Familial Transthyretin Cardiac Amyloidosis with Homozygous Val122Ile Mutation Mimicking Hypertrophic Cardiomyopathy

Abstract

Systemic amyloidosis is a group of diseases caused by the deposition of an amyloid protein that forms fibrils and deposits in tissues. With respect to age and phenotype, patients with the Val122Ile transthyretin (TTR) mutation are similar to those with wild-type cardiac amyloidosis, causing a late-onset restrictive cardiomyopathy with minimal neuropathy, whose median age of onset is 69 years. Homozygous mutation is rare. We report the case of a male patient who had recent-onset heart failure and phenotype of hypertrophic cardiomyopathy. Technetium scintigraphy showed cardiac uptake and absence of circulating immunoglobulins, suggesting TTR cardiac amyloidosis. Genetic analysis confirmed cardiac amyloidosis caused by the homozygous Val122Ile mutant TTR protein.