Lessons learned from testing cardiac channelopathy and cardiomyopathy genes in individuals who died suddenly: A two‐year prospective study in a large medical examiner’s office with an in‐house molecular genetics laboratory and genetic counseling services

Molecular autopsy in Chinese sudden cardiac death in the young

Inherited cardiovascular conditions are significant causes of sudden cardiac death in the young (SCDY), making their investigation using molecular autopsy and prevention a public health priority. However, the molecular autopsy data in Chinese population is lacking. The 5-year result (2017-2021) of molecular autopsy services provided for victims of SCDY (age 1-40 years) was reviewed. The outcome of family cascade genetic screening and clinical evaluation was reviewed. A literature review of case series reporting results of molecular autopsy on SCDY in 2016-2023 was conducted. Among the 41 decedents, 11 were found to carry 13 sudden cardiac death (SCD)-causative genetic variants. Likely pathogenic (LP) variants were identified in the DSP, TPM1, TTN, and SCN5A genes. Cascade genetic testing identified four family members with LP variants. One family member with familial TPM1 variant was found to have hypertrophic cardiomyopathy upon clinical evaluation. This study provided insight into the genetic profile of molecular autopsy in a Chinese cohort of SCDY. The detection of important SCD-causative variants through molecular autopsy has facilitated family cascade screening by targeted genetic testing and clinical evaluation of at-risk family members. A literature review of the current landscape of molecular autopsy in the investigation of SCDY was conducted.

Principles of Genetic Counseling in Inherited Heart Conditions

Cardiac genetic counseling is the process of helping individuals adapt to a personal diagnosis or family history of an inherited heart condition. The process is shown to benefit patients and includes specialized skills, such as counseling children and interpreting complex genetic results. Emerging areas include: evolving service delivery models for caring for patients and communicating risk to relatives, new areas of need including postmortem molecular autopsy, and new populations of individuals found to carry a likely pathogenic/pathogenic cardiac variant identified through genomic screening. This article provides an overview of the cardiac genetic counseling process and evolving areas in the field.

Molecular autopsy: Twenty years of post-mortem diagnosis in sudden cardiac death

In the forensic medicine field, molecular autopsy is the post-mortem genetic analysis performed to attempt to unravel the cause of decease in cases remaining unexplained after a comprehensive forensic autopsy. This negative autopsy, classified as negative or non-conclusive, usually occurs in young population. In these cases, in which the cause of death is unascertained after a thorough autopsy, an underlying inherited arrhythmogenic syndrome is the main suspected cause of death. Next-generation sequencing allows a rapid and cost-effectives genetic analysis, identifying a rare variant classified as potentially pathogenic in up to 25% of sudden death cases in young population. The first symptom of an inherited arrhythmogenic disease may be a malignant arrhythmia, and even sudden death. Early identification of a pathogenic genetic alteration associated with an inherited arrhythmogenic syndrome may help to adopt preventive personalized measures to reduce risk of malignant arrhythmias and sudden death in the victim's relatives, at risk despite being asymptomatic. The current main challenge is a proper genetic interpretation of variants identified and useful clinical translation. The implications of this personalized translational medicine are multifaceted, requiring the dedication of a specialized team, including forensic scientists, pathologists, cardiologists, pediatric cardiologists, and geneticists.

Postmortem Genetic Testing Is an Increasingly Utilized Tool in Death Investigation

Introduction

Postmortem genetic testing (PMGT) can provide valuable information about an individual's cause of death and potentially allow at-risk relatives to discern their risks for inherited cardiac disease. Postmortem genetic testing is most often successful with certain specimens.

Methods

Investigators collected data on postmortem referrals to GeneDx, LLC for PMGT. Orders were reviewed and stratified based on provider, specimen type, and tests ordered.

Discussion

This cohort included 601 deceased individuals referred for PMGT with a total of 673 genetic tests ordered from 247 different providers. The most common test categories ordered were arrhythmia (33.4%) and cardiomyopathy (29.3%). A likely pathogenic or pathogenic genetic variant was identified in approximately 15% of patients. Blood in EDTA was received for 21.6% of patients with a 95% success rate for completion of all test components. Blood samples in EDTA were most successful in completing PMGT, but sequencing was still successful in the majority of suboptimal specimens.

Conclusion

The use of PMGT is increasing. Obtaining optimal samples (blood in EDTA) is important for successful completion of genetic testing. Obstacles may still exist for obtaining and storing ideal specimens. Continued efforts are needed for education and awareness around appropriate specimen types, storage and shipping of specimens, DNA banking, and overall availability of PMGT. In addition, access to resources such as supplies, proper storage conditions, DNA banking, and PMGT will allow for more opportunities to complete testing.

Life-threatening cardiac arrhythmia and sudden death during electronic gaming: An international case series and systematic review

BACKGROUND

Electronic gaming has recently been reported as a precipitant of life-threatening cardiac arrhythmia in susceptible individuals.

OBJECTIVE

The purpose of this study was to describe the population at risk, the nature of cardiac events, and the type of game linked to cardiac arrhythmia associated with electronic gaming.

METHODS

A multisite international case series of suspected or proven cardiac arrhythmia during electronic gaming in children and a systematic review of the literature were performed.

RESULTS

Twenty-two patients (18 in the case series and 4 via systematic review; aged 7-16 years; 19 males [86%]) were identified as having experienced suspected or proven ventricular arrhythmia during electronic gaming; 6 (27%) had experienced cardiac arrest, and 4 (18%) died suddenly. A proarrhythmic cardiac diagnosis was known in 7 (31%) patients before their gaming event and was established afterward in 12 (54%). Ten patients (45%) had catecholaminergic polymorphic ventricular tachycardia, 4 (18%) had long QT syndrome, 2 (9%) were post-congenital cardiac surgery, 2 (9%) had "idiopathic" ventricular fibrillation, and 1 (after Kawasaki disease) had coronary ischemia. In 3 patients (14%), including 2 who died, the diagnosis remains unknown. In 13 (59%) patients for whom the electronic game details were known, 8 (62%) were war games.

CONCLUSION

Electronic gaming can precipitate lethal cardiac arrhythmias in susceptible children. The incidence appears to be low, but syncope in this setting should be investigated thoroughly. In children with proarrhythmic cardiac conditions, electronic war games in particular are a potent arrhythmic trigger.

Variants of uncertain significance in the era of next-generation sequencing

ABSTRACT

Next-generation sequencing (NGS) is now widely used in diagnosing rare diseases. However, it has some limitations, such as variants of uncertain significance (VUS). This can present difficulties even for nurse practitioners involved in clinical genetics. We present three cases from our clinical practice: two targeted panel testing and one exome sequencing. Whole blood samples were collected and sent for NGS analysis. In case 1, a VUS was found in the LITAF gene, which is associated with autosomal dominant Charcot-Marie-Tooth disease type 1C. In case 2, a VUS was reported in the MEFV gene, which is associated with autosomal recessive and autosomal dominant familial Mediterranean fever. In these cases, the reported VUS corresponded to the clinical diagnosis. In case 3, two variants in the heterozygous state were found in the ATP7B gene, which is associated with Wilson disease, and the disorder was later clinically recognized. According to the published guidelines, VUSs should not be discussed as a cause for an observed genetic condition. Nevertheless, if the reported variant is in a gene associated with the clinically diagnosed disorder, and there is a strong genotype-phenotype correlation, it could be suggestive of the etiological role of this variant.

Racial Disparities in Ion Channelopathies and Inherited Cardiovascular Diseases Associated With Sudden Cardiac Death

Cardiovascular disease (CVD) continues to be the most common cause of death worldwide, and cardiac arrhythmias account for approximately one half of these deaths. The morbidity and mortality from CVD have been reduced significantly over the past few decades; however, disparities in racial or ethnic populations still exist. This review is based on available literature to date and focuses on known cardiac channelopathies and other inherited disorders associated with sudden cardiac death in African American/Black subjects and the role of epigenetics in phenotypic manifestations of CVD, and illustrates existing disparities in treatment and outcomes. The review also highlights the knowledge gaps that limit understanding of the manifestation of phenotypic abnormalities across racial or ethnic groups and discusses disparities associated with device underuse in the management of patients at risk for sudden cardiac death. We discuss factors related to reports in the United States, that the overall mortality attributed to CVD and the number of out-of-hospital cardiac arrests are higher among African American/Black subjects when compared with other racial or ethnic groups. African American/Black subjects are disproportionally affected by CVD, including cardiac arrhythmias and sudden cardiac death, thus highlighting a major concern in this population that remains underrepresented in clinical trials with limited genetic testing and device underuse. The proposed solutions include (1) early identification of genetic variants, which is crucial in tailoring a preventive management strategy; (2) inclusion of diverse racial or ethnic groups in clinical trials; (3) compliance with guideline-directed medical treatment and referral to cardiovascular subspecialists; and (4) training and mentoring of underrepresented junior faculty in cardiovascular health disparities research.

Cardiomyopathies and Genetic Testing in Heart Failure: Role in Defining Phenotype-Targeted Approaches and Management

Cardiomyopathies represent an important cause of heart failure, often affecting young individuals, and have important implications for relatives. Genetic testing for cardiomyopathies is an established care pathway in contemporary cardiology practice. The primary cardiomyopathies where genetic testing is indicated are hypertrophic, dilated, arrhythmogenic, and restrictive cardiomyopathies, with left ventricular noncompaction as a variant phenotype. Early identification and initiation of therapies in patients with inherited cardiomyopathies allow for targeting asymptomatic and presymptomatic patients in stages A and B of the American College of Cardiology/American Heart Association classification of heart failure. The current approach for genetic testing uses gene panel-based testing with the ability to extend to whole-exome and whole-genome sequencing in rare instances. The central components of genetic testing include defining the genetic basis of the diagnosis, providing prognostic information, and the ability to screen and risk-stratify relatives. Genetic testing for cardiomyopathies should be coordinated by a multidisciplinary team including adult and pediatric cardiologists, genetic counsellors, and geneticists, with access to expertise in cardiac imaging and electrophysiology. A pragmatic approach for addressing genetic variants of uncertain significance is important. In this review, we highlight the indications for genetic testing in the various cardiomyopathies, the value of early diagnosis and treatment, family screening, and the care process involved in genetic counselling and testing.