Project description:The lysosomal storage disorders are a clinically heterogeneous group of inborn errors of metabolism, associated with the accumulation of incompletely degraded macromolecules within several cellular sites. Affected individuals present with a broad range of clinical problems, including hepatosplenomegaly and skeletal dysplasia. Onset of symptoms may range from birth to adulthood. Most are associated with neurologic features. Later-onset forms are often misdiagnosed as symptoms, which might include psychiatric manifestations, are slowly progressive, and may precede other neurologic or systemic features. Symptomatic care, which remains the mainstay for most subtypes, can lead to significant improvement in quality of life.
Project description:Lysosomes are cytoplasmic organelles that contain a variety of different hydrolases. A genetic deficiency in the enzymatic activity of one of these hydrolases will lead to the accumulation of the material meant for lysosomal degradation. Examples include glycogen in the case of Pompe disease, glycosaminoglycans in the case of the mucopolysaccharidoses, glycoproteins in the cases of the oligosaccharidoses, and sphingolipids in the cases of Niemann-Pick disease types A and B, Gaucher disease, Tay-Sachs disease, Krabbe disease, and metachromatic leukodystrophy. Sometimes, the lysosomal storage can be caused not by the enzymatic deficiency of one of the hydrolases, but by the deficiency of an activator protein, as occurs in the AB variant of GM2 gangliosidosis. Still other times, the accumulated lysosomal material results from failed egress of a small molecule as a consequence of a deficient transporter, as in cystinosis or Salla disease. In the last couple of decades, enzyme replacement therapy has become available for a number of lysosomal storage diseases. Examples include imiglucerase, taliglucerase and velaglucerase for Gaucher disease, laronidase for Hurler disease, idursulfase for Hunter disease, elosulfase for Morquio disease, galsulfase for Maroteaux-Lamy disease, alglucosidase alfa for Pompe disease, and agalsidase alfa and beta for Fabry disease. In addition, substrate reduction therapy has been approved for certain disorders, such as eliglustat for Gaucher disease. The advent of treatment options for some of these disorders has led to newborn screening pilot studies, and ultimately to the addition of Pompe disease and Hurler disease to the Recommended Uniform Screening Panel (RUSP) in 2015 and 2016, respectively.
Project description:Lysosomal storage diseases (LSDs) are a class of metabolic disorders caused by mutations in proteins critical for lysosomal function. Such proteins include lysosomal enzymes, lysosomal integral membrane proteins, and proteins involved in the post-translational modification and trafficking of lysosomal proteins. There are many recognized forms of LSDs and, although individually rare, their combined prevalence is estimated to be 1 in 8000 births. Over two-thirds of LSDs involve central nervous system (CNS) dysfunction (progressive cognitive and motor decline) and these symptoms are often the most debilitating. Although the genetic basis for these disorders is clear and the biochemistry of the proteins well understood, the cellular mechanisms by which deficiencies in these proteins disrupt neuronal viability remain ambiguous. In this review, we provide an overview of the widespread cellular perturbations occurring in LSDs, how they might be linked and interventions that may specifically or globally correct those defects.
Project description:Lysosomal storage diseases (LSDs) are a group of metabolic inborn errors caused by defective enzymes in the lysosome, resulting in the accumulation of undegraded substrates. LSDs are progressive diseases that exhibit variable rates of progression depending on the disease and the patient. The availability of effective treatment options, including substrate reduction therapy, pharmacological chaperone therapy, enzyme replacement therapy, and bone marrow transplantation, has increased survival time and improved the quality of life in many patients with LSDs. However, these therapies are not sufficiently effective, especially against central nerve system abnormalities and corresponding neurological and psychiatric symptoms because of the blood-brain barrier that prevents the entry of drugs into the brain or limiting features of specific treatments. Gene therapy is a promising tool for the treatment of neurological pathologies associated with LSDs. Here, we review the current state of gene therapy for several LSDs for which clinical trials have been conducted or are planned. Several clinical trials using gene therapy for LSDs are underway as phase 1/2 studies; no adverse events have not been reported in most of these studies. The administration of viral vectors has achieved good therapeutic outcomes in animal models of LSDs, and subsequent human clinical trials are expected to promote the practical application of gene therapy for LSDs.
Project description:BackgroundThe diagnostic workup in patients with a clinical suspicion of lysosomal storage diseases (LSD) is often difficult due to the variability in the clinical phenotype. The gold standard for diagnosis of LSDs consists of enzymatic testing. However, due to the sequential nature of this methodology and inconsistent genotype-phenotype correlations of certain LSDs, finding a diagnosis can be challenging.MethodWe developed and clinically implemented a gene panel covering 50 genes known to cause LSDs when mutated. Over a period of 18 months, we analyzed 150 patients who were referred for LSD testing and compared these results with the data of patients who were previously enrolled in a scheme of classical biochemical testing.ResultsOur panel was able to determine the molecular cause of the disease in 22 cases (15%), representing an increase in diagnostic yield compared to biochemical tests developed for 21 LSDs (4.6%). We were furthermore able to redirect the diagnosis of a mucolipidosis patient who was initially suspected to be affected with galactosialidosis. Several patients were identified as being affected with neuronal ceroid lipofuscinosis, which cannot readily be detected by enzyme testing. Finally, several carriers of pathogenic mutations in LSD genes related to the disease phenotype were identified as well, thus potentially increasing the diagnostic yield of the panel as heterozygous deletions cannot be detected.ConclusionWe show that the implementation of a gene panel for LSD diagnostics results in an increased yield in comparison to classical biochemical testing. As the panel is able to cover a wider range of diseases, we propose to implement this methodology as a first-tier test in cases of an aspecific LSD presentation, while enzymatic testing remains the first choice in patients with a more distinctive clinical presentation. Positive panel results should however still be enzymatically confirmed whenever possible.
Project description:A biomarker is generally an analyte that indicates the presence and/or extent of a biological process, which is in itself usually directly linked to the clinical manifestations and outcome of a particular disease. The biomarkers in the field of lysosomal storage diseases (LSDs) have particular relevance where spectacular therapeutic initiatives have been achieved, most notably with the introduction of enzyme replacement therapy (ERT). There are two main types of biomarkers. The first group is comprised of those molecules whose accumulation is directly enhanced as a result of defective lysosomal function. These molecules represent the storage of the principal macro-molecular substrate(s) of a specific enzyme or protein, whose function is deficient in the given disease. In the second group of biomarkers, the relationship between the lysosomal defect and the biomarker is indirect. In this group, the biomarker reflects the effects of the primary lysosomal defect on cell, tissue, or organ functions. There is no "gold standard" among biomarkers used to diagnosis and/or monitor LSDs, but there are a number that exist that can be used to reasonably assess and monitor the state of certain organs or functions. A number of biomarkers have been proposed for the analysis of the most important LSDs. In this review, we will summarize the most promising biomarkers in major LSDs and discuss why these are the most promising candidates for screening systems.
Project description:Treating the central nervous system manifestations of subjects with neuropathic lysosomal storage diseases remains a major technical challenge. This is because of the low efficiency by which lysosomal enzymes in systemic circulation are able to traverse the blood brain barrier into the central nervous system. Intracranial transplantation of neural stems cells genetically modified to overexpress the respective deficient enzymes represents a potential approach to addressing this group of diseases. The unique properties of neural stem cells and progenitor cells, such as their ability to migrate to distal sites, differentiate into various cell types and integrate within the host brain without disrupting normal function, making them particularly attractive therapeutic agents. In addition, neural stem cells are amenable to ex vivo propagation and modification by gene transfer vectors. In this regard, transplanted cells can serve not only as a source of lysosomal enzymes but also as a means to potentially repair the injured brain by replenishing the organ with healthy cells and effecting the release of neuroprotective factors. This review discusses some of the well-characterized neural stem cell types and their possible use in treating neuropathic lysosomal storage diseases such as the Niemann Pick A disease.
Project description:Ease of design, relatively low cost and a multitude of gene-altering capabilities have all led to the adoption of the sophisticated and yet simple gene editing system: clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9). The CRISPR/Cas9 system holds promise for the correction of deleterious mutations by taking advantage of the homology directed repair pathway and by supplying a correction template to the affected patient's cells. Currently, this technique is being applied in vitro in human-induced pluripotent stem cells (iPSCs) to correct a variety of severe genetic diseases, but has not as of yet been used in iPSCs derived from patients affected with a lysosomal storage disease (LSD). If adopted into clinical practice, corrected iPSCs derived from cells that originate from the patient themselves could be used for therapeutic amelioration of LSD symptoms without the risks associated with allogeneic stem cell transplantation. CRISPR/Cas9 editing in a patient's cells would overcome the costly, lifelong process associated with currently available treatment methods, including enzyme replacement and substrate reduction therapies. In this review, the overall utility of the CRISPR/Cas9 gene editing technique for treatment of genetic diseases, the potential for the treatment of LSDs and methods currently employed to increase the efficiency of this re-engineered biological system will be discussed.
Project description:Lysosomal storage diseases (LSDs) are inherited conditions caused by impaired lysosomal function and consequent substrate storage, leading to a range of clinical manifestations, including cardiovascular disease. This may lead to significant symptoms and even cardiac failure, which is an important cause of death among patients. Currently available treatments do not completely correct cardiac involvement in the LSDs. Gene therapy has been tested as a therapeutic alternative with promising results for the heart disease. In this review, we present the results of different approaches of gene therapy for LSDs, mainly in animal models, and its effects in the heart, focusing on protocols with cardiac functional analysis.
Project description:Autophagy is a complex pathway regulated by numerous signaling events that recycles macromolecules and can be perturbed in lysosomal storage diseases (LSDs). The concept of LSDs, which are characterized by aberrant, excessive storage of cellular material in lysosomes, developed following the discovery of an enzyme deficiency as the cause of Pompe disease in 1963. Great strides have since been made in better understanding the biology of LSDs. Defective lysosomal storage typically occurs in many cell types, but the nervous system, including the central nervous system and peripheral nervous system, is particularly vulnerable to LSDs, being affected in two-thirds of LSDs. This review provides a summary of some of the better characterized LSDs and the pathways affected in these disorders.