Copy Number Variants of Neuro-Cardiac Ion Channel Genes and the Risk of SUDEP

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DESCRIPTION (provided by applicant): Our data incriminate defective ion channels co-expressed in heart and brain as important molecular risk factors for sudden unexpected death in epilepsy (SUDEP). We propose a novel array-based analysis of candidate SUDEP genes in samples from SUDEP cases and their families. This proposal complements our ongoing work in support of our central hypothesis: "Mutations in ion channel genes co-expressed in heart and brain underlie the phenotype of cardiac arrhythmias and seizures and may ultimately lead to SUDEP." Many idiopathic cardiac arrhythmias in the young are linked to channelopathies and mutations of ion channel genes are recognized causes of epileptogenicity. SUDEP is a catastrophic complication of epilepsy of unknown cause. The literature-based evidence and mouse model data originating from our laboratory indicate that defective ion channels co-expressed in heart and brain are important molecular risk factors for SUDEP. We performed a feasibility study on a cohort of 47 patients with epilepsy and analyzed several SUDEP cases using our custom built ion channel gene-specific comparative hybridization array (ICCH array) interrogating over 250 ion channel subunits, including all main cardiac arrhythmia genes. We identified copy number variants (CNVs) which may play a critical role in the SUDEP pathophysiology. Based on these positive pilot results I propose using our ICCH platform to analyze samples from SUDEP families for CNVs in (1) all major ion channel subunit genes known to be associated with inherited malignant cardiac arrhythmias, (2) in all non-arrhythmia ion channel genes, and (3) to map mutant novel ion channel genes identified in aim 2 within the neuro-cardiac axis. In addition, I have laid ground work for the development of the first centralized publicly accessible SUDEP repository of high quality fresh frozen SUDEP samples by working with the NIH Coriell Repository. I expect to find many variants leading to the discovery of novel genes and a better understanding of molecular mechanisms of SUDEP and definition of a gene profile of the epilepsy population at risk. Our discoveries will be of clinical use in the initiation of preventative strategies in SUDEP.