Valdivia et al. had reported a V54G mutation in SCN3B of a patient diagnosed with idiopathic ventricular fibrillation (IVF) and indicated this mutation to cause “loss-of-function” of SCN3B by decreasing INa by 70 and 90% in HEK293 and primate fibroblastoid COS cells, respectively (28). Here, SCN3B is linked to ventricular fibrillation.