2889A novel serum biomarker identifying Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)

Introduction: Extending the paradigm of cutaneous desmosomal disease, caused by either gene mutations or anti-desmosomal antibodies, we sought to identify antibodies to cardiac desmosomal proteins among ARVC patients. Methods: A cohort of 20 subjects with definite or borderline Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) was assessed for the presence of antibodies to any of the three cadherins present in cardiac desmosomes or adherence junctions: desmocollin-2, desmoglein-2 (DSG2), or N-cadherin compared to 32 control sera. We used DSG2 protein to assess for antibodies by both Western blot (exposed to 1:100 diluted serum) and enzyme-linked immune-sorbent assay (ELISA). A validation cohort of 25 subjects with definite ARVC from the Zurich ARVC Program was assessed using the same methods to confirm our findings. We also assessed whether antibody density correlated with the burden of premature ventricular contractions on ambulatory ECG monitor, a measure of disease burden. As an additional validation, we assessed the naturally occurring ARVC model in the Boxer dog breed, comparing serum from dogs affected by ARVC to unaffected dogs without a pedigree history of ARVC, as well as unaffected dogs with ARVC in their pedigree. Finally, we used an automated robotic system to measure gap junction function in confluent human induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) cultures by single cell small molecular weight dye injection, comparing cells exposed to patient sera with cells exposed to either normal control sera or a commercial anti- DSG2 antibody as a positive control.