The impact of damaging epilepsy and cardiac genetic variant burden in sudden death in the young.

BACKGROUND: Sudden unexpected death in children is a tragic event. Understanding the genetics of sudden death in the young (SDY) enables family counseling and cascade screening. The objective of this study was to characterize genetic variation in an SDY cohort using whole genome sequencing. METHODS: The SDY Case Registry is a National Institutes of Health/Centers for Disease Control and Prevention surveillance effort to discern the prevalence, causes, and risk factors for SDY. The SDY Case Registry prospectively collected clinical data and DNA biospecimens from SDY cases < 20 years of age. SDY cases were collected from medical examiner and coroner offices spanning 13 US jurisdictions from 2015 to 2019. The cohort included 211 children (median age 0.33 year; range 0-20 years), determined to have died suddenly and unexpectedly and from whom DNA biospecimens for DNA extractions and next-of-kin consent were ascertained. A control cohort consisted of 211 randomly sampled, sex- and ancestry-matched individuals from the 1000 Genomes Project. Genetic variation was evaluated in epilepsy, cardiomyopathy, and arrhythmia genes in the SDY and control cohorts. American College of Medical Genetics/Genomics guidelines were used to classify variants as pathogenic or likely pathogenic. Additionally, pathogenic and likely pathogenic genetic variation was identified using a Bayesian-based artificial intelligence (AI) tool. RESULTS: The SDY cohort was 43% European, 29% African, 3% Asian, 16% Hispanic, and 9% with mixed ancestries and 39% female. Six percent of the cohort was found to harbor a pathogenic or likely pathogenic genetic variant in an epilepsy, cardiomyopathy, or arrhythmia gene. The genomes of SDY cases, but not controls, were enriched for rare, potentially damaging variants in epilepsy, cardiomyopathy, and arrhythmia-related genes. A greater number of rare epilepsy genetic variants correlated with younger age at death. CONCLUSIONS: While damaging cardiomyopathy and arrhythmia genes are recognized contributors to SDY, we also observed an enrichment in epilepsy-related genes in the SDY cohort and a correlation between rare epilepsy variation and younger age at death. These findings emphasize the importance of considering epilepsy genes when evaluating SDY.

A pilot study of a family history risk assessment tool for cardiovascular disease.

This study evaluated the effectiveness of using a family history questionnaire to ascertain patients and families at-risk for inherited cardiovascular disease. A questionnaire composed of 21 questions was developed based on the experience of a cardiovascular genetic counselor. This questionnaire was administered to 39 patients at a University-based cardiology practice reflecting general and specialized aspects of cardiovascular medicine. Using the number and degree of relatedness of relatives reported and limited age of onset information participants were ranked into three familial risk categories. Thirty-nine patients participated in this pilot study. Of the 39 patients, six Mendelian diseases were identified. All individuals surveyed in this study were found to be at high and/or moderate risk for at least one disease based on the family history questionnaire. Twenty-five out of 39 participants (64.1%) were found to be at high risk for at least one cardiovascular disease, and thirty-three out of 39 participants (84.6%) were found to be at moderate risk for at least one disease. A family history of arrhythmia disorders, hypertension, hyperlipidemia, coronary artery disease and diabetes were more likely to be associated with a personal history in family histories of both moderate and high risk. Family history questionnaires in cardiology clinics can be a cost-effective tool for identifying patients and families who are in the greatest need of genetic evaluation and genetic counseling services.

Phospholamban R14 deletion results in late-onset, mild, hereditary dilated cardiomyopathy.

OBJECTIVES: The purpose of this research was to determine the phenotypic spectrum associated with phospholamban gene (PLN) mutations. BACKGROUND: Inheritance contributes to the development of dilated cardiomyopathy. Mutations in the gene encoding PLN have been associated with dilated cardiomyopathy characterized by early onset and the presence of lethal ventricular arrhythmias. METHODS: We screened a cohort of 260 unrelated dilated cardiomyopathy patients from a tertiary care referral center for mutations in the PLN gene. RESULTS: Family history of cardiomyopathy was present in approximately one-half the individuals in this cohort. We identified 1 family with a deletion of arginine 14 in the PLN. Interestingly, unlike other individuals reported with the identical PLN mutation, these individuals were not diagnosed with dilated cardiomyopathy until their seventh decade when they were only mildly symptomatic with congestive heart failure. CONCLUSIONS: The identical PLN mutation can be associated with both mild and severe forms of dilated cardiomyopathy. Additionally, PLN mutations should be considered in late onset cardiomyopathy. (Genetics of Cardiovascular and Neuromuscular Disease; http://www.clinicaltrials.gov/ct/show/NCT00138931?order=1; NCT00138931)

Lamin A/C truncation in dilated cardiomyopathy with conduction disease.

BACKGROUND: Mutations in the gene encoding the nuclear membrane protein lamin A/C have been associated with at least 7 distinct diseases including autosomal dominant dilated cardiomyopathy with conduction system disease, autosomal dominant and recessive Emery Dreifuss Muscular Dystrophy, limb girdle muscular dystrophy type 1B, autosomal recessive type 2 Charcot Marie Tooth, mandibuloacral dysplasia, familial partial lipodystrophy and Hutchinson-Gilford progeria. METHODS: We used mutation detection to evaluate the lamin A/C gene in a 45 year-old woman with familial dilated cardiomyopathy and conduction system disease whose family has been well characterized for this phenotype 1. RESULTS: DNA from the proband was analyzed, and a novel 2 base-pair deletion c.908_909delCT in LMNA was identified. CONCLUSIONS: Mutations in the gene encoding lamin A/C can lead to significant cardiac conduction system disease that can be successfully treated with pacemakers and/or defibrillators. Genetic screening can help assess risk for arrhythmia and need for device implantation.