The Broad Spectrum of LMNA Cardiac Diseases: From Molecular Mechanisms to Clinical Phenotype

The Role of Genetics in Risk Stratification Strategy of Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) is a heart disorder of diverse etiologies that affects millions of people worldwide, associated with increased mortality rate and high risk of sudden cardiac death. Patients with DCM are characterized by a wide range of clinical and pre-clinical phenotypes which are related with different outcomes. Dominant studies have failed to demonstrate the value of the left ventricular ejection fraction as the only indicator for patients' assessment and arrhythmic events prediction, thus making sudden cardiac death (SCD) risk stratification strategy improvement, more crucial than ever. The multifactorial two-step approach, examining non-invasive and invasive risk factors, represents an alternative process that enhances the accurate diagnosis and the individualization of patients' management. The role of genetic testing, regarding diagnosis and decision making, is of great importance, as pathogenic variants have been detected in several patients either they had a disease relative family history or not. At the same time there are specific genes mutations that have been associated with the prognosis of the disease. The aim of this review is to summarize the latest data regarding the genetic substrate of DCM and the value of genetic testing in patients' assessment and arrhythmic risk evaluation. Undoubtedly, the appropriate application of genetic testing and the thoughtful analysis of the results will contribute to the identification of patients who will receive major benefit from an implantable defibrillator as preventive treatment of SCD.

Atrial cardiomyopathy: from cell to bedside

Atrial cardiomyopathy refers to structural and electrical remodelling of the atria, which can lead to impaired mechanical function. While historical studies have implicated atrial fibrillation as the leading cause of cardioembolic stroke, atrial cardiomyopathy may be an important, underestimated contributor. To date, the relationship between atrial cardiomyopathy, atrial fibrillation, and cardioembolic stroke remains obscure. This review summarizes the pathogenesis of atrial cardiomyopathy, with a special focus on neurohormonal and inflammatory mechanisms, as well as the role of adipose tissue, especially epicardial fat in atrial remodelling. It reviews the current evidence implicating atrial cardiomyopathy as a cause of embolic stroke, with atrial fibrillation as a lagging marker of an increased thrombogenic atrial substrate. Finally, it discusses the potential of antithrombotic therapy in embolic stroke with undetermined source and appraises the available diagnostic techniques for atrial cardiomyopathy, including imaging techniques such as echocardiography, computed tomography, and magnetic resonance imaging as well as electroanatomic mapping, electrocardiogram, biomarkers, and genetic testing. More prospective studies are needed to define the relationship between atrial cardiomyopathy, atrial fibrillation, and embolic stroke and to establish a prompt diagnosis and specific treatment strategies in these patients with atrial cardiomyopathy for the secondary and even primary prevention of embolic stroke.

Emerging Genotype-Phenotype Associations in Dilated Cardiomyopathy

PURPOSE OF REVIEW

The disease burden of inherited dilated cardiomyopathy (DCM) is large and likely underestimated. This population stands to benefit immensely from therapeutic approaches tailored to the underlying genetic causes. Here, we review recent advances in understanding novel genotype-phenotype relationships and how these can improve the care of patients with inherited DCM.

RECENT FINDINGS

In the last several years, discovery of novel DCM-associated genes, gene-specific DCM outcomes, and nuanced information about variant-environment interactions have advanced our understanding of inherited DCM. Specifically, novel associations of genes with specific clinical phenotypes can help to assess sudden cardiac death risk and guide counseling around behavioral and environmental exposures that may worsen disease. Important expansions of the current genotype-phenotype profiling include the newly DCM-associated FLNC variant, prognostically significant LMNA, DSP inflammatory cardiomyopathy, and the highly penetrant features of RBM20 variants as well as the role of TTN variants in compounding the effects of environmental factors on toxin-mediated DCM. Future directions to improve diagnostic accuracy and prognostic improvement in DCM will center not just on identification of new genes, but also on understanding the interaction of known and novel variants in known DCM genes with patient genetic background and environment.

Genetic Background and Clinical Features in Arrhythmogenic Left Ventricular Cardiomyopathy: A Systematic Review

In recent years a phenotypic variant of Arrhythmogenic cardiomyopathy has been described, characterized by predominant left ventricular (LV) involvement with no or minor right ventricular abnormalities, referred to as Arrhythmogenic left ventricular cardiomyopathy (ALVC). Different disease-genes have been identified in this form, such as Desmoplakin (DSP), Filamin C (FLNC), Phospholamban (PLN) and Desmin (DES). The main purpose of this critical systematic review was to assess the level of knowledge on genetic background and clinical features of ALVC. A search (updated to April 2022) was run in the PubMed, Scopus, and Web of Science electronic databases. The search terms used were “arrhythmogenic left ventricular cardiomyopathy” OR “arrhythmogenic cardiomyopathy” and “gene” OR “arrhythmogenic dysplasia” and “gene”. The most represented disease-gene turned out to be DSP, accounting for half of published cases, followed by FLNC. Overall, ECG abnormalities were reported in 58% of patients. Major ventricular arrhythmias were recorded in 26% of cases; an ICD was implanted in 29% of patients. A total of 6% of patients showed heart failure symptoms, and 15% had myocarditis-like episodes. DSP is confirmed to be the most represented disease-gene in ALVC patients. An analysis of reported clinical features of ALVC patients show an important degree of electrical instability, which frequently required an ICD implant. Moreover, myocarditis-like episodes are common.

LMNA mutation leads to cardiac sodium channel dysfunction in the Emery-Dreifuss muscular dystrophy patient

Pathogenic variants in the LMNA gene are known to cause laminopathies, a broad range of disorders with different clinical phenotypes. LMNA genetic variants lead to tissue-specific pathologies affecting various tissues and organs. Common manifestations of laminopathies include cardiovascular system abnormalities, in particular, cardiomyopathies and conduction disorders. In the present study, we used induced pluripotent stem cells from a patient carrying LMNA p.R249Q genetic variant to create an in vitro cardiac model of laminopathy. Induced pluripotent stem cell-derived cardiomyocytes with LMNA p.R249Q genetic variant showed a decreased sodium current density and an impaired sodium current kinetics alongside with changes in transcription levels of cardiac-specific genes. Thus, we obtained compelling in vitro evidence of an association between LMNA p.R249Q genetic variant and cardiac-related abnormalities.

The Paradox of Nuclear Lamins in Pathologies: Apparently Controversial Roles Explained by Tissue-Specific Mechanobiology

The nuclear lamina is a complex meshwork of intermediate filaments (lamins) that is located beneath the inner nuclear membrane and the surrounding nucleoplasm. The lamins exert both structural and functional roles in the nucleus and, by interacting with several nuclear proteins, are involved in a wide range of nuclear and cellular activities. Due their pivotal roles in basic cellular processes, lamin gene mutations, or modulations in lamin expression, are often associated with pathological conditions, ranging from rare genetic diseases, such as laminopathies, to cancer. Although a substantial amount of literature describes the effects that are mediated by the deregulation of nuclear lamins, some apparently controversial results have been reported, which may appear to conflict with each other. In this context, we herein provide our explanation of such “controversy”, which, in our opinion, derives from the tissue-specific expression of nuclear lamins and their close correlation with mechanotransduction processes, which could be very different, or even opposite, depending on the specific mechanical conditions that should not be compared (a tissue vs. another tissue, in vivo studies vs. cell cultures on glass/plastic supports, etc.). Moreover, we have stressed the relevance of considering and reproducing the “mechano-environment” in in vitro experimentation. Indeed, when primary cells that are collected from patients or donors are maintained in a culture, the mechanical signals deriving from canonical experimental procedures of cell culturing could alter the lamin expression, thereby profoundly modifying the assessed cell type, in some cases even too much, compared to the cell of origin.

High-Dose Dexmedetomidine for Severe Hyperactive Delirium Secondary to Intravenous Levetiracetam on Two Separate Occasions in the Same Patient

We describe the case of a 5-year-old male who developed severe hyperactive delirium with aggressive violent behavior following the administration of IV levetiracetam for the treatment of status epilepticus on two occasions. The child's symptoms ranged from attacking his parents and the intensive care staff. Risperidone was given without any improvement in symptoms. A high-dose continuous infusion of IV dexmedetomidine was administered, and his violent behavior and delirium significantly improved. The two episodes of hyperactive delirium following IV levetiracetam administration occurred at ages 3 and 5, resulting in extensive work up including laboratory testing and cranial imaging, along with cerebral spinal fluid analysis and were normal. IV dexmedetomidine provided rapid symptom relief to prevent harm for the child, staff, and family on both occasions.

Arrhythmias as Presentation of Genetic Cardiomyopathy

There is increasing evidence regarding the prevalence of genetic cardiomyopathies, for which arrhythmias may be the first presentation. Ventricular and atrial arrhythmias presenting in the absence of known myocardial disease are often labelled as idiopathic, or lone. While ventricular arrhythmias are well-recognized as presentation for arrhythmogenic cardiomyopathy in the right ventricle, the scope of arrhythmogenic cardiomyopathy has broadened to include those with dominant left ventricular involvement, usually with a phenotype of dilated cardiomyopathy. In addition, careful evaluation for genetic cardiomyopathy is also warranted for patients presenting with frequent premature ventricular contractions, conduction system disease, and early onset atrial fibrillation, in which most detected genes are in the cardiomyopathy panels. Sudden death can occur early in the course of these genetic cardiomyopathies, for which risk is not adequately tracked by left ventricular ejection fraction. Only a few of the cardiomyopathy genotypes implicated in early sudden death are recognized in current indications for implantable cardioverter defibrillators which otherwise rely upon a left ventricular ejection fraction ≤0.35 in dilated cardiomyopathy. The genetic diagnoses impact other aspects of clinical management such as exercise prescription and pharmacological therapy of arrhythmias, and new therapies are coming into clinical investigation for specific genetic cardiomyopathies. The expansion of available genetic information and implications raises new challenges for genetic counseling, particularly with the family member who has no evidence of a cardiomyopathy phenotype and may face a potentially negative impact of a genetic diagnosis. Discussions of risk for both probands and relatives need to be tailored to their numeric literacy during shared decision-making. For patients presenting with arrhythmias or cardiomyopathy, extension of genetic testing and its implications will enable cascade screening, intervention to change the trajectory for specific genotype-phenotype profiles, and enable further development and evaluation of emerging targeted therapies.

Rare and potential pathogenic mutations of LMNA and LAMA4 associated with familial arrhythmogenic right ventricular cardiomyopathy/dysplasia with right ventricular heart failure, cerebral thromboembolism and hereditary electrocardiogram abnormality

Background

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is associated with ventricular arrhythmia, heart failure (HF), and sudden death. Thromboembolism is also an important and serious complication of ARVC/D. However, the etiology of ARVC/D and thromboembolism and their association with genetic mutations are unclear.

Methods

Genomic DNA samples of peripheral blood were conducted for whole-exome sequencing (WES) and Sanger sequencing in the ARVC/D family. Then, we performed bioinformatics analysis for genes susceptible to cardiomyopathies and arrhythmias. Further, we analyzed how the potential pathogenic mutations were affecting the hydrophobicity and phosphorylation of amino acids and their joint pathogenicity by ProtScale, NetPhos and ORVAL algorisms.

Results

We discovered a Chinese Han family of ARVC/D with right ventricular HF (RVHF), cerebral thromboembolism, arrhythmias (atrial fibrillation, atrial standstill, multifocal ventricular premature, complete right bundle block and third-degree atrioventricular block) and sudden death. Based on the WES data, the variants of LMNA p.A242V, LAMA4 p.A225P and RYR2 p.T858M are highly conserved and predicated as “deleterious” by SIFT and MetaSVM algorithms. Their CADD predicting scores are 33, 27.4 and 25.8, respectively. These variants increase the hydrophobicity of their corresponding amino acid residues and their nearby sequences by 0.378, 0.266 and 0.289, respectively. The LAMA4 and RYR2 variants lead to changes in protein phosphorylation at or near their corresponding amino acid sites. There were high risks of joint pathogenicity for cardiomyopathy among these three variants. Cosegregation analysis indicated that LMNA p.A242V might be an important risk factor for ARVC/D, electrocardiogram abnormality and cerebral thromboembolism, while LAMA4 p.A225P may be a pathogenic etiology of ARVC/D and hereditary electrocardiogram abnormality.

Conclusions

The LMNA p.A242V may participate in the pathogenesis of familial ARVC/D with RVHF and cerebral thromboembolism, while LAMA4 p.A225P may be associated with ARVC/D and hereditary electrocardiogram abnormality.

Use of machine learning to classify high-risk variants of uncertain significance in lamin A/C cardiac disease

BACKGROUND

Variation in lamin A/C results in a spectrum of clinical disease, including arrhythmias and cardiomyopathy. Benign variation is rare, and classification of LMNA missense variants via in silico prediction tools results in a high rate of variants of uncertain significance (VUSs).

OBJECTIVE

The goal of this study was to use a machine learning (ML) approach for in silico prediction of LMNA pathogenic variation.

METHODS

Genetic sequencing was performed on family members with conduction system disease, and patient cell lines were examined for LMNA expression. In silico predictions of conservation and pathogenicity of published LMNA variants were visualized with uniform manifold approximation and projection. K-means clustering was used to identify variant groups with similarly projected scores, allowing the generation of statistically supported risk categories.

RESULTS

We discovered a novel LMNA variant (c.408C>A:p.Asp136Glu) segregating with conduction system disease in a multigeneration pedigree, which was reported as a VUS by a commercial testing company. Additional familial analysis and in vitro testing found it to be pathogenic, which prompted the development of an ML algorithm that used in silico predictions of pathogenicity for known LMNA missense variants. This identified 3 clusters of variation, each with a significantly different incidence of known pathogenic variants (38.8%, 15.0%, and 6.1%). Three hundred thirty-nine of 415 head/rod domain variants (81.7%), including p.Asp136Glu, were in clusters with highest proportions of pathogenic variants.

CONCLUSION

An unsupervised ML method successfully identified clusters enriched for pathogenic LMNA variants including a novel variant associated with conduction system disease. Our ML method may assist in identifying high-risk VUS when familial testing is unavailable.

Analysis of incidental findings in Qatar genome participants reveals novel functional variants in LMNA and DSP

In order to report clinically actionable incidental findings in genetic testing, the American College of Medical Genetics and Genomics (ACMG) recommended the evaluation of variants in 59 genes associated with highly penetrant mutations. However, there is a lack of epidemiological data on medically actionable rare variants in these genes in Arab populations. We used whole genome sequencing data from 6045 participants from the Qatar Genome Programme and integrated it with phenotypic data collected by the Qatar Biobank. We identified novel putative pathogenic variants in the 59 ACMG genes by filtering previously unrecorded variants based on computational prediction of pathogenicity, variant rarity and segregation evidence. We assessed the phenotypic associations of candidate variants in genes linked to cardiovascular diseases. Finally, we used a zebrafish knockdown and synthetic human mRNA co-injection assay to functionally characterize two of these novel variants. We assessed the zebrafish cardiac function in terms of heart rate, rhythm and hemodynamics, as well as the heart structure. We identified 52 492 novel variants, which have not been reported in global and disease-specific databases. A total of 74 novel variants were selected with potentially pathogenic effect. We prioritized two novel cardiovascular variants, DSP c.1841A > G (p.Asp614Gly) and LMNA c.326 T > G (p.Val109Gly) for functional characterization. Our results showed that both variants resulted in abnormal zebrafish heart rate, rhythm and structure. This study highlights medically actionable variants that are specific to the Middle Eastern Qatari population.

Familial risk of atrioventricular block in first-degree relatives

Objective

Rare cases of genetically inherited atrioventricular block (AVB) have been reported; however, the heredity of AVB remains unknown. We aimed to assess the heredity of AVB.

Design, setting and participants

Using data from the Danish Civil Registration Registry, we established a nationwide cohort of individuals with parental links. Data were merged with information from the Danish Pacemaker and Implantable Cardioverter Defibrillator Registry, containing information on all pacemaker implantations performed in Denmark during the study period, to identify patients who received a first-time pacemaker because of AVB.

Results

A total of 4 648 204 individuals had parental links and a total of 26 880 consecutive patients received a first-time pacemaker due to AVB. Overall, the adjusted rate ratio (RR) of pacemaker implantation due to AVB was 2.1 (95% CI 1.8 to 2.5) if a father, mother or sibling had AVB compared with the risk in the general population. The adjusted RR was 2.2 (1.7–2.9) for offspring of mothers with AVB, 1.9 (1.5–2.4) for offspring of fathers with AVB and 3.5 (2.3–5.4) for siblings to a patient with AVB. The risk increased inversely proportionally with the age of the index case at the time of pacemaker implantation. The corresponding adjusted RRs were 15.8 (4.8–52.3) and 10.0 (3.3–30.4) if a mother or father, respectively, had a pacemaker implantation before 50 years.

Conclusion and relevance

First-degree relatives to a patient with AVB carry an increased risk of AVB with the risk being strongly inversely associated with the age of the index case at pacemaker implantation. These findings indicate a genetic component in the development of AVB in families with an early-onset disease.

Targeted therapies in genetic dilated and hypertrophic cardiomyopathies: From molecular mechanisms to therapeutic targets

Genetic cardiomyopathies are disorders of the cardiac muscle, most often explained by pathogenic mutations in genes encoding sarcomere, cytoskeleton, or ion channel proteins. Clinical phenotypes such as heart failure and arrhythmia are classically treated with generic drugs, but aetiology‐specific and targeted treatments are lacking. As a result, cardiomyopathies still present a major burden to society, and affect many young and older patients. The Translational Committee of the Heart Failure Association (HFA) and the Working Group of Myocardial Function of the European Society of Cardiology (ESC) organized a workshop to discuss recent advances in molecular and physiological studies of various forms of cardiomyopathies. The study of cardiomyopathies has intensified after several new study setups became available, such as induced pluripotent stem cells, three‐dimensional printing of cells, use of scaffolds and engineered heart tissue, with convincing human validation studies. Furthermore, our knowledge on the consequences of mutated proteins has deepened, with relevance for cellular homeostasis, protein quality control and toxicity, often specific to particular cardiomyopathies, with precise effects explaining the aberrations. This has opened up new avenues to treat cardiomyopathies, using contemporary techniques from the molecular toolbox, such as gene editing and repair using CRISPR‐Cas9 techniques, antisense therapies, novel designer drugs, and RNA therapies. In this article, we discuss the connection between biology and diverse clinical presentation, as well as promising new medications and therapeutic avenues, which may be instrumental to come to precision medicine of genetic cardiomyopathies.

Phenotypic Variability in iPSC-Induced Cardiomyocytes and Cardiac Fibroblasts Carrying Diverse LMNA Mutations

Mutations in the LMNA gene (encoding lamin A/C) are a significant cause of familial arrhythmogenic cardiomyopathy. Although the penetrance is high, there is considerable phenotypic variability in disease onset, rate of progression, arrhythmias, and severity of myopathy. To begin to address whether this variability stems from specific LMNA mutation sites and types, we generated seven patient-specific induced pluripotent stem cell (iPSC) lines with various LMNA mutations. IPSC-derived cardiomyocytes (iCMs) and cardiac fibroblasts (iCFs) were differentiated from each line for phenotypic analyses. LMNA expression and extracellular signal-regulated kinase pathway activation were perturbed to differing degrees in both iCMs and iCFs from the different lines. Enhanced apoptosis was observed in iCMs but not in iCFs. Markedly diverse irregularities of nuclear membrane morphology were present in iCFs but not iCMs, while iCMs demonstrated variable sarcomere disarray. Heterogenous electrophysiological aberrations assayed by calcium indicator imaging and multi-electrode array suggest differing substrates for arrhythmia that were accompanied by variable ion channel gene expression in the iCMs. Coculture studies suggest enhancement of the LMNA mutation effects on electrophysiological function exerted by iCFs. This study supports the utility of patient-specific iPSC experimental platform in the exploration of mechanistic and phenotypic heterogeneity of different mutations within a cardiac disease-associated gene. The addition of genetically defined coculture of cardiac-constituent non-myocytes further expands the capabilities of this approach.

Most myopathic lamin variants aggregate: a functional genomics approach for assessing variants of uncertain significance

Hundreds of LMNA variants have been associated with several distinct disease phenotypes. However, genotype-phenotype relationships remain largely undefined and the impact for most variants remains unknown. We performed a functional analysis for 178 variants across five structural domains using two different overexpression models. We found that lamin A aggregation is a major determinant for skeletal and cardiac laminopathies. An in vitro solubility assay shows that aggregation-prone variants in the immunoglobulin-like domain correlate with domain destabilization. Finally, we demonstrate that myopathic-associated LMNA variants show aggregation patterns in induced pluripotent stem cell derived-cardiomyocytes (iPSC-CMs) in contrast to non-myopathic LMNA variants. Our data-driven approach (1) reveals that striated muscle laminopathies are predominantly protein misfolding diseases, (2) demonstrates an iPSC-CM experimental platform for characterizing laminopathic variants in human cardiomyocytes, and (3) supports a functional assay to aid in assessing pathogenicity for myopathic variants of uncertain significance.

Pro-inflammatory cytokines as emerging molecular determinants in cardiolaminopathies

Mutations in Lamin A/C gene (lmna) cause a wide spectrum of cardiolaminopathies strictly associated with significant deterioration of the electrical and contractile function of the heart. Despite the continuous flow of biomedical evidence, linking cardiac inflammation to heart remodelling in patients harbouring lmna mutations is puzzling. Therefore, we profiled 30 serum cytokines/chemokines in patients belonging to four different families carrying pathogenic lmna mutations segregating with cardiac phenotypes at different stages of severity (n = 19) and in healthy subjects (n = 11). Regardless lmna mutation subtype, high levels of circulating granulocyte colony‐stimulating factor (G‐CSF) and interleukin 6 (IL‐6) were found in all affected patients’ sera. In addition, elevated levels of Interleukins (IL) IL‐1Ra, IL‐1β IL‐4, IL‐5 and IL‐8 and the granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) were measured in a large subset of patients associated with more aggressive clinical manifestations. Finally, the expression of the pro‐inflammatory 70 kDa heat shock protein (Hsp70) was significantly increased in serum exosomes of patients harbouring the lmna mutation associated with the more severe phenotype. Overall, the identification of patient subsets with overactive or dysregulated myocardial inflammatory responses could represent an innovative diagnostic, prognostic and therapeutic tool against Lamin A/C cardiomyopathies.

Insights into the SARS-CoV-2-Mediated Alteration in the Stress Granule Protein Regulatory Networks in Humans

The rapidly and constantly evolving coronavirus, SARS-CoV-2, imposes a great threat to human health causing severe lung disease and significant mortality. Cytoplasmic stress granules (SGs) exert anti-viral activities due to their involvement in translation inhibition and innate immune signaling. SARS-CoV-2 sequesters important SG nucleator proteins and impairs SG formation, thus evading the host response for efficient viral replication. However, the significance of SGs in COVID-19 infection remains elusive. In this study, we utilize a protein-protein interaction network approach to systematically dissect the crosstalk of human post-translational regulatory networks governed by SG proteins due to SARS-CoV-2 infection. We uncovered that 116 human SG proteins directly interact with SARS-CoV-2 proteins and are involved in 430 different brain disorders including COVID-19. Further, we performed gene set enrichment analysis to identify the drugs against three important key SG proteins (DYNC1H1, DCTN1, and LMNA) and also looked for potential microRNAs (miRNAs) targeting these proteins. We identified bexarotene as a potential drug molecule and miRNAs, hsa-miR-615-3p, hsa-miR-221-3p, and hsa-miR-124-3p as potential candidates for the treatment of COVID-19 and associated manifestations.

Understanding the genetics of adult-onset dilated cardiomyopathy: what a clinician needs to know

There is increasing understanding of the genetic basis to dilated cardiomyopathy and in this review, we offer a practical primer for the practising clinician. We aim to help all clinicians involved in the care of patients with dilated cardiomyopathy to understand the clinical relevance of the genetic basis of dilated cardiomyopathy, introduce key genetic concepts, explain which patients and families may benefit from genetic testing, which genetic tests are commonly performed, how to interpret genetic results, and the clinical applications of results. We conclude by reviewing areas for future research in this dynamic field.

Genetic Cardiomyopathies: The Lesson Learned from hiPSCs

Genetic cardiomyopathies represent a wide spectrum of inherited diseases and constitute an important cause of morbidity and mortality among young people, which can manifest with heart failure, arrhythmias, and/or sudden cardiac death. Multiple underlying genetic variants and molecular pathways have been discovered in recent years; however, assessing the pathogenicity of new variants often needs in-depth characterization in order to ascertain a causal role in the disease. The application of human induced pluripotent stem cells has greatly helped to advance our knowledge in this field and enabled to obtain numerous in vitro patient-specific cellular models useful to study the underlying molecular mechanisms and test new therapeutic strategies. A milestone in the research of genetically determined heart disease was the introduction of genomic technologies that provided unparalleled opportunities to explore the genetic architecture of cardiomyopathies, thanks to the generation of isogenic pairs. The aim of this review is to provide an overview of the main research that helped elucidate the pathophysiology of the most common genetic cardiomyopathies: hypertrophic, dilated, arrhythmogenic, and left ventricular noncompaction cardiomyopathies. A special focus is provided on the application of gene-editing techniques in understanding key disease characteristics and on the therapeutic approaches that have been tested.

A splicing LMNA mutation causing laminopathies accompanied by aortic valve malformation

BACKGROUND

Laminopathies caused by LMNA gene mutations are characterized by different clinical manifestations. Among them, cardiac involvement is one of the most severe phenotypes.

CASE PRESENTATION

A 30-year-old man visited the hospital because of palpitations, shortness of breath, and fatigue. He also had muscular dystrophy, joint contractures, scoliosis, and mild dysphagia. A novel de novo heterozygous LMNA splice variant (c.810+1G>T) with dilated cardiomyopathy, Emery-Dreifuss muscular dystrophy, and progressive cardiac conduction defect was identified by genetic analysis. The patient also presented with congenital aortic valve malformation, which has never been reported in laminopathies.

CONCLUSIONS

The LMNA mutation (c.810+1G>T) was identified for the first time, enriching the mutation spectrum of the LMNA gene. The correlation between an LMNA mutation and congenital aortic valve malformation deserves further study.