SIGMAR1 and Timothy syndrome type 1: We also tested two preclinically investigated compounds: dextromethorphan, a sigma non-opioid intracellular receptor 1 agonist shown to restore the inactivation of CaV1.2 channel in iPSC-derived cardiomyocytes from a patient with TS1 (ref. 14), and 3-nitro-N-(4-phenoxyphenyl)benzamide (ICA-105574)27, an hERG channel agonist shown to increase IKr current, thus abbreviating the ventricular repolarization28–30.