Genetics of heart failure

Natriuretic Peptide Receptors (NPRs) as a Potential Target for the Treatment of Heart Failure

PURPOSE OF REVIEW

Heart failure is defined as a complex clinical syndrome that results from any structural or functional impairment of ventricular filling or ejection of blood. The natriuretic peptide is known to exert its biological action on the kidney, heart, blood vessels, renin-angiotensin system, autonomous nervous system, and central nervous system. The natriuretic peptide-natriuretic receptor system plays an important role in the regulation of blood pressure and body fluid volume through its pleiotropic effects.

RECENT FINDINGS

The clinical and animal studies suggest that natriuretic peptide-natriuretic receptors are important targets for the treatment of heart failure and other cardiovascular diseases. Even though attempts targeting natriuretic peptide receptors are underway for heart failure treatment, they seem insufficient despite the receptor systems' potential. This review summarizes natriuretic peptide-natriuretic receptor system's physiological actions and potential target for the treatment of heart failure. Natriuretic peptides play multiple roles in different parts of the body, almost all of the activities related to this receptor system appear to have the potential to be harnessed to treat heart failure or symptoms associated with heart failure.

HFIP: an integrated multi-omics data and knowledge platform for the precision medicine of heart failure

As the terminal clinical phenotype of almost all types of cardiovascular diseases, heart failure (HF) is a complex and heterogeneous syndrome leading to considerable morbidity and mortality. Existing HF-related omics studies mainly focus on case/control comparisons, small cohorts of special subtypes, etc., and a large amount of multi-omics data and knowledge have been generated. However, it is difficult for researchers to obtain biological and clinical insights from these scattered data and knowledge. In this paper, we built the Heart Failure Integrated Platform (HFIP) for data exploration, fusion analysis and visualization by collecting and curating existing multi-omics data and knowledge from various public sources and also provided an auto-updating mechanism for future integration. The developed HFIP contained 253 datasets (7842 samples), multiple analysis flow, and 14 independent tools. In addition, based on the integration of existing databases and literature, a knowledge base for HF was constructed with a scoring system for evaluating the relationship between molecular signals and HF. The knowledge base includes 1956 genes and annotation information. The literature mining module was developed to assist the researcher to overview the hotspots and contexts in basic and clinical research. HFIP can be used as a data-driven and knowledge-guided platform for the basic and clinical research of HF.

Database URL: http://heartfailure.medical-bigdata.com

The Human Explanted Heart Program: A translational bridge for cardiovascular medicine

The progression of cardiovascular research is often impeded by the lack of reliable disease models that fully recapitulate the pathogenesis in humans. These limitations apply to both in vitro models such as cell-based cultures and in vivo animal models which invariably are limited to simulate the complexity of cardiovascular disease in humans. Implementing human heart tissue in cardiovascular research complements our research strategy using preclinical models. We established the Human Explanted Heart Program (HELP) which integrates clinical, tissue and molecular phenotyping thereby providing a comprehensive evaluation into human heart disease. Our collection and storage of biospecimens allow them to retain key pathogenic findings while providing novel insights into human heart failure. The use of human non-failing control explanted hearts provides a valuable comparison group for the diseased explanted hearts. Using HELP we have been able to create a tissue repository which have been used for genetic, molecular, cellular, and histological studies. This review describes the process of collection and use of explanted human heart specimens encompassing a spectrum of pediatric and adult heart diseases, while highlighting the role of these invaluable specimens in translational research. Furthermore, we highlight the efficient procurement and bio-preservation approaches ensuring analytical quality of heart specimens acquired in the context of heart donation and transplantation.

Mitochondrial DNA: Hotspot for Potential Gene Modifiers Regulating Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a prevalent and untreatable cardiovascular disease with a highly complex clinical and genetic causation. HCM patients bearing similar sarcomeric mutations display variable clinical outcomes, implying the involvement of gene modifiers that regulate disease progression. As individuals exhibiting mutations in mitochondrial DNA (mtDNA) present cardiac phenotypes, the mitochondrial genome is a promising candidate to harbor gene modifiers of HCM. Herein, we sequenced the mtDNA of isogenic pluripotent stem cell-cardiomyocyte models of HCM focusing on two sarcomeric mutations. This approach was extended to unrelated patient families totaling 52 cell lines. By correlating cellular and clinical phenotypes with mtDNA sequencing, potentially HCM-protective or -aggravator mtDNA variants were identified. These novel mutations were mostly located in the non-coding control region of the mtDNA and did not overlap with those of other mitochondrial diseases. Analysis of unrelated patients highlighted family-specific mtDNA variants, while others were common in particular population haplogroups. Further validation of mtDNA variants as gene modifiers is warranted but limited by the technically challenging methods of editing the mitochondrial genome. Future molecular characterization of these mtDNA variants in the context of HCM may identify novel treatments and facilitate genetic screening in cardiomyopathy patients towards more efficient treatment options.

Coexisting Morbidities in Heart Failure: No Robust Interaction with the Left Ventricular Ejection Fraction

PURPOSE OF REVIEW

Heart failure (HF) patients often present with multiple coexisting morbidities. In this review, we contend that coexisting morbidities are highly prevalent and clinically important regardless of the left ventricular ejection fraction (LVEF).

RECENT FINDINGS

Multimorbidity is prevalent in the ambulatory subjects of the community and increases with age. Differences in the prevalence of coexisting morbidities between HF with preserved LVEF (> 50%), mid-range LVEF (40-50%), and reduced LVEF (< 40%) are either not demonstrable or whenever present are small and unrelated to morbidity and mortality. The constellation of coexisting morbidities together with the disease modifiers (age, sex, genes, other) defines the HF phenotype and outcome. There is no robust evidence supporting an interaction in HF patients between the prevalence and clinical significance of coexisting morbidities and the LVEF.

An Integrative Transcriptome Analysis Reveals Consistently Dysregulated Long Noncoding RNAs and Their Transcriptional Regulation Relationships in Heart Failure

Accumulating evidence suggests that long noncoding RNAs (lncRNAs) are emerging as important regulators involved in diseases, including heart failure (HF). In this study, we used microarray profiles to examine the transcriptome of lncRNAs in left ventricle samples derived from HF patients. We designed a custom pipeline to reannotate lncRNAs from microarray data and identified a set of consistently dysregulated lncRNAs in HF across the three independent cohorts. In total, 84 lncRNAs were found to be consistently dysregulated in at least two cohorts. By using a rank aggregation method, we integrated correlated protein-coding genes of the consistently dysregulated lncRNAs derived from HF samples and characterized their biological functions based on the correlated genes. The transcriptional regulation relationships of these lncRNAs ranged from 104 to 261, suggesting their important regulatory functions. Among the conserved lncRNAs, AC018647.1 and AC009113.1 showed significant dysregulation across all three cohorts. Our results showed that the two lncRNAs were involved in development-associated and cardiac cycle-associated functions.

Playing the genome card

In the 1990s, prominent biologists and journalists predicted that by 2020 each of us would carry a genome card, which would allow physicians to access our entire genome sequence and routinely use this information to diagnose and treat common and debilitating conditions. This is not yet the case. Why not? Common and debilitating diseases are rarely caused by single-gene mutations, and this was recognized before these genome card predictions had been made. Debilitating conditions, including common psychiatric disorders, are typically caused either by rare mutations or by complex interactions of many genes, each having a small effect, and epigenetic, environmental, and microbial factors. In such cases, having a complete genome sequence may have limited utility in diagnosis and treatment. Genome sequencing technologies have transformed biological research in many ways, but had a much smaller effect than expected on treatments of common diseases. Thus, early proponents of genome sequencing effectively "mis-promised" its benefits. One reason may be that there are incentives for both biologists and journalists to tell simple stories, including the idea of relatively simple genetic causation of common, debilitating diseases. These incentives may have led to misleading predictions, which to some extent continue today. Although the Human Genome Project has facilitated biological research generally, the mis-promising of medical benefits, at least for treating common and debilitating disorders, could undermine support for scientific research over the long term.

A Swedish Nationwide Adoption Study of the Heritability of Heart Failure

Importance

Heart failure (HF) aggregates in families, but the heritability of HF has not been determined. Discerning the genetic and environmental contributions to HF risk is important to further helping to identify individuals at risk. Adoption studies may establish the genetic contribution to HF.

Objective

This nationwide adoption study aimed to determine the heritability of HF.

Design, Setting, and Participants

This case-control study and cohort study design used logistic regression for calculating risks of HF in adoptees. Adoptees who were born in Sweden between 1942 and 1990 were linked to their adoptive parents and biological parents. The Swedish Multi-Generation Register was linked to the Swedish Patient Register for information on hospital inpatient and outpatient admissions and to the Swedish Cause of Death Register for the period 1964 through 2015. Heritability (h2 with a standard error) for HF was determined both with Falconer regression and with tetrachoric correlation. Data analysis was completed from July 2017 to April 2018.

Exposures

Heart failure in biological parents and/or adoptive parents.

Main Outcomes and Measures

Heritability; risk of HF, expressed as odds ratios.

Results

A total of 21 643 adoptees were included (of whom 10 626 [49.1%] were female), as well as 35 016 adoptive parents (14 872 [42.5%] female) and 43 286 biological parents (21 643 [50.0%] female). There were 194 cases of HF in adoptees, 3972 cases of HF in adoptive parents, and 3657 cases of HF in biological parents. The cohort study odds ratio (OR) for heart failure was 1.45 in adoptees (95% CI, 1.04-2.03) for biological parents with HF, compared with those without an affected biological parent. If cardiomyopathies were excluded, this OR was 1.58 (95% CI, 1.03-2.42). The corresponding OR associated with an affected adoptive parent were nonsignificant, both with cardiomyopathies included (OR, 0.83 [95% CI, 0.57-1.20]) and with cardiomyopathies excluded (OR, 0.79 [95% CI, 0.49-1.29]). The heritability of HF per Falconer regression (h2) was 26% (SE, 14%). With exclusion of cardiomyopathies the heritability using Falconer regression was 34% (SE, 18%).

Conclusions and Relevance

Heart failure in a biological parent is an HF risk factor that is worth clinical consideration. The increased heritability of HF suggests that genetic factors are important in HF pathogenesis.

Mortality risks associated with sibling heart failure

BACKGROUND

The mortality in individuals with a family history of heart failure (HF) has not been determined. This nationwide sib-pair study aimed to determine mortality in individuals with a sibling affected with HF.

METHODS

Sib-pairs were linked using the Swedish Multi-Generation Register, the Hospital Discharge Register and the Cause of Death Register for the period 1987-2012. Families with cardiomyopathy or congenital heart disease were excluded. Mortality hazard ratios (HRs) were calculated for siblings of individuals who had been diagnosed with HF compared with siblings of individuals unaffected by HF as the reference group. Similar analyses were made for spouses. HRs were determined for overall mortality, cardiovascular mortality, and death of unknown cause.

RESULTS

Among siblings, the adjusted HR for overall mortality was 1.21 (95% CI 1.18-1.25). This risk remained (HR = 1.19, 95% CI 1.15-1.23) also among subjects without HF themselves. The adjusted HRs for cardiovascular mortality and death of unknown cause were 1.39 (95% CI 1.32-1.45) and 1.58 (95% CI 1.29-1.95), respectively. The mortality risk associations with spousal HF were all minimal, with an overall mortality HR of 1.02 (1.01-1.02). Early sibling age of onset of HF < 50 years was associated with higher HRs for overall mortality, cardiovascular mortality, and death of unknown cause, 1.33 (1.27-1.41), 1.54 (1.40-1.68) and 1.84 (1.27-2.67), respectively.

CONCLUSIONS

Sibling HF, especially early-onset HF, is associated with increased mortality. The low risk in spouses suggests genetic factors might be of importance. Screening for HF, and cardiovascular disease in general, in these individuals may be warranted.

Genetic architecture of recent-onset dilated cardiomyopathy in Moravian region assessed by whole-exome sequencing and its clinical correlates

AIMS

Recent-onset dilated cardiomyopathy (RODCM) is a disease of heterogeneous aetiology and clinical outcome. In this pilot study, we aimed to assess its genetic architecture and correlate genotype with left ventricular reverse remodelling (LVRR).

PATIENTS AND METHODS

In this multi-centre prospective observational study, we enrolled 83 Moravian patients with RODCM and a history of symptoms of less than 6 months, for whole-exome sequencing (WES). All patients underwent 12-month clinical and echocardiographic follow-up. LVRR was defined as an absolute increase in left ventricular ejection fraction > 10% accompanied by a relative decrease of left ventricular end-diastolic diameter > 10% at 12 months.

RESULTS

WES identified at least one disease-related variant in 45 patients (54%). LVRR occurred in 28 patients (34%), most often in carriers of isolated titin truncated variants, followed by individuals with a negative, or inconclusive WES and carriers of other disease-related variants (56% vs. 42% vs. 19%, P=0.041).

CONCLUSION

A substantial proportion of RODCM cases have a monogenic or oligogenic genetic background. Carriers of non-titin disease-related variants are less likely to reach LVRR at 12- months than other individuals. Genetic testing could contribute to better prognosis prediction and individualized treatment of RODCM.

Association of CKIP-1 P21A polymorphism with risk of chronic heart failure in a Chinese population

Pathological cardiac hypertrophy is an independent risk factor for chronic heart failure. Casein kinase-2 interacting protein-1 (CKIP-1) can inhibit pathological cardiac hypertrophy. Therefore, we investigated whether CKIP-1 nonsynonymous polymorphism rs2306235 (Pro21Ala) contributes to risk and prognosis of chronic heart failure in a Chinese population.A total of 923 adult patients with chronic heart failure and 1020 age- and gender-matched healthy controls were recruited. CKIP-1 rs2306235 polymorphism was genotyped using PCR-restriction fragment length polymorphism. Additional follow-up data for 140 chronic heart failure patients was evaluated. The rs2306235 G allele was associated with an increased risk of chronic heart failure (OR = 1.38, 95% CI = 1.09-1.75, p = 0.007), especially in patients with hypertension (OR = 1.45, 95% CI = 1.09-1.75, p = 0.006) and coronary heart disease (OR = 1.41, 95% CI = 1.09-1.83, p = 0.010) after adjustment for multiple cardiovascular risk factors. However, rs2306235 polymorphism was not associated with cardiovascular mortality in chronic heart failure (p = 0.875). CKIP-1 rs2306235 polymorphism may be a risk factor for chronic heart failure in a Chinese Han population.

Circulating Biomarkers in Heart Failure

Biological markers have served for diagnosis, risk stratification and guided therapy of heart failure (HF). Our knowledge regarding abilities of biomarkers to relate to several pathways of HF pathogenesis and reflect clinical worsening or improvement in the disease is steadily expanding. Although there are numerous clinical guidelines, which clearly diagnosis, prevention and evidence-based treatment of HF, a strategy regarding exclusion of HF, as well as risk stratification of HF, nature evolution of disease is not well established and requires more development. The aim of the chapter is to discuss a role of biomarker-based approaches for more accurate diagnosis, in-depth risk stratification and individual targeting in treatment of patients with HF.

Basigin rs8259 Polymorphism Confers Decreased Risk of Chronic Heart Failure in a Chinese Population

Left ventricular remodeling is an essential risk factor contributing to the pathogenesis of chronic heart failure (CHF). Basigin (BSG) promotes cardiovascular inflammation and myocardial remodeling processes by induction of extracellular matrix metalloproteinases and inflammatory cytokines. BSG rs8259 polymorphism was associated with BSG expression and risk of acute coronary syndrome. Therefore, we investigated whether rs8259 polymorphism contributes to risk and prognosis of CHF in Chinese patients. In total 922 adult patients with CHF and 1107 matched healthy controls were enrolled. BSG rs8259 polymorphism was genotyped using PCR-restriction fragment length polymorphism. Whole blood BSG mRNA expression data from Genotype-Tissue Expression project was accessed. Evaluation of follow-up data was performed in only 15.2% (140) of the patients with CHF. BSG rs8259 TT genotype was associated with a decreased risk of CHF (OR = 0.83, 95% CI = 0.72–0.96, p = 0.010), especially in patients with hypertension (OR = 0.80, 95% CI = 0.68–0.95, p = 0.011) and coronary heart disease (OR = 0.81, 95% CI = 0.69–0.96, p = 0.013) after adjustment for multiple cardiovascular risk factors. Rs8259 T allele was associated with decreased BSG mRNA in whole blood from 338 healthy normal donors (p = 1.31 × 10⁻⁶). However, rs8259 polymorphism failed to exhibit an association with cardiovascular mortality (p = 0.283). BSG rs8259 polymorphism may contribute to decreased risk of CHF in a Chinese Han population.

The association of heart failure-related microRNAs with neurohormonal signaling

Heart failure (HF) is a widely prevalent syndrome imposing a significant burden of morbidity and mortality world-wide. Differential circulating microRNA profiles observed in HF cohorts suggest the diagnostic utility of microRNAs as biomarkers. Given their function in fine tuning gene expression, alternations in microRNA landscape could reflecting the underlying mechanisms of disease and present potential therapeutic targets. Using multiple computational target predicting algorithms together with the luciferase-based reporting platform, the interactions between HF-related microRNAs and the 3' untranslated regions (3'UTRs) of neurohormone associated genes were examined and compared. Our results indicate that although in silico prediction provides an overview of possible microRNA-mRNA target pairs, less than half of the predicted interactions were experimentally confirmed by reporter assays in HeLa cells. Thus, the establishment of microRNA/3'UTR reporters is essential to systemically evaluate the roles of microRNAs for signaling cascades of interest, including cardiovascular neurohormonal signaling. The physiological relevance of HF-related microRNAs on the expression of putative gene targets was further established by using gain-of-function assays in two human cardiac-derived cells. Our findings, for the first time, provide direct evidence of the regulatory effects of HF-related microRNAs on the neurohormonal signaling in cardiac cells. More importantly, our study presents a rational approach to further exploring microRNA profiling data in deciphering the role of microRNA in complex syndromes such as HF. This article is part of a Special Issue entitled: Genetic and epigenetic control of heart failure - edited by Jun Ren & Megan Yingmei Zhang.

RNAseq analysis of heart tissue from mice treated with atenolol and isoproterenol reveals a reciprocal transcriptional response

Background

The transcriptional response to many widely used drugs and its modulation by genetic variability is poorly understood. Here we present an analysis of RNAseq profiles from heart tissue of 18 inbred mouse strains treated with the β-blocker atenolol (ATE) and the β-agonist isoproterenol (ISO).

Results

Differential expression analyses revealed a large set of genes responding to ISO (n = 1770 at FDR = 0.0001) and a comparatively small one responding to ATE (n = 23 at FDR = 0.0001). At a less stringent definition of differential expression, the transcriptional responses to these two antagonistic drugs are reciprocal for many genes, with an overall anti-correlation of r = −0.3. This trend is also observed at the level of most individual strains even though the power to detect differential expression is significantly reduced. The inversely expressed gene sets are enriched with genes annotated for heart-related functions. Modular analysis revealed gene sets that exhibit coherent transcription profiles across some strains and/or treatments. Correlations between these modules and a broad spectrum of cardiovascular traits are stronger than expected by chance. This provides evidence for the overall importance of transcriptional regulation for these organismal responses and explicits links between co-expressed genes and the traits they are associated with. Gene set enrichment analysis of differentially expressed groups of genes pointed to pathways related to heart development and functionality.

Conclusions

Our study provides new insights into the transcriptional response of the heart to perturbations of the β-adrenergic system, implicating several new genes that had not been associated to this system previously.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-3059-6) contains supplementary material, which is available to authorized users.

Chronic Heart Failure and Inflammation

As a greater proportion of patients survive their initial cardiac insult, medical systems worldwide are being faced with an ever-growing need to understand the mechanisms behind the pathogenesis of chronic heart failure (HF). There is a wealth of information about the role of inflammatory cells and pathways during acute injury and the reparative processes that are subsequently activated. We discuss the different causes that lead to chronic HF development and how the sum of initial inflammatory and reparative responses only sets the trajectory for disease progression. Unfortunately, comparatively little is known about the contribution of the immune system once the trajectory has been set, and chronic HF has been established—which clinically represents the majority of patients. It is known that chronic HF is associated with circulating inflammatory cytokines that can predict clinical outcomes, yet the causative role inflammation plays in disease progression is not well defined, and the majority of clinical trials that target aspects of inflammation in patients with chronic HF have largely been negative. This review will present what is currently known about inflammation in chronic HF in both humans and animal models as a means to highlight the gap in our knowledge base that requires further examination.

Determined to Fail--the Role of Genetic Mechanisms in Heart Failure

Genetic variants contribute to several steps during heart failure pathophysiology. The mechanisms include frequent polymorphisms that increase the susceptibility to heart failure in the general population and rare variants as causes of an underlying cardiomyopathy. In this review, we highlight recent discoveries made by genetic approaches and provide an outlook onto the role of epigenetic modifiers of heart failure.

The Discovery of Novel Genomic, Transcriptomic, and Proteomic Biomarkers in Cardiovascular and Peripheral Vascular Disease: The State of the Art

Cardiovascular disease (CD) and peripheral vascular disease (PVD) are leading causes of mortality and morbidity in western countries and also responsible of a huge burden in terms of disability, functional decline, and healthcare costs. Biomarkers are measurable biological elements that reflect particular physiological or pathological states or predisposition towards diseases and they are currently widely studied in medicine and especially in CD. In this context, biomarkers can also be used to assess the severity or the evolution of several diseases, as well as the effectiveness of particular therapies. Genomics, transcriptomics, and proteomics have opened new windows on disease phenomena and may permit in the next future an effective development of novel diagnostic and prognostic medicine in order to better prevent or treat CD. This review will consider the current evidence of novel biomarkers with clear implications in the improvement of risk assessment, prevention strategies, and medical decision making in the field of CD.

Genetics of systolic and diastolic heart failure

Heart failure accounts for a significant portion of heart diseases. Molecular mechanisms gradually emerge that participate in pathways leading to left ventricular dysfunction in common systolic heart failure (SHF) and diastolic heart failure (DHF). A human genome-wide association study (GWAS) identified two markers for SHF and no GWAS on DHF has been documented. However, genetic analyses in rat models of SHF and DHF have begun to unravel the genetic components known as quantitative trait loci (QTLs) initiating systolic and diastolic function. A QTL for systolic function was detected and the gene responsible for it is identified to be that encoding the soluble epoxide hydrolase. Diastolic function is determined by multiple QTLs and the Ccl2/monocyte chemotactic protein gene is the strongest candidate. An amelioration on diastolic dysfunction is merely transient from changing such a single QTL accompanied by a blood pressure reduction. A long-term protection can be achieved only via combining alleles of several QTLs. Thus, distinct genes in synergy are involved in physiological mechanisms durably ameliorating or reversing diastolic dysfunction. These data lay the foundation for identifying causal genes responsible for individual diastolic function QTLs and the essential combination of them to attain a permanent protection against diastolic dysfunction, and consequently will facilitate the elucidation of pathophysiological mechanisms underlying hypertensive diastolic dysfunction. Novel pathways triggering systolic and diastolic dysfunction have emerged that will likely provide new diagnostic tools, innovative therapeutic targets and strategies in reducing, curing and even reversing SHF and DHF.

An uncommon clinical presentation of relapsing dilated cardiomyopathy with identification of sequence variations in MYNPC3, KCNH2 and mitochondrial tRNA cysteine

We describe a young girl with dilated cardiomyopathy, long QT syndrome, and possible energy deficiency. Two major sequence changes were identified by whole exome sequencing (WES) and mitochondrial DNA analysis that were interpreted as potentially causative. Changes were identified in the KCNH2 gene and mitochondrial tRNA for cysteine. A variation was also seen in MYPBC3. Since the launch of WES as a clinically available technology in 2010, there has been concern regarding the identification of variants unrelated to the patient's phenotype. However, in cases where targeted sequencing fails to explain the clinical presentation, the underlying etiology could be more complex than anticipated. In this situation, the extensive reach of this tool helped explain both her phenotype and family history.

Rescue of neonatal cardiac dysfunction in mice by administration of cardiac progenitor cells in utero

Striated preferentially expressed gene (Speg) is a member of the myosin light chain kinase family. We previously showed that disruption of the Speg gene locus in mice leads to a dilated cardiomyopathy with immature-appearing cardiomyocytes. Here we show that cardiomyopathy of Speg^−/− mice arises as a consequence of defects in cardiac progenitor cell (CPC) function, and that neonatal cardiac dysfunction can be rescued by in utero injections of wild-type CPCs into Speg^−/− foetal hearts. CPCs harvested from Speg^−/− mice display defects in clone formation, growth and differentiation into cardiomyocytes in vitro, which are associated with cardiac dysfunction in vivo. In utero administration of wild-type CPCs into the hearts of Speg^−/− mice results in CPC engraftment, differentiation and myocardial maturation, which rescues Speg^−/− mice from neonatal heart failure and increases the number of live births by fivefold. We propose that in utero administration of CPCs may have future implications for treatment of neonatal heart diseases.

The protein Speg is expressed in the developing mouse heart, where its absence leads to neonatal cardiac disease. Here the authors trace the cardiomyopathy of Speg KO mice back to defects in cardiac progenitor cells (CPCs) and rescue it with injections of wild type CPCs into the foetal heart.

Heart failure: advanced development in genetics and epigenetics

Heart failure (HF) is a complex pathophysiological syndrome that arises from a primary defect in the ability of the heart to take in and/or eject sufficient blood. Genetic mutations associated with familial dilated cardiomyopathy, hypertrophic cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy can contribute to the various pathologies of HF. Therefore, genetic screening could be an approach for guiding individualized therapies and surveillance. In addition, epigenetic regulation occurs via key mechanisms, including ATP-dependent chromatin remodeling, DNA methylation, histone modification, and RNA-based mechanisms. MicroRNA is also a hot spot in HF research. This review gives an overview of genetic mutations associated with cardiomyopathy and the roles of some epigenetic mechanisms in HF.

Genetics and epigenetics of arrhythmia and heart failure

Heart failure (HF) is the end stage of several pathological cardiac conditions including myocardial infarction, cardiac hypertrophy and hypertension. Various molecular and cellular mechanisms are involved in the development of HF. At the molecular level, the onset of HF is associated with reprogramming of gene expression, including downregulation of the alpha-myosin heavy chain (α-MHC) gene and sarcoplasmic reticulum Ca ²⁺ ATPase genes and reactivation of specific fetal cardiac genes such as atrial natriuretic factor and brain natriuretic peptide. These deviations in gene expression result in structural and electrophysiological changes, which eventually progress to HF. Cardiac arrhythmia is caused by altered conduction properties of the heart, which may arise in response to ischemia, inflammation, fibrosis, aging or from genetic factors. Because changes in the gene transcription program may have crucial consequences as deteriorated cardiac function, understanding the molecular mechanisms involved in the process has become a priority in the field. In this context, various studies besides having identified different DNA methylation patterns in HF patients, have also focused on specific disease processes and their underlying mechanisms, also introducing new concepts such as epigenomics. This review highlights specific genetic mutations associated with the onset and progression of HF, also providing an introduction to epigenetic mechanisms such as histone modifications, DNA methylation and RNA-based modification, and highlights the relation between epigenetics, arrhythmogenesis and HF.