Cardiogenetics

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

Intense athletic training and competition can rarely result in sudden cardiac death (SCD). Despite the introduction of pre-participation cardiovascular screening, especially among young competitive athletes, sport-related SCD remains a debated issue among medical personnel, sports communities and laypersons alike, and generates significant media attention. The most frequent cause of SCD is a hidden inherited cardiomyopathy, the athletes may not even be aware of. Predictive medicine, by searching the presence of pathogenic alterations in cardiac genes, may be an integrative tool, besides the conventional ones used in cardiology (mainly electro and echocardiogram), to reach a definitive diagnosis in athletes showing signs/symptoms, even borderline, of inherited cardiomyopathy/ channelopathy, and in athletes presenting family history of SCD and/or of hereditary cardiac disease. In this review, we revised the molecular basis of the major cardiac diseases associated to sudden cardiac death and the clinical molecular biology approach that can be used to perform risk assessment at DNA level of sudden cardiac death, contributing to the early implementation of adequate therapy. Alterations can occur in ion channel genes, in genes encoding desmosomal and junctional proteins, sarcomeric and Z-disc proteins, proteins for the cytoskeleton and the nuclear envelope. The advent of next generation sequencing (NGS) technology has provided the means to search for mutations in all these genes, at the same time. Therefore, this molecular approach should be the preferred methodology for the aforementioned purpose. Full article

Management of symptoms in patients with inoperable aortic stenosis is often hard in clinical practice. We report a case of a patient with Hutchinson-Gilford progeria syndrome and end-stage aortic stenosis, considered not suitable for surgical or percutaneous approach, to whom the administration of ranolazine resulted in a considerable improvement of angina, refractory to other treatments. Full article

The majority of familial noncompaction cardiomyopathy (NCCM) is explained by pathogenic variants in the same sarcomeric genes that are associated with hypertrophic (HCM) and dilated (DCM) cardiomyopathy. Pathogenic variants in the filamin C gene (FLNC) have been linked to HCM and DCM. We expand the spectrum of FLNC related cardiomyopathies by presenting two families with likely pathogenic FLNC variants showing familial segregation of NCCM and concurrent coarctation of the aorta and/or mitral valve abnormalities. Full article

Kearns-Sayre syndrome (KSS) is a rare mitochondrial disease in which cardiac involvement has been associated with poor prognosis. Although the most common clinical manifestation is progressive conduction system impairment, patients can suffer from ventricular arrhythmias. Yet, they show a high prevalence of sudden cardiac death, whose etiopathological mechanism is not completely understood. Cardiac magnetic resonance is a rising tool to detect subclinical heart involvement in many heart diseases and was recently able to detect nonischemic scar, which is an arrhythmogenic substrate, in patients affected by KSS. Full article

Carcinoid syndrome is a paraneoplastic condition, which usually affects the lungs or gastrointestinal tract but uncommonly cardiac valves can be involved, causing carcinoid heart disease. We describe a case of a 60-year-old man presented with a twelve-month history of worsening shortness of breath and decreased exercise tolerance. Investigations confirmed grade 1 metastatic neuroendocrine carcinoma (carcinoid tumour) of likely gastrointestinal tract origin. Two months after diagnosis he underwent successful tricuspid valve replacement and pulmonary root replacement. Cytoreductive surgery of the right lobe of the liver and the ileal primary is planned. Cardiac surgery is the only definitive treatment for carcinoid heart disease and should be considered in all those with symptoms and evidence of severe valvular disease. Full article

Predominant causes for newly diagnosed postpartum heart failure are preeclampsia and peripartum cardiomyopathy. Being an anatomical variant of Takotsubo syndrome (TTS) reverse TTS in this period is rare. We present a 36 year old patient, who had delivered triplets by cesarean section. Because of postpartum bleeding she was administered sulprostone. Later she was transferred to the Intensive Care Unit with sudden development of dyspnea, tachypnea and tachycardia. Clinical symptoms, laboratory findings and chest radiograph showed signs of acute heart failure. Transthoracic echocardiography (TTE) revealed reverse TTS with moderately reduced left ventricular ejection fraction (LVEF 39%). The patient stabilized with loop diuretic, angiotensine-converting enzyme inhibitors and beta-blockade. Breast-feeding was discouraged and bromocriptine administered. Left ventricular function normalized (LVEF 60%) within four weeks. TTS should be considered in patients with early postpartum development of heart failure. Rapid cardiac recompensation after the start of adequate therapy and complete resolution of clinical symptoms and TTE findings are typical for postpartum TTS. Full article

Genome editing, or genome engineering is a type of genetic engineering in which DNA is inserted, deleted or replaced in the genome of a living organism using engineered nucleases, or molecular scissors. Genome editing is being rapidly adopted into all fields of biomedical research, including the cardiovascular field, where it has facilitated a greater understanding of lipid metabolism, electrophysiology, cardiomyopathies, and other cardiovascular disorders, has helped to create a wider variety of cellular and animal models, and has opened the door to a new class of therapies. In this review, we discuss the applications of in vivo genome-editing therapies for cardiovascular disorder. Full article

Variants in the LMNA gene, which encodes Lamin-A/C, have been commonly associated with cardiac conduction system diseases usually accompanying cardiomyopathy. We have seen two unrelated patients who presented with atrioventricular block (AVB) with or without cardiomyopathy. Genetic testing identified the LMNA missense variant c.1634G>A (p.R545H) and the single nucleotide deletion c.859delG (p.A287Lfs*193). The deletion leads to a shift in the reading frame and subsequent protein truncation. Since impaired Na_v1.5 function has been reported to cause AVB, we sought to investigate the effects of abnormal Lamins on Na_v1.5 in HEK-293 cells using patch-clamp methods. Patch-clamp studies showed that p.R545H decreased the peak I_Na by approximately 70%. The voltage-dependency of steady state inactivation was rightward shifted in the cells transfected with p.R545H. The p.A287Lfs*193 also decreased the peak I_Na by approximately 62%. The voltagedependency of steady state inactivation was rightward shifted in the cells transfected with p.A287Lfs*193. Variants of the LMNA gene caused significant reduction of the peak I_Na in HEK-293 cells, which may account for the patients’ AVB. Full article

Hypertrophic cardiomyopathy (HCM) is defined as left ventricular hypertrophy in the absence of loading conditions sufficient to cause the observed abnormality. The true prevalence in childhood is unknown; the aetiology is more heterogeneous than that seen in adult populations, and includes inborn errors of metabolism, malformation syndromes and neuromuscular syndromes. However, one of the greatest clinical challenges in managing young patients with HCM is identifying those at greatest risk of sudden cardiac death. Full article

Our understanding of arrhythmogenic right ventricular cardiomyopathy (ARVC) has advanced considerably over the past 30- 40 years. This is an inherited cardiomyopathy with complicated genetic inheritance and variable penetrance. Desmosomal dysfunction underlies most cases, and appreciating this pathophysiology has contributed to patient management, particularly with respect to exercise restriction to reduce disease progression. The diagnosis is made according to a series of Task Force Criteria, and subsequent management is guided by expert consensus in the absence of comparative data. ARVC is associated with sudden cardiac death (SCD), particularly in young athletic individuals who unknowingly harbour the condition. Risk stratification is important to guide implantable cardioverter- defibrillator use and reduce SCD. Residual gaps in our understanding, particularly surrounding incomplete penetrance, the underlying pathophysiology and risk stratification, are being targeted by collaborative efforts, large registries, prospective studies and translational research. Full article

Arrhythmogenic cardiomyopathy (AC) is a rare mostly hereditary disease, in which fibro-fatty tissue replaces cardiomyocytes. Typically, the first alterations of the disease can be encountered in the epicardium of the right ventricle in adolescent patients. From there, the disease usually progresses over time. Besides the development of heart failure, the clinical significance of the disease is determined by the predisposition to potentially lethal ventricular arrhythmias. Hence, a majority of patients with AC require an implantable cardioverter-defibrillator (ICD) to be protected from sudden cardiac death. A recently developed alternative to transvenous systems are subcutaneous ICDs (S-ICD), associated with a lower risk of device-related complications such as endocarditis since no foreign material is implanted within the heart and vascular system. In this report, we describe and discuss our experience with the implantation of a S-ICD in a patient with AC, who had low QRS voltage and persistent atrial fibrillation precluding successful S-ICD implantation, as well as the challenges encountered during subsequent transvenous lead implantation. Full article

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by progressive fibro-fatty replacement of the myocardium that represents the substrate for recurrent sustained ventricular tachycardia (VT). These arrhythmias characterize the clinical course of a sizeable proportion of patients and have significant implications for their quality of life and long-term prognosis. Antiarrhythmic drugs are often poorly tolerated and usually provide incomplete control of arrhythmia relapses. Catheter ablation is a potentially effective strategy to treat frequent VT episodes and ICD shocks in ARVC patients. The aims of this review are to discuss the electrophysiological and electroanatomic substrates of ventricular tachycardia in patients with ARVC and to analyze the role of catheter ablation in their management with particular reference to selection of patients, technical issues, potential complications and outcomes. Full article

Pompe disease also known as glycogen storage disease type II, is a rare and progressive lysosomal storage disorder caused by the deficiency of the enzyme acid α-glucosidase. This results in the accumulation of glycogen in various tissues particularly involving the heart, skeletal muscle and liver. It is inherited in an autosomal recessive manner due to mutations in the GAA gene. There are several known pathogenic variants, some of which are particularly common in certain geographical regions. Pompe disease is a single disease exhibiting a heterogeneous clinical spectrum depending on the extent of enzyme deficiency, the age of onset, the progression of the disease and the degree of organ involvement. It may lead to muscle weakness, hypotonia, respiratory compromise and premature death. Pompe disease is classically divided into two forms, infantile and late-onset disease. The infantile form is further subdivided into classical and non-classical subtypes. Cardiac involvement is particularly seen in the infantile phenotype of the condition, presenting as severe cardiomyopathy associated with conduction abnormalities. Enzyme replacement therapy with recombinant human acid α-glucosidase is the approved treatment option for patients with this metabolic condition. Further research is currently being done to explore more treatment options. One must keep in mind other metabolic and mitochondrial conditions, which may give a similar cardiac and neurological clinical picture. Full article