The Double Mutation DSG2-p.S363X and TBX20-p.D278X Is Associated with Left Ventricular Non-Compaction Cardiomyopathy: Case Report

Advances and challenges in the diagnosis and management of left ventricular noncompaction in adults: A literature review

In the realm of cardiovascular health, isolated left ventricular noncompaction (LVNC) stands out for its distinct morphological features and the clinical challenges it presents, particularly in adults. This literature review explores the intricacies of LVNC, aiming to unravel its epidemiological spread, diagnostic hurdles, and therapeutic strategies. Despite technological advancements in cardiac imaging that have improved the recognition of LVNC, a significant gap persists alongside a fragmented understanding of its pathogenesis. The studies scrutinized reveal a broad spectrum of prevalence rates influenced by diverse diagnostic tools and demographic variables. This variation underscores the complexity of accurately identifying LVNC and the resultant implications for clinical management. The review succinctly addresses the need for precise guidelines to navigate the diagnosis of LVNC and outlines the imperative for tailored clinical management approaches that cater to the wide array of patient presentations, from asymptomatic cases to those with severe cardiac dysfunction. By highlighting the critical gaps in current literature-namely the absence of standardized diagnostic criteria and a comprehensive pathogenic model-the review sets the stage for future research directions. These endeavors are essential for enhancing diagnostic accuracy, refining management protocols, and ultimately improving patient outcomes in this complex subset of cardiomyopathy, thus contributing significantly to the advancement of cardiovascular medicine.

TBX20 loss-of-function variants in families with left ventricular non-compaction cardiomyopathy

TBX20 encodes a cardiac transcription factor that is associated with atrial septal defects. Recent studies implicate loss-of-function TBX20 variants with left ventricular non-compaction cardiomyopathy (LVNC), although clinical and genetic data in families are limited. We report four families with TBX20 loss-of-function variants that segregate with LVNC. Genetic testing using genome or exome sequencing was performed in index cases, variants were validated with Sanger sequencing, and cascade genetic testing was performed in family members. A multi-exon deletion, small deletion, essential splice site variant and nonsense variant in TBX20 were found in four families. The index cases in two families were symptomatic children with identical congenital heart diseases and LVNC who developed different cardiomyopathy phenotypes with one developing heart failure requiring transplantation. In another family, the child index case had LVNC and congestive heart failure requiring heart transplantation. In the fourth family, the index case was a symptomatic adult with LVNC. In all families, the variants segregated in relatives with isolated LVNC, or with congenital heart disease or cardiomyopathy. Family members displayed a clinical spectrum from asymptomatic to severe presentations including heart failure. Our data strengthen TBX20 loss-of-function variants as a rare cause of LVNC and support TBX20 inclusion in genetic testing of LVNC.

The Trouble with Trabeculation: How Genetics Can Help to Unravel a Complex and Controversial Phenotype

Excessive trabeculation of the cardiac left ventricular wall is a complex phenotypic substrate associated with various physiological and pathological processes. There has been considerable conjecture as to whether hypertrabeculation contributes to disease and whether left ventricular non-compaction (LVNC) cardiomyopathy is a distinct pathology. Building on recent insights into the genetic basis of LVNC cardiomyopathy, in particular three meta-analysis studies exploring genotype-phenotype associations using different methodologies, this review examines how genetic research can advance our understanding of trabeculation. Three groups of genes implicated in LVNC are described-those associated with other cardiomyopathies, other cardiac/syndromic conditions and putatively with isolated LVNC cardiomyopathy-demonstrating how these findings can inform the underlying pathologies in LVNC patients and aid differential diagnosis and management in clinical practice despite the limited utility suggested for LVNC genetic testing in recent guidelines. The outstanding questions and future research priorities for exploring the genetics of hypertrabeculation are discussed.

From Death to Life/Back to the Future: Detailed Premorbid Clinical and Family History Can Save Lives and Address the Final Diagnosis in Sudden Unexplained Deaths With Negative Autopsy

Sudden cardiac death is a sudden, unexpected death developed by one of the many different causes of cardiac arrest that occur within 1 hour of the onset of new symptoms. Sudden unexplained death (SUD) comprises a normal heart at postmortem examination and negative toxicological analysis. SUD often arises from cardiac genetic disease, particularly channelopathies. Channelopathies, or inherited arrhythmia syndromes, are a group of disorders characterized by an increased risk of sudden cardiac death, abnormal cardiac electrical function, and, typically, a structurally normal heart. They share an underlying genetic etiology where disease-causing genetic variants may lead to the absence or dysfunction of proteins involved in the generation and propagation of the cardiac action potential. Our study aimed to evaluate the importance of next-generation sequencing in the postmortem investigations of SUD cases. In this study, 5 forensic SUD cases were investigated for inherited cardiac disorders. We screened a total of 68 cardiac genes for the sibling of case 1, as well as case 2, and 51 genes for cases 3, 4, and 5. Of the 12 variants identified, 2 likely pathogenic variants (16.7%) were the TMEM43 _ c.1000+2T>C splice site mutation and the SCN5A _ p.W703X nonsense mutation. The remaining 10 variants of uncertain significance were detected in the TRPM4 , RANGRF , A KAP9 , KCND3 , KCNE1 , DSG2 , CASQ1 , and SNTA1 genes. Irrespective of genetic testing, all SUD families require detailed clinical testing to identify relatives who may be at risk. Molecular autopsy and detailed premorbid clinical and family histories can survive family members of SUD cases.

Novel MYBPC3 Mutations in Indian Population with Cardiomyopathies

Background

Mutations in Myosin Binding Protein C (MYBPC3) are one of the most frequent causes of cardiomyopathies in the world, but not much data are available in India.

Methods

We carried out targeted direct sequencing of MYBPC3 in 115 hypertrophic (HCM) and 127 dilated (DCM) cardiomyopathies against 197 ethnically matched healthy controls from India.

Results

We detected 34 single nucleotide variations in MYBPC3, of which 19 were novel. We found a splice site mutation [(IVS6+2T) T>G] and 16 missense mutations in Indian cardiomyopathies [5 in HCM; E258K, T262S, H287L, R408M, V483A: 4 in DCM; T146N, V321L, A392T, E393K and 7 in both HCM and DCM; L104M, V158M, S236G, R272C, T290A, G522E, A626V], but those were absent in 197 normal healthy controls. Interestingly, we found 7 out of 16 missense mutations (V158M, E258K, R272C, A392T, V483A, G522E, and A626V) in MYBPC3 were altering the evolutionarily conserved native amino acids, accounted for 8.7% and 6.3% in HCM and DCM, respectively. The bioinformatic tools predicted that those 7 missense mutations were pathogenic. Moreover, the co-segregation of those 7 mutations in families further confirmed their pathogenicity. Remarkably, we also identified compound mutations within the MYBPC3 gene of 6 cardiomyopathy patients (5%) with more severe disease phenotype; of which, 3 were HCM (2.6%) [(1. K244K + E258K + (IVS6+2T) T>G); (2. L104M + G522E + A626V); (3. P186P + G522E + A626V]; and 3 were DCM (2.4%) [(1. 5'UTR + A392T; 2. V158M+G522E; and 3.V158M + T262T + A626V].

Conclusion

The present comprehensive study on MYBPC3 has revealed both single and compound mutations in MYBPC3 and their association with disease in Indian Population with Cardiomyopathies. Our findings may perhaps help in initiating diagnostic strategies and eventually recognizing the targets for therapeutic interventions.

Application of next generation sequencing in cardiology: current and future precision medicine implications

Inherited cardiovascular diseases are highly heterogeneous conditions with multiple genetic loci involved. The application of advanced molecular tools, such as Next Generation Sequencing, has facilitated the genetic analysis of these disorders. Accurate analysis and variant identification are required to maximize the quality of the sequencing data. Therefore, the application of NGS for clinical purposes should be limited to laboratories with a high level of technological expertise and resources. In addition, appropriate gene selection and variant interpretation can result in the highest possible diagnostic yield. Implementation of genetics in cardiology is imperative for the accurate diagnosis, prognosis and management of several inherited disorders and could eventually lead to the realization of precision medicine in this field. However, genetic testing should also be accompanied by an appropriate genetic counseling procedure that clarifies the significance of the genetic analysis results for the proband and his family. In this regard, a multidisciplinary collaboration among physicians, geneticists, and bioinformaticians is imperative. In the present review, we address the current state of knowledge regarding genetic analysis strategies employed in the field of cardiogenetics. Variant interpretation and reporting guidelines are explored. Additionally, gene selection procedures are accessed, with a particular emphasis on information concerning gene-disease associations collected from international alliances such as the Gene Curation Coalition (GenCC). In this context, a novel approach to gene categorization is proposed. Moreover, a sub-analysis is conducted on the 1,502,769 variation records with submitted interpretations in the Clinical Variation (ClinVar) database, focusing on cardiology-related genes. Finally, the most recent information on genetic analysis's clinical utility is reviewed.

Atherosclerosis and Other Related-Arterial Diseases

Cardiovascular diseases (CVD) are a major cause of morbidity and mortality worldwide, accounting for more than 17 million deaths each year [...].

Genetic landscape in Russian patients with familial left ventricular noncompaction

Background

Left ventricular noncompaction (LVNC) cardiomyopathy is a disorder that can be complicated by heart failure, arrhythmias, thromboembolism, and sudden cardiac death. The aim of this study is to clarify the genetic landscape of LVNC in a large cohort of well-phenotyped Russian patients with LVNC, including 48 families (n=214).

Methods

All index patients underwent clinical examination and genetic analysis, as well as family members who agreed to participate in the clinical study and/or in the genetic testing. The genetic testing included next generation sequencing and genetic classification according to ACMG guidelines.

Results

A total of 55 alleles of 54 pathogenic and likely pathogenic variants in 24 genes were identified, with the largest number in the MYH7 and TTN genes. A significant proportion of variants -8 of 54 (14.8%) -have not been described earlier in other populations and may be specific to LVNC patients in Russia. In LVNC patients, the presence of each subsequent variant is associated with increased odds of having more severe LVNC subtypes than isolated LVNC with preserved ejection fraction. The corresponding odds ratio is 2.77 (1.37 -7.37; p <0.001) per variant after adjustment for sex, age, and family.

Conclusion

Overall, the genetic analysis of LVNC patients, accompanied by cardiomyopathy-related family history analysis, resulted in a high diagnostic yield of 89.6%. These results suggest that genetic screening should be applied to the diagnosis and prognosis of LVNC patients.

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.