Molecular Autopsy of Sudden Cardiac Death in the Genomics Era

Abstract

Molecular autopsy is the process of investigating sudden death through genetic analysis. It is particularly useful in cases where traditional autopsy is negative or only shows non-diagnostic features, i.e., in sudden unexplained deaths (SUDs), which are often due to an underlying inherited arrhythmogenic cardiac disease. The final goal of molecular autopsy in SUD cases is to aid medico-legal inquiries and to guide cascade genetic screening of the victim's relatives. Early attempts of molecular autopsy relied on Sanger sequencing, which, despite being accurate and easy to use, has a low throughput and can only be employed to analyse a small panel of genes. Conversely, the recent adoption of next-generation sequencing (NGS) technologies has allowed exome/genome wide examination, providing an increase in detection of pathogenic variants and the discovery of newer genotype-phenotype associations. NGS has nonetheless brought new challenges to molecular autopsy, especially regarding the clinical interpretation of the large number of variants of unknown significance detected in each individual.

Keywords: genetics; molecular autopsy; next-generation sequencing; sudden cardiac death.

Figure 1

Next-generation sequencing molecular autopsy. DNA of the deceased is extracted from the blood or tissues and then processed via next-generation sequencing tools (usually employing targeted gene pales or exome sequencing), which are faster and more cost-efficient for testing large numbers of genes compared to traditional Sanger sequencing. Once sample DNA sequencing is completed, detected variants must undergo several processes of filtration and prioritization which significantly reduce their number to a small relevant selection for clinical interpretation. ACMG, American College of Medical Genetics and Genomics; DANN, deleterious annotation of genetic variants using neural networks; EDTA, ethylenediaminetetraacetic acid; FATHMM, functional analysis through hidden Markov models; FFPET, formalin-fixed and paraffin-embedded tissue; GERP, genomic evolutionary rate profiling; MAF, minor allele frequency; OMIM, online Mendelian inheritance in man; Polyphen2, polymorphism phenotyping 2; PROVEAN, protein variation effect analyzer; Sift, sorting intolerant from tolerant; WebGestalt, web-based gene set analysis toolkit.