Search Results (112)

Background: Lysosomal storage diseases (LSDs) are a genetically and clinically heterogeneous group of inborn errors of metabolism caused by variants in genes encoding lysosomal hydrolases, membrane proteins, activator proteins, or transporters. These disease-causing variants lead to enzymatic deficiencies and the progressive accumulation of undegraded substrates within lysosomes, disrupting cellular function across multiple organ systems. While classical phenotypes typically manifest in infancy or early childhood with severe multisystem involvement, a combination of advances in molecular diagnostics [particularly next-generation sequencing (NGS)] and improved understanding of disease heterogeneity have enabled the identification of attenuated forms characterised by residual enzyme activity and later-onset presentations. These milder phenotypes often evade early recognition due to nonspecific or isolated symptoms, resulting in significant diagnostic delays and missed therapeutic opportunities. Objectives/Methods: This study characterises the clinical, biochemical, and molecular profiles of 10 adult patients diagnosed with LSDs, all representing attenuated forms, and discusses them alongside a narrative review. Results: Enzyme activity, molecular data, and phenotypic assessments are described to explore genotype–phenotype correlations and identify diagnostic challenges. Conclusions: These findings highlight the variable expressivity and organ involvement of attenuated LSDs and reinforce the importance of maintaining clinical suspicion in adults presenting with unexplained cardiovascular, neurological, ophthalmological, or musculoskeletal findings. Enhanced recognition of atypical presentations is critical to facilitate earlier diagnosis, guide management, and enable cascade testing for at-risk family members. Full article

Lysosomal storage disorders (LSDs) are inherited metabolic conditions characterized by lysosomal enzyme deficiencies leading to substrate accumulation. As genetic diseases, LSDs can be treated with gene therapies (GT), including the CRISPR/Cas systems. The CRISPR/Cas systems enable precise and programmable genome editing, leading to targeted modifications at specific genomic loci. While the classical CRISPR/Cas9 system has been extensively used to generate LSD disease models and correct disease-associated genetic alterations through homologous recombination (HR), recently described Cas proteins as well as CRISPR/Cas9-derived strategies such as base editing, prime editing, and homology-independent targeted integration (HITI) offer a novel way to develop innovative treatments for LSDs. The direct administration of the CRISPR/Cas9 system remains the primary strategy evaluated in several LSDs; nevertheless, the ex vivo CRISPR/Cas9-based approach has been recently explored, primarily in central nervous system-affecting LSDs. Ex vivo approaches involve genetically modifying, in theory, any patient cells in the laboratory and reintroducing them into the patient to provide a therapeutic effect. This manuscript reviews the molecular aspects of the CRISPR/Cas technology and its implementation in ex vivo strategies for LSDs while discussing novel approaches beyond the classical CRISPR/Cas9 system. Full article

Background/Objectives: Niemann-Pick disease Type C (NPC) represents an autosomal recessive disorder with an incidence rate of 1 in 100,000 live births that belongs to the lysosomal storage diseases (LSDs). NPC is characterized by the abnormal accumulation of unesterified cholesterol, in addition to being an autosomal recessive inherited pathology, which belongs to LSDs. It occurs in 95% of cases due to mutations in the NPC1 gene, while 5% of cases are due to mutations in the NPC2 gene. In the cerebral cortex (CC), the disease shows lipid inclusions, increased cholesterol and multiple sphingolipids in neuronal membranes, and protein aggregates such as hyperphosphorylated tau, α-Synuclein, TDP-43, and β-amyloid peptide. Mitochondrial damage and oxidative stress are some alterations at the cellular level in NPC. Therefore, the aim of this work was to determine the gene expression profile in the CC of NPC1 mice in order to identify altered molecular pathways that may be related to the pathophysiology of the disease. Methods: In this study, we performed a microarray analysis of a 22,000-gene chip from the cerebral cortex of an NPC mutant mouse compared to a WT mouse. Subsequently, we performed a bioinformatic analysis in which we found groups of dysregulated genes, and their expression was corroborated by qPCR. Finally, we performed Western blotting to determine the expression of proteins probably dysregulated. Results: We found groups of dysregulated genes in the cerebral cortex of the NPC mouse involved in the ubiquitination, fatty acid metabolism, differentiation and development, and underexpression in genes with mitochondrial functions, which could be involved in intrinsic apoptosis reported in NPC, in addition, we found a generalized deregulation in the cortical circadian rhythm pathway, which could be related to the depressive behavior that has even been reported in NPC patients. Conclusions: Recognizing that there are changes in the expression of genes related to ubiquitination, mitochondrial functions, and cortical circadian rhythm in the NPC mutant mouse lays the basis for targeting treatments to new potential therapeutic targets. Full article

Lysosomal storage disorders (LSDs) constitute a group of monogenic systemic diseases resulting from deficiencies in specific lysosomal enzymes that cause the intralysosomal accumulation of non- or partially degraded substrates, leading to lysosomal dysfunction. In some cases of LSDs, the bone is more severely affected, thus producing skeletal manifestations in patients. Current therapies, such as enzyme replacement therapy (ERT) and gene therapy (GT), show limited efficacy in correcting skeletal abnormalities. Increasing evidence suggests that microenvironmental disturbances also contribute significantly to disease pathogenesis. Therefore, therapeutic strategies targeting lysosomal dysfunction and microenvironmental dysregulation are needed. Mesenchymal stem-cell-derived extracellular vesicles (MSC-EVs) are emerging as promising candidates in regenerative medicine due to their immunomodulatory, pro-regenerative, and paracrine properties. MSC-EVs have shown potential to modulate the microenvironment and favor tissue repair in bone-related disorders such as osteoarthritis and osteoporosis. Interestingly, MSC-EVs can be engineered to reach the bone and carry therapeutics, including ERT- and GT-related molecules, enabling targeted delivery to hard-to-reach bone regions. This review describes the main features of MSC-EVs and discusses the therapeutic potential of MSC-EVs as a potential cell-free strategy for bone-affected LSDs. Full article

Newborn screening laboratories are increasingly adding lysosomal storage disorders (LSDs), such as Mucopolysaccharidosis I (MPS I) and Pompe disease, to their screening panels. Without newborn screening, LSDs are frequently diagnosed only after the onset of symptoms; late detection can lead to profound and irreversible organ damage and mortality. While screening of these disorders has accelerated over the past five years, there is little published information regarding the potential correlation of demographic variables (age at sample collection, birthweight, gestational age, gender, etc.) with lysosomal enzyme activity. The Missouri State Public Health Laboratory prospectively screened more than 475,000 newborns for MPS I, Pompe disease, Gaucher disease, and Fabry disease between 15 January 2013 and 15 May 2018. This report investigates trends between several demographic variables and activities of four lysosomal enzymes: α-L-iduronidase (IDUA), acid α-glucosidase (GAA), acid β-glucocerebrosidase (GBA), and acid α-galactosidase (GLA). This information provides a valuable resource to newborn screening laboratories for the implementation of screening for lysosomal storage disorders and the establishment of screening cutoffs. Full article

Newborn bloodspot screening for one or more lysosomal storage disorders (NBS-LSD) is currently performed by many public health NBS laboratories globally. The screening tests measure activities of selected lysosomal enzymes on dried blood spot (DBS) specimens collected from newborns by the heel stick method Because these assays measure enzyme activity, the quantitative results are dependent on the particular analytical method. DBS quality control (DBS QC) materials with assay-specific certified values that span the relevant range from typical to LSD-affected newborns are an important component of quality assurance in NBS laboratories. The Newborn Screening Quality Assurance Program (NSQAP) at the U.S. Centers for Disease Control and Prevention (CDC) provides public health NBS laboratories with DBS QC sets for NBS-LSD comprising four admixtures of pooled umbilical cord blood and a base pool made from leukodepleted peripheral blood and heat-inactivated serum. To evaluate the suitability of these materials for use with digital microfluidics fluorometry (DMF) assays which can currently measure the activity of four enzymes (acid α-galactosidase (GLA); acid β-glucocerebrosidase (GBA); acid α-glucosidase (GAA); and iduronidase (IDUA)), CDC collaborated with the Newborn Screening Unit at the Missouri State Public Health Laboratory (MSPHL). Using MSPHL criteria, we found that the certified results from each of two DBS QC lots collectively spanned the range from typical (screen negative) to enzyme deficient (screen positive) newborn DBS levels for each of the four lysosomal enzymes measured. The range included borderline results that would require repeat screening of the newborn under the MSPHL protocol. We conclude that these DBS QC preparations are suitable for use as external quality control materials for DMF assays used to detect LSDs in newborns. Full article

Background: Lysosomal storage disorders (LSDs) are rare inherited metabolic diseases characterized by defects in lysosomal enzyme function or membrane transport. These defects lead to substrate accumulation and multisystemic manifestations. This review focuses on gastrointestinal (GI) involvement in LSDs, which is a significant but often overlooked aspect of these disorders. Methods: A comprehensive literature review was conducted to examine the pathophysiology, clinical presentation, diagnosis and management of GI manifestations in several LSDs, including Fabry disease, Gaucher disease, Pompe disease, Niemann–Pick disease type C, mucopolysaccharidoses and Wolman disease. Results: The pathogenesis of GI involvement in LSDs varies and encompasses substrate accumulation in enterocytes, mesenteric lymphadenopathy, mass effects, smooth muscle dysfunction, vasculopathy, neuropathy, inflammation and alterations to the microbiota. Clinical presentations range from non-specific symptoms, such as abdominal pain, diarrhea and malabsorption, to more severe complications, such as protein-losing enteropathy and inflammatory bowel disease. Diagnosis often requires a high level of suspicion, as GI symptoms may precede the diagnosis of the underlying LSD or be misattributed to more common conditions. Management strategies include disease-specific treatments, such as enzyme replacement therapy or substrate reduction therapy, as well as supportive care and targeted interventions for specific GI complications. Conclusions: This review highlights the importance of recognizing and properly managing GI manifestations in LSDs to improve patient outcomes and quality of life. It also emphasizes the need for further research to develop more effective treatments for life-threatening GI complications associated with these rare genetic disorders. Full article

Lysosomal storage diseases (LSDs) are characterized by the accumulation of undegraded substrates within lysosomes, often associated with oxidative stress and impaired lysosomal function. In this study, we investigate the role of the c-Abl/TFEB pathway in different LSDs: Gaucher, Niemann-Pick type A (NPA), and Niemann-Pick type C (NPC). Our findings identify c-Abl activation (p-c-Abl) as a common pathogenic mechanism in these disorders. We demonstrate that c-Abl phosphorylates TFEB at Tyr173, leading to its cytoplasmic retention. Using pharmacological models of Gaucher, NPA and NPC in SH-SY5Y neuronal cells and HeLa cells, we assess the effects of the c-Abl inhibitors Imatinib and Neurotinib, as well as the antioxidant α-Tocopherol (α-TOH), on TFEB nuclear translocation and p-c-Abl protein levels. Additionally, we explore the effects of c-Abl inhibitors in cholesterol accumulation in LSDs neuronal models. Our results show that treatment with c-Abl inhibitors or α-TOH promotes TFEB nuclear translocation, enhances lysosomal clearance, and reduces cholesterol accumulation in all three LSD models. These findings highlight the c-Abl/TFEB pathway as a potential therapeutic target for LSDs and potentially other neurodegenerative disorders associated with lysosomal dysfunction. Full article

Mucopolysaccharidosis type I (MPS-I) is an autosomal recessive, progressive, multisystem hereditary lysosomal storage disease (LSD), which is characterized by the gradual accumulation of dermatan sulphate (DS), heparan sulphate (HS), and glycosaminoglycans (GAGs) in all organs and tissues due to the deficiency of the enzyme α-L-hyduronidase. The multisystem clinical manifestations of varying severities of MPS-I are present in two forms—the “severe form of MPS I” (Hurler type) and the “attenuated form of MPS-I” (Hurler–Scheie or Scheie type). These forms represent the entire case history of the disease. The three phenotypes share common symptoms, including musculoskeletal abnormalities, facial dysmorphisms, hernias, short stature, finger stiffness, carpal tunnel syndrome, and corneal opacities. Abnormalities affecting the internal organs include hepatomegaly, splenomegaly, and valvulopathy. There is some evidence to suggest a similarity and overlap with the clinical symptoms of MPS-I, particularly in cases of another rare LSD that is autosomal and recessively inherited—l’α-mannosidosis. This disorder has been observed to result from a dysfunction of the corresponding α-mannosidase enzyme, which has been shown to lead to the accumulation of mannose-rich N-linked oligosaccharides. This review compares the phenotypic similarities and molecular differences between mucopolysaccharidosis type I (MPS-I) and α-mannosidosis. We review genotype–phenotype correlations, diagnostic difficulties, and the applicability of artificial intelligence for the assistance of differential diagnosis, with the goal of facilitating the earlier and more accurate diagnosis of these rare lysosomal storage diseases. Full article

Mucopolysaccharidosis (MPS) IVA is a bone-affecting lysosomal storage disease (LSD) caused by impaired degradation of the glycosaminoglycans (GAGs) keratan sulfate (KS) and chondroitin 6-sulfate (C6S) due to deficient N-acetylgalactosamine-6-sulfatase (GALNS) enzyme activity. Previously, we successfully developed and validated a CRISPR/nCas9-based gene therapy (GT) to insert an expression cassette at the AAVS1 and ROSA26 loci in human MPS IVA fibroblasts and MPS IVA mice, respectively. In this study, we have extended our approach to evaluate the effectiveness of our CRISPR/nCas9-based GT in editing human CD34+ cells to mediate cross-correction of MPS IVA fibroblasts. CD34+ cells were electroporated with the CRISPR/nCas9 system, targeting the AAVS1 locus. The nCas9-mediated on-target donor template insertion, and the stemness of the CRISPR/nCas-edited CD34+ cells was evaluated. Additionally, MPS IVA fibroblasts were co-cultured with CRISPR/nCas-edited CD34+ cells to assess cross-correction. CRISPR/nCas9-based gene editing did not affect the stemness of CD34+ cells but did lead to supraphysiological levels of the GALNS enzyme. Upon co-culture, MPS IVA fibroblasts displayed a significant increase in the GALNS enzyme activity along with lysosomal mass reduction, pro-oxidant profile amelioration, mitochondrial mass recovery, and pro-apoptotic and pro-inflammatory profile improvement. These results show the potential of our CRISPR/nCas9-based GT to edit CD34+ cells to mediate cross-correction. Full article

Gaucher disease (GD) is a lysosomal storage disorder (LSD) characterized by glycosphingolipid accumulation. Age of symptomonset and disease progression varies across types of disease. Newborn screening (NBS) for Gaucher disease facilitates early identification of affected individuals and enables pre-symptomatic monitoring with the goal of starting therapies early and improving clinical outcomes. This multi-center study involved New Jersey NBS referral centers. Data regarding initial NBS results, confirmatory testing, diagnosis, and treatment were collected. For patients on therapy, monitoring biomarkers and exam findings are available as of the last clinical evaluation. Between July 2019 and December 2023, 438,515 newborns were screened, with 60 screen-positive cases. Of those positive screens, 19 cases with positive screens did not undergo confirmatory testing due to parental refusal, loss to follow-up, or death; 23 cases were false positives; 14 newborns were diagnosed with GD type I; 2 newborns were diagnosed with suspected type I GD; 2 newborns were diagnosed with GD type II; and 1 case is still pending. Three type I GD patients started enzyme replacement therapy, with the youngest starting at 28 months of age. Post-treatment data are available for these individuals. One type II case was referred to experimental gene therapy, and one was started on ERT. Our results demonstrate that NBS for GD is a valuable public health tool that can facilitate early diagnosis and intervention. Full article

Background: Multiplex Ligation Probe Amplification (MLPA) is a widely used technique for the diagnosis of lysosomal storage diseases (LSDs). It analyses over 40 DNA sequences in a single reaction, identifying copy number variations and large deletions/insertions in genes. The diagnostic process in LSDs starts with analysis of the missing or reduced enzyme, followed by genetic investigation and, if possible, a search for accumulated substrates. However, while genetic analysis using Sanger sequencing is excellent at detecting small genetic variations such as single-nucleotide variants (SNVs) and small insertions or deletions, it cannot detect large deletions or insertions. Methods: In the present study, a total of 800 patients with clinical suspicion of Fabry, Gaucher, or Pompe diseases were investigated. An enzyme assay was carried out on each patient, followed by genetic analysis using PCR, Sanger sequencing, and MLPA. Results: Nine patients with deficient or absent enzyme activity had Sanger sequencing results that could not confirm the molecular genetic diagnosis because either no mutation (Fabry) or only one mutation (Gaucher and Pompe) was identified. Subsequent analysis by MLPA identified two males with a hemizygous deletion and two females with a heterozygous deletion for FD. For PD, one female and two males had a heterozygous deletion. For GD, one male had a homozygous deletion and one female had a heterozygous deletion. The remaining patients were analyzed by MLPA with negative results. Conclusions: The results obtained suggest that MLPA should be used in combination with classical sequencing methods to ensure a correct and timely diagnosis of LSDs. Full article

Sphingolipidoses, a subgroup of lysosomal storage diseases (LSDs), are rare and debilitating disorders caused by defects in sphingolipid metabolism. Despite advancements in treatment, therapeutic options remain limited. Miglustat, a glucosylceramide synthase EC 2.4.1.80 (GCS) inhibitor, is one of the few available pharmacological treatments; however, it is associated with significant adverse effects that impact patients’ quality of life. Drug repurposing offers a promising strategy to identify new therapeutic agents from approved drugs, expanding treatment options for rare diseases with limited therapeutic alternatives. This study aims to identify potential alternative inhibitors of GCS through a drug-repurposing approach, using computational and experimental methods to assess their therapeutic potential for sphingolipidoses. A library of approved drugs was screened using advanced computational techniques, including molecular docking, molecular dynamics simulations, and metadynamics, to identify potential GCS inhibitors. Promising candidates were selected for further in vitro validation to evaluate their inhibitory activity and potential as therapeutic alternatives to Miglustat. Computational screening identified several potential GCS inhibitors, with Dapagliflozin emerging as the most promising candidate. Experimental validation confirmed its efficacy, revealing a complementary mechanism of action to Miglustat while potentially offering a more favorable side effect profile. This study underscores the utility of computational and experimental methodologies in drug repurposing for rare diseases. The identification of Dapagliflozin as a potential GCS inhibitor provides a foundation for further preclinical and clinical evaluation, supporting its potential application in the treatment of sphingolipidoses. Full article

Background: Persistent splenomegaly, often an incidental finding, can originate from a number of inherited metabolic disorders (IMDs). Variants of APOE are primarily known as risk factors in terms of cardiovascular disease; however, severe dysfunction of APOE can result in a disease phenotype with considerable overlap with lysosomal storage disorders (LSDs), including splenomegaly and gross elevation of N-palmitoyl-O-phosphocholine-serine (PPCS). Methods: A case study (deep phenotyping, genetic and FACS analysis) and literature study was conducted. Results: The index patient, with a family history of early-onset cardiovascular disease, presented with splenic infarctions in a grossly enlarged spleen. The identified genetic cause was homozygosity for two APOE variants (c.604C>T, p.(Arg202Cys) and c.512G>A, p.(Gly171Asp); ε1/ε1), resulting in a macrophage storage phenotype resembling an LSD that was also present in the brother of the index patient. A FACS analysis of the circulating monocytes showed increased lipid content and the expression of activation markers (CD11b, CCR2, CD36). This activated state enhances lipoprotein intake, which eventually converts these monocytes/macrophages into foam cells, accumulating in tissues (e.g., spleen and vascular wall). A literature search identified seven individuals with splenomegaly caused by APOE variants (deletion of leucine at position 167). The combined data from all patients identified male gender, splenectomy and obesity as potential modifiers determining the severity of the phenotype (i.e., degree of triglyceride increase in plasma and/or spleen size). Symptoms are (partially) reversible by lipid-lowering medication and energy restricted diets and splenectomy is contra-indicated. Conclusions: Inherited dyslipidemic splenomegaly caused by disruptive APOE variants should be included in the differential diagnoses of unexplained splenomegaly with abnormal lipid profiles. A plasma lipid profile consistent with dysbetalipoproteinemia is a diagnostic biomarker for this IMD. Full article

Extracellular vesicles (EVs) are nanosized, membrane-bound structures that have emerged as promising tools for drug delivery, especially in the treatment of lysosomal storage disorders (LSDs) with central nervous system (CNS) involvement. This review highlights the unique properties of EVs, such as their biocompatibility, capacity to cross the blood–brain barrier (BBB), and potential for therapeutic cargo loading, including that of enzymes and genetic material. Current therapies for LSDs, like enzyme replacement therapy (ERT), often fail to address neurological symptoms due to their inability to cross the BBB. EVs offer a viable alternative, allowing for targeted delivery to the CNS and improving therapeutic outcomes. We discuss recent advancements in the engineering and modification of EVs to enhance targeting, circulation time and cargo stability, and provide a detailed overview of their application in LSDs, such as Gaucher and Fabry diseases, and Sanfilippo syndrome. Despite their potential, challenges remain in scaling production, ensuring isolation purity, and meeting regulatory requirements. Future developments will focus on overcoming these barriers, paving the way for the clinical translation of EV-based therapies in LSDs and other CNS disorders. Full article