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Oligosaccharidoses are a group of lysosomal storage disorders characterized by abnormal storage and excretion of incompletely processed glycan structures. As with other inherited metabolic disorders, early diagnosis and initiation of treatment are essential for optimizing outcomes. Biochemical investigation of suspected oligosaccharidoses has traditionally included thin layer chromatography to detect the presence of disease-specific free oligosaccharides in urine; however, this qualitative method has long been known to have limited sensitivity and specificity. In this unit, a quantitative technique for measuring oligosaccharides utilizing high-performance liquid chromatography-tandem mass spectrometry is described, which provides substantial improvements over other methods, in terms of sensitivity and specificity; moreover, it is relatively inexpensive, accessible, and requires significantly less time, effort, sample volume, and reagents to perform. © 2024 Wiley Periodicals LLC. Basic Protocol: Analysis of urinary FOS by HPLC-MS/MS., (© 2024 Wiley Periodicals LLC.)

Thesaurismosis or storage diseases are rare genetic disorders due to an abnormal accumulation of an organic compound or its metabolite within cells. These conditions are either secondary to a defect in catabolism caused by enzymatic dysfunction or to a deficiency in transport proteins. They encompass lysosomal storage diseases, lipid storage diseases or dyslipidemias, and glycogen storage disorders or glycogenoses. Diagnosis is typically based on clinical and biological anomalies but may be made or suggested by the pathologist when symptoms are atypical or when biochemical or genetic tests are challenging to interpret. For accurate diagnosis, it is crucial to freeze a portion of the samples. Special staining and electronic microscopy can also aid in the diagnostic process. As the diagnosis is multidisciplinary, collaboration with clinicians, biochemists and geneticists is essential., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

A systematic literature review was conducted to determine the global status of newborn screening (NBS) for mucopolysaccharidosis (MPS) II (Hunter syndrome; OMIM 309900). Electronic databases were searched in July 2023 for articles referencing NBS for lysosomal storage diseases: 53 featured MPS II. Until recently, only Taiwan and two US states (Illinois and Missouri) formally screened newborns for MPS II, although pilot programs have been conducted elsewhere (Japan, New York, and Washington). In 2022, MPS II was added to the US Recommended Uniform Screening Panel, with increased uptake of NBS anticipated across the USA. While the overall MPS II birth prevalence, determined from NBS initiatives, was higher than in previous reports, it was lower in the USA (approximately 1 in 73,000 according to recent studies in Illinois and Missouri) than in Asia (approximately 1 in 15,000 in Japan). NBS programs typically rely on tandem mass spectrometry quantification of iduronate-2-sulfatase activity for first-tier testing. Diagnosis is often confirmed via molecular genetic testing and/or biochemical testing but may be complicated by factors such as pseudodeficiency alleles and variants of unknown significance. Evidence relating to MPS II NBS is lacking outside Taiwan and the USA. Although broad benefits of NBS are recognized, few studies specifically explored the perspectives of families of children with MPS II.

Lysosomal storage diseases (LSDs) are caused by the deficient activity of a lysosomal hydrolase or the lack of a functional membrane protein, transporter, activator, or other protein. Lysosomal enzymes break down macromolecular compounds, which contribute to metabolic homeostasis. Stored, undegraded materials have multiple effects on cells that lead to the activation of autophagy and apoptosis, including the toxic effects of lyso-lipids, the disruption of intracellular Ca 2+ ion homeostasis, the secondary storage of macromolecular compounds, the activation of signal transduction, apoptosis, inflammatory processes, deficiencies of intermediate compounds, and many other pathways. Clinical observations have shown that carriers of potentially pathogenic variants in LSD-associated genes and patients affected with some LSDs are at a higher risk of cancer, although the results of studies on the frequency of oncological diseases in LSD patients are controversial. Cancer is found in individuals affected with Gaucher disease, Fabry disease, Niemann-Pick type A and B diseases, alfa-mannosidosis, and sialidosis. Increased cancer prevalence has also been reported in carriers of a potentially pathogenic variant of an LSD gene, namely CLN3 , SGSH , GUSB , NEU1 , and, to a lesser extent, in other genes. In this review, LSDs in which oncological events can be observed are described.

Background: Gene therapy is currently in development for several monogenetic diseases including lysosomal storage disorders. Limited evidence is available on patient preferences for gene therapy in this population. In this study, we compare gene therapy-related risk tolerance between people affected by three lysosomal storage diseases currently faced with different therapeutic options and prognoses., Methods: A survey including the probabilistic threshold technique was developed in which respondents were asked to choose between gene therapy and the current standard of care. The attributes included to establish participants' risk tolerance were previously identified in focus groups of affected people or their representatives, namely: risk of mild side effects, severe side effects, the need for additional medication, and the likelihood of long-term effectiveness. The survey was distributed among people receiving outpatient care for type 1 Gaucher disease (good prognosis with current treatment options), Fabry disease (varying prognosis with current treatment options, XY-genotype on average more severely affected than XX), and parents representing people with severe forms of mucopolysaccharidosis type III A/B (poor prognosis, no disease-specific therapy available)., Results: A total of 85 surveys were completed (15 Gaucher disease respondents, 62 Fabry disease respondents (17 self-identifying male), eight parents of ten people with mucopolysaccharidosis type III). Disease groups with higher disease severity trended towards higher risk tolerance: Gaucher disease respondents were most cautious and predominantly preferred the current standard of care as opposed to MPS III representatives who were more risk tolerant. Respondents with Fabry disease were most heterogeneous in their risk tolerance, with male participants being more risk tolerant than female participants. Long-term effectiveness was the attribute in which respondents tolerated the least risk., Conclusions: People affected by a lysosomal storage disease associated with a poorer prognosis and less effective current treatment options trended towards more risk tolerance when choosing between gene therapy and the current standard of care. This study shows the importance of involvement of patient preferences before and during the development process of new treatment modalities such as gene therapy for rare diseases, to ensure that innovative therapies align with the wishes and needs of people affected by these diseases., (© 2024. The Author(s).)

Lysosomal storage diseases (LSDs) encompass a group of rare inherited metabolic disorders characterized by the accumulation of undegraded substrates within lysosomes, leading to multisystemic manifestations, including profound neurological involvement. This article provides a concise overview of the neurological manifestations of LSDs, with a focus on central nervous system (CNS) involvement and treatment strategies. While the paper intricacies of each LSD subtype and its associated CNS manifestations, it aims to provide a summary of the essential findings and implications. The neurological manifestations of LSDs encompass a spectrum of symptoms, including cognitive impairment, motor dysfunction, seizures, and sensory deficits, which significantly impact patients' quality of life and pose therapeutic challenges. Current treatment strategies primarily aim to alleviate symptoms and slow disease progression, with limited success in reversing established neurological damage. Enzyme replacement therapy, substrate reduction therapy, and emerging gene therapies hold promise for addressing CNS involvement in LSDs. However, challenges such as blood-brain barrier penetration and long-term efficacy remain. In addition to discussing treatment modalities, this article highlights the importance of early diagnosis, multidisciplinary care, and patient advocacy in optimizing outcomes for individuals affected by LSDs. Ethical considerations are also addressed, including equitable access to emerging treatments and integrating personalized medicine approaches. Overall, this article underscores the complex interplay between genetics, neuroscience, and clinical care in understanding and managing the neurological manifestations of LSDs while emphasizing the need for continued research and collaboration to advance therapeutic interventions and improve patient outcomes., Competing Interests: The views and opinions expressed in this paper are solely those of the authors and do not necessarily reflect any institution or organization’s official policy or position. The authors declare no conflicts of interest or financial disclosures related to this research.Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Background: Children and adolescents with Pompe disease (PD) face chronic and progressive myopathy requiring time-intensive enzyme replacement therapy (ERT). Little is known about their perspectives on the disease and its treatment. This study explored their perceptions of disease symptoms and functioning status, and more subjective feelings about the impacts on their lives as part of developing a disease-specific questionnaire., Methods: Eleven pediatric patients aged 8-18 years and 26 caregivers from six children's hospitals in Germany, Austria, and Switzerland underwent semi-structured interviews. Data were recorded, transcribed using MAXQDA software, and analyzed using qualitative content analysis. A system of meaningful categories was developed., Results: Sixteen main categories were derived across four major thematic areas: perceptions of symptoms and limitations, experiences to do with the biopsychosocial impact of PD, treatment experiences, and general emotional well-being/burden. Participants demonstrated broad heterogeneity in symptom perceptions such as muscle weakness, breathing difficulties, pain, and fatigue. Emotional appraisals of limitations were not directly proportional to their severity, and even comparatively minor impairments were often experienced as highly frustrating, particularly for social reasons. The main psychosocial topics were social exclusion vs. inclusion and experiences to do with having a disease. The main finding regarding treatment was that switching ERT from hospital to home was widely viewed as a huge relief, reducing the impact on daily life and the burden of infusions. Emotional well-being ranged from not burdened to very happy in most children and adolescents, including the most severely affected., Conclusion: This study provided qualitative insights into the perceptions and experiences of pediatric PD patients. Interestingly, biopsychosocial burden was not directly related to disease severity, and tailored psychosocial support could improve health-related quality of life. The present findings ensure the content validity of a novel questionnaire to be tested as a screening tool to identify patients in need of such support., (© 2024. The Author(s).)

Background: Fabry disease (FD) is an X-linked inherited lysosomal storage disease that is caused by deficient activity of the enzyme alpha-galactosidase A. Cardiovascular magnetic resonance (CMR) imaging can detect cardiac sphingolipid accumulation using native T1 mapping. The kidneys are often visible in cardiac CMR native T1 maps; however, it is currently unknown if the maps can be used to detect sphingolipid accumulation in the kidneys of FD patients. Therefore, the aim of this study was to evaluate if cardiac-dedicated native T1 maps can be used to detect sphingolipid accumulation in the kidneys., Methods: FD patients (n = 18, 41 ± 10 years, 44% (8/18) male) and healthy subjects (n = 38, 41 ± 16 years, 47% (18/38) male) were retrospectively enrolled. Native T1 maps were acquired at 1.5T using modified Look-Locker inversion recovery research sequences. Native T1 values were measured by manually delineating regions of interest (ROI) in the renal cortex, renal medulla, heart, spleen, blood, and liver. Endo- and epicardial borders were delineated in the myocardium and averaged across all slices. Blood ROIs were placed in the left ventricular blood pool in the midventricular slice., Results: There were no differences in native T1 between the FD patients and the healthy subjects in the renal cortex (1034 ± 88 ms vs 1056 ± 59 ms, p = 0.29), blood (1614 ± 111 ms vs 1576 ± 100 ms, p = 0.22), spleen (1143 ± 45 ms vs 1132 ± 70 ms, p = 0.54), or liver (568 ± 49 ms vs 557 ± 47 ms, p = 0.41). Native myocardial T1 was lower in FD patients compared to healthy subjects (951 ± 79 vs 1006 ± 38, p<0.01), and higher in the renal medulla (1635 ± 144 vs 1514 ± 81, p<0.01)., Conclusion: Compared to healthy subjects, patients with FD and cardiac involvement showed no differences in native T1 of the renal cortex. FD patients had higher native T1 in the renal medulla, which is not totally explained by differences in blood native T1 but may reflect a hyperfiltration state in the development of renal failure. The findings suggest that sphingolipid accumulation in the renal cortex in FD patients could not be detected with cardiac-dedicated research native T1 maps., Competing Interests: Declaration of competing interests The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Jannike Nickander report financial support was provided by Swedish Research Council, Swedish Heart and Lung Foundation, and Region of Stockholm. Kelvin Chow reports a relationship with Siemens Healthcare that includes employment. Jannike Nickander reports a relationship with Sanofi Genzyme Sweden that includes speaking and lecture fees. Mikael Oscarson reports a relationship with Sanofi Genzyme Sweden that includes speaking and lecture fees. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Diseases caused by lysosomal dysfunction often exhibit multisystemic involvement, resulting in substantial morbidity and mortality. Ensuring accurate diagnoses for individuals with lysosomal diseases (LD) is of great importance, especially with the increasing prominence of genetic testing as a primary diagnostic method. As the list of genes associated with LD continues to expand due to the use of more comprehensive tests such as exome and genome sequencing, it is imperative to understand the clinical validity of the genes, as well as identify appropriate genes for inclusion in multi-gene testing and sequencing panels. The Clinical Genome Resource (ClinGen) works to determine the clinical importance of genes and variants to support precision medicine. As part of this work, ClinGen has developed a semi-quantitative framework to assess the strength of evidence for the role of a gene in a disease. Given the diversity in gene composition across LD panels offered by various laboratories and the evolving comprehension of genetic variants affecting secondary lysosomal functions, we developed a scoring system to define LD (Lysosomal Disease Scoring System - LDSS). This system sought to aid in the prioritization of genes for clinical validity curation and assess their suitability for LD-targeted sequencing panels., Methods: Through literature review encompassing terms associated with both classically designated LD and LFRD, we identified 14 criteria grouped into "Overall Definition," "Phenotype," and "Pathophysiology." These criteria included concepts such as the "accumulation of undigested or partially digested macromolecules within the lysosome" and being "associated with a wide spectrum of clinical manifestations impacting multiple organs and systems." The criteria, along with their respective weighted values, underwent refinement through expert panel evaluation differentiating them between "major" and "minor" criteria. Subsequently, the LDSS underwent validation on 12 widely acknowledged LD and was later tested by applying these criteria to the Lysosomal Disease Network's (LDN) official Gene List., Results: The final LDSS comprised 4 major criteria and 10 minor criteria, with a cutoff of 2 major or 1 major and 3 minor criteria established to define LD. Interestingly, when applied to both the LDN list and a comprehensive gene list encompassing genes included in clinical panels and published as LFRD genes, we identified four genes (GRN, SLC29A3, CLN7 and VPS33A) absent from the LDN list, that were deemed associated with LD. Conversely, a subset of non-classic genes included in the LDN list, such as MTOR, OCRL, and SLC9A6, received lower LDSS scores for their associated disease entities. While these genes may not be suitable for inclusion in clinical LD multi-gene panels, they could be considered for inclusion on other, non-LD gene panels., Discussion: The LDSS offers a systematic approach to prioritize genes for clinical validity assessment. By identifying genes with high scores on the LDSS, this method enhanced the efficiency of gene curation by the ClinGen LD GCEP., Conclusion: The LDSS not only serves as a tool for gene prioritization prior to clinical validity curation, but also contributes to the ongoing discussion on the definition of LD. Moreover, the LDSS provides a flexible framework adaptable to future discoveries, ensuring its relevance in the ever-expanding landscape of LD research., Competing Interests: Declaration of competing interest D.B., H.C., C.H., R.M., and T.Y., are employed by laboratories offering free-for-service testing related to lysosomal diseases. L.C. is a paid consultant with Genzyme/Sanofi related to the MPS I (IDUA) registry. The other authors declare no conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Rare disorders comprise of ~ 7500 different conditions affecting multiple systems. Diagnosis of rare diseases is complex due to dearth of specialized medical professionals, testing labs and limited therapeutic options. There is scarcity of data on the prevalence of rare diseases in different populations. India being home to a large population comprising of 4600 population groups, of which several thousand are endogamous, is likely to have a high burden of rare diseases. The present study provides a retrospective overview of a cohort of patients with rare genetic diseases identified at a tertiary genetic test centre in India., Results: Overall, 3294 patients with 305 rare diseases were identified in the present study cohort. These were categorized into 14 disease groups based on the major organ/ organ system affected. Highest number of rare diseases (D = 149/305, 48.9%) were identified in the neuromuscular and neurodevelopmental (NMND) group followed by inborn errors of metabolism (IEM) (D = 47/305; 15.4%). Majority patients in the present cohort (N = 1992, 61%) were diagnosed under IEM group, of which Gaucher disease constituted maximum cases (N = 224, 11.2%). Under the NMND group, Duchenne muscular dystrophy (N = 291/885, 32.9%), trinucleotide repeat expansion disorders (N = 242/885; 27.3%) and spinal muscular atrophy (N = 141/885, 15.9%) were the most common. Majority cases of β-thalassemia (N = 120/149, 80.5%) and cystic fibrosis (N = 74/75, 98.7%) under the haematological and pulmonary groups were observed, respectively. Founder variants were identified for Tay-Sachs disease and mucopolysaccharidosis IVA diseases. Recurrent variants for Gaucher disease (GBA:c.1448T > C), β-thalassemia (HBB:c.92.+5G > C), non-syndromic hearing loss (GJB2:c.71G > A), albinism (TYR:c.832 C > T), congenital adrenal hyperplasia (CYP21A2:c.29-13 C > G) and progressive pseudo rheumatoid dysplasia (CCN6:c.298T > A) were observed in the present study., Conclusion: The present retrospective study of rare disease patients diagnosed at a tertiary genetic test centre provides first insight into the distribution of rare genetic diseases across the country. This information will likely aid in drafting future health policies, including newborn screening programs, development of target specific panel for affordable diagnosis of rare diseases and eventually build a platform for devising novel treatment strategies for rare diseases., (© 2024. The Author(s).)

Mucopolysaccharidosis type II (MPS II; Hunter syndrome) is a rare, X-linked disorder caused by deficient activity of the enzyme iduronate-2-sulfatase. Signs and symptoms typically emerge at 1.5-4 years of age and may include cognitive impairment, depending on whether patients have the neuronopathic or non-neuronopathic form of the disease. Treatment is available in the form of enzyme replacement therapy (ERT) with recombinant iduronate-2-sulfatase (idursulfase). A systematic literature review was conducted to assess the evidence regarding efficacy, effectiveness, and safety of ERT with intravenous idursulfase for MPS II. Electronic databases were searched in January 2023, and 33 eligible articles were found. These were analyzed to evaluate the effects of intravenous idursulfase and the overall benefits and disadvantages in patient subgroups. Studies showed that intravenous idursulfase treatment resulted in improved short- and long-term clinical and patient-centered outcomes, accompanied by a favorable safety profile. Patients with non-neuronopathic MPS II had more pronounced improvements in clinical outcomes than those with neuronopathic MPS II. In addition, the review identified that improvements in clinical outcomes are particularly apparent if intravenous idursulfase is started early in life, strengthening previous recommendations for early ERT initiation to maximally benefit patients. This review provides a comprehensive summary of our current knowledge on the efficacy of ERT in different populations of patients with MPS II and will help to inform the overall management of the disease in an evolving treatment landscape.

Fabry's disease is a rare X chromosome-linked inherited lysosomal storage disease characterized by insufficient metabolism of the substrate globotriaosylceramide (Gb 3 ) due to reduced alpha-galactosidase A (AGAL) activity. Lysosomal Gb 3 accumulation causes a multisystemic disease which, if untreated, reduces the life expectancy in females and males by around 10 and 20 years, respectively, due to progressive renal dysfunction, hypertrophic cardiomyopathy, cardiac arrhythmia and early occurrence of cerebral infarction. The diagnosis is confirmed by determining the reduced AGAL activity in leukocytes in males and molecular genetic detection of a -mutation causing the disease in females. The treatment comprises enzyme replacement therapy (ERT), agalsidase alfa, 0.2 mg/kg body weight (BW), agalsidase beta 1.0 mg/kg BW or pegunigalsidase alfa 1.0 mg/kg BW every 2 weeks i.v. or oral chaperone therapy (one capsule of migalastat 123 mg every other day) in the presence of amenable mutations. This article summarizes the data on the treatment of Fabry's disease and on complications in practice. The current guideline recommendations are addressed and new study results that could expand the therapeutic repertoire in the future are discussed., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Introduction: Lysosomal storage diseases (LSDs) constitute a group of metabolic disorders characterized by the accumulation of substrates within lysosomes. For their treatment, disease-specific enzyme replacement therapy (ERT) is employed. In cases of hypersensitivity reactions that may occur during these treatments, desensitization of enzyme therapy becomes necessary. Repeated desensitization procedures may result some degree of tolerance. This study presents cases of patients received abbreviated desensitization protocols following repeated desensitization procedures., Method: During the period between September 2019 and January 2024, pediatric patients who experienced anaphylactic reactions to ERT and whose desensitization protocols were abbreviated after receiving uneventful treatment with desensitization for at least a year were included in the study., Result: Six patients, four with Pompe disease, one with mucopolysaccharidosis type 2, and one with mucopolysaccharidosis type 4, had been receiving uninterrupted ERT by desensitization for at least 1 year. The mean age of the patients was 117.6 months (median: 104.5, IQR: 85.2-144). All patients experienced anaphylaxis as the initial reaction. Skin and intradermal tests were repeated on patients prior to protocol abbreviation. Premedication previously given to all patients was discontinued, and desensitization protocols were subsequently shortened by increasing the infusion rate and/or reducing the number of steps., Conclusion: The study investigated patients whose desensitization protocols were abbreviated. It demonstrated that some level of tolerance could be attained through repeated applications. This approach aims to identify concise, safe, and efficient protocols, thereby reducing hospitalizations, nosocomial infections, and treatment expenses., (© 2024 S. Karger AG, Basel.)

People with rare lysosomal storage diseases face challenges in their care that arise from disease complexity and heterogeneity, compounded by many healthcare professionals being unfamiliar with these diseases. These challenges can result in long diagnostic journeys and inadequate care. Over 30 years ago, the Rare Disease Registries for Gaucher, Fabry, Mucopolysaccharidosis type I and Pompe diseases were established to address knowledge gaps in disease natural history, clinical manifestations of disease and treatment outcomes. Evidence generated from the real-world data collected in these registries supports multiple stakeholders, including patients, healthcare providers, drug developers, researchers and regulators. To maximise the impact of real-world evidence from these registries, engagement and collaboration with the patient communities is essential. To this end, the Rare Disease Registries Patient Council was established in 2019 as a partnership between the Rare Disease Registries and global and local patient advocacy groups to share perspectives on how registry data are used and disseminated. The Patient Council has resulted in a number of patient initiatives including patient representation at Rare Disease Registries advisory boards; development of plain language summaries of registry publications to increase availability of real-world evidence to patient communities; and implementation of digital innovations such as electronic patient-reported outcomes, and patient-facing registry reports and electronic consent (in development), all to enhance patient engagement. The Patient Council is building on the foundations of industry-patient advocacy group collaboration to fully integrate patient communities in decision-making and co-create solutions for the rare disease community., (© 2024. The Author(s).)

MPS IIIC is a lysosomal storage disease caused by mutations in heparan-α-glucosaminide N-acetyltransferase (HGSNAT), for which no treatment is available. Because HGSNAT is a trans-lysosomal-membrane protein, gene therapy for MPS IIIC needs to transduce as many cells as possible for maximal benefits. All cells continuously release extracellular vesicles (EVs) and communicate by exchanging biomolecules via EV trafficking. To address the unmet need, we developed a rAAV-hHGSNAT EV vector with an EV-mRNA-packaging signal in the 3'UTR to facilitate bystander effects, and tested it in an in vitro MPS IIIC model. In human MPS IIIC cells, rAAV-hHGSNAT EV enhanced HGSNAT mRNA and protein expression, EV-hHGSNAT-mRNA packaging, and cleared GAG storage. Importantly, incubation with EVs led to hHGSNAT protein expression and GAG contents clearance in recipient MPS IIIC cells. Further, rAAV-hHGSNAT EV transduction led to the reduction of pathological EVs in MPS IIIC cells to normal levels, suggesting broader therapeutic benefits. These data demonstrate that incorporating the EV-mRNA-packaging signal into a rAAV-hHGSNAT vector enhances EV packaging of hHGSNAT-mRNA, which can be transported to non-transduced cells and translated into functional rHGSNAT protein, facilitating cross-correction of disease pathology. This study supports the therapeutic potential of rAAV EV for MPS IIIC, and broad diseases, without having to transduce every cell., (© 2024 The Author(s). Journal of Extracellular Vesicles published by Wiley Periodicals LLC on behalf of International Society for Extracellular Vesicles.)

MFSD12 protein has recently risen as a key factor in malignancy and plays a potential role in a variety of complex oncogenic signaling cascades. Current studies suggest that MFSD12 has a positive complex role in the growth and progression of tumors such as melanoma, breast cancer, and lung cancer. At the same time, as a transporter of cysteine, MFSD12 is also involved in the development of lysosomal storage diseases. Therefore, MFSD12 may be an effective target to inhibit tumor development, block metastasis, and expand the therapeutic effect. This article reviews the molecular mechanisms of MFSD12 in a variety of cancers and lysosomal storage diseases., Competing Interests: The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Ding.)

Gene therapy in hematopoietic stem and progenitor cells (HSPCs) shows great potential for the treatment of inborn metabolic diseases. Typical HSPC gene therapy approaches rely on constitutive promoters to express a therapeutic transgene, which is associated with multiple disadvantages. Here, we propose a novel promoterless intronic gene editing approach that triggers transgene expression only after cellular differentiation into the myeloid lineage. We integrated a splicing-competent eGFP cassette into the first intron of CD11b and observed expression of eGFP in the myeloid lineage but minimal to no expression in HSPCs or differentiated non-myeloid lineages. In vivo, edited HSPCs successfully engrafted in immunodeficient mice and displayed transgene expression in the myeloid compartment of multiple tissues. Using the same approach, we expressed alpha-L-iduronidase (IDUA), the defective enzyme in Mucopolysaccharidosis type I, and observed a 10-fold supraendogenous IDUA expression exclusively after myeloid differentiation. Edited cells efficiently populated bone marrow, blood, and spleen of immunodeficient mice, and retained the capacity to secrete IDUA ex vivo. Importantly, cells edited with the eGFP and IDUA transgenes were also found in the brain. This approach may unlock new therapeutic strategies for inborn metabolic and neurological diseases that require the delivery of therapeutics in brain., Competing Interests: Declaration of interests E.S., A.O.L., S.P., A.B., D.T., A.J., P.D., and J.V. are employees and/or own stock in Cellectis., (Copyright © 2024 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.)

Niemann-Pick disease (NPD) is another type of metabolic disorder that is classified as lysosomal storage diseases (LSDs). The main cause of the disease is mutation in the SMPD1 (type A and B) or NPC1 or NPC2 (type C) genes, which lead to the accumulation of lipid substrates in the lysosomes of the liver, brain, spleen, lung, and bone marrow cells. This is followed by multiple cell damage, dysfunction of lysosomes, and finally dysfunction of body organs. So far, about 346, 575, and 30 mutations have been reported in SMPD1, NPC1, and NPC2 genes, respectively. Depending on the type of mutation and the clinical symptoms of the disease, the treatment will be different. The general aim of the current study is to review the clinical and molecular characteristics of patients with NPD and study various treatment methods for this disease with a focus on gene therapy approaches., (© 2024 John Wiley & Sons Ltd.)

Pulmonologists may be involved in managing pulmonary diseases in children with complex clinical pictures without a diagnosis. Moreover, they are routinely involved in the multidisciplinary care of children with rare diseases, at baseline and during follow-up, for lung function monitoring. Lysosomal storage diseases (LSDs) are a group of genetic diseases characterised by a specific lysosomal enzyme deficiency. Despite varying pathogen and organ involvement, they are linked by the pathological accumulation of exceeding substrates, leading to cellular toxicity and subsequent organ damage. Less severe forms of LSDs can manifest during childhood or later in life, sometimes being underdiagnosed. Respiratory impairment may stem from different pathogenetic mechanisms, depending on substrate storage in bones, with skeletal deformity and restrictive pattern, in bronchi, with obstructive pattern, in lung interstitium, with altered alveolar gas exchange, and in muscles, with hypotonia. This narrative review aims to outline different pulmonary clinical findings and a diagnostic approach based on key elements for differential diagnosis in some treatable LSDs like Gaucher disease, Acid Sphingomyelinase deficiency, Pompe disease and Mucopolysaccharidosis. Alongside their respiratory clinical aspects, which might overlap, we will describe radiological findings, lung functional patterns and associated symptoms to guide pediatric pulmonologists in differential diagnosis. The second part of the paper will address follow-up and management specifics. Recent evidence suggests that new therapeutic strategies play a substantial role in preventing lung involvement in early-treated patients and enhancing lung function and radiological signs in others. Timely diagnosis, driven by clinical suspicion and diagnostic workup, can help in treating LSDs effectively.

Background: Lysosomal storage diseases (LSDs), a group of inborn errors of metabolism, include various subtypes, for example, mucopolysaccharidosis (MPS) and Gaucher disease (GD). Besides the physical/mental disabilities, they suffer from several oral deteriorations., Aim: To evaluate the oral health status of Egyptian children with LSD., Design: Thirty LSD children and thirty non-LSD children were enrolled for this study according to the inclusion and exclusion criteria. Dental indices were used to assess caries prevalence and periodontal status. Saliva samples were collected from all enrolled children to estimate interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and protein levels as well as Streptococcus mutans and Lactobacilli colony counts., Results: Children with MPS and GD showed non-significant differences in decayed, missing, or filled teeth (DMFT) scores (p = .115). Scores of dmft showed a significant increase in MPS, but not in GD children (p = .020, p = .127). Children with LSD showed significantly increased Modified Gingival Index (MGI), Plaque Index (PI), Oral Hygiene Index (OHI-s) scores (p < .001) and salivary IL-6 and TNF-α (p = .007, p = .001, p < .0001, p = .002, respectively) and salivary total proteins (p = .001) levels. Unexpectedly, non-significant differences were observed in salivary Streptococcus mutans or Lactobacilli counts in children with MPS and GD (p = .058, p = .420, p = .502, p = .053, respectively)., Conclusion: To our knowledge, this is the first article that evaluates Egyptian children with LSD. We demonstrated high caries prevalence in primary teeth, not permanent teeth, in children with MPS and poor gingival/hygiene status in children with MPS and GD, which triggered a state of inflammation. The daily supplement intake prevented oral bacterial growth. The most probable cause of oral alterations is decreased salivary flow rate, as deduced from a significantly increased salivary protein., (© 2024 BSPD, IAPD and John Wiley & Sons Ltd.)

Infantile-onset Pompe disease (IOPD) results from pathogenic variants in the GAA gene, which encodes acid α-glucosidase. The correction of pathogenic variants through genome editing may be a valuable one-time therapy for PD and improve upon the current standard of care. We performed adenine base editing in human dermal fibroblasts harboring three transition nonsense variants, c.2227C>T (p.Q743∗; IOPD-1), c.2560C>T (p.R854∗; IOPD-2), and c.2608C>T (p.R870∗; IOPD-3). Up to 96% adenine deamination of target variants was observed, with minimal editing across >50 off-target sites. Post-base editing, expressed GAA protein was up to 0.66-fold normal (unaffected fibroblasts), an improvement over affected fibroblasts wherein GAA was undetectable. GAA enzyme activity was between 81.91 ± 13.51 and 129.98 ± 9.33 units/mg protein at 28 days post-transfection, which falls within the normal range (50-200 units/mg protein). LAMP2 protein was significantly decreased in the most robustly edited cell line, IOPD-3, indicating reduced lysosomal burden. Taken together, the findings reported herein demonstrate that base editing results in efficacious adenine deamination, restoration of GAA expression and activity, and reduction in lysosomal burden in the most robustly edited cells. Future work will assess base editing outcomes and the impact on Pompe pathology in two mouse models, Gaa c.2227C>T and Gaa c.2560C>T ., Competing Interests: The authors declare no competing interests., (© 2024 The Author(s).)

Fabry disease (FD) is an X-linked lysosomal storage disorder, characterised by the cellular accumulation of globotriaosylceramide due to impaired alpha-galactosidase A enzyme activity. FD may manifest with multisystem pathology, including reduced bone mineral density (BMD). Registry data suggest that the introduction of Fabry-specific therapies (enzyme replacement therapy or chaperone therapy) has led to significant improvements in overall patient outcomes; however, there are limited data on the impact on bone density. The aim of this study was to describe the effect of Fabry-specific therapies on longitudinal changes in bone mineral density (BMD) in FD. We performed a retrospective observational study analysing bone densitometry (DXA) in patients with genetically confirmed FD. Patients were grouped based on the use of Fabry-specific therapies. The between-group longitudinal change in BMD Z-score was analysed using linear mixed effects models. A total of 88 FD patients were analysed (50 untreated; 38 treated). The mean age at first DXA was 38.5 years in the untreated group (84% female) and 43.7 years in the treated group (34% female). There was no significant longitudinal between-group difference in the BMD Z-score at the lumbar spine. However, the Z-score per year at the total hip (β = -0.105, p < 0.001) and femoral neck (β = -0.081, p = 0.001) was significantly lower over time in the treated than the untreated group. This may reflect those receiving therapy having a more severe underlying disease. Nevertheless, this suggests that Fabry-specific therapies do not reverse all disease mechanisms and that the additional management of BMD may be required in this patient population.

Lysosomes are the terminal end of catabolic pathways in the cell, as well as signaling centers performing important functions such as the recycling of macromolecules, organelles, and nutrient adaptation. The importance of lysosomes in human health is supported by the fact that the deficiency of most lysosomal genes causes monogenic diseases called as a group Lysosomal Storage Diseases (LSDs). A common phenotypic hallmark of LSDs is the expansion of the lysosomal compartment that can be detected by using conventional imaging methods based on immunofluorescence protocols or overexpression of tagged lysosomal proteins. These methods require the alteration of the cellular architecture (i.e., due to fixation methods), can alter the behavior of cells (i.e., by the overexpression of proteins), and require sample preparation and the accurate selection of compatible fluorescent markers in relation to the type of analysis, therefore limiting the possibility of characterizing cellular status with simplicity. Therefore, a quantitative and label-free methodology, such as Quantitative Phase Imaging through Digital Holographic (QPI-DH), for the microscopic imaging of lysosomes in health and disease conditions may represent an important advance to study and effectively diagnose the presence of lysosomal storage in human disease. Here we proof the effectiveness of the QPI-DH method in accomplishing the detection of the lysosomal compartment using mouse embryonic fibroblasts (MEFs) derived from a Mucopolysaccharidosis type III-A (MSP-IIIA) mouse model, and comparing them with wild-type (WT) MEFs. We found that it is possible to identify label-free biomarkers able to supply a first pre-screening of the two populations, thus showing that QPI-DH can be a suitable candidate to surpass fluorescent drawbacks in the detection of lysosomes dysfunction. An appropriate numerical procedure was developed for detecting and evaluate such cellular substructures from in vitro cells cultures. Results reported in this study are encouraging about the further development of the proposed QPI-DH approach for such type of investigations about LSDs., (© 2024 International Society for Advancement of Cytometry.)

Mutations in Drosophila Swiss cheese (SWS) gene or its vertebrate orthologue neuropathy target esterase (NTE) lead to progressive neuronal degeneration in flies and humans. Despite its enzymatic function as a phospholipase is well established, the molecular mechanism responsible for maintaining nervous system integrity remains unclear. In this study, we found that NTE/SWS is present in surface glia that forms the blood-brain barrier (BBB) and that NTE/SWS is important to maintain its structure and permeability. Importantly, BBB glia-specific expression of Drosophila NTE/SWS or human NTE in the sws mutant background fully rescues surface glial organization and partially restores BBB integrity, suggesting a conserved function of NTE/SWS. Interestingly, sws mutant glia showed abnormal organization of plasma membrane domains and tight junction rafts accompanied by the accumulation of lipid droplets, lysosomes, and multilamellar bodies. Since the observed cellular phenotypes closely resemble the characteristics described in a group of metabolic disorders known as lysosomal storage diseases (LSDs), our data established a novel connection between NTE/SWS and these conditions. We found that mutants with defective BBB exhibit elevated levels of fatty acids, which are precursors of eicosanoids and are involved in the inflammatory response. Also, as a consequence of a permeable BBB, several innate immunity factors are upregulated in an age-dependent manner, while BBB glia-specific expression of NTE/SWS normalizes inflammatory response. Treatment with anti-inflammatory agents prevents the abnormal architecture of the BBB, suggesting that inflammation contributes to the maintenance of a healthy brain barrier. Considering the link between a malfunctioning BBB and various neurodegenerative diseases, gaining a deeper understanding of the molecular mechanisms causing inflammation due to a defective BBB could help to promote the use of anti-inflammatory therapies for age-related neurodegeneration., Competing Interests: MT, AY, JH, BB, DT, HS No competing interests declared, (© 2024, Tsap et al.)

The Golgi apparatus plays a crucial role in lysosome biogenesis and the delivery of lysosomal enzymes, essential for maintaining cellular homeostasis and ensuring cell survival. Deficiencies in Golgi structure and function can profoundly impact lysosomal homeostasis, leading to various lysosomal storage diseases and neurodegenerative disorders. In this review, we highlight the role of the Golgi Reassembly Stacking Proteins (GRASPs) in the formation and function of the Golgi apparatus, emphasizing the current understanding of the association between the Golgi apparatus, lysosomes, and lysosomal storage diseases. Additionally, we discuss how Golgi dysfunction leads to the secretion of lysosomal enzymes. This review aims to serve as a concise resource, offering insights into Golgi structure, function, disease-related defects, and their consequential effects on lysosomal biogenesis and function. By highlighting Golgi defects as an underappreciated contributor to lysosomal dysfunction across various diseases, we aim to enhance comprehension of these intricate cellular processes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Akaaboune and Wang.)

Objectives: Gaucher disease (GD) is a lysosomal storage disease caused by glucocerebrosidase (GCase) enzyme deficiency. Gaucher cells transformed from the macrophages by progressive sphingolipid accumulation and infiltrate bone marrow, spleen, liver, and other organs. The accumulation of substrate causes inflammation, compromised cellular homeostasis, and disturbed autophagy. It has been hypothesized that this proinflammatory state of GD leads cytokines and chemokines release. As a result of inflammatory process, the cellular dysfunction caused by disruption of cellular signaling, organelle dysfunction, or autoimmune antibodies may affect endocrine profile of GD patients such as hormone levels, lipid profile, and bone mineral density status., Methods: A total of 13 patients confirmed to have GD, 12 non-neuronopathic type and one subacute neuronopathic type, were enrolled in our study., Results: The median treatment duration in the enzyme therapy was 13.33 years (9-26 years). At least one endocrinological abnormality was detected in blood tests of nine patients. Hyperinsulinism was the most common finding although fasting blood glucose levels HgbA1c levels were normal in all patients. Two patients had osteopenia, and osteoporosis was detected in two patients. Low HDL levels were detected in six patients, but HDL levels below 23 mg/dL associated with disease severity have been detected in two patients who have not receiving enzyme replacement therapy. None of patients had thyroidal dysfunction., Conclusions: This study had revealed endocrinological abnormalities in GD patients that have not led any severe morbidity in our patients. However, thyroid hormone abnormalities, insulin resistance, or lipid profile abnormalities may cause unpredictable comorbidities. Endocrinological assessment in GD patients in routine follow-up may prevent possible clinical manifestation in long term as well as can define efficacy of ERT on endocrine abnormalities., (© 2024 Walter de Gruyter GmbH, Berlin/Boston.)

Background: Mucopolysaccharidosis II (MPS II) is a rare lysosomal storage disease characterized by iduronate-2-sulfatase gene (IDS) deficiency and downstream glycosaminoglycan accumulation. Two-thirds of patients present with neuronopathic disease and evaluating cognitive function in these patients is challenging owing to limitations of currently available tests. During the clinical development of intrathecal idursulfase (idursulfase-IT), regulatory authorities requested qualitative data to further understand the neurocognitive changes observed by the investigators through the clinical trials., Results: This qualitative study consisted of semi-structured interviews with all nine of the principal investigators who participated in the idursulfase-IT phase 2/3 (NCT02055118) and extension (NCT02412787) trials. These investigators enrolled the 56 patients with neuronopathic MPS II who qualified for the extension phase of the trial. The investigators were asked to rate the disease status of their patients. Of the 56 patients, 49 (88%) were rated as having disease that was improved/improving, stabilized or slowing progression compared with the expected outcomes with no treatment. Three patients were rated as worsening, while the remaining four patients were considered to have slowing progression or worsening disease. Similar results were demonstrated for patients aged from 3 to under 6 years at baseline, with 33 of 39 patients (85%) rated as having disease that was improved/improving, stabilized or slowing progression. Of the seven patients rated with slowing progression/worsening or worsening disease, five of them had an IDS variant other than missense, while two had a missense class variant. All the assigned improved/improving ratings were in patients receiving idursulfase-IT from the start of the phase 2/3 trial. Moreover, patients under 3 years of age at baseline were all rated as either improved/improving or stabilized disease. In a blinded review of patient profiles, investigators were requested to assign a disease status rating to 18 patients with large IDS deletions; 67% of these patients were rated as improved/improving or stabilized disease., Conclusions: This qualitative analysis provides a snapshot of clinicians' considerations when evaluating treatment in patients with neuronopathic MPS II, compared with the expected decline in cognitive function in the absence of treatment. The results highlight the importance of robust assessment tools in treatment evaluation., (© 2024. The Author(s).)

Gaucher disease (GD) is a lysosomal storage disorder caused by a deficiency in the GBA1-encoded enzyme, β-glucocerebrosidase. Enzyme replacement therapy is ineffective for neuronopathic Gaucher disease (nGD). High-dose ambroxol has been administered as an alternative treatment for a group of patients with nGD. However, little is known about the clinical indication and the long-term outcome of patients after ambroxol therapy. We herein report a case of a female patient who presented with a progressive disease of GD type 2 from 11 months of age and had the pathogenic variants of p.L483P (formerly defined as p.L444P) and p.R502H (p.R463H) in GBA1. A combined treatment of imiglucerase with ambroxol started improving the patient's motor activity in 1 week, while it kept the long-lasting effect of preventing the deteriorating phenotype for 30 months. A literature review identified 40 patients with nGD, who had received high-dose ambroxol therapy. More than 65% of these patients favorably responded to the molecular chaperone therapy, irrespective of p.L483P homozygous, heterozygous or the other genotypes. These results highlight the long-lasting effect of ambroxol-based chaperone therapy for patients with an expanding spectrum of mutations in GBA1., (© 2024 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals LLC.)

Progranulin (PGRN), encoded by the GRN gene in humans, was originally isolated as a secreted growth factor that implicates in a multitude of processes ranging from regulation of tumorigenesis, inflammation to neural proliferation. Compelling evidence indicating that GRN mutation can lead to various common neuronal degenerative diseases and rare lysosomal storage diseases. These findings have unveiled a critical role for PGRN as a lysosomal protein in maintaining lysosomal function. The phenotypic spectrum of PGRN imbalance has expanded to encompass a broad spectrum of diseases, including autoimmune diseases, metabolic, musculoskeletal and cardiovascular diseases. These diseases collectively referred to as Progranulinopathy- a term encompasses the wide spectrum of disorders influenced by PGRN imbalance. Unlike its known extracellular function as a growth factor-like molecule associated with multiple membrane receptors, PGRN also serves as an intracellular co-chaperone engaged in the folding and traffic of its associated proteins, particularly the lysosomal hydrolases. This chaperone activity is required for PGRN to exert its diverse functions across a broad range of diseases, encompassing both the central nervous system and peripheral systems. In this comprehensive review, we present an update of the emerging role of PGRN in Progranulinopathy, with special focus on elucidating the intricate interplay between PGRN and a diverse array of proteins at various levels, ranging from extracellular fluids and intracellular components, as well as various pathophysiological processes involved. This review seeks to offer a comprehensive grasp of PGRN's diverse functions, aiming to unveil intricate mechanisms behind Progranulinopathy and open doors for future research endeavors., Competing Interests: Declaration of Competing Interest The authors declare no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Cipaglucosidase alfa plus miglustat (cipa + mig) is a novel, two-component therapy for Pompe disease. We report data from the Phase I/II ATB200-02 study for up to 48 months of treatment. Four adult cohorts, including one non-ambulatory ERT-experienced (n = 6) and three ambulatory cohorts, (two enzyme replacement therapy [ERT]-experienced cohorts [2-6 years (n = 11) and ≥ 7 years (n = 6)]), one ERT-naïve cohort (n = 6), received 20 mg/kg intravenous-infused cipa plus 260 mg oral mig biweekly. Change from baseline (CFBL) for multiple efficacy endpoints at 12, 24, 36, and 48 months, pharmacodynamics, pharmacokinetics, safety, and immunogenicity data were assessed. Six-minute walking distance (% predicted) improved at 12, 24, 36, and 48 months: pooled ambulatory ERT-experienced cohorts, mean(± standard deviation [SD]) CFBL: 6.1(± 7.84), n = 16; 5.4(± 10.56), n = 13; 3.4(± 14.66), n = 12; 5.9(± 17.36), n = 9, respectively; ERT-naïve cohort: 10.7(± 3.93), n = 6; 11.0(± 5.06), n = 6; 9.0(± 7.98), n = 5; 11.7(± 7.69), n = 4, respectively. Percent predicted forced vital capacity was generally stable in ERT-experienced cohorts, mean(± SD) CFBL - 1.2(± 5.95), n = 16; 1.0(± 7.96), n = 13; - 0.3(± 6.68), n = 10; 1.0(± 6.42), n = 6, respectively, and improved in the ERT-naïve cohort: 3.2(± 8.42), n = 6; 4.7(± 5.09), n = 6; 6.2(± 3.35), n = 5; 8.3(± 4.50), n = 4, respectively. Over 48 months, CK and Hex4 biomarkers improved in ambulatory cohorts. Overall, cipa + mig was well tolerated with a safety profile like alglucosidase alfa. ATB200-02 results show the potential benefits of cipa + mig as a long-term treatment option for Pompe disease. Trial registration number: NCT02675465 January 26, 2016., (© 2023. The Author(s).)

Niemann-Pick Type C (NPC) represents an autosomal recessive disorder with an incidence rate of 1 in 150,000 live births, classified within lysosomal storage diseases (LSDs). The abnormal accumulation of unesterified cholesterol characterizes the pathophysiology of NPC. This phenomenon is not unique to NPC, as analogous accumulations have also been observed in Alzheimer's disease, Parkinson's disease, and other neurodegenerative disorders. Interestingly, disturbances in the folding of the mutant protein NPC1 I1061T are accompanied by the aggregation of proteins such as hyperphosphorylated tau, α-synuclein, TDP-43, and β-amyloid peptide. These accumulations suggest potential disruptions in proteostasis, a regulatory process encompassing four principal mechanisms: synthesis, folding, maintenance of folding, and protein degradation. The dysregulation of these processes leads to excessive accumulation of abnormal proteins that impair cell function and trigger cytotoxicity. This comprehensive review delineates reported alterations across proteostasis mechanisms in NPC, encompassing changes in processes from synthesis to degradation. Additionally, it discusses therapeutic interventions targeting pharmacological facets of proteostasis in NPC. Noteworthy among these interventions is valproic acid, a histone deacetylase inhibitor (HDACi) that modulates acetylation during NPC1 synthesis. In addition, various therapeutic options addressing protein folding modulation, such as abiraterone acetate, DHBP, calnexin, and arimoclomol, are examined. Additionally, treatments impeding NPC1 degradation, exemplified by bortezomib and MG132, are explored as potential strategies. This review consolidates current knowledge on proteostasis dysregulation in NPC and underscores the therapeutic landscape targeting diverse facets of this intricate process.

Gaucher and Fabry diseases are lysosomal storage disorders in which deficient enzyme activity leads to pathological accumulation of sphingolipids. These diseases have a broad phenotypic presentation. Musculoskeletal symptoms and pain complaints are frequently reported by patients. Thus, rheumatologists can be contacted by these patients, contributing to the correct diagnosis, earlier indication of appropriate treatment and improvement of their prognosis. This review describes important concepts about Gaucher and Fabry diseases that rheumatologists should understand to improve patients' quality of life and change the natural history of these diseases., (© 2024. The Author(s).)

Among the many lysosomal storage disorders (LSDs) that would benefit from the establishment of novel cell models, either patient-derived or genetically engineered, is mucopolysaccharidosis type II (MPS II). Here, we present our results on the establishment and characterization of two MPS II patient-derived stem cell line(s) from deciduous baby teeth. To the best of our knowledge, this is the first time a stem cell population has been isolated from LSD patient samples obtained from the dental pulp. Taking into account our results on the molecular and biochemical characterization of those cells and the fact that they exhibit visible and measurable disease phenotypes, we consider these cells may qualify as a valuable disease model, which may be useful for both pathophysiological assessments and in vitro screenings. Ultimately, we believe that patient-derived dental pulp stem cells (DPSCs), particularly those isolated from human exfoliated deciduous teeth (SHEDs), may represent a feasible alternative to induced pluripotent stem cells (iPSCs) in many labs with standard cell culture conditions and limited (human and economic) resources.

Clinical findings of hepatomegaly and splenomegaly, the abnormal enlargement of the liver and spleen, respectively, should prompt a broad differential diagnosis that includes metabolic, congestive, neoplastic, infectious, toxic, and inflammatory conditions. Among the metabolic diseases, lysosomal storage diseases (LSDs) are a group of rare and ultrarare conditions with a collective incidence of 1 in 5000 live births. LSDs are caused by genetic variants affecting the lysosomal enzymes, transporters, or integral membrane proteins. As a result, abnormal metabolites accumulate in the organelle, leading to dysfunction. Therapeutic advances, including early diagnosis and disease-targeted management, have improved the life expectancy and quality of life of people affected by certain LSDs. To access these new interventions, LSDs must be considered in patients presenting with hepatomegaly and splenomegaly throughout the lifespan. This review article navigates the diagnostic approach for individuals with hepatosplenomegaly particularly focusing on LSDs. We provide hints in the history, physical exam, laboratories, and imaging that may identify LSDs. Additionally, we discuss molecular testing, arguably the preferred confirmatory test (over biopsy), accompanied by enzymatic testing when feasible.

Prenatal molecular genetic testing for familial variants that cause inherited disorders has been performed for decades and is accepted as standard of care. However, the spectrum of genes considered for prenatal testing is expanding because of genetic testing for hereditary cancer risk (HCR) and inclusion of conditions with associated cancer risk in carrier screening panels. A few of these disorders, such as ataxia telangiectasia and Bloom syndrome, include increased cancer risk as part of the phenotype, already meet professional guidelines for prenatal testing, and may be associated with increased cancer risk in heterozygous carriers. In addition, recent studies implicate heterozygosity for variants in lysosomal storage disease genes in HCR etiology. Currently, there is no specific professional guidance regarding prenatal testing for HCR. To determine the prevalence of such testing, we reviewed 1345 consecutive prenatal specimens received in our laboratory for familial variant-specific testing and identified 65 (4.8%) with a known or likely HCR component, plus 210 (15.6%) for lysosomal storage disease. These specimens were classified into five distinct categories for clarity and to enable evaluation. Our experience assessing prenatal specimens for variants associated with HCR, with or without a constitutional phenotype, provides metrics for and contributes to the points to consider in prenatal testing for HCR., (Copyright © 2024 Association for Molecular Pathology and American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Sulfatases catalyze essential cellular reactions, including degradation of glycosaminoglycans (GAGs). All sulfatases are post-translationally activated by the formylglycine generating enzyme (FGE) which is deficient in multiple sulfatase deficiency (MSD), a neurodegenerative lysosomal storage disease. Historically, patients were presumed to be deficient of all sulfatase activities; however, a more nuanced relationship is emerging. Each sulfatase may differ in their degree of post-translational modification by FGE, which may influence the phenotypic spectrum of MSD. Here, we evaluate if residual sulfatase activity and accumulating GAG patterns distinguish cases from controls and stratify clinical severity groups in MSD. We quantify sulfatase activities and GAG accumulation using three complementary methods in MSD participants. Sulfatases differed greatly in their tolerance of reduction in FGE-mediated activation. Enzymes that degrade heparan sulfate (HS) demonstrated lower residual activities than those that act on other GAGs. Similarly, HS-derived urinary GAG subspecies preferentially accumulated, distinguished cases from controls, and correlated with disease severity. Accumulation patterns of specific sulfatase substrates in MSD provide fundamental insights into sulfatase regulation and will serve as much-needed biomakers for upcoming clinical trials. This work highlights that biomarker investigation of an ultra-rare disease can simultaneously inform our understanding of fundamental biology and advance clinical trial readiness efforts., (© 2023 SSIEM.)

Mucopolysaccharidosis type VII (MPS VII) is an ultra-rare, life-threatening, progressive disease caused by genetic mutations that affect lysosomal storage/function. MPS VII has an estimated prevalence of <1:1,000,000 and accounts for <3% of all MPS diagnoses. Given the rarity of MPS VII, comprehensive information on the disease is limited and we present a review of the current understanding. In MPS VII, intracellular glycosaminoglycans accumulate due to a deficiency in the lysosomal enzyme that is responsible for their degradation, β-glucuronidase, which is encoded by the GUSB gene. MPS VII has a heterogeneous presentation. Features can manifest across multiple systems and can vary in severity, age of onset and progression. The single most distinguishing clinical feature of MPS VII is non-immune hydrops fetalis (NIHF), which presents during pregnancy. MPS VII usually presents within one month of life and become more prominent at 3 to 4 years of age; key features are skeletal deformities, hepatosplenomegaly, coarse facies, and cognitive impairment, although phenotypic variation is a hallmark. Current treatments include hematopoietic stem cell transplantation and enzyme replacement therapy with vestronidase alfa. Care should be individualized for each patient. Development of consensus guidelines for MPS VII management and treatment is needed, as consolidation of expert knowledge and experience (for example, through the MPS VII Disease Monitoring Program) may provide a significant positive impact to patients., Competing Interests: Declaration of competing interest Deborah Marsden is an employee and shareholder of Ultragenyx Pharmaceutical Inc. Fatih Ezgü has been an investigator for Ultragenyx clinical trials. Christina Grant has received honoraria from Sanofi and Amicus Therapeutics, and her place of employment received research support from Ultragenyx. Jaime López-Valdez has received research funding and grants from Ultragenyx., (Copyright © 2023. Published by Elsevier Inc.)

Background: Metachromatic leukodystrophy (MLD) is an autosomal recessive lysosomal storage disease caused by deficiency in arylsulfatase A (ASA) activity arising primarily from ASA gene (ARSA) variants. Late-infantile, juvenile and adult clinical subtypes are defined by symptom onset at ≤ 2.5, > 2.5 to < 16 and ≥ 16 years, respectively. Epidemiological data were sought to address knowledge gaps and to inform decisions regarding the clinical development of an investigational drug., Methods: To synthesize all available estimates of MLD incidence and birth prevalence worldwide and in selected countries, Ovid MEDLINE and Embase were searched systematically (March 11, 2022) using a population, intervention, comparator, outcome, time and setting framework, complemented by pragmatic searching to reduce publication bias. Where possible, results were stratified by clinical subtype. Data were extracted from non-interventional studies (clinical trials, non-clinical studies and case reports were excluded; reviews were used for snowballing only)., Results: Of the 31 studies included, 14 reported birth prevalence (13 countries in Asia-Pacific, Europe, the Middle East, North America and South America), one reported prevalence and none reported incidence. Birth prevalence per 100,000 live births ranged from 0.16 (Japan) to 1.85 (Portugal). In the three European studies with estimates stratified by clinical subtypes, birth prevalence was highest for late-infantile cases (0.31-1.12 per 100,000 live births). The distribution of clinical subtypes reported in cases diagnosed over various time periods in 17 studies varied substantially, but late-infantile and juvenile MLD accounted for at least two-thirds of cases in most studies., Conclusions: This review provides a foundation for further analysis of the regional epidemiology of MLD. Data gaps indicate the need for better global coverage, increased use of epidemiological measures (e.g. prevalence estimates) and more stratification of outcomes by clinical and genetic disease subtype., (© 2024. The Author(s).)

The brain is, after the adipose tissue, the organ with the greatest amount of lipids and diversity in their composition in the human body. In neurons, lipids are involved in signaling pathways controlling autophagy, a lysosome-dependent catabolic process essential for the maintenance of neuronal homeostasis and the function of the primary cilium, a cellular antenna that acts as a communication hub that transfers extracellular signals into intracellular responses required for neurogenesis and brain development. A crosstalk between primary cilia and autophagy has been established; however, its role in the control of neuronal activity and homeostasis is barely known. In this review, we briefly discuss the current knowledge regarding the role of autophagy and the primary cilium in neurons. Then we review the recent literature about specific lipid subclasses in the regulation of autophagy, in the control of primary cilium structure and its dependent cellular signaling in physiological and pathological conditions, specifically focusing on neurons, an area of research that could have major implications in neurodevelopment, energy homeostasis, and neurodegeneration., Competing Interests: None

The ceroid lipofuscinosis neuronal 1 (CLN1) disease, formerly called infantile neuronal ceroid lipofuscinosis, is a fatal hereditary neurodegenerative lysosomal storage disorder. This disease is caused by loss-of-function mutations in the CLN1 gene, encoding palmitoyl-protein thioesterase-1 (PPT1). PPT1 catalyzes depalmitoylation of S-palmitoylated proteins for degradation and clearance by lysosomal hydrolases. Numerous proteins, especially in the brain, require dynamic S-palmitoylation (palmitoylation-depalmitoylation cycles) for endosomal trafficking to their destination. While 23 palmitoyl-acyl transferases in the mammalian genome catalyze S-palmitoylation, depalmitoylation is catalyzed by thioesterases such as PPT1. Despite these discoveries, the pathogenic mechanism of CLN1 disease has remained elusive. Here, we report that in the brain of Cln1 -/- mice, which mimic CLN1 disease, the mechanistic target of rapamycin complex-1 (mTORC1) kinase is hyperactivated. The activation of mTORC1 by nutrients requires its anchorage to lysosomal limiting membrane by Rag GTPases and Ragulator complex. These proteins form the lysosomal nutrient sensing scaffold to which mTORC1 must attach to activate. We found that in Cln1 -/- mice, two constituent proteins of the Ragulator complex (vacuolar (H + )-ATPase and Lamtor1) require dynamic S-palmitoylation for endosomal trafficking to the lysosomal limiting membrane. Intriguingly, Ppt1 deficiency in Cln1 -/- mice misrouted these proteins to the plasma membrane disrupting the lysosomal nutrient sensing scaffold. Despite this defect, mTORC1 was hyperactivated via the IGF1/PI3K/Akt-signaling pathway, which suppressed autophagy contributing to neuropathology. Importantly, pharmacological inhibition of PI3K/Akt suppressed mTORC1 activation, restored autophagy, and ameliorated neurodegeneration in Cln1 -/- mice. Our findings reveal a previously unrecognized role of Cln1/Ppt1 in regulating mTORC1 activation and suggest that IGF1/PI3K/Akt may be a targetable pathway for CLN1 disease., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Published by Elsevier Inc.)

Fabry disease (FD) is a rare, X-linked lysosomal storage disorder affecting both males and females caused by genetic abnormalities in the gene encoding the enzyme α-galactosidase A. FD-affected patients represent a highly variable clinical course with first symptoms already appearing in young age. The disease causes a progressive multiple organ dysfunction affecting mostly the heart, kidneys and nervous system, eventually leading to premature death. Disease-specific management of FD includes enzyme replacement therapy with agalsidase α and β or pharmacological oral chaperone migalastat. Migalastat is a low-molecular-mass iminosugar, that reversibly binds to active site of amenable enzyme variants, stabilizing their molecular structure and improving trafficking to the lysosome. Migalastat was approved in the EU in 2016 and is an effective therapy in the estimated 35-50% of all patients with FD with amenable GLA gene variants. This position statement is the first comprehensive review in Central and Eastern Europe of the current role of migalastat in the treatment of FD. The statement provides an overview of the pharmacology of migalastat and summarizes the current evidence from the clinical trial program regarding the safety and efficacy of the drug and its effects on organs typically involved in FD. The position paper also includes a practical guide for clinicians on the optimal selection of patients with FD who will benefit from migalastat treatment, recommendations on the optimal selection of diagnostic tests and the use of tools to identify patients with amenable GLA mutations. Areas for future migalastat clinical research have also been identified., (© 2024. The Author(s).)

Leukodystrophies are a heterogeneous group of rare genetic disorders primarily affecting the white matter of the central nervous system. These conditions can present a diagnostic challenge, requiring a comprehensive approach that combines clinical evaluation, neuroimaging, metabolic testing, and genetic testing. While MRI is the main tool for diagnosis, advances in molecular diagnostics, particularly whole-exome sequencing, have significantly improved the diagnostic yield. Timely and accurate diagnosis is crucial to guide symptomatic treatment and assess eligibility to participate in clinical trials. Despite no specific cure being available for most leukodystrophies, gene therapy is emerging as a potential treatment avenue, rapidly advancing the therapeutic prospects in leukodystrophies. This review will explore diagnostic and therapeutic strategies for leukodystrophies, with particular emphasis on new trials., (© 2023. The Author(s).)

Glycosaminoglycans (GAGs) are sulfated polysaccharides comprising repeating disaccharides, uronic acid (or galactose) and hexosamines, including chondroitin sulfate, dermatan sulfate, heparan sulfate, and keratan sulfate. Hyaluronan is an exception in the GAG family because it is a non-sulfated polysaccharide. Lysosomal enzymes are crucial for the stepwise degradation of GAGs to provide a normal function of tissues and extracellular matrix (ECM). The deficiency of one or more lysosomal enzyme(s) results in the accumulation of undegraded GAGs, causing cell, tissue, and organ dysfunction. Accumulation of GAGs in various tissues and ECM results in secretion into the circulation and then excretion in urine. GAGs are biomarkers of certain metabolic disorders, such as mucopolysaccharidoses (MPS) and mucolipidoses. GAGs are also elevated in patients with various conditions such as respiratory and renal disorders, fatty acid metabolism disorders, viral infections, vomiting disorders, liver disorders, epilepsy, hypoglycemia, myopathy, developmental disorders, hyperCKemia, heart disease, acidosis, and encephalopathy. MPS are a group of inherited metabolic diseases caused by the deficiency of enzymes required to degrade GAGs in the lysosome. Eight types of MPS are categorized based on lack or defect in one of twelve specific lysosomal enzymes and are described as MPS I through MPS X (excluding MPS V and VIII). Clinical features vary with the type of MPS and clinical severity of the disease. This chapter addresses the historical overview, synthesis, degradation, distribution, biological role, and method for measurement of GAGs., (Copyright © 2024. Published by Elsevier Inc.)

Glucosylsphingosine (lyso-GL1) is a biomarker used to monitor disease and treatment response in Gaucher disease. Data from adults show that higher values of lyso-GL1 are associated with increased disease progression, however similar data in the pediatric population is lacking. In a cohort of pediatric patients, we present a relationship between lyso-GL1 value and Gaucher type, age, and treatment response. Data from this study may serve as a reference for providers monitoring children with Gaucher disease., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Nanoparticles have been used in neurological research in recent years because of their blood-brain barrier penetration activity. However, their potential neuronanotoxicity remains a concern. In particular, microglia, which are resident phagocytic cells, are mainly exposed to nanoparticles in the brain. We investigated the changes in lysosomal function in silica-coated magnetic nanoparticles containing rhodamine B isothiocyanate dye [MNPs@SiO 2 (RITC)]-treated BV2 murine microglial cells. In addition, we analyzed amyloid beta (Aβ) accumulation and molecular changes through the integration of transcriptomics, proteomics, and metabolomics (triple-omics) analyses. Aβ accumulation significantly increased in the 0.1 μg/μl MNPs@SiO 2 (RITC)-treated BV2 cells compared to the untreated control and 0.01 μg/μl MNPs@SiO 2 (RITC)-treated BV2 cells. Moreover, the MNPs@SiO 2 (RITC)-treated BV2 cells showed lysosomal swelling, a dose-dependent reduction in proteolytic activity, and an increase in lysosomal swelling- and autophagy-related protein levels. Moreover, proteasome activity decreased in the MNPs@SiO 2 (RITC)-treated BV2 cells, followed by a concomitant reduction in intracellular adenosine triphosphate (ATP). By employing triple-omics and a machine learning algorithm, we generated an integrated single molecular network including reactive oxygen species (ROS), autophagy, lysosomal storage disease, and amyloidosis. In silico analysis of the single triple omics network predicted an increase in ROS, suppression of autophagy, and aggravation of lysosomal storage disease and amyloidosis in the MNPs@SiO 2 (RITC)-treated BV2 cells. Aβ accumulation and lysosomal swelling in the cells were alleviated by co-treatment with glutathione (GSH) and citrate. These findings suggest that MNPs@SiO 2 (RITC)-induced reduction in lysosomal activity and proteasomes can be recovered by GSH and citrate treatment. These results also highlight the relationship between nanotoxicity and Aβ accumulation., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Canadian patients and families affected by rare genetic lysosomal storage diseases (LSDs) suffer from numerous challenges related to disease management, including issues navigating healthcare and social support services, access to orphan drugs, and intensive treatment regimens. These challenges significantly impact people's quality of life, yet they remain obscure and have not been the subject of comprehensive analysis. Thus, we conducted qualitative interviews with Canadian patients and caregivers living with LSDs to advance current understanding of their experiences with rare-disease (RD) management and health systems navigation to support patient-focused RD policies and programs and improve the health outcomes of the 2.8 million Canadians affected by RDs. This study employed a qualitative descriptive research design with inductive thematic analysis. The study data were collected using semi-structured interviews. Thirty Canadian participants were interviewed in person or remotely via video chat to allow for an interactive discussion and the acquisition of rich data related to the insights and perceptions of people with LSDs. Between April and November 2019, 30 participants (16 patients and 14 caregivers) with experiences with nine types of LSDs and living in seven Canadian provinces were interviewed. Five themes were identified using comprehensive thematic analysis. These themes were the complexity of the diagnosis process; navigation of healthcare systems; psychological, social, and financial implications of LSDs; access to social support services; and access to orphan drugs. Our findings reveal that patients' access to appropriate healthcare and social services is subject to significant delays and lacks care coordination. The process of accessing orphan drugs in Canada is extremely complex and convoluted. The study results also illuminate experiences of RD stigma when navigating healthcare and social support systems. Our study offers new insights into the complex nature and extensive needs of Canadians with LSDs that are currently unmet. The management of these complex diseases requires holistic patient care and support beyond having access to orphan drugs. Our findings highlight the importance of bridging existing gaps between health and social care for RD patients. Policymakers should utilize these results when developing the forthcoming national RD strategy., Competing Interests: The authors declare that they have no competing interests., (© 2023 The Authors. JIMD Reports published by John Wiley & Sons Ltd on behalf of SSIEM.)