Channelopathy as a SUDEP Biomarker in Dravet Syndrome Patient-Derived Cardiac Myocytes

Summary: Dravet syndrome (DS) is a severe developmental and epileptic encephalopathy with a high incidence of sudden unexpected death in epilepsy (SUDEP). Most DS patients carry de novo variants in SCN1A, resulting in Nav1.1 haploinsufficiency. Because SCN1A is expressed in heart and in brain, we proposed that cardiac arrhythmia contributes to SUDEP in DS. We generated DS patient and control induced pluripotent stem cell-derived cardiac myocytes (iPSC-CMs). We observed increased sodium current (INa) and spontaneous contraction rates in DS patient iPSC-CMs versus controls. For the subject with the largest increase in INa, cardiac abnormalities were revealed upon clinical evaluation. Generation of a CRISPR gene-edited heterozygous SCN1A deletion in control iPSCs increased INa density in iPSC-CMs similar to that seen in patient cells. Thus, the high risk of SUDEP in DS may result from a predisposition to cardiac arrhythmias in addition to seizures, reflecting expression of SCN1A in heart and brain. : In this article, Isom, Parent, and colleagues show that the high risk of SUDEP in the developmental and epileptic encephalopathy, Dravet syndrome, may result from a predisposition to cardiac arrhythmias in addition to neuronal hyperexcitability, reflecting haploinsufficiency of SCN1A in heart and brain causing potential compensatory overexpression of other sodium-channel genes in those tissues. Keywords: epilepsy, cardiac arrhythmia, sodium channel, SUDEP, induced pluripotent stem cell (iPSC), developmental and epileptic encephalopathy