Myocardial transcriptome analysis of human arrhythmogenic right ventricular cardiomyopathy (ARVC)

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy primarily of the right ventricle characterized through fibrofatty replacement of cardiomyocytes. The genetic etiology in ARVC patients is most commonly caused by dominant inheritance and high genetic heterogeneity. Though histological examinations of ARVC affected human myocardium reveals fibrolipomatous replacement, the molecular mechanisms leading to loss of cardiomyocytes are largely unknown. We therefore analyzed the transcriptomes of 6 ARVC specimen derived from heart transplantation candidates and compared our findings to 6 non-failing donor hearts (NF) which could not be transplanted for technical reasons. In addition, we compared our findings to 7 hearts from patients with idiopathic dilated cardiomyopathy. From each heart left (LV) and right ventricular (RV) myocardial samples were analyzed by Affymetrix HG-U133 Plus 2.0 arrays, adding up to six sample groups. Unsupervised cluster analyses of the six sample groups revealed a clear separation of NF and cardiomyopathy samples. However, in contrast to the other samples, unsupervised cluster analyses revealed no distinct expression pattern in LV and RV samples from ARVC-hearts. We further identified differentially expressed transcripts using t-tests and found transcripts separating diseased and NF ventricular myocardium. Of note, in failing myocardium only about 15-16% of the genes are commonly regulated compared to NF samples. In addition both cardiomyopathies are clearly distinct on the transcriptome level. Comparison of the expression patterns between the failing RV and LV using a paired t-test revealed a lack of major differences between LV and RV gene expression in ARVC hearts. Microarrays were used to elucidate the differences between non-failing control hearts and those, suffering from arrhythmogenic right ventricular cardiomyopathy (ARVC).