Materials and methods

Study population and case selection

All medico-legal autopsies performed at the Institute of Legal Medicine and Forensic Sciences of Murcia between 2009 and 2023 were retrospectively reviewed. During this period, 343 cases fulfilled criteria for SUD and the cause of death was established through conventional autopsy, including comprehensive cardiac examination, histopathological analysis, and toxicological screening. In cases in which a familial inherited cardiac condition was suspected, particularly channelopathies, postmortem genetic testing was also performed as part of the forensic investigation.

From the overall SUD cohort, 12 cases were deliberately selected for inclusion in the present study based on their specific medico-legal relevance. Selection criteria were the absence of a definitive cause of death after conventional autopsy and/or the presence of findings suggestive of an underlying hereditary cardiac disorder with potential implications for medico-legal interpretation. Importantly, these cases were not selected solely on the basis of having undergone genetic testing, but because they represented recurrent and clinically relevant forensic scenarios in which post-mortem genetic testing could play a decisive role in establishing, refining, or excluding the cause of death.

These scenarios included sudden death in children and young individuals with structurally normal hearts, deaths occurring during physical exertion or emotional stress with possible alternative medico-legal interpretations, and cases presenting sub-diagnostic or borderline cardiac findings suggestive of concealed or early-stage inherited cardiomyopathy.

Medical history was systematically investigated through interviews with close relatives and, when feasible, by contacting the decedent’s treating cardiologists.

Autopsy review

Autopsies were performed according to the guidelines for autopsy investigation of SCD [4]. During external examination or autopsy 5 mL blood from the femoral artery was collected for isolation of genomic DNA. All samples were isolated within 48 h postmortem and stored at −20 °C until further processing. Full autopsy included standardized dissection of the heart, its histological examination and toxicological screening.

Genetic analysis

DNA was isolated from whole blood using standard protocols. Targeted next-generation sequencing (NGS) was performed using custom gene panels tailored to SCD, cardiomyopathies, and channelopathies (see Annex I). All variants were subsequently confirmed by Sanger sequencing and variant classification was performed according to the 2015 guidelines of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) [11]. Co-segregation analysis and phenotypic correlation with family history were also considered when available after genetic counselling. Cardiological examination was recommended to first-degree relatives-independent of their participation in this study.

Ethical approval and informed consent

This work was performed under approval from the local Ethics Committee from University Hospital Virgen de la Arrixaca (2021-10−3-HCUVA). All procedures conducted complied with current ethical and legal standards. The next of kin of decedents provided signed specific informed consent for the genetic study, allowing the use of the samples and collected data for research purposes.