Factors Influencing the Phenotypic Expression of Hypertrophic Cardiomyopathy in Genetic Carriers

Hypertrophic cardiomyopathy in MYBPC3 carriers in aging

Hypertrophic cardiomyopathy (HCM) is characterized by abnormal thickening of the myocardium, leading to arrhythmias, heart failure, and elevated risk of sudden cardiac death, particularly among the young. This inherited disease is predominantly caused by mutations in sarcomeric genes, among which those in the cardiac myosin binding protein-C3 (MYBPC3) gene are major contributors. HCM associated with MYBPC3 mutations usually presents in the elderly and ranges from asymptomatic to symptomatic forms, affecting numerous cardiac functions and presenting significant health risks with a spectrum of clinical manifestations. Regulation of MYBPC3 expression involves various transcriptional and translational mechanisms, yet the destiny of mutant MYBPC3 mRNA and protein in late-onset HCM remains unclear. Pathogenesis related to MYBPC3 mutations includes nonsense-mediated decay, alternative splicing, and ubiquitin-proteasome system events, leading to allelic imbalance and haploinsufficiency. Aging further exacerbates the severity of HCM in carriers of MYBPC3 mutations. Advancements in high-throughput omics techniques have identified crucial molecular events and regulatory disruptions in cardiomyocytes expressing MYBPC3 variants. This review assesses the pathogenic mechanisms that promote late-onset HCM through the lens of transcriptional, post-transcriptional, and post-translational modulation of MYBPC3, underscoring its significance in HCM across carriers. The review also evaluates the influence of aging on these processes and MYBPC3 levels during HCM pathogenesis in the elderly. While pinpointing targets for novel medical interventions to conserve cardiac function remains challenging, the emergence of personalized omics offers promising avenues for future HCM treatments, particularly for late-onset cases.

Understanding the Genetic and Molecular Basis of Familial Hypertrophic Cardiomyopathy and the Current Trends in Gene Therapy for Its Management

Hypertrophic cardiomyopathy (HCM) is a genetically acquired disease of cardiac myocytes. Studies show that 70% of this disease is a result of different mutations in various sarcomere genes. This review aims to discuss several genetic mutations, epigenetic factors, and signal transduction pathways leading to the development of HCM. In addition, this article elaborates on recent advances in gene therapies and their implications for managing this condition. We start by discussing the founding mutations in HCM and their effect on power stroke generation. The less explored field of epigenetics including methylation, acetylation, and the role of different micro RNAs in the development of cardiac muscle hypertrophy has been highlighted in this article. The signal transduction pathways that lead to gene transcription, which in turn lead to increased protein synthesis of cardiac muscle fibers are elaborated. Finally, the microscopic events leading to the pathophysiologic macro events of cardiac failure, and the current experimental trials of gene therapy models, and the clustered regularly interspaced short palindromic repeats (CRISPR) type 2 system proteins, are discussed. We have concluded our discussion by emphasizing the need for more studies on epigenomics and experimental designs for gene therapy in HCM patients. This review focuses on the process of HCM from initial mutation to the development of phenotypic expression and various points of intervention in cardiac myocardial hypertrophy development.

Shared Molecular Mechanisms of Hypertrophic Cardiomyopathy and Its Clinical Presentations: Automated Molecular Mechanisms Extraction Approach

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiovascular disease with a prevalence of 1 in 500 people and varying clinical presentations. Although there is much research on HCM, underlying molecular mechanisms are poorly understood, and research on the molecular mechanisms of its specific clinical presentations is scarce. Our aim was to explore the molecular mechanisms shared by HCM and its clinical presentations through the automated extraction of molecular mechanisms. Molecular mechanisms were congregated by a query of the INDRA database, which aggregates knowledge from pathway databases and combines it with molecular mechanisms extracted from abstracts and open-access full articles by multiple machine-reading systems. The molecular mechanisms were extracted from 230,072 articles on HCM and 19 HCM clinical presentations, and their intersections were found. Shared molecular mechanisms of HCM and its clinical presentations were represented as networks; the most important elements in the intersections’ networks were found, centrality scores for each element of each network calculated, networks with reduced level of noise generated, and cooperatively working elements detected in each intersection network. The identified shared molecular mechanisms represent possible mechanisms underlying different HCM clinical presentations. Applied methodology produced results consistent with the information in the scientific literature.

Genetic Factors Involved in Cardiomyopathies and in Cancer

Cancer therapy-induced cardiomyopathy (CCM) manifests as left ventricular (LV) dysfunction and heart failure (HF). It is associated withparticular pharmacological agents and it is typically dose dependent, but significant individual variability has been observed. History of prior cardiac disease, abuse of toxics, cardiac overload conditions, age, and genetic predisposing factors modulate the degree of the cardiac reserve and the response to the injury. Genetic/familial cardiomyopathies (CMY) are increasingly recognized in general populations with an estimated prevalence of 1:250. Association between cardiac and oncologic diseases regarding genetics involves not only the toxicity process, but pathogenicity. Genetic variants in germinal cells that cause CMY (LMNA, RAS/MAPK) can increase susceptibility for certain types of cancer. The study of mutations found in cancer cells (somatic) has revealed the implication of genes commonly associated with the development of CMY. In particular, desmosomal mutations have been related to increased undifferentiation and invasiveness of cancer. In this article, the authors review the knowledge on the relevance of environmental and genetic background in CCM and give insights into the shared genetic role in the pathogenicity of the cancer process and development of CMY.

Trends of the prevalence and incidence of hypertrophic cardiomyopathy in Korea: A nationwide population-based cohort study

Temporal trends of the prevalence and incidence of hypertrophic cardiomyopathy (HCM) have not been well established in Asian populations. Using the Korean National Health Insurance Services database, we identified patients with a confirmed diagnosis of HCM between 2010 and 2016. The annual prevalence and incidence of HCM, and their clinical characteristics were investigated. The prevalence of HCM has increased from 0.016% (n = 6313) in 2010 to 0.031% (n = 13,035) in 2016. During a 7-year period, 13,229 patients were newly diagnosed with HCM. The incidence rate increased from 4.15 (per 100,000 person-years) in 2010 to 5.6 in 2016. The prevalence and incidence of HCM increased with age and peaked during the 70s, with male predominance in all age groups. Chest pain is the most frequent clinical presentation followed by shortness of breath and syncope. Hypertension and dyslipidemia were the two most common comorbidities. Heart failure and atrial fibrillation was diagnosed in about 1/3 and 1/4 of patients with HCM, respectively. The prevalence and incidence of HCM gradually increased from 2010 to 2016, possibly due to heightened recognition of the disease. Given the progressively high incidence of HCM with age and high prevalence of coexisting modifiable risk factors, continued efforts are required to increase awareness regarding HCM-related symptoms and potential complications.

Deletion Polymorphism of Angiotensin Converting Enzyme Gene is Associated with Left Ventricular Hypertrophy in Uighur Hypertension-Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) Patients

Background

This study aimed to explore the association of angiotensin converting enzyme (ACE) gene insertion/deletion polymorphisms with left ventricular hypertrophy (LVH) in Han and Uighur hypertension-OSAHS (obstructive sleep apnea hypopnea syndrome) patients in China.

Material/Methods

A total of 162 Han and 72 Uygur patients with hypertension-OSAHS were independently subdivided into an LVH group and a non-LVH (NLVH) group based on the left ventricular mass index. The insertion/deletion polymorphisms of ACE gene were determined by polymerase chain reaction. The association of ACE gene insertion/deletion polymorphisms with LVH was assessed by chi-squared test. Logistic regression analysis was performed to obtain the odds ratios and 95% confidence intervals for the risk of LVH after adjusting for confounding factors.

Results

In Uighur patients, the distributions of D allele and DD genotype showed significant differences between the LVH group and the NLVH group. The difference of DD genotype remained significant after multivariate adjustment. In contrast, no significant differences were observed in the distributions of D allele and DD genotype between the LVH group and the NLVH group in Han patients. Moreover, moderate-severe OSAHS was an independent risk factor for LVH.

Conclusions

D allele and DD genotype of ACE gene are possible genetic markers for the risk of LVH in Uighur but not Han hypertension-OSAHS patients.