryo-EM structure of a mammalian prion isolated directly from scrapie-infected (Sc) brains and can be also observed in the amyloid fibril structure of acute phase protein serum amyloid A1 involved in systemic amyloidosis (sAA; Liberta et al., 2019; Kraus et al., 2021).