Arrhythmogenic right ventricular cardiomyopathy in Boxer dogs is associated with calstabin2 deficiency.

Abstract

OBJECTIVE: To examine the presence and effect of calstabin2-deficiency in Boxer dogs with arrhythmogenic right ventricular cardiomyopathy (ARVC). ANIMALS: Thirteen Boxer dogs with ARVC. MATERIALS AND METHODS: Tissue samples were collected for histopathology, oligonucleotide microarray, PCR, immunoelectrophoresis, ryanodine channel immunoprecipitation and single-channel recordings, and calstabin2 DNA sequencing. RESULTS: In cardiomyopathic Boxer dogs, myocardial calstabin2 mRNA and protein were significantly decreased as compared to healthy control dogs (calstabin2 protein normalized to tetrameric cardiac ryanodine receptor (RyR2) complex: affected, 0.51+/-0.04; control, 3.81+/-0.22; P<0.0001). Calstabin2 deficiency in diseased dog hearts was associated with a significantly increased open probability of single RyR2 channels indicating intracellular Ca(2+) leak. PCR-based sequencing of the promoter, exonic and splice site regions of the canine calstabin2 gene did not identify any causative mutations. CONCLUSIONS: Calstabin2 deficiency is a potential mechanism of Ca(2+) leak-induced ventricular arrhythmias and heart disease in Boxer dogs with ARVC.