Cardiogenetics

Amyloidosis is a group of diseases in which amyloid fibrils build up in tissues, leading to organ dysfunction. Cardiac involvement is observed in immunoglobulin light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR) and, when it occurs, the prognosis worsens. Cardiac tissue infiltration can lead to restrictive cardiomyopathy with clinical signs of diastolic heart failure, without reduction of ejection fraction (HFpEF). The aim of multiple and less invasive diagnostic tests is to discern peculiar characteristics and reach the diagnosis without performing an invasive endomyocardial biopsy. These diagnostic tools allow early diagnosis, and they are crucial to best benefit from target therapy. In this review article, we describe the mechanism behind amyloid fibril formation, infiltration of tissues, and consequent clinical signs, focusing on the diagnostic tools and the red flags to obtain a diagnosis. Full article

Cardiac amyloidosis (CA) is a common and potentially fatal infiltrative cardiomyopathy. Contrast-enhanced cardiac MRI (CMR) is used as a diagnostic tool. However, utility of CMR for the comprehensive analysis of biventricular strains and strain rates is not reported as extensively as echocardiography. In addition, RV strain analysis using CMR has not been described previously. Objectives: We sought to study the global and regional indices of biventricular strain and strain rates in endomyocardial biopsy (EMB)-proven, genotyped cases of CA. Methods: A database of 80 EMBs was curated from 2012 to 2019 based on histology. A total of 19 EMBs positive for CA were subjected to further tissue-characterization with histology, and compared with four normal biopsy specimens. Samples were genotyped for ATTR- or AL-subtypes. Five patients, with both echocardiography and contrast-enhanced CMR performed 72-h apart, were subjected to comprehensive analysis of biventricular strain and strain-rates. Results: Histology confirmed that the selected samples were indeed positive for cardiac amyloid. Echocardiography showed reduced global and regional left-ventricular (LV) longitudinal strain indices. CMR with tissue-characterization of LV showed global reductions in circumferential, radial and longitudinal strains and strain-rates, following a general trend with the echocardiographic findings. The basal right-ventricular (RV) segments had reduced circumferential strains with no changes in longitudinal strain. Conclusions: In addition to providing a clinical diagnosis of CA based on contrast clearance-dynamics, CMR can be a potent tool for accurate functional assessment of global and regional changes in strain and strain-rates involving both LV and RV. Further studies are warranted to validate and curate the strain imaging capacity of CMR in CA. Full article

Background. Each year, approximately 5000 New Zealanders are admitted to hospital with first-time acute coronary syndrome (ACS). The Multi-Ethnic New Zealand Study of Acute Coronary Syndromes (MENZACS) is a prospective longitudinal cohort study embedded within the All New Zealand Acute Coronary Syndrome Quality Improvement (ANZACS-QI) registry in six hospitals. The objective of MENZACS is to examine the relationship between clinical, genomic, and cardiometabolic markers in relation to presentation and outcomes post-ACS. Methods. Patients with first-time ACS are enrolled and study-specific research data is collected alongside the ANZACS-QI registry. The research blood samples are stored for future genetic/biomarker assays. Dietary information is collected with a food frequency questionnaire and information about physical activity, smoking, and stress is also collected via questionnaire. Detailed family history, ancestry, and ethnicity data are recorded on all participants. Results. During the period between 2015 and 2019, there were 2015 patients enrolled. The mean age was 61 years, with 60% of patients aged <65 years and 21% were female. Ethnicity and cardiovascular (CV) risk factor distribution was similar to ANZACS-QI: 13% Māori, 5% Pacific, 5% Indian, and 74% NZ European. In terms of CV risk factors, 56% were ex-/current smokers, 42% had hypertension, and 19% had diabetes. ACS subtype was ST elevation myocardial infarction (STEMI) in 41%, non-ST elevation myocardial infarction (NSTEM) in 54%, and unstable angina in 5%. Ninety-nine percent of MENZACS participants underwent coronary angiography and 90% had revascularization; there were high rates of prescription of secondary prevention medications upon discharge from hospital. Conclusion. MENZACS represents a cohort with optimal contemporary management and will be a significant epidemiological bioresource for the study of environmental and genetic factors contributing to ACS in New Zealand’s multi-ethnic environment. The study will utilise clinical, nutritional, lifestyle, genomic, and biomarker analyses to explore factors influencing the progression of coronary disease and develop risk prediction models for health outcomes. Full article

Genetic variants in MYBPC3 are one of the most common causes of hypertrophic cardiomyopathy (HCM). While variants in MYBPC3 affecting canonical splice site dinucleotides are a well-characterised cause of HCM, only recently has work begun to investigate the pathogenicity of more deeply intronic variants. Here, we present three patients with HCM and intronic splice-affecting MYBPC3 variants and analyse the impact of variants on splicing using in vitro minigene assays. We show that the three variants, a novel c.927-8G>A variant and the previously reported c.1624+4A>T and c.3815-10T>G variants, result in MYBPC3 splicing errors. Analysis of blood-derived patient RNA for the c.3815-10T>G variant revealed only wild type spliced product, indicating that mis-spliced transcripts from the mutant allele are degraded. These data indicate that the c.927-8G>A variant of uncertain significance and likely benign c.3815-10T>G should be reclassified as likely pathogenic. Furthermore, we find shortcomings in commonly applied bioinformatics strategies to prioritise variants impacting MYBPC3 splicing and re-emphasise the need for functional assessment of variants of uncertain significance in diagnostic testing. Full article

Sudden death, especially at a young age, may be caused by an underlying genetic cause. Hereditary conditions with an increased risk of sudden death at a young age include cardiomyopathies, arrhythmia syndromes, and hereditary thoracic aortic aneurysms and dissections. The identification of a genetic cause allows for genetic testing and cardiological surveillance in at-risk relatives. Three sudden death cases from our hospital illustrate the value of autopsy, genetic, and cardiological screening in relatives following a sudden death. On autopsy, histology consistent with hereditary cardiomyopathy is a reason for the referral of relatives. In addition, in the absence of an identifiable cause of death by autopsy in young sudden death patients, arrhythmia syndrome should be considered as a potential genetic cause. Full article

Systems biology is established as an integrative computational analysis methodology with practical and theoretical applications in clinical cardiology. The integration of genetic and molecular components of a disease produces interacting networks, modules and phenotypes with clinical applications in complex cardiovascular entities. With the holistic principle of systems biology, some of the features of complexity and natural progression of cardiac diseases are approached and explained. Two important interrelated holistic concepts of systems biology are described; the emerging field of personalized medicine and the constraint-based thinking with downward causation. Constraints in cardiovascular diseases embrace three scientific fields related to clinical cardiology: biological and medical constraints; constraints due to limitations of current technology; and constraints of general resources for better medical coverage. Systems healthcare and personalized medicine are connected to the related scientific fields of: ethics and legal status; data integration; taxonomic revisions; policy decisions; and organization of human genomic data. Full article

Cardiovascular disorders are the main complication in autosomal dominant polycystic kidney disease (ADPKD). contributing to both morbidity and mortality. This review considers clinical studies unveiling cardiovascular features in patients with ADPKD. Additionally, it focuses on basic science studies addressing the dysfunction of the polycystin proteins located in the cardiovascular system as a contributing factor to cardiovascular abnormalities. In particular, the effects of polycystin proteins’ deficiency on the cardiomyocyte function have been considered. Full article

Hypertrophic cardiomyopathy and left ventricular noncompaction commonly occur as separate disorders with distinct clinical and pathoanatomical features. However, these cardiomyopathies may have a similar genetic origin with mutations encoding sarcomeric proteins. The described case report demonstrates an example in which phenotypic expression of both diseases occurred in the same patient, who has two different alterations; one of them is a likely pathogenic variant in the MYL3 gene (MIM#160790) and the second variant in the MYH6 gene (MIM#160710) of unknown significance so far. To better understand associations between specific genetic variants and phenotypical expression of these genetic alterations and to stratify patient risk and decide on the most appropriate treatment, a comprehensive multimodality imaging approach and experienced multidisciplinary cardiomyopathy team decisions are warranted. In the clinical routine, awareness of the existence of complex cardiomyopathy phenotypes should be paid more attention during echocardiographic examination and should encourage a broader use of cardiovascular magnetic resonance. Full article

Purpose: To evaluate the clinical features, laboratory and instrumental tests results and the effectiveness of complex treatment in a patient with multiple etiologies of dilated cardiomyopathy (DCM) with a high risk of sudden cardiac death. Methods: Female patient was 34 years old. Follow up period was seven years. Since the age of 23 (after a respiratory infection), chest pains and shortness of breath appeared. Coronary arteries were intact. After syncope in 2013, Holter-ECG was performed: 2048 premature ventricular beats (PVBs)/day and episode of sustained ventricular tachycardia (VT, 1 min) were registered. MRI was performed, and a cardioverter defibrillator (ICD) was implanted. Results: ECG showed low QRS voltage and negative T waves in leads V2-V6, III, aVF. In signal-averaged ECG, late potentials were detected. Echocardiography (EchoCG) demonstrated left and right ventricular dilatation, diffuse reduction of left ventricular (LV) contractility and multiple pseudochordae in LV. MRI showed LV noncompaction (LVNC), thickening of the epicardial fat and hypo-/dyskinesia of the anterior wall of the right ventricular (RV), dilatation of both ventricles with decrease of their ejection fraction and subepicardial gadolinium enhancement in the early and late phase in the LV, intraventricular septum and the free walls of the RV. The presence of LVNC was confirmed by cardiac computed tomography (CT). Late contrast enhancement in the middle and subendocardial layer of the LV was observed as well. The level of anticardiac antibodies was high (1:160–1:320). The reasons for statement of a possible diagnosis of myocarditis in this case were the connection of the onset of symptoms with viral infection, high titers of anticardiac antibodies, and early and late subepicardial contrast enhancement by MRI and CT. The endomyocardial biopsy was obtained, and subendocardial lipomatosis, separation of myocardium by fibrous septa, lymphocytic infiltrates (more than 14 cells/mm²) and vasculitis were found. Viral genome in myocardium was not detected. A new splicing mutation in the desmoplakin (DSP) gene was found (NM_004415.4: c.1141-2A>G/N (rs794728111)). Combination of arrhythmogenic right ventricular cardiomyopathy (ARVC), LVNC and myocarditis was diagnosed. Immunosuppressive therapy (prednisone and azathioprine) was prescribed, LV ejection fraction stabilized at the level of 40%. The appropriate shocks of the ICD due to sustainedVT (HR 210/min) with transformation into ventricular fibrillation were recorded twice. For this reason, sotalol was temporarily replaced with amiodarone. After the suppression of myocarditis activity, sustained VT and ICD interventions were not observed. Conclusions: In a young patient with arrhythmogenic syncope and DCM syndrome, a combination of ARVC (two major and three minor criteria, definite diagnosis) and LVNC with the biopsy proved virus-negative chronic myocarditis was diagnosed. DCM as a syndrome can have multiple causes, and the combination of myocarditis and primary cardiomyopathy is not rare. LVNC can be observed in patients with typical desmosomal protein mutations. The use of immunosuppressive therapy led to the stabilization of heart failure and decreased the risk of arrhythmic events. Full article

Heart involvement in Cardiac Amyloidosis (CA) results in a worsening of the prognosis in almost all patients with both light-chain (AL) and transthyretin amyloidosis (ATTR). The mainstream CA is a restrictive cardiomyopathy with hypertrophic phenotype at cardiac imaging that clinically leads to heart failure with preserved ejection fraction (HFpEF). An early diagnosis is essential to reduce cardiac damage and to improve the prognosis. Many therapies are available, but most of them have late benefits to cardiac function; for this reason, novel therapies are going to come soon. Full article

We describe a 55 year old male diagnosed with cardiomyopathy due to Fabry disease. Biochemical testing of blood spot and plasma showed low-normal alpha-galactosidase A (α-Gal A) levels. Genetic testing revealed somatic mosaicism for GLA c.901C>T, p.(Arg301Ter). Usually, males with Fabry disease due to loss of function variants in GLA show symptoms of the multisystemic features of the condition early in life, and have very low levels of the α-Gal A enzyme. This demonstrates that the diagnosis of Fabry disease in males with cardiomyopathy should still be considered even in the context of a normal plasma enzyme assay. Full article

Objectives: Fetuin-A is a circulating calcification inhibitor that prevents coronary artery calcification (CAC) by increasing calcium phosphate solubility and inhibiting VSMC differentiation and apoptosis. In this study, we investigated the correlation between rs4918 and CAC in patients with coronary artery disease (CAD). Methods: Forty-two healthy individuals and eighty-one CAD patients were recruited in the present study. The CAC score (CACS) was measured by CT angiography and the genotype analysis of rs4918 single-nucleotide polymorphism SNP was performed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Results: The CACS was significantly higher in CAD patients compared to healthy individuals (p < 0.001); however, there was no significant difference between the mean CACS in the presence and absence of rs4918 (p = 0.792). The mean calcium score of the left main coronary artery (LMCA) was significantly lower in carriers of the rs4918 allele (p = 0.036). The frequency of rs4918 SNP was almost similar in the control group and CAD patients (p = 0.846). Conclusions: in patients with CAD, we found no significant association between rs4918 SNP and CACS, indicating that carriers of this allele are not at increased risk of developing cardiovascular diseases compared with those without. Full article

Anomalous Left Coronary Artery from the Pulmonary Artery (ALCAPA) is a rare coronary artery anomaly which accounts for 0.25–0.5% of all congenital cardiac diseases, where most die within the first year of life. We present a case report of a 50-year-old lady who presented to hospital with persistent palpitations. Her admission electrocardiogram found her to be in Atrial Fibrillation (AF). She was rate-controlled and subsequently discharged. Despite that, she represented with further episodes of AF and was referred for an outpatient transthoracic echocardiogram. This revealed a dilated right coronary artery, retrograde flow in the left coronary artery and collateral flow in the myocardium. To investigate, the patient had undergone further imaging which confirmed the diagnosis. As such, she was later shortlisted for surgical intervention. Conclusively, our case exemplifies the role of multimodal imaging to identify the features of ALCAPA and may be useful for the purposes of surgical intervention. Full article

We report the first case of a 294 kb loss, notable for including the entirety of GPD1L, on chromosome 3p22.3—p24 in a 3-year-old girl with multiple congenital anomalies including absent left foot, single umbilical artery, bilateral vesico-ureteral reflux, rectovaginal fistula, and imperforate anus. Although GPD1L mutations have been associated with cardiac arrhythmias, including Brugada syndrome and sudden unexpected infant death syndrome, full deletions in the GPD1L gene have not been reported neither the patient nor her mother, who was later identified to carry the variant, have any signs or symptoms of Brugada syndrome. This may indicate these individuals have findings that have not yet been identified, full gene deletions of GDP1L are not necessarily disease causing, or there is incomplete penetrance of this gene or cardiac manifestations can occur at a later age. Full article

Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder caused by a deficiency of the lysosomal enzyme, agalactosidase A. The inadequate enzymatic activity leads to systemic storage of glycosphingolipids, mostly globotriaosylceramide, in the lysosomes. As of now, enzyme replacement therapy is the only approved treatment for AFD. However, it does not induce a complete and lasting response in several clinical contexts. Genemediated enzyme replacement is an emerging approach that could overcome these limits. The single gene nature of AFD enhances the possibility to transfect and modify a small number of cells, making them capable to affect the correction of a larger number of cells. This review summarizes the history and the state of the art of gene therapy in AFD, showing potential benefits and limits. Full article

Heterozygous RYR2 missense variants cause catecholaminergic polymorphic ventricular tachycardia. Rarely, loss of function variants can result in ventricular arrhythmias. We used splice prediction tools and an ex vivo splicing assay to investigate whether RYR2 missense variants result in altered splicing. Ten RYR2 variants were consistently predicted to disrupt splicing, however none altered splicing in the splicing assay. In summary, missense RYR2 variants are unlikely to cause disease by altered splicing. Full article