A mutant mRNA expression in an endomyocardial biopsy sample obtained from a patient with a cardiac variant of Fabry disease caused by a novel acceptor splice site mutation in the invariant AG of intron 5 of the α-galactosidase A gene.

We herein describe the case of a 58-year-old man who presented with dilated-phase hypertrophic cardiomyopathy (HCM) and required an implantable cardioverter defibrillator implant. Subsequently, the patient was diagnosed with Fabry disease (FD), which was suspected based on the results of an endomyocardial biopsy and diagnosed following demonstration of deficient α-galactosidase A (GLA) activity. Molecular studies showed a novel point mutation in the 3' splice site consensus sequence of intron 5 in the gene encoding GLA that created a new splicing site, resulting in the expression of mutant mRNA. FD should be considered a cause of HCM in patients with severe tachyarrhythmia without other remarkable manifestations of FD.