Danon Disease Research Articles

NEJM at AHA — Phase 1 Study of AAV9.LAMP2B Gene Therapy in Danon Disease

NEJM at AHA — Phase 1 Study of AAV9.LAMP2B Gene Therapy in Danon Disease

Abstract 4125497: Diagnostic Discrepancies Revealed by Explant Pathology at the Time of Cardiac Transplant in Patients Clinically Diagnosed with Nonischemic Cardiomyopathy: Role of Cardiac Magnetic Resonance Imaging

Background: Differentiating between causes of non-ischemic cardiomyopathy is important for disease-directed treatment. Cardiac MRI (CMR) and the use of late gadolinium enhancement (LGE) have proven useful for enhancing diagnostic accuracy. Definitive assessment of cardiomyopathy etiology by explant pathology facilitates direct evaluation of CMR utility. Hypothesis: We hypothesized direct comparison between pre-transplant (Tx) CMR and explant pathology will improve the characterization of undifferentiated cardiomyopathy through examination of cases where pre- and post-Tx diagnoses were discordant. Aims: To evaluate discrepant cases to describe imaging patterns in relation to post-Tx diagnosis. Methods: Institutional Tx recipients between 2000 and June 2023 were queried for pre-Tx MRI (n=122). Discrepant cases were identified (n=8). Pre-Tx diagnostic modalities, including CMR, were reviewed, and CMR patterns were evaluated in association with ultimate explant diagnosis. Results: Of the eight patients with discrepant diagnoses, five carried clinical diagnosis of dilated cardiomyopathy, one hypertrophic cardiomyopathy, one peripartum cardiomyopathy, and one congenital heart disease having undergone tricuspid valve and ASD repair. Pathologic evaluation most frequently identified biventricular or left ventricular arrhythmogenic cardiomyopathy (ARVC) (n=6), where CMR disclosed a diffuse pattern of subepicardial LGE and pre-Tx diagnosis of DCM was most common. Two of these pathologic descriptions represented a different disease on genetic evaluation: one patient had Danon disease, another had a LMNA pathogenic variant. The presumed peripartum cardiomyopathy was identified as Fabry’s disease on pathology (however, genetic testing consistent with Danon disease). Both Danon disease patients had primarily subendocardial LGE on CMR. One patient with a DCM phenotype had HCM pathologically. Results summarized in Table 1. Conclusions: Cardiac MRI can be a useful modality for the evaluation of underlying cardiomyopathy and should prompt appropriate genetic testing. Diffuse subepicardial LGE frequently accompanied the diagnosis of ARVC whereas a non-subepicardial pattern reflected alternative etiologies identified only through genetic testing.

History and Perspective of LAMP-2 Deficiency (Danon Disease).

Danon disease, an X-linked dominant vacuolar cardiomyopathy and skeletal myopathy, is caused by a primary deficiency of lysosome-associated membrane protein-2 (LAMP-2). This disease is one of the autophagy-related muscle diseases. Male patients present with the triad of cardiomyopathy, myopathy, and intellectual disability, while female patients present with cardiomyopathy. The disease's leading cause of death is heart failure, and its prognostic factor is cardiomyopathy. Pathologically, the disease is characterized by the appearance of unique autophagic vacuoles with sarcolemmal features (AVSFs). Twenty-six families have been found to have this disease in Japan. It has been over 40 years since the first report of this disease by Danon et al. and over 20 years since the identification of the causative gene, LAMP2, by Nishino et al. Although the pathogenetic mechanism of Danon disease remains unestablished, the first clinical trials using AAV vectors have finally begun in recent years. The development of novel therapies is expected in the future.

Clinical and genetic profile of Chinese children with Danon disease: A single-center retrospective cohort study

BackgroundDanon disease (DD) is a rare X-linked dominant lysosomal storage disorder. Studies on DD pediatric patients are limited due to the small number of cases and challenges in early detection. MethodsWe retrospectively analyzed clinical and genetic data of 29 pediatric patients who visited our hospital for treatment or genetic counseling of DD from July 2014 to December 2023. ResultsThe mean age at diagnosis was 7.2±5.9 years for males (n=21) and 9.4±5.0 years for females (n=8). Asymptomatic elevated liver aminotransferase and/or creatine kinase (CK) levels were initial manifestations detected in 10 (48%) male patients and absent in female patients. Hypertrophic cardiomyopathy (HCM) was observed in 20 (95%) male and 7 (88%) female patients, while dilated cardiomyopathy (DCM) was not detected. Ventricular preexcitation (VP) was observed initially in 10 (36%) patients and in 15 (54%) at latest evaluation. Patients with VP had higher left ventricular posterior wall thickness in diastole z-scores than those without VP (5.6±2.2 vs. 3.5±2.1, p=0.029). During a median 2.7-years follow-up, two males received heart transplants. One boy and one girl died of heart failure and sudden cardiac arrest, respectively. Twenty-three pathogenic LAMP2 variants were identified, including seven novel variants. ConclusionsA retrospective review of 29 DD cases suggests an underrecognized asymptomatic period in male DD patients, characterized by elevations in serum CK and transaminases. HCM appears to be the only cardiac manifestation in pediatric female patients, unlike a high incidence of DCM in adult female patients. The incidence of VP may increase with disease progression.

Post-COVID Myocarditis in Patients with Primary Cardiomyopathies: Diagnosis, Clinical Course and Outcomes.

The aim of this study was to evaluate the clinical course and outcomes of post-COVID myocarditis in patients with cardiomyopathies (CMP). This case series includes 10 patients with different CMPs who had COVID-19 (seven men; 48.4 ± 11.4 yr.): left ventricular non-compaction (n = 2), arrhythmogenic right ventricular CMP in combination with a heterozygous form of hemochromatosis (n = 1, HFE), restrictive CMP (n = 1, MyBPC3), laminopathy (n = 1, LMNA), dilated cardiomyopathy (n = 1, MYH7 + MyBPC3), Danon's disease (n = 1, LAMP2) and AL cardiac amyloidosis (n = 3). Myocardial morphological examination with immunohistochemical staining and PCR for SARS-CoV-2 and cardiotropic viruses was performed in six patients, while cardiac MRI and anti-cardiac antibody titres were evaluated in all patients. Post-COVID lymphocytic myocarditis was confirmed morphologically in six patients (with LVNC, RCM, ARCV, Danon's disease, and AL amyloidosis). Spike and nucleocapsid coronavirus proteins were detected in cell infiltrates, endothelium and cardiomyocytes in all biopsies; SARS-CoV-2 RNA was found in five out of six. In four patients, the diagnosis of myocarditis was based on MRI, high titres of anti-cardiac antibodies and clinical data. The mean time from COVID-19 to the diagnosis of myocarditis was 7 (5; 10.5) months. Myocarditis manifested with the onset/increase of arrhythmias and heart failure. Immunosuppressive therapy with corticosteroids was administered to six patients and led to an increase in ejection fraction and improvement of heart failure symptoms in five of them. CMPs are a favourable background for the development of post-COVID myocarditis. The onset or deterioration of heart failure and/or arrhythmias in patients with CMPs after COVID-19 requires the exclusion of myocarditis and, if present, the administration of immunosuppressive therapy.

Cardiomyopathies – genetic and molecular issues

Abstract Cardiomyopathy is a condition that may have a genetic basis. It is a serious ailment because it affects almost half of the individuals who die suddenly in childhood, adolescence, or related to heart transplant procedures. The inheritance patterns of this disease can vary. For example, as described in the work on HCM and ARVC, they are inherited in an autosomal dominant manner. De novo mutations may involve genes related to myofilaments, Z-discs, components related to cellular calcium handling, or desmosomes, among others. However, detailed molecular aspects should be correlated with clinical features because changes within a single gene may be associated with diverse abnormalities. Depending on the manifestation of the action of certain allele changes, they may range from microscopic deviations to causing heart failure and impaired blood flow through other organs, thereby disrupting the functionality of the entire body, hindering daily life and lowering its quality. Currently, the analysis of the degree of interaction of genetic determinants in cardiomyopathy is becoming increasingly accessible due to modernization and improvement of tools in the field of diagnosing anomalies in gene sequences and expression. A more precise understanding of causative mutations and associated conditions may contribute to determining strategic points for the future regarding the most beneficial course of action in specific circumstances and evaluating the effectiveness of the steps taken in the long run. In addition to mutations typically causing cardiomyopathy, there are also mutations contributing to their development within the spectrum of other diseases. This includes the PRKAG2-related cardiac syndrome, associated with abnormal metabolism, Danon disease, mitochondrial disorders, ion channelopathies, or conduction disorders.

Endovascular treatment in Danon disease: a case report

BackgroundDanon disease is a lysosomal storage disorder with X-linked inheritance. The classic triad is severe hypertrophic cardiomyopathy, myopathy, and intellectual disability, with different phenotypes between both genders. Ischemic stroke is an uncommon complication, mostly cardioembolic, related to intraventricular thrombus or atrial fibrillation, among others.Case reportWe report the case of a 14-year-old Caucasian male patient with Danon disease who suffered from an acute ischemic stroke due to occlusion in the M1 segment of the middle cerebral artery. He underwent mechanical thrombectomy, resulting in successful revascularization with satisfactory clinical outcome. We objectified the intraventricular thrombus in the absence of arrhythmic events.ConclusionTo our knowledge, we report the first case of ischemic stroke related to Danon disease treated with endovascular treatment.

Frameshift mutation of LAMP2:c.667delT in a 17-year-old male with hypertrophic cardiomyopathy and dyslexia: a novel pathogenic variant for Danon disease.

Frameshift mutation of LAMP2:c.667delT in a 17-year-old male with hypertrophic cardiomyopathy and dyslexia: a novel pathogenic variant for Danon disease.

Multidisciplinary approach in the differential diagnosis of left ventricular hypertrophy: a case report

Left ventricular (LV) hypertrophy implies structural cardiac changes and, as a consequence, an increase in myocardial mass. Currently, there are many causes of this condition as follows: hypertension, aortic stenosis, hypertrophic cardiomyopathy, exercise, storage diseases (AL, ATTR amyloidosis, Danon disease, Anderson-­Fabry disease, etc.), metabolic disorders. Despite the currently existing diagnostic algorithms for LV hypertrophy, establishing a correct diagnosis can take a long time, and controversial research results can lead to false conclusions. This article presents a case report of a patient with LV hypertrophy, an atypical clinical performance and ambiguous paraclinical data, which led to certain diagnostic difficulties.

A Mutational Hotspot in The LAMP2 Gene: Unravelling Intrafamilial Phenotypic Variation and Global Distribution of The c.877C>T Variant: A Descriptive Study.

Danon disease is defined by a clinical trio of cardiomyopathy, skeletal myopathy, and cognitive impairment. It results from the lysosomal-associated membrane protein-2 (LAMP2) gene variants. The aim of study is determination of genotype and phenotype of a newly diagnosed Iranian family with a unique phenotype due to a pathogenic variant of the LAMP2 gene along with a phenotypic comparison of all reported patients. In this descriptive study, we evaluated the demographic data, clinical features, management procedures, as well as genetic analysis of both patients in this newly diagnosed family. Whole genome sequencing (WGS) and in silico structural and functional predictions were applied. A comprehensive search of the c.877C>T variant in LAMP2 was conducted using the PubMed, Google Scholar, VarSome, ClinVar, Human Gene Mutation Database (HGMD), and Franklin databases to identify any genotype-phenotype correlations. Nine patients were carriers of the c.877C>T variant. All patients were male, and displayed variable degrees of left ventricular hypertrophy (LVH) that ranged from mild to severe. All patients exhibited typical cardiac conduction abnormalities consistent with Danon disease. Four underwent heart transplants and survived. Skeletal muscle involvement and cognitive impairment were observed in four patients each. The mean age of onset was 14 years. The proband in this study exhibited an earlier onset of cardiac symptoms. Genetic analysis is the preferred diagnosis approach for Danon disease and can assist families in managing affected patients, identify carriers, and assist with future family planning. This study highlights the intrafamilial phenotypic variability of Danon disease. It is possible that variants of this gene may be frequent in Iran.

CASE-FB-03 - Danon Disease: Diagnosis Made by Cardiac Magnetic Resonance

CASE-FB-03 - Danon Disease: Diagnosis Made by Cardiac Magnetic Resonance

Danon Disease Presenting with Slowly Progressive Cardiomyopathy and Harboring a Novel Missense Variant in the Lysosome-associated Membrane Protein Type 2 (LAMP-2) gene: A Case Report.

Danon disease (DD) is a rare lysosomal storage disorder resulting from pathogenic variants of the lysosome-associated membrane protein type 2 (LAMP-2) gene. The disease is characterized by severe cardiomyopathy, which rapidly progresses to end-stage heart failure. This case, with DD caused by a missense variant, exhibited slow progressive cardiomyopathy and survived for an extended period despite being a male. A pathological analysis revealed that only a minority of the samples exhibited autophagic vacuoles with unique sarcolemmal features (AVSFs), which are typical of DD. Importantly, LAMP-2 expression was absent and the myocardial tissue contained a substantial amount of p62-positive aggregates.

Abstract 14213: A Retrospective Natural History Study of Danon Disease

Introduction: Danon disease (DD) is a rare X-linked dominant cardioskeletal myopathy caused by mutations in the lysosome-associated membrane protein-2 (LAMP2) gene. The purpose of this study is to characterize disease progression and outcomes in males and females with DD. Methods: Data were from the International Danon Disease Registry that includes patients from the United States and Europe consented between 2005 and 2022. Records were obtained from the first episode of care to the date of enrollment and included demographics, clinical characteristics and outcomes. Chi square and Wilcoxon testing were used for cross-sectional and mixed effects models used for longitudinal analyses. Data were censored after TXP or LVAD. Results: This study included 112 patients with a median follow up of 6.8 yrs (IQR: 2.5-12.8 yrs). Demographics and outcomes are in Table 1. Males were more likely to experience the combined heart failure outcome. At least mild ventricular dysfunction occurred in 30% of patients, and almost all patients had LV hypertrophy. Regarding arrhythmias, WPW and CIED placement were common. Over time, LVEF decreased in both sexes and LV wall thickness did not increase, although LV mass increased in males only. BNP, CPK and AST did not change. [Table 2] Conclusions: DD is a multisystem and progressive disease with potential for cardiac arrhythmias, progressive hypertrophy and ventricular dysfunction. Currently, there are no disease modifying therapies for DD, although gene therapy trials are underway. Understanding the natural history of DD is critical for informing patient selection of therapies, including heart transplantation and new gene modifying therapies.

Abstract 18811: Heart Failure in a Carrier of Danon Disease

Background: Danon Disease is a rare X-linked dominant genetic condition characterized by hypertrophic cardiomyopathy, skeletal muscle myopathy, and intellectual disability, among other serious complications. The disease is a lysosomal storage disorder in which a mutation in the LAMP-2 gene causes a defect in the lysosome membrane and an accumulation of glycogen in vital tissue including cardiac muscle cells. It occurs more commonly in males, who are also more severely affected than females with this condition. There are no specific treatments available, although studies involving gene therapy have been ongoing. Patients with Danon Disease often require heart transplantation as treatment for end-stage heart failure. Description of Case: A 37-year-old female with a known family history of Danon Disease was discovered to be a carrier of the LAMP-2 mutation after presenting to the hospital with dizziness and palpitations. An echocardiogram obtained at the time of diagnosis revealed left ventricular hypertrophy and left ventricular apical thrombus with normal ejection fraction. She was started on anticoagulation and began following closely with a heart failure clinic. Since diagnosis, she has had multiple echocardiograms which have shown a steady decline in her ejection fraction to 25% and biventricular failure. An ICD was placed, with no shocks ever administered. She has had multiple hospital admissions for exacerbations of heart failure since diagnosis. Telemetry monitoring during these admissions revealed frequent premature ventricular contractions attributed to the patient’s severe cardiomyopathy. Despite continuation of guideline-directed medical treatment, this patient’s systolic heart failure is anticipated to continue worsening. She will likely require heart transplant, for which evaluation has already been initiated. Discussion: Danon Disease is a rare lysosomal storage disorder that often involves progressively worsening cardiomyopathy. Individuals with a known family history of this condition should be referred early for genetic testing. If found to have the condition or be a carrier, they should begin following with a heart failure specialist and consideration for advanced therapies, like transplant, should be initiated.

Prevalence of myocarditis and its contribution to the course of primary myocardial hypertrophy

Aim. To assess the incidence of myocarditis in patients with primary myocardial hypertrophy and to study its contribution to the disease course.Material and methods. The study included 100 patients with primary left ventricular myocardial hypertrophy, 52 men and 48 women (mean age, 51,5±15,7 years; followup period 10,4 [2,1; 36,1] months). All patients underwent electrocardiography, 24-hour electrocardiographic monitoring, echocardiography, as well as DNA analysis (n=96), myocardium pathological study (n=29), cardiac magnetic resonance imaging (n=31), cardiac multislice computed tomography (n=26), assessment of anti-cardiac antibodies (n=43), free light chain level in serum and urine by immunofixation method (n=10); 99mTc-pyrophosphate myocardial scintigraphy (n=5); biopsy of the rectal mucosa and/or subcutaneous fat for amyloid (n=9).Results. In 68%, true (sarcomeric) hypertrophic cardiomyopathy (HCM) was diagnosed, in 16% — amyloidosis with cardiac involvement, in 10% — storage diseases, in 3% — neuromuscular diseases, in 2% — myocardial hypertrophy was combined with severe restriction (mixed phenotype), and in 1% — LEOPARD syndrome. Concomitant myocarditis was diagnosed in 30% of patients. In HCM, myocarditis was detected in 31% of cases. These patients had a significantly higher heart failure class (heart failure class 3 [2; 3] vs 2 [1; 3], p=0,026) and mortality (33,3% vs 6,4%, p=0,01). In amyloidosis, the incidence of myocarditis was 31,3%. In these patients, ventricular tachycardia was observed significantly more often: 80,0% vs 18,2% (p=0,036). The prevalence of concomitant myocarditis in the subgroup of storage diseases was 30%: 2 patients with Fabry disease and 1 patient with Danon disease. Of the three patients with neuromuscular diseases, myocarditis was diagnosed in 1. In the subgroups with the restrictive phenotype and LEOPARD syndrome, no cases of myocarditis were recorded. Treatment of myocarditis made it possible to stabilize the patients' condition.Conclusion. Concomitant myocarditis led to heart failure progression, worsening ventricular arrhythmias and, as a consequence, an increased risk of sudden cardiac death. It is necessary to actively diagnose and treat myocarditis in patients with primary myocardial hypertrophy.

Hypertrophic Cardiomyopathy versus Storage Diseases with Myocardial Involvement.

One of the main causes of heart failure is cardiomyopathies. Among them, the most common is hypertrophic cardiomyopathy (HCM), characterized by thickening of the left ventricular muscle. This article focuses on HCM and other cardiomyopathies with myocardial hypertrophy, including Fabry disease, Pompe disease, and Danon disease. The genetics and pathogenesis of these diseases are described, as well as current and experimental treatment options, such as pharmacological intervention and the potential of gene therapies. Although genetic approaches are promising and have the potential to become the best treatments for these diseases, further research is needed to evaluate their efficacy and safety. This article describes current knowledge and advances in the treatment of the aforementioned cardiomyopathies.

Danon disease: Rare cause of cardiomyopathy.

Danon disease: Rare cause of cardiomyopathy.

Mitochondria are secreted in extracellular vesicles when lysosomal function is impaired.

Mitochondrial quality control is critical for cardiac homeostasis as these organelles are responsible for generating most of the energy needed to sustain contraction. Dysfunctional mitochondria are normally degraded via intracellular degradation pathways that converge on the lysosome. Here, we identified an alternative mechanism to eliminate mitochondria when lysosomal function is compromised. We show that lysosomal inhibition leads to increased secretion of mitochondria in large extracellular vesicles (EVs). The EVs are produced in multivesicular bodies, and their release is independent of autophagy. Deletion of the small GTPase Rab7 in cells or adult mouse heart leads to increased secretion of EVs containing ubiquitinated cargos, including intact mitochondria. The secreted EVs are captured by macrophages without activating inflammation. Hearts from aged mice or Danon disease patients have increased levels of secreted EVs containing mitochondria indicating activation of vesicular release during cardiac pathophysiology. Overall, these findings establish that mitochondria are eliminated in large EVs through the endosomal pathway when lysosomal degradation is inhibited.

Clinical manifestations and MRI features of Danon disease: a case series

BackgroundDanon disease (DD) is an exceptionally uncommon X-linked dominant lysosomal glycogen storage disorder characterized by pronounced ventricular hypertrophy and cardiac insufficiency. The timely identification of cardiac impairment in individuals with DD holds significant clinical importance.Case presentationWe present a case of Danon Disease in a three-generation pedigree from Anhui Province, China. Clinical features and laboratory data were collected and analyzed for a 16-year-old male proband (III-1) and two affected female family members (II-2 and II-3). The proband exhibited Wolf-Parkinson-White syndrome, hypertrophic cardiomyopathy, abnormal cognitive function, and muscle weakness. Gene sequencing confirmed a mutation (c.963G > A) in the LAMP-2 gene.ConclusionPatients with DD may present both dilated and hypertrophic cardiomyopathy. Comprehensive myocardial tissue characterization by MRI plays a key role in the diagnosis of the disease.

Effect of pharmacological heart failure drugs and gene therapy on Danon's cardiomyopathy

Danon disease is a rare X-linked genetic disease resulting from LAMP2 mutations leading to defective lysosomal function. Heart failure is the main causes of morbidity and mortality. Mice with an LAMP2-exon-6-deletion (L2Δ6), develop cardiac hypertrophy followed by dilated cardiomyopathy, in association with accumulation of autophagosomes, fibrosis and oxidative stress. We investigated the effect of drugs used to treat heart failure and of LAMP2 gene therapy on the phenotype, molecular markers and ROS in LAMP2 cardiomyopathy. L2Δ6 mice were treated with Angiotensin II, Ramipril, Metoprolol or Spironolactone. Gene therapy was delivered by IP injection of Adeno-associated-virus (AAV9) -LAMP2 vector to neonates (“AAVLAMP2-Prevention”), or at 15 weeks of age (“AAVLAMP2-Treatment”). Angiotensin II markedly aggravated the cardiac phenotype. Ramipril and Spironolactone were effective in attenuating left ventricular hypertrophy and preserving the systolic function. Cardiac protection was associated with decreased autophagosome accumulation, reduced fibrosis and oxidative stress. Gene therapy effectively attenuated autophagosome accumulation and ROS in L2Δ6 hearts, lowering troponin release to nearly normal levels. AAVLAMP2-Prevention protected against systolic dysfunction and decreased hypertrophy. AAVLAMP2-Treatment prevented ventricular dilatation and dysfunction but had no effect on wall thickness. We conclude that RAAS inhibitors are highly effective against cardiomyopathy progression in an experimental mouse model of Danon's and shall be considered in human patients for this purpose until novel therapies become clinically available.