TTR and amyloidosis: Cardiac involvement is frequently observed for three types of systemic amyloidosis: (i) amyloid light chain amyloidosis (caused by excess monoclonal light chain production by a plasma cell clone), (ii) hereditary transthyretin (TTR) amyloidosis (ATTRv, inherited in an autosomal dominant manner and caused by the deposition of mutant TTR protein), and (iii) wild-type (non-hereditary) TTR amyloidosis (ATTRwt).