# Cardiac Genetic Variants in Sudden, Unexpected Death in Epilepsy: From Challenging DNA Extraction Methods to Updated NGS Panels for Improved Genetic Analysis

## TL;DR

This study explores genetic factors linked to sudden unexpected death in epilepsy (SUDEP) by analyzing DNA from blood and tissue samples using new extraction methods and next-generation sequencing.

## Contribution

The study introduces a new DNA extraction method for FFPE tissue and identifies genetic variants potentially linked to SUDEP.

## Key findings

- Genetic variants of unknown significance were found in genes RYR2, SCN8A, and AKAP9.
- Low DNA coverage in FFPE samples suggests limitations in detecting variants in unamplified regions.
- Variants in blood samples may be associated with SUDEP based on literature.

## Abstract

Background/Objectives: SUDEP is the sudden, unexpected death of someone with epilepsy, and occurs mainly during sleep or at rest, or when the individual does not seem to have experienced a convulsive seizure. The cause of death in SUDEP is still unknown, and it may differ between cases. Cardiac factors are among the most prevalent causes observed in SUDEP. Therefore, within the forensic medicine framework, identifying well-known DNA markers involved in cardiac sudden and unexpected death would aid in understanding the cause of SUDEP, as well as in finding cardiac risk markers in patients with epilepsy. The purpose of this study was to identify any genetic variants by analyzing blood and formalin-fixed paraffin-embedded (FFPE) tissue samples, utilizing next-generation sequencing techniques. Methods: We investigated five cases of SUDEP that were examined at the Legal Medicine department of Ancona (Italy). Peripheral blood or FFPE cardiac tissues were collected, and different DNA extraction methods were performed. In particular, this study underlines a new extraction method from FFPE tissue, adapting the Casework kit for forensic application to our purpose. Later, about one hundred genes correlated to inherited cardiac diseases were sequenced through the Ion PGM System and Ion GeneStudio S5 Systems. Results: Bioinformatic analysis showed some genetic variants of unknown significance (VUS) on genes involved in SUDEP: RYR2, SCN8A, and AKAP9. Conclusions: As expected, very low coverage of the target base was observed for FFPE tissue samples because of the complexity of the biological material. Therefore, the presence of any significant variants in unamplified regions cannot be excluded in the FFPE samples. As suggested by the literature, the variants found in the blood samples are potentially associated with SUDEP.