LAMP-2 deficient mice show depressed cardiac contractile function without significant changes in calcium handling (original) (raw)
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European Journal of Medical Genetics, 2019
Danon disease is a rare X-linked cardiac and skeletal muscle disorder with multisystem clinical manifestations. Genetic defects at the lysosome-associated membrane 2 protein (LAMP2) are the cause of the disorder. Due to the rarity of the disease, there is limited progress in understanding the correlation between genotype and phenotype, and explaining the large variability of the clinical features of the disease. In this study, we report two patients, twin sisters, referred to our hospital for end stage heart failure due to dilated cardiomyopathy, requiring heart transplant evaluation. Genetic analysis, using targeted next generation sequencing, showed that the proband carried a LAMP2 missense variant, c.928G > A. The mutation was also detected in her twin sister by sanger sequencing. This variant has already been reported by other investigators and was correlated with the clinical triad of Danon disease i.e. hypertrophic cardiomyopathy, mental retardation and peripheral myopathy. The new phenotype of dilated cardiomyopathy associated with this mutation, confirms the phenotypic heterogeneity of the particular mutation, as well as of Danon disease.
A 13-year-old girl with proximal weakness and hypertrophic cardiomyopathy with danon disease
Muscle & Nerve, 2010
Danon disease is caused by deficiency of lysosome-associated membrane protein-2 (LAMP-2). It is characterized clinically by cardiomyopathy, myopathy, and mental retardation in boys. Herein we report a 13-year-old female patient with Danon disease who presented with early-onset skeletal myopathy and cardiomyopathy. She had a de novo novel mutation in the LAMP2 gene, and her muscles showed many autophagic vacuoles with sarcolemmal features and complete absence of LAMP-2 expression. To the best of our knowledge, this girl is one of the earliest-onset manifesting carriers of Danon disease with typical muscle pathology.
LAMP2 Cardiomyopathy: Consequences of Impaired Autophagy in the Heart
Journal of the American Heart Association
Background Human mutations in the X‐linked lysosome‐associated membrane protein‐2 ( LAMP2 ) gene can cause a multisystem Danon disease or a primary cardiomyopathy characterized by massive hypertrophy, conduction system abnormalities, and malignant ventricular arrhythmias. We introduced an in‐frame LAMP2 gene exon 6 deletion mutation (denoted L2 Δ6 ) causing human cardiomyopathy, into mouse LAMP2 gene, to elucidate its consequences on cardiomyocyte biology. This mutation results in in‐frame deletion of 41 amino acids, compatible with presence of some defective LAMP2 protein. Methods and Results Left ventricular tissues from L2 Δ6 and wild‐type mice had equivalent amounts of LAMP2 RNA, but a significantly lower level of LAMP2 protein. By 20 weeks of age male mutant mice developed left ventricular hypertrophy which was followed by left ventricular dilatation and reduced systolic function. Cardiac electrophysiology and isolated cardiomyocyte studies demonstrated ventricular arrhythmia, ...
The American Journal of Pathology, 2006
Danon disease, an X-linked dominant disorder, results from mutations in the lysosome-associated membrane protein-2 (LAMP2) gene and presents with hypertrophic cardiomyopathy, skeletal myopathy, and mental retardation. To investigate the effects of LAMP2 gene mutations on protein expression in different tissues, we screened LAMP2 gene mutations and LAMP-2 protein deficiency in the skeletal muscle of nine unrelated patients with hypertrophic cardiomyopathy and vacuolar myopathy. We identified three novel families (including one affected mother) with unreported LAMP2 gene null mutations and LAMP-2 protein deficiency in skeletal and myocardial muscle, leukocytes, and fibroblasts. LAMP-2 protein deficiency was detectable in various tissues, including leukocytes, explaining the multisystem clinical involvement. Skeletal muscle immunopathology showed that mutant protein was not localized in the Golgi complex, vacuolar membranes expressed sarcolemmal-specific proteins, and the degree of muscle fiber vacuolization correlated with clinical muscle involvement. In our female patient, muscle histopathology and LAMP-2 protein analysis was inconclusive, indicating that diagnosis in females requires mutation identification. The random X-chromosome inactivation found in muscle and leukocytes excluded the possibility that selective involvement of some tissues in females is due to skewed X-chromosome inactivation. Therefore, biochemical analysis of leukocytes might be used for screening in male patients, but genetic screening is required in females.
Medicine 5 (2021): 250-258. Abstract Danon disease is a rare X-linked dominant disorder caused by the lysosome-associated membrane protein 2 (LAMP2) gene. It is characterized by the triad of hypertrophic cardiomyopathy (HCM), myopathy, and intellectual disability. Genetic analysis was performed to confirm LAMP2 gene mutation in a family with Danon disease. We collected the clinical data included electrocardiography (ECG), echocardiography, and cardiac magnetic resonance imaging (cMRI) in a family with Danon disease to reveal the clinical phenotype. Genetic analysis showed that LAMP2 gene deletion mutation (c.257_258delCC) in this family. The proband and his 13-year-old cousin developed HCM with a typical Wolff-Parkinson-White (WPW) pre-excitation pattern. cMRI with late gadolinium enhancement (LGE) further confirms the myocardial fibrosis. The clinical expression of Danon disease is different in different genders. Conclusions: Genetic and pharmaceutical approaches to upregulate LAMP2 gene expression may provide a novel therapy for patients with Danon disease.
Identification of Two Novel LAMP2 Gene Mutations in Danon Disease
Canadian Journal of Cardiology, 2016
The identification of two novel mutations (p.Trp321Ter and p.Pro324+24X) in the LAMP2 gene, encoding for lysosome-associated membrane protein-2 and causing Danon disease in two families is reported. Including the two young male index cases, eight mutation carriers were identified. Cardiac phenotype was hypertrophic cardiomyopathy in all affected cases. The clinical course of the disease was characterized by a high rate of disease-related death at an early age and a high prevalence of arrhythmias or conduction abnormalities.
Danon disease presenting with dilated cardiomyopathy and a complex phenotype
Journal of Human Genetics, 2007
X-linked dilated cardiomyopathy (XLCM) was first described in 1987 and associated with dystrophin gene (DMD) mutations a decade later in one of the original two families. Here we report long-term follow-up of the second family (XLCM-2), for which a DMD mutation was never found. Analysis of the lysosome-associated membrane protein-2 (LAMP-2) gene detected a novel mutation, confirming a diagnosis of Danon disease. The broad phenotype in this family included dilated and hypertrophic cardiomyopathy, cardiac pre-excitation, skeletal myopathy with high serum creatine kinase, cognitive impairment (in males), and a pigmentary retinopathy in affected females. Cardiac biopsy specimens showed extensive vacuolar changes in an affected adult male. Remarkably, the skeletal muscle biopsy in a 13-month-old mutation-carrying male showed no vacuolization by standard histology. We conclude that XLCM may be the presenting sign of Danon disease and, in the presence of a familial history of HCM, pre-excitation, skeletal muscle involvement and retinal pigmentary dystrophy should prompt LAMP-2 clinical testing. Furthermore, the absence of vacuolar myopathy in biopsies from young patients may not exclude Danon disease.
Multisystemic LAMP-2 defect in Danon disease
Basic and applied myology: BAM
Danon disease is an X-linked dominant disorder due to mutations in the LAMP2 gene, presenting with hypertrophic cardiomyopathy, skeletal myopathy and mental retardation. To investigate the effects of LAMP2 gene mutations on protein expression in different tissues, we screened LAMP2 gene mutations and LAMP-2 protein deficiency in the skeletal muscle of 9 unrelated patients with hypertrophic cardiomyopathy and vacuolar myopathy. We identified 3 novel families with unreported LAMP2 gene null mutations and LAMP-2 protein deficiency in skeletal and myocardial muscle, leukocytes and fibroblasts. LAMP-2 protein deficiency was detectable in various tissues indicating that the biochemical diagnosis can be obtained on leukocytes and might be used for screening in male patients, and that the multiorgan protein deficiency would explain the multisystem clinical involvement. In our female patient, muscle histopathology and LAMP-2 protein analysis was inconclusive, indicating that the diagnosis in females can be obtained only by mutation identification.