Sudden cardiac death (SCD) is a major global health issue, defined as sudden natural death presumed to be of cardiac cause. While in the elderly SCD is commonly associated with coronary artery disease, in the younger population it is linked to inherited cardiomyopathies or channelopathies, even though SCD can remain unexplained even after a comprehensive autopsy in a substantial proportion of cases. In this context, genetic testing has gained importance, supported by the widespread availability of techniques such as next-generation and whole-exome/genome sequencing and their reduced costs. This state-of-the-art review summarizes the genetic bases of sudden cardiac death among cardiomyopathies, channelopathies and in sudden unexplained death presumed to be of arrhythmic cause. Among the structural causes, inherited cardiomyopathies such as hypertrophic, dilated, non-dilated left ventricular, arrhythmogenic right ventricular and restrictive ones represent major substrates for malignant ventricular arrhythmias mostly arising from variants in sarcomeric or desmosomal genes. Channelopathies (long or short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia) are caused by variants in genes encoding cardiac ion channels and/or regulatory proteins, which equally predispose to high risk of life-threatening ventricular arrhythmias. In sudden arrhythmic death syndrome, with a structurally normal heart, post-mortem genetic testing (molecular autopsy) can uncover an underlying inherited condition. However, variants of uncertain significance are detected in more than half of the cases, underscoring the need for a multidisciplinary approach. Genetic testing also plays a key role in cascade screening of first-degree relatives. While monogenic variants drive risk in inherited cardiac disorders, emerging evidence suggests that polygenic contributions may modulate SCD susceptibility, highlighting future roles for polygenic risk scores in risk stratification.

Mitral annular disjunction (MAD) is associated with an increased risk of ventricular arrhythmias and sudden cardiac death, yet its genetic background remains poorly defined. We report the case of a 50-year-old man with MAD who survived cardiac arrest and carries three variants of unknown significance (VUS) in genes involved in cardiomyopathy pathogenesis. To explore the genetic basis of non-syndromic MAD, we performed a systematic review of the literature, identifying five case reports and one retrospective cohort study. The case reports described patients with MAD harboring four pathogenic variants and ten VUS. Two pathogenic variants were linked to cardiomyopathies, involving proteins of the nuclear envelope and cytoskeleton, while two were associated with channelopathies. The retrospective cohort study identified a recurrent variant in a gene involved in intercellular adhesion segregating within a family affected by MAD. Overall, available evidence suggests that genetic factors may hypothetically modulate susceptibility to MAD, not only in connective tissue disorders but also in isolated mitral valve disease. Variants associated with arrhythmogenic cardiomyopathies and channelopathies appear to cluster in families with non-syndromic MAD and arrhythmic phenotypes, suggesting a role in the arrhythmic substrate. However, in absence of definitive functional, segregation, or longitudinal data, the contribution of genetic variants to MAD should be interpreted with caution. Further genomic studies are needed to clarify their genetic contribution and prognostic implications.

Background: PRKAG2 cardiac syndrome is a rare autosomal dominant glycogen-storage cardiomyopathy that mimics sarcomeric hypertrophic cardiomyopathy (HCM) but features ventricular pre-excitation, progressive conduction disease and concentric hypertrophy due to intracellular glycogen accumulation. The c.905G>A (p.Arg302Gln) variant is one of the most frequently reported pathogenic substitutions. Case summary: We describe a three-generation family carrying the heterozygous PRKAG2 p.Arg302Gln variant. The proband, a 41-year-old man, presented with paroxysmal atrial fibrillation, short PR interval and abnormal intraventricular conduction associated with concentric left ventricular hypertrophy and preserved ejection fraction. Holter monitoring disclosed episodes of high-grade atrioventricular block, prompting implantation of a primary-prevention dual-chamber ICD. Two gene-positive brothers exhibited milder hypertrophy but shared sinus bradycardia, ventricular pre-excitation and supraventricular arrhythmias; one underwent catheter ablation of a posteroseptal accessory pathway. The affected mother displayed a hypertrophic phenotype complicated by sick sinus syndrome and permanent atypical atrial flutter requiring pacemaker implantation. No relevant extracardiac involvement was detected in any family member. Review and novelty: Using this family as a starting point, we provide a concise narrative review of PRKAG2 syndrome with emphasis on the Arg302Gln genotype, molecular mechanisms and emerging treatment strategies. We highlight key multimodality imaging and tissue-characterization features that help distinguish diffuse, concentric glycogen-storage hypertrophy from the often-asymmetric pattern of sarcomeric HCM. Integration of our findings with published Arg302Gln cohorts illustrates the broad phenotypic variability in conduction disease, pre-excitation and atrial arrhythmias. Conclusions: PRKAG2 p.Arg302Gln-related cardiomyopathy should be suspected in patients with otherwise unexplained left ventricular hypertrophy associated with short PR interval, pre-excitation or early brady–tachy arrhythmias. Early recognition of red-flag features, systematic genetic testing, family screening and tailored arrhythmia/device management are crucial, while emerging gene- and pathway-targeted therapies may offer future disease-modifying potential.

Hypertrophic cardiomyopathy (HCM), the most common inherited cardiac disorder, is usually caused by pathogenic variants in sarcomeric genes and is inherited in an autosomal dominant manner. Around 5% of cases are caused by variants in non-sarcomeric genes, which may involve alternative modes of inheritance. This study presents the first reported case of HCM associated with digenic contribution of heterozygous variants in two non-sarcomeric genes: ALPK3 and TRIM63. The patient was incidentally diagnosed with non-obstructive HCM in childhood and developed extreme myocardial hypertrophy with moderate heart failure at the age of 18. Rapid progressive left ventricular dysfunction promptly resulted in death at the age of 26. Genetic testing with an extended HCM panel identified no sarcomeric variants but revealed two truncating variants in the ALPK3 and TRIM63 genes. Whole-genome sequencing excluded any other causes of the disease. Heterozygous ALPK3 variants are typically associated with late-onset HCM, whereas TRIM63 variants are only considered pathogenic in a recessive state. This case, therefore, suggests a synergistic contribution of both variants to the development of a severe phenotype. The potential mechanisms of interaction between the protein products of ALPK3 and TRIM63 within the M-band of the sarcomere are discussed.

Danon Disease (DD) is a rare X-linked autophagic vacuolar myopathy caused by pathogenic variants in the lysosome-associated membrane protein 2 (LAMP-2) gene. Alternative splicing of the terminal exon 9 leads to the creation of three different isoforms, each with essential roles in regulating autophagy. DD is characterized by cardiomyopathy, skeletal myopathy, cognitive impairment, and retinal disorders, with cardiac involvement being the primary cause of morbidity and mortality. Muscle biopsy may reveal signs of vacuolar myopathy, but the diagnosis is typically confirmed through sequencing and deletion/duplication analysis of the LAMP-2 gene using peripheral blood. Although few genotype–phenotype correlations have been described, with most being limited to isoform 2B of exon 9, the most significant prognostic indicator remains sex. The disease manifests earlier and with a more severe systemic presentation in males due to their hemizygous status, whereas in females, the typical presentation is late-onset hypertrophic or dilated cardiomyopathy, generally without extracardiac involvement. Cases of severely affected women have been described, potentially due to non-random or defective X-inactivation. The less typical and delayed clinical presentation in females can result in incorrect or missed diagnoses. The aim of this narrative review is to summarize the natural history, diagnostic criteria, management strategies, and recent advancements in the understanding of DD in women.

Introduction: Clinical variability within families harbouring disease-causing genetic variants hampers clinical care and risk stratification. We studied a multigenerational family presenting with sinus bradycardia and long QT syndrome type 2 (LQTS2). The family harboured a pathogenic variant in KCNH2, which co-segregated with the observed LQTS2. We studied the genetic cause of the high occurrence of sinus bradycardia in this family. Methods: Clinical data was collected, including heart rate, QT-interval, symptoms, and echocardiographic parameters. QTc was calculated using the Bazett and the Fridericia formula. Sanger sequencing of HCN4 was performed, followed by segregation analysis of the identified variant with sinus bradycardia. The biophysiological consequences of two variants, KCNH2-p.L69P (c.206T>C) and HCN4-p.R666W (c.1996C>T), were assessed by patch-clamp experiments. Therefore, a heterologous model was generated by transfection of HEK293A or CHO-k1 cells, respectively. Results: Sanger sequencing of HCN4 identified HCN4-p.R666W (c.1996C>T), which has a stronger segregation with the observed sinus bradycardia than KCNH2-p.L69P. Patch-clamp experiments revealed that KCNH2-p.L69P and HCN4-p.R666W lead to a decrease in the corresponding current densities, which explains the LQTS and sinus bradycardia observed in the patients. Carriers of both genetic variants have a more severe LQTS2 phenotype, reflected in longer QT and higher incidence of syncope. Conclusions: We identified two (likely) pathogenic variants, KCNH2-p.L69P and HCN4-p.R666W, co-segregating with LQTS2 and sinus bradycardia, respectively. Patients carrying both variants showed a more severe phenotype. These findings highlight the importance of additional genetic testing when discordant features are present, thereby enabling more accurate diagnosis, risk prediction, and management.

Background: PRKAG2-related disease is an autosomal dominant disorder caused by pathogenic variants in the PRKAG2 gene, leading to glycogen accumulation in cardiomyocytes. It is characterized by left ventricular hypertrophy (LVH), ventricular pre-excitation, and conduction disease. Due to the rarity of the condition and the frequent occurrence of private variants, functional or pathological testing is required for definitive pathogenicity classification. Case Presentation: We describe a 22-year-old male referred for evaluation after experiencing exertional dyspnea and a syncopal episode. Family history revealed sudden cardiac deaths and conduction disease requiring pacemaker implantation. The patient exhibited mild LVH on imaging, conduction abnormalities on electrophysiological study, and a heterozygous PRKAG2 variant (c.1643C>T; p.Ser548Leu), classified as likely pathogenic according to ACMG guidelines. Cascade screening identified the variant in three family members, one of whom exhibited a positive phenotype. Endomyocardial biopsy revealed glycogen accumulation, providing histopathological confirmation of PRKAG2-related disease. Conclusions: This case underscores the importance of integrating genetic, clinical, and histopathological data in variant interpretation. Endomyocardial biopsy can provide definitive evidence to reclassify a PRKAG2 variant as pathogenic, thereby guiding management and family screening.

Background: Regular endurance training induces physiological changes in cardiac structure and function. The precise epigenetic mechanisms by which cardiovascular adaptations are mediated are still unclear. This review seeks to clarify the role of epigenetic regulation in exercise-induced cardiovascular adaptation. Methods: This systematic review was conducted in accordance with the PRISMA guidelines up to 30 April 2025, using the databases PubMed, VHL, and LILACS Plus. Studies were included if they focused on microRNA expression and DNA methylation in individuals with cardiovascular disease who underwent endurance training. Results: Six articles, including 384 participants with heart failure, coronary artery disease, and hypertension, were included in the final analysis. Changes in DNA methylation and microRNA expression of specific genes involved in cardiovascular structural and functional adaptation were observed. Significant improvements were found in body composition, VO2peak, systolic and diastolic blood pressure, and left ventricular function and structure. Conclusions: Endurance training has a positive impact on epigenetic mechanisms related to cardiovascular structural and functional adaptation. A clear causal link between epigenetic modifications and clinical outcomes remains to be established.

Congenital genetic heart defects are major contributors to pediatric morbidity and mortality, underscoring the importance of early detection and individualized therapeutic strategies. This review aimed to summarize current knowledge on a spectrum of inherited cardiovascular disorders, with a focus on their genetic etiology, molecular pathogenesis, and phenotypic presentation in children. Conditions discussed include Marfan syndrome, Noonan syndrome, various cardiomyopathies, Duchenne muscular dystrophy, DiGeorge syndrome, and the tetralogy of Fallot. These six conditions were selected to represent the spectrum of pediatric cardiovascular genetic diseases, encompassing connective tissue disorders, multisystem syndromes, primary myocardial diseases, neuromuscular cardiac involvement, and structural congenital defects, thereby illustrating how distinct genotypes lead to diverse phenotypes. For each disorder, the underlying genetic mutations, associated molecular pathways, cardiovascular involvement, clinical features, and approaches to diagnosis and management are examined. Emphasis is placed on the role of timely diagnosis, genetic counseling, and personalized treatment in improving patient outcomes. The review concludes by highlighting emerging research directions and novel therapeutic interventions aimed at enhancing care for these complex pediatric conditions.

Background: Polygenic risk scores (PRSs) aggregate the effects of many common genetic variants and are being investigated as tools to refine coronary artery disease (CAD) risk prediction beyond traditional clinical models. Methods and Results: We review the development of PRS from early unweighted scores to contemporary genome-wide models and summarize evidence from major studies. We identified key studies through PubMed searches using the terms “polygenic risk score,” “genetic risk prediction,” and “coronary artery disease,” supplemented by citation chaining of highly cited articles and recent reviews. Large cohorts, such as the UK Biobank, show that individuals in the highest PRS percentiles have a 3–5-fold higher risk of CAD, and may gain the greatest benefit from statin therapy. PRS can also reclassify younger adults at borderline or intermediate risk and may complement coronary artery calcium (CAC) scoring. Conclusions: PRSs hold promise for lifetime risk stratification and targeted prevention in CAD but are limited by ancestry bias in GWAS, underrepresentation of diverse populations, inconsistency in individual estimates, and lack of standardized reporting. Future research should focus on expanding multi-ancestry databases, standardizing methods, prospective validation, and effective communication strategies to support equitable and evidence-based clinical use.