IMPORTANCEPostmortem genetic testing of young individuals with sudden death has previously identified pathogenic gene variants. However, prior studies primarily considered highly penetrant monogenic variants, often without detailed decedent and family clinical information.OBJECTIVE To assess genotype and phenotype risk in a diverse cohort of young decedents with sudden death and their families.DESIGN, SETTING, AND PARTICIPANTS Pathological and whole-genome sequence analysis was conducted in a cohort referred from a national network of medical examiners. Cases were accrued prospectively from May 2015 to March 2019 across 24 US states. Analysis began September 2016 and ended November 2020.EXPOSURES Evaluation of autopsy and clinical data integrated with whole-genome sequence data and family member evaluation.RESULTS A total of 103 decedents (mean [SD] age at death, 23.7 [11.9] years; age range, 1-44 years), their surviving family members, and 140 sex-and genetic ancestry-matched controls were analyzed. Among 103 decedents, autopsy and clinical data review categorized 36 decedents with postmortem diagnoses, 23 decedents with findings of uncertain significance, and 44 with sudden unexplained death. Pathogenic/likely pathogenic (P/LP) genetic variants in arrhythmia or cardiomyopathy genes were identified in 13 decedents (12.6%). A multivariable analysis including decedent phenotype, ancestry, and sex demonstrated that younger decedents had a higher burden of P/LP variants and select variants of uncertain significance (effect size, −1.64; P = .001). These select, curated variants of uncertain significance in cardiac genes were more common in decedents than controls (83 of 103 decedents [86%] vs 100 of 140 controls [71%]; P = .005), and decedents harbored more rare cardiac variants than controls (2.3 variants per individual vs 1.8 in controls; P = .006). Genetic testing of 31 parent-decedent trios and 14 parent-decedent dyads revealed 8 transmitted P/LP variants and 1 de novo P/LP variant. Incomplete penetrance was present in 6 of 8 parents who transmitted a P/LP variant.CONCLUSIONS AND RELEVANCE Whole-genome sequencing effectively identified P/LP variants in cases of sudden death in young individuals, implicating both arrhythmia and cardiomyopathy genes. Genomic analyses and familial phenotype association suggest potentially additive, oligogenic risk mechanisms for sudden death in this cohort.
Background After sudden cardiac death in people aged <40 years, heart weight is a surrogate for cardiomegaly and a marker for cardiomyopathy. However, thresholds for cardiomegaly based on heart weight have not been validated in a cohort of cases of sudden cardiac death in young people. Methods and Results We surveyed medical examiner offices to determine which tools were used to assess heart weight norms. The survey determined that there was no gold standard for cardiomegaly (52 centers reported 22 different methods). We used a collection of heart weight data from sudden deaths in the Northwestern Sudden Death Collaboration (NSDC) to test the 22 methods. We found that the methods reported in our survey had little consistency: they classified between 18% and 81% of NSDC hearts with cardiomegaly. Therefore, we obtained biometric and postmortem data from a reference population of 3398 decedents aged <40 years. The reference population was ethnically diverse and had no known cardiac pathology on autopsy or histology. We derived and validated a multivariable regression model to predict normal heart weights and a threshold for cardiomegaly (upper 95% CI limit) in the young reference population (the Chicago model). Using the new model, the prevalence of cardiomegaly in hearts from the NSDC was 19%. Conclusions Medical examiner offices use a variety of tools to classify cardiomegaly. These approaches produce inconsistent results, and many overinterpret cardiomegaly. We recommend the model proposed to classify postmortem cardiomegaly in cases of sudden cardiac death in young people.
Genetic testing for cardiac disorders continues to change. Our objective was to assess trends in variant classification in pediatric arrhythmia and cardiomyopathy. We conducted a retrospective review of patients tested for genetic arrhythmia and cardiomyopathy disorders from 2006–2017. Variants were classified by CLIA laboratories. Trends were assessed by the Spearman correlation. There were 914 variants in 583 patients from 337 families. The total number of tests ordered increased over time, accelerating after 2012. There was a strong positive correlation between the average number of genes tested per panel and year of testing (r = .97, p < .001) and a weak correlation between the year and a decrease in the percentage of clinically actionable variants (r = −.20, p = .005). By 2011, VUS represented >50% of variants reported on panels. Over 12 years, 203 genes were interrogated; one or more variants were reported in 91 of 203 genes (45%). 32% of patients had at least one clinically actionable variant; 28% had at least one VUS. Reclassification is an important long‐term issue, with 21.5% variants changing clinical interpretation. We observed an increase over time in three areas: total number of tests ordered, average number of genes/panel, and percentage of VUS. Providers may need to interpret results from 90 + genes, and ongoing education is critical. Due to their specific training in test result interpretation, we recommend the inclusion of a genetic counselor in pediatric electrophysiology and cardiomyopathy teams.
OBJECTIVES/SPECIFIC AIMS: Sudden death in the young (SDY) occurs in people between 1 and 40 years of age who do not have a known premortem risk factor for early death. Cardiovascular diseases account for the majority of causes of SDY. Sequencing of genes associated with congenital arrhythmia susceptibility and familial cardiomyopathy reveals pathogenic variants in 30% of postmortem cases (often called “molecular autopsy”). However, better data are needed to determine the prevalence of phenotype and genotype abnormalities in surviving relatives. METHODS/STUDY POPULATION: A retrospective cohort study was performed at a tertiary pediatric center including all subjects with a family history of SDY. Cases were identified using ICD-9 codes (798.1 or .9, V17.41, V17.49, V19.8, V61.07), search of cardiology databases, and by recursive identification of all family members of a subject. Phenotype data was independently reviewed by a pediatric cardiologist. Genotype results were available when obtained by the original treating physician. RESULTS/ANTICIPATED RESULTS: Cardiac evaluations were performed in 279 subjects from 175 families, of whom 117 subjects (42%) were first-degree relatives of the proband. Mean age of the subject at time of evaluation was 9 years (SD 5.9). Most probands were over 18 years at the time of SDY: 1–4 years of age (9%); 5–12 (5%); 13–17 (16%); 18–24 (18%); 25–40 (42%). A final diagnosis was determined in 55 families (20%), and a variant in a gene potentially causative of SDY was discovered in 20/55 (36%) of those families. Variants were classified as 50% pathogenic/likely pathogenic, 50% variants of unknown significance. Cardiac testing (ECG, echo, EST, signal averaged ECG, cardiac MRI, or EP study) was abnormal in 124/279 subjects (44%). Among those with abnormal studies, 57/124 (46%) were from a family where a final diagnosis could be determined (LQT 43%, HCM 21%, ARVC 4%, other cardiomyopathy 19%, WPW 5%, CPVT 2%). However, 67/279 of total subjects (24%) had at least 1 abnormal study and a final diagnosis was not determined in the family. DISCUSSION/SIGNIFICANCE OF IMPACT: An abnormal phenotype is common among relatives referred for cardiac evaluation after SDY. While testing identifies a family diagnosis in 20% of families, many patients have abnormal cardiac testing and no clear diagnosis can be made. An improved postmortem protocol for phenotype testing in relatives of a SDY victim and improved postmortem genetic testing may lead to a higher diagnosis rate and improved risk determination in surviving family members.
Background: Postoperative infections can occur during surgical replacement of pulse generators for pacemakers and implantable cardioverter-defibrillators. The incidence of infection is poorly documented in children and patients with adult congenital heart disease. The utility of surveillance cultures obtained from device pocket swabs is unknown in this group. Methods: We reviewed surgical replacements of cardiovascular implantable pulse generators from 2010 to 2017. Two cohorts were defined. In a surveillance cohort (123 patients), aerobic and anaerobic culture swabs of the device pocket were obtained at the time of generator change. In a nonsurveillance cohort (107 patients), generator change occurred without obtaining cultures. Results: During 230 generator changes (mean patient age 19 years; 77% with structural congenital heart disease), two clinical infections occurred at the surgical site (0.9% incidence). Neither infection occurred in the surveillance cohort. Cultures were positive in 12 (9.8%) of 123 patients in the surveillance cohort, but 11 of 12 were likely contaminants and none were subsequently associated with clinical disease. There was no association between clinical infection or positive surveillance cultures and the location of pulse generator, the presence of other concurrent surgeries, or a history of prior pocket infection. Conclusions: Clinical infection was rare after pulse generator change in children and young adults. No cases required reintervention on the pocket. Surveillance cultures did not improve clinical care. These data extend current recommendations that surveillance cultures are not required during generator change to the pediatric and young adult population.
Introduction: Genetic testing after sudden death in the young can identify pathogenic cardiac gene variants. Hypothesis: Genomic methods, coupled with phenotype evaluation, reveal non-Mendalian risks. Methods: We conducted clinical analysis and whole genome sequencing on 103 decedents aged 1-40 (mean age at death 23.7 years) accrued prospectively from 2015 to 2019 across 22 states. Postmortem pathological findings were classified as: known cardiac disorders, findings of uncertain significance (FUS), or sudden unexplained death (SUD, indicating no postmortem pathological diagnosis). Parental DNA and clinical data were obtained where possible. Variants were classified by an independent clinical genetic laboratory. Results: Among the 103 decedents, 34 had a postmortem clinical diagnosis, 23 had FUS, and 46 were classified as SUD. Pathogenic/likely pathogenic (P/LP) variants in arrhythmia or cardiomyopathy genes were identified in 17 (16.5%) decedents. The distribution of P/LP variants was not associated with age at death (OR 1.01 [0.97, 1.05], p=0.54); however, a multivariable analysis including decedent phenotype, ancestry and sex demonstrated that younger decedents had a higher burden of curated P/LP/VUS variants (effect size -1.5, p=0.0019). DNA from 31 parent-decedent trios and 14 parent-decedent dyads revealed 9 transmitted P/LP variants and 1 de novo P/LP variant. More than half of parents transmitting a P/LP variant (5/9) did not have clinical findings associated with the genotype. Conclusions: Whole genome sequencing effectively revealed P/LP variants in cases of sudden death in the young, implicating both arrhythmia and cardiomyopathy genes. In addition, both genotype and phenotype analyses suggest additional non-Mendelian risk mechanisms.
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