RYR2 and arrhythmogenic right ventricular cardiomyopathy: Mechanistically, TMEM43 interacts with lamin B2, and the TMEM43‐P386S mutation induces lamin B2 mislocalization and abnormal nuclear envelope structure in ARVC iPSC‐CMs, resulting in decreased chromatin opening of promoters associated with downregulated genes, including ryanodine receptor 2 (RYR2).