The substitution of valine for methionine at position 30 (V30M) in the TTR polypeptide chain was the first mutation to be identified and, is the most common mutation associated with ATTR polyneuropathy (ATTR-PN) (previously designated familial amyloid polyneuropathy—FAP) (Saraiva et al., 1984). This evidence concerns the gene TTR and familial amyloid neuropathy.