TTR and Familial transthyretin-related amyloidosis: The mainly amyloidal components that infiltrate in the heart causing cardiac amyloidosis are immunoglobulin light chain amyloid fibril protein (AL) and transthyretin amyloidosis (ATTR), and thus cardiac amyloidosis can be classified into AL-cardiac amyloidosis (AL-CA) and TTR-cardiac amyloidosis (ATTR-CA) (Benson et al., 2018).