HCN4 and cardiomyopathy: We previously showed that dnNRSF‐Tg mice develop progressive cardiomyopathy and begin to die from ventricular tachyarrhythmias at about 8 weeks of age.9 In dnNRSF‐Tg hearts, HCN2 and HCN4, 2 genes encoding HCN channels and transcriptional targets of NRSF/REST, were upregulated, and there was a corresponding increase in If amplitude in the isolated ventricular myocytes.