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.

Whole exome sequencing of FFPE samples—expanding the horizon of forensic molecular autopsies

“…A diagnostic yield of 15-30% has been reported for molecular autopsies [8]. The diagnostic yield of WES as a tool for molecular autopsies depends on the analysed cohort, and the availability of family members, with a yield of close to 50% in highly selected cohorts [18]. In this study, three of 24 cases were positive, giving a diagnostic yield of 12.5%.…”

“…Detailed phenotyping in combination with analysis of a few genes with high evidence of gene-disease relationship often has the advantage of a high diagnostic yield with few VUS [18]. Collection and curation of these high-evidence gene-disease relationships are carried out by initiatives like ClinGen [33] and PanelApp [32].…”

“…Collection and curation of these high-evidence gene-disease relationships are carried out by initiatives like ClinGen [33] and PanelApp [32]. Broader genetic investigations using larger gene panels (> 150 genes) have the advantage of potentially finding pathogenic variants in genes more loosely associated with disease, a possible use of phenotypic data for ranking of variants, but the disadvantage of increasing the numbers of VUS [18,61,62]. Furthermore, with broader panels follows the increased risk of finding variants unrelated to the death.…”

“…Genetic testing in forensic applications has therefore mostly been limited to analysis of specific genes or smaller gene panels using molecular methods that works with fragmented FFPE material. Whole exome sequencing (WES) from FFPE has been advised to be used with caution as evidence indicates the presence of formalin-induced artefacts [18,19]. Using new techniques that can overcome these obstacles and ensure the quality of WES from FFPE samples would be beneficial in a molecular autopsy setting.…”

Wykorzystanie klinicznych badań molekularno-genetycznych w opiniowaniu sądowo-lekarskim

“…Zastosowanie klinicznych badań molekularno--genetycznych w medycynie sądowej jest możliwe i zawsze wnosi istotne dodatkowe informacje rozszerzające możliwości opiniodawcze i ułatwiające postawienie rozpoznania [8]. Jak wykazano powyżej, obszarami, w których tego rodzaju badania mogą być szczególnie przydatne, są co najmniej: • diagnostyka podłoża powikłań zakrzepowo-zatorowych w przypadkach nagłych zgonów, zwłaszcza młodych osób i kobiet ciężarnych [9], • nowoczesna zintegrowana diagnostyka morfologiczno-molekularna nowotworów (ang.…”