A case of late onset cardiac amyloidosis with a new transthyretin variant (lysine 92).

A new transthyretin (TTR) variant (lysine 92), which causes late onset cardiac amyloidosis, is described in a 71-year-old man. The patient at first had syncope due to ventricular tachycardia and was admitted our hospital. Typical findings of cardiac amyloidosis were observed by echocardiography, and a diagnosis of systemic amyloidosis was made by rectal biopsy. The man died approximately 3 years and 6 months after first admission, with gradually worsening congestive heart failure. Pathological examination showed prominent amyloid deposits in the heart and the vascular wall of many organs including the liver, pancreas, kidney, lung, and gastrointestinal tracts. Amyloid protein of transthyretin type was indicated by immunohistochemical study, and DNA sequencing identified a novel mutation in the transthyretin gene encoding 92 glutamine --> lysine. A polymerase chain reaction-induced mutation restriction analysis with a mismatched antisense primer showed that the patient was heterozygous for the TTR Lys92 allele.