Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q00604 (X-linked)
 16,883 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lysosome-associated membrane protein-2 deficiency (LAMP-2 deficiency), or Danon disease, is a rare X-linked lysosomal disease characterized by cardiomyopathy, vacuolar myopathy, and mental retardation. Less than 20 families with mutations of the Lamp-2 gene have been reported. We describe a family from Sardinia with eight affected patients (4 females and 4 males) and a novel mutation in exon 2 of the Lamp-2 gene (c.102_103delAG). Females developed isolated cardiomyopathy in adulthood, whereas males presented with cardiomyopathy, myopathy, and mental retardation before the age of 20 years. Cardiomyopathy was lethal in three females in their 40s and in three males before the age 20 years. One patient was successfully treated by heart transplantation with more than 5-year follow-up. This study demonstrates that Danon disease is a frequently fatal condition that is potentially treatable with heart transplantation.
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PMID:Novel Lamp-2 gene mutation and successful treatment with heart transplantation in a large family with Danon disease. 1637 18

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.
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PMID:Generalized lysosome-associated membrane protein-2 defect explains multisystem clinical involvement and allows leukocyte diagnostic screening in Danon disease. 1656 4

Autophagic vacuoles are a frequent feature in numerous neuromuscular disorders. However, they are also pathognomonic morphologic hallmarks in a slowly emerging new group of conditions called autophagic vacuolar myopathies (AVMs), of which Danon disease, originally called "lysosomal glycogen storage disease with normal acid maltase," is the best known entity. Other such conditions, often although not always described from Japan, are X-linked myopathy with excessive authophagy, infantile autophagic vacuolar myopathy, adult-onset autophagic vacuolar myopathy with multiorgan involvement, and X-linked congenital autophagic vacuolar myopathy. Although only 1 protein, the transmembranous lysosomal protein LAMP-2, has been found mutated in Danon disease, the remaining AVMs are genetically still incompletely identified. Several of these conditions not only share autophagic vacuoles, but such autophagic vacuoles also have morphologic properties of the sarcolemma, thus rendering them autophagic vacuoles with sarcolemmal features, an almost pathognomonic phenomenon of this group of disorders.
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PMID:Autophagic vacuolar myopathy. 1702 58

Danon disease is a rare X-linked dominant disorder caused by lysosomal-associated membrane protein 2 (LAMP2) deficiency and is characterized by hypertrophic cardiomyopathy, cardiac conduction abnormalities, skeletal vacuolar myopathy, variable degree of mental retardation, and peripheral pigmentary retinopathy. We describe a novel splice mutation in the LAMP2 gene in a French Canadian family. By identifying this novel mutation we were able to offer genetic screening and counseling to all family members. Presymptomatic diagnosis is important as cardiac surveillance can be life-saving.
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PMID:Danon disease due to a novel splice mutation in the LAMP2 gene. 1800 70

We describe a case of a 30-year-old man with Danon's disease, an X-linked genetic disorder due to deficiency of lysosomal-associated membrane protein 2 with secondary intracytoplasmatic glycogen and autophagic material storage. This disease is characterized by skeletal muscle involvement, mental retardation, ophthalmic abnormalities, and cardiac disease. In this patient, cardiac involvement was characterized by hypertrophic cardiomyopathy in young age, preexcitation, and parossistic atrioventricular block. The patient underwent to an implantable cardioverter defibrillator implantation for conduction disorders and for primary prevention of sudden death, a frequent event in Danon's disease. This case report describes cardiac involvement with conduction disorders and multiple pacemaker malfunctions in Danon's disease.
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PMID:Pacemaker malfunctions in Danon's disease. 1818 22

We report a case of a 16-yr-old male with Danon disease caused by a novel mutation in the LAMP-2 gene. Mutations in the LAMP-2 gene result in the absence of LAMP-2 on immunohistochemical staining of muscle tissue, thus defining Danon disease, a rare X-linked myopathy. It is characterized clinically by HCM or left ventricular hypertrophy, a WPW pattern on ECG, variable degrees of muscular weakness (skeletal myopathy), mental retardation, and retinal changes. The patient presented with severe skeletal muscular weakness and respiratory failure. He also had a history of two OHTs, the first one for severe HCM and the second for allograft rejection. The patient's myopathy was initially presumed to be exclusively related to steroid-induced "critical care myopathy." However, further evaluation with a thigh muscle biopsy revealed autophagic vacuoles with sarcolemnal features suggestive of a lysosomal storage disorder. DNA analysis ultimately identified a previously unreported hemizygous IVS6+3_+6delGAGT splice site deletion mutation in the LAMP-2 gene located within the 5' splice site of intron 6, consistent with Danon disease.
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PMID:Danon disease with typical early-onset cardiomyopathy in a male: focus on a novel LAMP-2 mutation. 1828 7

Danon disease is an X-linked disorder resulting from mutations in the lysosome-associated membrane protein-2 (LAMP2) gene. We report a male patient with skeletal myopathy, mental retardation, and massive hypertrophic obstructive cardiomyopathy necessitating heart transplantation. Immunohistochemistry of skeletal muscle and leukocytes, western blot analysis of leukocytes and cardiac muscle, flow cytometry, and DNA sequencing were performed. Muscle biopsy revealed autophagic vacuolar myopathy and lack of immunohistochemically detectable LAMP-2. Diagnosis of Danon disease was confirmed by western blot analysis of myocardial tissue and peripheral blood sample of the patient showing deficiency of LAMP-2 in myocardium and leukocytes. Moreover, absence of LAMP-2 in lymphocytes, monocytes and granulocytes was shown by flow cytometric analysis. Genetic analysis of the LAMP2 gene revealed a novel 1-bp deletion at position 179 (c.179delC) at the 3' end of exon 2, resulting in a frameshift with a premature stop codon.
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PMID:Danon disease: case report and detection of new mutation. 1958 70

Autophagic vacuolar myopathy (AVM) is an entity defined by the presence of autophagic vacuoles on muscle pathology. There are two emerging categories in AVM in addition to the best characterized Pompe disease. One is Danon disease and its related disorders, which are characterized by autophagic vacuoles with unique sarcolemmal features (AVSF). AVSF express virtually all sarcolemmal proteins, in addition to acetylcholinesterase, on their vacuolar membranes. Danon disease is caused by primary deficiency of a lysosomal membrane protein, LAMP-2. Interestingly, in this disease, the number of AVSF increases as the patients age. Other AVSF myopathies include X-linked myopathy with excessive autophagy which is now known to be caused by VMA21 mutations. The other AVM is typified by the presence of rimmed vacuoles, which are actually clusters of autophagic vacuoles on electron microscopy. One of the well known diseases in this group is distal myopathy with rimmed vacuoles (DMRV), also called hereditary inclusion body myopathy (HIBM). DMRV is caused by mutations in GNE gene that encode a rate-limiting enzyme in the sialic acid biosynthetic pathway. Interestingly, in DMRV model mice, sialic acid supplementation almost completely precluded the disease phenotype, indicating that decreased sialic acid is the cause of myopathic phenotype and sialic acid supplementation can prevent the disease process. Interestingly, both genetically diagnosable AVSF myopathies are primarily due to lysosomal dysfunctions. In contrast, rimmed vacuoles are secondarily caused by extra-lysosomal defects, such as hyposialylation in DMRV/HIBM, and are formed at later stages of the disease.
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PMID:[Eludication of pathomechanism of and development of therapy for autophagic vacuolar myopathies]. 2012 Mar 46

Fabry disease (FD) is a rare X-linked lysosomal storage disorder of glycosphingolipids, mostly globotriaosylceramide (Gb3). Proteinuric chronic kidney disease develops frequently, and recognition of Fabry nephropathy on a kidney biopsy may be the first clue to the underlying diagnosis. Since the accumulated glycosphingolipids are largely extracted by the paraffin-embedding procedure, the most characteristic feature of Fabry nephropathy on routine light microscopy (LM) is nonspecific cell vacuolization. To test whether residual Gb3 in kidney tissue might be exploited for the specific diagnosis of Fabry nephropathy, paraffin-embedded kidney biopsies of nine FD patients (one boy, four men, four women) and of a female carrier of a mild genetic mutation, with no evidence of Fabry nephropathy, were immunostained with an anti-Gb3 antibody. The adult biopsies were additionally co-stained with a lysosomal marker (anti-lysosomal-associated membrane protein 2 (anti-LAMP2) antibody). The distribution of Gb3 deposits was scored per cell type and compared to the histological scorings of glycosphingolipid inclusions on semi-thin sections. FD patients had residual Gb3 in all types of glomerular, tubular, interstitial and vascular kidney cells. The highest expression of LAMP2 was seen in tubular cells, but there were no meaningful associations between LAMP2 expression and prevalence of Gb3 deposits on different kidney cell types. The histological scorings of glycosphingolipid inclusions were relatively higher than the corresponding immunohistochemical scorings of Gb3 deposits. In the mildly affected female, Gb3 expression was limited to tubular cells, a pattern similar to controls. Gb3 immunostaining allows the specific diagnosis of Fabry nephropathy even in kidney biopsies routinely processed for LM.
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PMID:Immunohistochemical diagnosis of Fabry nephropathy and localisation of globotriaosylceramide deposits in paraffin-embedded kidney tissue sections. 2220 10

Danon disease (DD) is a monogenic X-linked disorder characterized by cardiomyopathy, skeletal myopathy and variable degrees of intellectual disability. DD develops due to mutations in the gene encoding lysosomal-associated membrane protein 2 (LAMP2). We report on a family exhibiting the clinical phenotype comprising of hypertrophic cardiomyopathy and ventricular pre-excitation, myopia and mild myopathy in two male patients and cardiomyopathy and myopia in a female patient. The diagnosis of DD in this family was based on the assessment of the clinical phenotypes and the absence of LAMP2 in skeletal and/or cardiac muscle biopsy specimens. Sequence analysis of the LAMP2 gene and its mRNA revealed a novel LAMP2 mutation (c.940delG) in all three patients. Approximately 25% of the female patient's cardiomyocytes were LAMP2 positive apparently due to the unfavorable skewing of X chromosome inactivation. We further performed qualitative LAMP2 immunohistochemistry on peripheral white blood cells using the smear technique and revealed the absence of LAMP2 in the male patients. LAMP2 expression was further assessed in granulocytes, CD4+ and CD8+ T lymphocytes, CD20+ B lymphocytes, CD14+ monocytes and CD56+ natural killer cells by quantitative polychromatic flow cytometry. Whereas the male DD patients lacked LAMP2 in all WBC populations, the female patient expressed LAMP2 in 15.1% and 12.8% of monocytes and granulocytes, respectively. LAMP2 expression ratiometrics of highly vs. weakly expressing WBC populations discriminated the DD patients from the healthy controls. WBCs are thus suitable for initial LAMP2 expression testing when DD is a differential diagnostic option. Moreover, flow cytometry represents a quantitative method to assess the skewing of LAMP2 expression in female heterozygotes. Because LAMP2 is a major protein constituent of the membranes of a number of lysosome-related organelles, we also tested the exocytic capacity of the lytic granules from CD8+ T lymphocytes in the patient samples. The degranulation triggered by a specific stimulus (anti-CD3 antibody) was normal. Therefore, this process can be considered LAMP2 independent in human T cells. The c.940delG mutation results in a putatively truncated protein (p.A314QfsX32), which lacks the transmembrane domain and the cytosolic tail of the wild-type LAMP2. We tested whether this variant becomes exocytosed because of a failure in targeting to late endosomes/lysosomes. Western blotting of cardiac muscle, WBCs and cultured skin fibroblasts (and their culture media) showed no intra- or extracellular truncated LAMP2. By comparing the expression pattern and intracellular targeting in cultured skin fibroblasts of normal LAMP2 isoforms (A, B and C) tagged with green fluorescent protein (GFP) and the A314Qfs32-GFP fusion, we found that the A314Qfs32-GFP protein is not even expressed. These observations suggest that the truncated protein is unstable and is co-translationally or early post-translationally degraded.
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PMID:Danon disease: a focus on processing of the novel LAMP2 mutation and comments on the beneficial use of peripheral white blood cells in the diagnosis of LAMP2 deficiency. 2236 87


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