Transthyretin amyloid fibrils adopt distinct folds in the brain.

Amyloid deposition in the central nervous system is increasingly recognized in transthyretin (ATTR) amyloidosis, particularly in patients with prolonged survival following liver transplantation or disease-modifying therapies. However, the structural basis of transthyretin aggregation in the brain remains unknown. Here we determine cryo-electron microscopy (cryo-EM) structures of ex vivo brain-derived ATTR fibrils from patients carrying the ATTRv-V30M and ATTRv-V30G variants. Both fibrils adopt folds distinct from those previously reported in peripheral tissues and the vitreous humor. V30M fibrils exhibit a continuous ordered core spanning residues Pro11-Asn124, whereas V30G fibrils consist of a substantially reduced ordered core, revealing pronounced structural divergence even within the same tissue environment. Despite this diversity, comparative analyses identify conserved regions across ATTR fibrils, including a segment implicated in transthyretin aggregation and targeted for diagnostic and therapeutic development. These results provide direct evidence that local tissue context can shape amyloid fibril architecture in human disease.