Cardiogenetics

Hypertrophic cardiomyopathy (HCM) is among the most common forms of cardiomyopathies, with a prevalence of 1:200 to 1:500 people. HCM is caused by variants in genes encoding cardiac sarcomeric proteins, of which a majority reside in MYH7, MYBPC3, and TNNT2. Up to 40% of the HCM cases do not have any known HCM variant. Genotype–phenotype associations in HCM remain incompletely understood. This study involved two visits of 46 adult patients with a confirmed diagnosis of HCM. In total, 174 genes were analyzed on the Next-Generation Sequencing platform, and transthoracic echocardiography was performed. Gene-specific discriminative echocardiogram findings were identified using the computer vision library Fast AI. This was accomplished with the generation of deep learning models for the classification of ultrasonic images based on the underlying genotype and a later analysis of the most decisive image regions. Gene-specific echocardiogram findings were identified: for variants in the MYH7 gene (vs. variant not detected), the most discriminative structures were the septum, left ventricular outflow tract (LVOT) segment, anterior wall, apex, right ventricle, and mitral apparatus; for variants in MYBPC3 gene (vs. variant not detected) these were the septum, left ventricle, and left ventricle/chamber; while for variants in the TNNT2 gene (vs. variant not detected), the most discriminative structures were the septum and right ventricle. Full article

Thoracic aortic aneurysms (TAAs) are commonly seen in cardiovascular practice. Acquired and genetic conditions contribute to TAA formation. The natural history of genetically mediated TAA underscores the importance of early detection, regular monitoring, and prompt treatment to prevent complications, including dissection or rupture. The prognosis is poor in the event of acute dissection, with high rates of in-hospital mortality. Healthcare providers need to remain vigilant in their efforts to identify and surveil TAA to reduce the risk of complications. In this manuscript, we review the natural history of TAA, discuss the most common causes leading to the development of TAA, assess the value and limitations of diagnostic modalities, and review the management and long-term surveillance of patients with aortic disease. Full article

Arrhythmogenic cardiomyopathy (ACM) may present with sudden cardiac arrest (SCA), and demonstration of a pathogenic variant in ACM-related genes is crucial for its definitive diagnosis. A 42-year-old female patient with family history of sudden cardiac death (SCD) was referred to the cardiomyopathy clinic after two episodes of aborted SCA. In the second episode, the patient was transported under cardiopulmonary resuscitation (downtime of 57 min) until extracorporeal membrane oxygenation was implanted. A thorough diagnostic work-up led to a diagnosis of biventricular ACM. Genetic testing revealed a previously undescribed variant in ACM patients in the MYH6 gene, c.3673G>T p.(Glu 1225*), which inserts a premature stop codon. This was considered a possible pathogenic variant originating a truncated protein, previously undescribed in ACM. The patient’s 23-year-old daughter was positive for the MYH6 variant and had ECG abnormalities suggestive of ACM. This case details the complex differential diagnosis of SCA and explores the current recommendations for the diagnosis of biventricular ACM. The identification of a MYH6 variant in a patient with ACM, recurrent SCA, and family history of SCD appears to support the hypothesis of the pathogenicity of MYH6 variants in ACM, in which the association of phenotype with sarcomere variants is still unclear. Full article

The likely pathogenic variant c.407A>T p.Asp136Val of the LMNA gene has been recently described in a young woman presenting with atypical progeroid syndrome, associated with severe aortic valve stenosis. We further describe the cardiovascular involvement associated with the syndrome in her family. We identified seven members with a general presentation suggestive of progeroid syndrome. All of them presented heart conduction abnormalities: degenerative cardiac diseases such as coronary artery disease (two subjects) and aortic stenosis (three subjects) occurred in the 3rd–5th decade, and a young patient developed a severe dilated cardiomyopathy, leading to death at 15 years of age. The likely pathogenic variant was found in all the patients who consented to carry out the genetic test. This diverse family cardiologic phenotype emphasizes the complex molecular background at play in lamin-involved cardiac diseases, and the need for early and thorough cardiac evaluations in patients with laminopathic progeroid syndromes. Full article

Patients carrying the heterozygous A414G mutation in the HCN4 gene, which encodes the HCN4 protein, demonstrate moderate to severe bradycardia of the heart. Tetramers of HCN4 subunits compose the ion channels in the sinus node that carry the hyperpolarization-activated ‘funny’ current (I_f), also named the ‘pacemaker current’. I_f plays an essential modulating role in sinus node pacemaker activity. To assess the mechanism by which the A414G mutation results in sinus bradycardia, we first performed voltage clamp measurements on wild-type (WT) and heterozygous mutant HCN4 channels expressed in Chinese hamster ovary (CHO) cells. These experiments were performed at physiological temperature using the amphotericin-perforated patch-clamp technique. Next, we applied the experimentally observed mutation-induced changes in the HCN4 current of the CHO cells to I_f of the single human sinus node cell model developed by Fabbri and coworkers. The half-maximal activation voltage V_1/2 of the heterozygous mutant HCN4 current was 19.9 mV more negative than that of the WT HCN4 current (p < 0.001). In addition, the voltage dependence of the heterozygous mutant HCN4 current (de)activation time constant showed a −11.9 mV shift (p < 0.001) compared to the WT HCN4 current. The fully-activated current density, the slope factor of the activation curve, and the reversal potential were not significantly affected by the heterozygous A414G mutation. In the human sinus node computer model, the cycle length was substantially increased, almost entirely due to the shift in the voltage dependence of steady-state activation, and this increase was more prominent under vagal tone. The introduction of a passive atrial load into the model sinus node cell further reduced the beating rate, demonstrating that the bradycardia of the sinus node was even more pronounced by interactions between the sinus node and atria. In conclusion, the experimentally identified A414G-induced changes in I_f can explain the clinically observed sinus bradycardia in patients carrying the A414G HCN4 gene mutation. Full article

Ebstein anomaly is a rare heterogeneous congenital heart defect (CHD) with a largely unknown etiology. We present a 6-year-old girl with Ebstein anomaly, atrial septum defect, hypoplastic right ventricle, and persistent left superior vena cava who has a de novo intragenic ~403 kb deletion of the GDP-mannose 4,6-dehydratase (GMDS) gene. GMDS is located on chromosome 6p25.3 and encodes the rate limiting enzyme in GDP-fucose synthesis, which is used to fucosylate many proteins, including Notch1, which plays a critical role during mammalian cardiac development. The GMDS locus has sporadically been associated with Ebstein anomaly (large deletion) and tetralogy of Fallot (small deletion). Given its function and the association with CHD, we hypothesized that loss-of-function of, or alterations in, GMDS could play a role in the development of Ebstein anomaly. We collected a further 134 cases with Ebstein anomaly and screened them for genomic aberrations of the GMDS locus. No additional GMDS genomic aberrations were identified. In conclusion, we describe a de novo intragenic GMDS deletion associated with Ebstein anomaly. Together with previous reports, this second case suggests that GMDS deletions could be a rare cause for congenital heart disease, in particular Ebstein anomaly. Full article

Hypertrophic cardiomyopathy (HCM) is the most common heritable cardiovascular disorder and is characterized by left ventricular hypertrophy (LVH), which is unexplained by abnormal loading conditions. HCM is inherited as an autosomal dominant trait and, in about 40% of patients, the causal mutation is identified in genes encoding sarcomere proteins. According to the results of genetic screening, HCM patients are currently categorized in two main sub-populations: sarcomeric-positive (Sarc+) patients, in whom the causal mutation is identified in a sarcomeric gene; and sarcomeric-negative (Sarc−) patients, in whom a causal mutation has not been identified. In rare cases, Sarc− HCM cases may be caused by pathogenic variants in non-sarcomeric genes. The aim of this review is to describe the differences in the phenotypic expression and clinical outcomes of Sarc+ and Sarc− HCM and to briefly discuss the current knowledge about HCM caused by rare non-sarcomeric mutations. Full article

Left ventricular outflow obstruction (LVOTO) and diastolic dysfunction are the main pathophysiological characteristics of hypertrophic cardiomyopathy (HCM)LVOTO, may be identified in more than half of HCM patients and represents an important determinant of symptoms and a predictor of worse prognosis. This review aims to clarify the LVOTO mechanism in, diagnosis of, and therapeutic strategies for patients with obstructive HCM. Full article

Brugada syndrome (BrS) is an inherited cardiac channelopathy with variable expressivity that can lead to sudden cardiac arrest (SCA). Studies worldwide suggest that BrS and Brugada pattern (BrP) have low prevalences in general. However, studies also note that BrS is most prevalent among certain Asian populations. Among the different global regions, the highest prevalence is believed to be in Southeast Asia, followed by the Middle East, South Asia, East Asia, Europe, and North America. It is not only important to recognize such varying degrees of BrS prevalence within Asia but also to understand that there may be significant differences in terms of presenting symptoms, occult risk factors, and the impact on clinical outcomes. The importance of identifying such differences lies in the necessity to develop improved risk assessment strategies to guide secondary prevention and treatment for these patients. Specifically, the decision to pursue placement of an implantable cardiac defibrillator (ICD) can be lifesaving for high-risk BrS patients. However, there remains a significant lack of consensus on how to best risk stratify BrS patients. While the current guidelines recommend ICD implantation in patients with spontaneous Type 1 ECG pattern BrS who present with syncope, there may still exist additional clinical factors that may serve as better predictors or facilitate more refined risk stratification before malignant arrhythmias occur. This carries huge relevance given that BrS patients often do not have any preceding symptoms prior to SCA. This review seeks to delineate the differences in BrS presentation and prevalence within the Asian continent in the hope of identifying potential risk factors to guide better prognostication and management of BrS patients in the future. Full article

(1) Background. One of the causes of myocardial infarction (MI) with nonobstructive coronary arteries (MINOCA) is thrombus formation in situ followed by lysis, resulting in a morphologically normal angiogram but with an underlying prothrombotic state that is potentially predisposed to recurrence. Recent studies have shown that a subset of MINOCA patients may have thrombophilic conditions at screening. Objective: To compare the prothrombotic trend in MINOCA patients with that of subjects with MI and obstructive coronary arteries (MIOCA) by testing for known congenital thrombophilias and markers of coagulation activation. (2) Materials and methods. Screening included congenital thrombophilias (factor V Leiden; assessment of protein C, protein S, and antithrombin III) and eight genes. Of these, four genes represented the folate pathway enzymes: MTHFR 677 C>T (rs1801133), MTHFR 1298 A>C (rs1801131), MTR 2756 A>G (rs1805087), and MTRR 66 A>G (rs1801394). The other four genes represented the blood coagulation system: F13 (163 G>T) rs5985, F1 (−455 G>A) rs1800790, GP IIb–IIIa (1565 T>C) rs5918, and PAI-I (−675 5G>4G) rs1799889. Additionally, we examined the levels of homocysteine and lipoprotein (LP) (a). (3) Results. Our study included 269 patients: 114 MINOCA patients and 155 MIOCA patients with lesions of one coronary artery. The frequencies of polymorphisms in the genes of the blood coagulation system and the folate pathway did not differ between the groups. The following genes were associated with in-hospital mortality in the MINOCA group: MTHFR 1298 A>C rs1801131 (OR 8.5; 95% CI 1.67–43.1) and F1 (−455 G>A) rs1800790 (OR 5.8; 95% CI 1.1–27.8). In the MIOCA group, the following genes were associated with in-hospital mortality: MTHFR 1298 A>C rs1801131 (OR 9.1; 95% CI 2.8–28.9), F1 (−455 G>A) rs1800790 (OR 11.4; 95% CI 3.6–35.9), GP IIb–IIIa (1565 T>C) rs5918 (OR 10.5; 95% CI 3.5–30.8), and PAI-I (−675 5G>4G) rs1799889 (OR 12.9; 95% CI 4.2–39.7). We evaluated long-term outcomes (case fatality rate, recurrent MI, and stroke) over a period of 12 months in both groups. The variables associated with these outcomes were laboratory parameters, such as protein C deficiency, hyperhomocysteinemia, and a content of LP (a) > 30 mg/dL. However, we did not reveal the prognostic value of polymorphisms of the studied genes representing the blood coagulation system and the folate pathway. (4) Conclusion. We established no statistically significant differences between the MINOCA and MIOCA groups in the prevalence of congenital thrombophilias and the prevalence of folate pathway enzyme genes and blood coagulation system genes. The MTHFR 1298 A>C (rs1801131) and F1 (−455 G>A) rs1800790 genes were associated with in-hospital mortality in both groups. More significant prognostic factors in both groups during the one-year period were protein C deficiency, hyperhomocysteinemia, and LP (a) > 30 mg/dL. Full article

Salt sensitivity is a trait in which high dietary sodium (Na⁺) intake causes an increase in blood pressure (BP). We previously demonstrated that in the gut, elevated dietary Na⁺ causes dysbiosis. The mechanistic interplay between excess dietary Na⁺-induced alteration in the gut microbiome and sex differences is less understood. The goal of this study was to identify novel metabolites in sex differences and blood pressure in response to a high dietary Na⁺ intake. We performed stool and plasma metabolomics analysis and measured the BP of human volunteers with salt intake above or below the American Heart Association recommendations. We also performed RNA sequencing on human monocytes treated with high salt in vitro. The relationship between BP and dietary Na⁺ intake was different in women and men. Network analysis revealed that fatty acids as top subnetworks differentially changed with salt intake. We found that women with high dietary Na⁺ intake have high levels of arachidonic acid related metabolism, suggesting a role in sex differences of the blood pressure response to Na⁺. The exposure of monocytes to high salt in vitro upregulates the transcription of fatty acid receptors and arachidonic acid-related genes. These findings provide potentially novel insights into metabolic changes underlying gut dysbiosis and inflammation in salt sensitivity of BP. Full article

Cell-free nuclear (cf-nDNA) and mitochondrial (cf-mDNA) DNA are released from damaged cells in type 2 diabetes mellitus (T2DM) patients, contributing to adverse cardiac remodeling, vascular dysfunction, and inflammation. The purpose of this study was to correlate the presence and type of cf-DNAs with HF in T2DM patients. A total of 612 T2DM patients were prescreened by using a local database, and 240 patients (120 non-HF and 120 HF individuals) were ultimately selected. The collection of medical information, including both echocardiography and Doppler imagery, as well as the assessment of biochemistry parameters and the circulating biomarkers, were performed at baseline. The N-terminal brain natriuretic pro-peptide (NT-proBNP) and cf-nDNA/cf-mtDNA levels were measured via an ELISA kit and real-time quantitative PCR tests, respectively. We found that HF patients possessed significantly higher levels of cf-nDNA (9.9 ± 2.5 μmol/L vs. 5.4 ± 2.7 μmol/L; p = 0.04) and lower cf-mtDNA (15.7 ± 3.3 μmol/L vs. 30.4 ± 4.8 μmol/L; p = 0.001) than those without HF. The multivariate log regression showed that the discriminative potency of cf-nDNA >7.6 μmol/L (OR = 1.07; 95% CI = 1.03–1.12; p = 0.01) was higher that the NT-proBNP (odds ratio [OR] = 1.10; 95% confidence interval [CI] = 1.04–1.19; p = 0.001) for HF. In conclusion, we independently established that elevated levels of cf-nDNA, originating from NT-proBNP, were associated with HF in T2DM patients. Full article

Background: Leptin is an obesity-associated adipokine that has been implicated in cardiac protection against ischemia-reperfusion injury (IRI). In this study, concentration-dependent effects of leptin on myocardial IRI were investigated in the isolated rat heart. In addition, we analyzed myocardial miRNAs expression in order to investigate their potential involvement in leptin-mediated cardioprotection. Methods: The effect of leptin on IRI was examined in Langendorff-perfused rat hearts preconditioned with two leptin concentrations (1.0 nM and 3.1 nM) for 60 min. The hearts were subjected to 30 min global ischemia and 120 min reperfusion with buffer containing leptin in the respective concentration. Heart function and arrhythmia incidence were analyzed. Infarct size was assessed histochemically. Expression of miRNA-144, -208a, -378, and -499 was analyzed in the ventricular myocardium using RT-PCR. Results: The addition of 1.0 nM leptin to the buffer exerted an infarct-limiting effect, preserved post-ischemic ventricular function, and prevented reperfusion arrhythmia compared to 3.1 nM leptin. Myocardial expression of miRNA-208a was decreased after heart exposure to 1.0 nM leptin and significantly elevated in the hearts perfused with leptin at 3.1 nM. Conclusion: Acute administration of leptin at low dose (1.0 nM) results in cardiac protection against IRI. This effect is associated with reduced myocardial expression of miRNA-208a. Full article

BACKGROUND. Spontaneous coronary artery dissection (SCAD) is a cause of myocardial infarction, especially in younger women without cardiovascular risk factors. Patient management and diagnostics are still largely based on retrospective and observational studies. Most patients with SCAD report chest pain and have elevated biomarkers with ECG findings. SCAD can lead to cardiogenic shock, ventricular arrhythmias and cardiac arrest, and is commonly associated with fibromuscular dysplasia (FMD). Genetic associations are still in their infancy with this disease process. METHODS. An Invitae 29 gene aortopathy panel was performed on a mother with a thoracic aortic aneurysm and her daughter who presented with SCAD and was noted to have FMD. RESULTS. The patient and her mother were both noted to have a heterozygous mutation of the Biglycan (BGN) gene (Variant c.1030T > G (p.Tyr344His)) of undetermined significance. An extensive literature review was performed, including a review of the UK Biobank. This is the first case to our knowledge showing a possible link between the BGN mutation and SCAD/FMD. CONCLUSIONS. The BGN mutation has been recognized to be correlated with aortic aneurysm and aortic dissection. It has not yet been explored to be associated with SCAD/FMD. This paper highlights the potential link between the BGN gene and SCAD/FMD. Further research looking at this association is warranted. Full article