The presence of plasmin in the bloodstream, its structural similarities to trypsin, and the reported activation of plasminogen activation system in other amyloid-related disorders, such as Alzheimer’s disease (AD) [60] and immunoglobulin light chain amyloidosis [61,62,63], suggest that plasmin could play a substantial key role in TTR amyloidogenesis. This evidence concerns the gene PLG and early-onset autosomal dominant Alzheimer disease.