Abbreviations: AP = action potential, APD = AP duration, CMs = cardiomyocytes, ECG = electrocardiogram, ESC = embryonic stem cell, hiPSCs = human induced pluripotent stem cells, LQTS = long QT syndrome, NVDCC = non-voltage-dependent Ca2 + channels, PBMCs = peripheral blood mononuclear cells, SCD = sudden cardiac death, TRPM4 = transient potential melastatin 4 gene, VT = ventricular tachycardia. Here, TRPM4 is linked to familial long QT syndrome.