Transthyretin amyloid cardiomyopathy (ATTR-CM) is characterized by pathologic accumulation of unstable extracellular tertiary structures that misfold, aggregate, and form insoluble fibrils in blood vessels, bones, and major organs.1,2 Transthyretin (TTR) misfolding and subsequent deposition in tissues are facilitated by TTR mutations that decrease the stability of the normally folded protein.3 The gene discussed is TTR; the disease is cardiac amyloidosis.