The predominance of the β-chain structure in the polypeptide chains of the TTR tetramer, and its organization as β-sheets contribute to the intrinsic propensity of the protein to aggregate, leading to the formation and deposition of fibrils under specific conditions (Figure 2), thus originating transthyretin amyloidosis (ATTR), a rare, yet underdiagnosed disease characterized by progressive impairment of neurologic and cardiac function [12,13]. Here, TTR is linked to Familial transthyretin-related amyloidosis.