Cardiac Amyloidosis Phenotype Associated With a Glu89Lys Transthyretin Mutation

We report a 45-year-old man with rapidly progressive cardiac amyloidosis, who required heart transplantation within 2 years of symptomatic onset. Hematologic testing and initial tissue biopsy results confirmed amyloid infiltration but were inconclusive for the amyloidogenic protein source. Mass spectroscopy and transthyretin (TTR) sequencing were required to reach a diagnosis of TTR amyloidosis resulting from a Glu89Lys mutation. Although a predominantly neuropathic phenotype has previously been described with this mutation, the present kinship documents a primarily cardiac presentation. This case report highlights the diagnostic challenge of TTR amyloidosis and the marked variability of the genotype-phenotype correlation.