Overlap phenotypes of the left ventricular noncompaction and hypertrophic cardiomyopathy with complex arrhythmias and heart failure induced by the novel truncated DSC2 mutation

Cardiomyopathy: pathogenesis and therapeutic interventions

Cardiomyopathy is a group of disease characterized by structural and functional damage to the myocardium. The etiologies of cardiomyopathies are diverse, spanning from genetic mutations impacting fundamental myocardial functions to systemic disorders that result in widespread cardiac damage. Many specific gene mutations cause primary cardiomyopathy. Environmental factors and metabolic disorders may also lead to the occurrence of cardiomyopathy. This review provides an in-depth analysis of the current understanding of the pathogenesis of various cardiomyopathies, highlighting the molecular and cellular mechanisms that contribute to their development and progression. The current therapeutic interventions for cardiomyopathies range from pharmacological interventions to mechanical support and heart transplantation. Gene therapy and cell therapy, propelled by ongoing advancements in overarching strategies and methodologies, has also emerged as a pivotal clinical intervention for a variety of diseases. The increasing number of causal gene of cardiomyopathies have been identified in recent studies. Therefore, gene therapy targeting causal genes holds promise in offering therapeutic advantages to individuals diagnosed with cardiomyopathies. Acting as a more precise approach to gene therapy, they are gradually emerging as a substitute for traditional gene therapy. This article reviews pathogenesis and therapeutic interventions for different cardiomyopathies.

Left Ventricular Non-Compaction in Children: Aetiology and Diagnostic Criteria

Left ventricular non-compaction (LVNC) is a heterogeneous myocardial disorder characterized by prominent trabeculae protruding into the left ventricular lumen and deep intertrabecular recesses. LVNC can manifest in isolation or alongside other heart muscle diseases. Its occurrence among children is rising due to advancements in imaging techniques. The origins of LVNC are diverse, involving both genetic and acquired forms. The clinical manifestation varies greatly, with some cases presenting no symptoms, while others typically manifesting with heart failure, systemic embolism, and arrhythmias. Diagnosis mainly relies on assessing heart structure using imaging tools like echocardiography and cardiac magnetic resonance. However, the absence of a universally agreed-upon standard and limitations in diagnostic criteria have led to ongoing debates in the scientific community regarding the most reliable methods. Further research is crucial to enhance the diagnosis of LVNC, particularly in early life stages.

Navigating the prime editing strategy to treat cardiovascular genetic disorders in transforming heart health

INTRODUCTION

After understanding the genetic basis of cardiovascular disorders, the discovery of prime editing (PE), has opened new horizons for finding their cures. PE strategy is the most versatile editing tool to change cardiac genetic background for therapeutic interventions. The optimization of elements, prediction of efficiency, and discovery of the involved genes regulating the process have not been completed. The large size of the cargo and multi-elementary structure makes the in vivo heart delivery challenging.

AREAS COVERED

Updated from recent published studies, the fundamentals of the PEs, their application in cardiology, potentials, shortcomings, and the future perspectives for the treatment of cardiac-related genetic disorders will be discussed.

EXPERT OPINION

The ideal PE for the heart should be tissue-specific, regulatable, less immunogenic, high transducing, and safe. However, low efficiency, sup-optimal PE architecture, the large size of required elements, the unclear role of transcriptomics on the process, unpredictable off-target effects, and its context-dependency are subjects that need to be considered. It is also of great importance to see how beneficial or detrimental cell cycle or epigenomic modifier is to bring changes into cardiac cells. The PE delivery is challenging due to the size, multi-component properties of the editors and liver sink.

[The role of imbalance of myocardial cell adhesion proteins in cardiac arrhythmia and heart failure]

A review of the literature data on the role of imbalance of cellular adhesion proteins (CAP) of the heart in the development of cardiac arrhythmias and heart failure. The CAPS of the intercalated discs belonging to the cadherin and desmin groups provide a mechanical connection of cardiomyocytes, proteins from the connexin group are responsible for the transmission of an electrical impulse. The imbalance of CAP has mainly a hereditary origin and is accompanied by the destruction of intercalated discs, blockage of impulse transmission with the development of electrical instability of the myocardium and cardiac arrhythmias, including ventricular and atrial fibrillation. This is the case with cardiomyopathies, coronary heart disease. Endothelial dysfunction also plays an essential role in atrial fibrillation, which is associated with an imbalance in the CAP of the endothelial lining of the endocardium and blood vessels.

NON-COMPACTION CARDIOMYOPATHY: ISSUES, CONTRADICTIONS AND SEARCH FOR EFFECTIVE DIAGNOSTIC CRITERIA. LITERATURE REVIEW. PART 2

Active research of non-compaction cardiomyopathy (NCM) has been going on for more than 30 years. A significant amount of information has been accumulated that is familiar to a much larger number of specialists than in the most recent past. Despite this, numerous issues remain unresolved, ranging from classification (congenital or acquired, nosology or morphological phenotype) to the ongoing search for clear diagnostic criteria that separate NCM from physiological hypertrabecularity and secondary non-compaction myocardium with the background of existing chronic processes. Meanwhile, a high risk of adverse cardiovascular events in a certain group of people with NCM is quite high. These patients need timely and often quite aggressive therapy. This review of sources of scientific and practical information is devoted to the current aspects of the classification, extremely diverse clinical picture, extremely complex genetic and instrumental diagnosis of NCM, and the possibilities of its treatment. The purpose of this review is to analyze current ideas about the controversial problems of non-compaction cardiomyopathy. The material for its preparation is the numerous sources of databases Web Science, PubMed, Google Scholar, eLIBRARY. As a result of their analysis, the authors tried to identify and summarize the main problems of the NCM and identify the ways to resolve them.

Whole exome sequencing in Brugada and long QT syndromes revealed novel rare and potential pathogenic mutations related to the dysfunction of the cardiac sodium channel

Background

Brugada syndrome (Brs) and long QT syndrome (LQTs) are the most observed “inherited primary arrhythmia syndromes” and “channelopathies”, which lead to sudden cardiac death.

Methods

Detailed clinical information of Brs and LQTs patients was collected. Genomic DNA samples of peripheral blood were conducted for whole-exome sequencing on the Illumina HiSeq 2000 platform. Then, we performed bioinformatics analysis for 200 genes susceptible to arrhythmias and cardiomyopathies. Protein interaction and transcriptomic co-expression were analyzed using the online website and GTEx database.

Results

All sixteen cases of Brs and six cases of LQTs were enrolled in the current study. Four Brs carried known pathogenic or likely pathogenic of single-point mutations, including SCN5A p.R661W, SCN5A p.R965C, and KCNH2 p.R692Q. One Brs carried the heterozygous compound mutations of DSG2 p.F531C and SCN5A p.A1374S. Two Brs carried the novel heterozygous truncated mutations (MAF < 0.001) of NEBL (p.R882X) and NPPA (p.R107X), respectively. Except for the indirect interaction between NEBL and SCN5A, NPPA directly interacts with SCN5A. These gene expressions had a specific and significant positive correlation in myocardial tissue, with high degrees of co-expression and synergy. Two Brs carried MYH7 p.E1902Q and MYH6 p.R1820Q, which were predicted as "damaging/possibly damaging" and "damaging/damaging" by Polyphen and SIFT algorithm. Two LQTs elicited the pathogenic single splicing mutation of KCNQ1 (c.922-1G > C). Three LQTs carried a single pathogenic mutation of SCN5A p.R1880H, KCNH2 p.D161N, and KCNQ1 p.R243S, respectively. One patient of LQTs carried a frameshift mutation of KCNH2 p. A188Gfs*143.

Conclusions

The truncated mutations of NEBL (p.R882X) and NPPA (p.R107X) may induce Brugada syndrome by abnormally affecting cardiac sodium channel. SCN5A (p.R661W, p.R965C and p.A1374S) and KCNH2 (p.R692Q) may cause Brugada syndrome, while SCN5A (p.R1880H), KCNQ1 (c.922-1G > C and p.R243S) and KCNH2 (p.D161N and p.A188Gfs*143) may lead to long QT syndrome.

Towards a Better Understanding of Genotype-Phenotype Correlations and Therapeutic Targets for Cardiocutaneous Genes: The Importance of Functional Studies above Prediction

Genetic variants in gene-encoding proteins involved in cell−cell connecting structures, such as desmosomes and gap junctions, may cause a skin and/or cardiac phenotype, of which the combination is called cardiocutaneous syndrome. The cardiac phenotype is characterized by cardiomyopathy and/or arrhythmias, while the skin particularly displays phenotypes such as keratoderma, hair abnormalities and skin fragility. The reported variants associated with cardiocutaneous syndrome, in genes DSP, JUP, DSC2, KLHL24, GJA1, are classified by interpretation guidelines from the American College of Medical Genetics and Genomics. The genotype−phenotype correlation, however, remains poorly understood. By providing an overview of variants that are assessed for a functional protein pathology, we show that this number (n = 115) is low compared to the number of variants that are assessed by in silico algorithms (>5000). As expected, there is a mismatch between the prediction of variant pathogenicity and the prediction of the functional effect compared to the real functional evidence. Aiding to improve genotype−phenotype correlations, we separate variants into ‘protein reducing’ or ‘altered protein’ variants and provide general conclusions about the skin and heart phenotype involved. We conclude by stipulating that adequate prognoses can only be given, and targeted therapies can only be designed, upon full knowledge of the protein pathology through functional investigation.

An Interesting Case of Treatment-Resistant Ventricular Tachycardia Secondary to Pheochromocytoma and Left Ventricular Non-compaction

A 51-year-old patient was admitted with chest pain and broad complex ventricular tachycardia. He received three consecutive direct cardioversion (DC) shocks and was commenced on amiodarone infusion via a central venous catheter or central line (CVC). He responded to treatment and normal sinus rhythm (NSR) was achieved. He had elevated troponin I and underwent coronary angiogram which initially was thought to be responsible for his ventricular tachycardia. Coronary angiogram (CAG) showed unobstructed coronary arteries. He was recently diagnosed with pheochromocytoma and was commenced on Phenoxybenzamine 10 mg two months back. He developed ventricular tachycardia (VT) again the next day that did not respond to four consecutive direct cardioversion shocks (DC) and antiarrhythmic medications. He was intubated and ventilated to terminate his VT and was transferred to the intensive care unit (ICU). He remained intubated for 48 hours and he remained in NSR, after which he was extubated. He was commenced on bisoprolol and was later stepped down to the coronary care unit (CCU). Cardiac magnetic resonance imaging (CMR) showed left ventricular non-compaction (LVNC) or possibly myocarditis in view of patient's known history of pheochromocytoma. He was discussed with surgical team at another hospital for surgical resection of the adrenal tumor and had a few further runs of VT while he was waiting to be transferred. The patient finally underwent surgical resection of the tumor and was booked for implantable cardioverter defibrillator (ICD) in view of his VT. This was an interesting case of treatment-resistant VT driven by pheochromocytoma and LVNC, and it is important to be familiar with the fact that conventional therapies may fail in these patients and may require intubation and ventilation to terminate VT storms.

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.

A Case of Severe Left-Ventricular Noncompaction Associated with Splicing Altering Variant in the FHOD3 Gene

Left ventricular noncompaction (LVNC) is a highly heterogeneous primary disorder of the myocardium. Its clinical features and genetic spectrum strongly overlap with other types of primary cardiomyopathies, in particular, hypertrophic cardiomyopathy. Study and the accumulation of genotype–phenotype correlations are the way to improve the precision of our diagnostics. We present a familial case of LVNC with arrhythmic and thrombotic complications, myocardial fibrosis and heart failure, cosegregating with the splicing variant in the FHOD3 gene. This is the first description of FHOD3-dependent LVNC to our knowledge. We also revise the assumed mechanism of pathogenesis in the case of FHOD3 splicing alterations.

Long QT syndrome and left ventricular non-compaction in a family with KCNH2 mutation: A case report

BACKGROUND

Left ventricular non-compaction (LVNC) is an abnormality of the myocardium, characterized by prominent left ventricular trabeculae and deep inter-trabecular recesses. Long QT syndrome (LQTS) is a cardiac ion channelopathy presenting with a prolonged QT interval on resting electrocardiogram and is associated with increased susceptibility to sudden death. The association between LVNC and LQTS is uncommon.

CASE PRESENTATION

We report an Italian family with a novel pathogenic KCNH2 variant who presented with clinical features of LVNC and LQTS. The proband came to our attention after two syncopal episodes without prodromal symptoms. His ECG showed QTc prolongation and deep T wave inversion in anterior leads, and the echocardiogram fulfilled LVNC criteria. After that, also his sister was found to have LQTS and LVNC, while his father only presented LQTS.

CONCLUSIONS

Physicians should be aware of the possible association between LVNC and LQTS. Even if this association is rare, patients with LVNC should be investigated for LQTS to prevent possible severe or even life-threatening arrhythmic episodes.