To further investigate genotype-positive cases with phenotype discordance, we extended phenotyping to myocardial expression studies in a truncating PKP2 P/LP variant carrier without ARVC phenotype and found evidence for escape of nonsense mediated decay to overcome haploinsufficiency as a mechanism for incomplete penetrance. The gene discussed is PKP2; the disease is arrhythmogenic right ventricular cardiomyopathy.