Biventricular Dysfunction in Knock-in Mice With Dsg2 Variants Specific for Japanese Arrhythmogenic Right Ventricular Cardiomyopathy.

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disease with a poor prognosis and no curative therapy. It may present as arrhythmogenic sudden cardiac death and inevitably progress to terminal heart failure due to the loss of contractile tissue. This study aimed to generate knock-in (KI) mice carrying the 2 genetic variants (DSG2 p.R292C and p.D494A) most frequently found in Japanese ARVC patients, characterize their cardiac phenotype, and compare the results with those of human ARVC.

Methods And Results: Variants were introduced using CRISPR/Cas9 genome editing at the corresponding mouse locations: Dsg2 p.R297C (RC) and p.D499A (DA). Cardiac function, morphology, and electrophysiology were evaluated using echography, magnetic resonance imaging, and telemetry. Tissue and cardiomyocytes were examined histologically. All mice with the variants developed biventricular cardiac dysfunction after 8 weeks of age, and it progressed with age. There was a significant variability in phenotype expression. Mice with RC died suddenly at 9 weeks of age. Some homozygous RC mice showed arrhythmia and conduction abnormalities on telemetry. In both variants, staining of cardiac sections revealed significant fibrosis, and apoptosis was detected using the terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling assay.

Conclusions: We generated a KI ARVC mouse model with significant similarities to human disease. This model could be used for the elucidation of pathogenesis and the development of optimal therapy for ARVC.