Inborn Errors of Metabolism Involving Complex Molecules: Lysosomal and Peroxisomal Storage Diseases

Safety outcomes and patients' preferences for home-based intravenous enzyme replacement therapy (ERT) in pompe disease and mucopolysaccharidosis type I (MPS I) disorder: COVID-19 and beyond

BACKGROUND

The Italian Medicines Agency (AIFA) demands precise information on benefit/risk profile of home-based enzyme replacement therapy (ERT) for the treatment of patients with Pompe disease and Mucopolysaccharidosis type I (MPS I). This passage is necessary to obtain the authorization for ERT home therapy, even after the coronavirus disease-19 (COVID-19) pandemic period. This research intends to evaluate the safety, treatment satisfaction, and compliance of MPS I patients treated with laronidase (Aldurazyme®) and Pompe Disease patients treated with alglucosidase alfa (Myozyme®) in a homecare setting.

RESULTS

We report herein an early interim analysis of the HomERT (Home infusions of ERT) study, a multicenter, non-interventional, double-cohort study that retrospectively analyzed 38 patients from 14 sites in Italy: cohort A (Pompe disease - 32 patients) and cohort B (MPS I - 6 patients). Among the selected patients who started home therapy before enrollment, the average number of missed home-based infusions was 0.7 (1.3) in cohort A and 3.8 (6.4) in cohort B with no return to the hospital setting. Irrespective of the treatment location, 3 prior ADRs per cohort were reported. The majority of patients preferred home-based infusions (cohort A: 96.9%; cohort B: 100%): the main reason was attributed to treatment convenience (cohort A: 81.3%; cohort B: 83.3%). Despite the underlying conditions, most patients self-evaluated their health as "good" (cohort A: 50%; cohort B: 83.3%).

CONCLUSIONS

Evidence of favorable safety profile, improved treatment compliance and personal satisfaction validates the use of ERT with laronidase and alglucosidase alfa as a strong candidate for home therapy.

Expert-opinion-based guidance for the care of children with lysosomal storage diseases during the COVID-19 pandemic: An experience-based Turkey perspective

This expert-opinion-based document was prepared by a group of specialists in pediatric inherited metabolic diseases and infectious diseases including administrative board members of Turkish Society for Pediatric Nutrition and Metabolism to provide guidance for the care of children with lysosomal storage disorders (LSDs) during the COVID-19 pandemic in Turkey. The experts reached consensus on key areas of focus regarding COVID-19-based risk status in relation to intersecting immune-inflammatory mechanisms and disease patterns in children with LSDs, diagnostic virus testing, particularly preventive measures and priorities during the pandemic, routine screening and diagnostic interventions for LSDs, psychological and socioeconomic impact of confinement measures and quarantines and optimal practice patterns in managing LSDs and/or COVID-19. The participating experts agreed on the intersecting characteristics of immune-inflammatory mechanisms, end-organ damage and prognostic biomarkers in LSD and COVID-19 populations, emphasizing the likelihood of enhanced clinical care when their interaction is clarified via further studies addressing certain aspects related to immunity, lysosomal dysfunction and disease pathogenesis. In the context of the current global COVID-19 pandemic, this expert-opinion-based document provides guidance for the care of children with LSDs during the COVID-19 pandemic based on the recent experience in Turkey.

Using analogue data to substantiate long-term durability of gene therapies: a narrative review

The number of gene therapies in clinical trials and moving toward licensure is increasing. Most gene therapies are designed to achieve long-term effects, but at licensure the data to support claims of long-term durability are often limited, as long-term monitoring studies are often part of post-approval commitments by companies. Health technology assessors must therefore assess the potential for the long-term durability of a product and the potential cost-effectiveness based on the data available. The authors explored the benefit of strengthening the ability to infer durability of effect using analogue category data. Different analogue categories were assessed for the potential to substantiate claims of sustainability of effect for gene therapies by leveraging biological plausibility arguments. The authors propose a pathway for identifying potential analogues. Such a pathway should help establish plausible or theoretical long-term outcomes that can be considered in value assessments of gene therapies.

Stem Cell Research Tools in Human Metabolic Disorders: An Overview

Metabolic disorders are very common in the population worldwide and are among the diseases with the highest health utilization and costs per person. Despite the ongoing efforts to develop new treatments, currently, for many of these disorders, there are no approved therapies, resulting in a huge economic hit and tension for society. In this review, we recapitulate the recent advancements in stem cell (gene) therapy as potential tools for the long-term treatment of both inherited (lysosomal storage diseases) and acquired (diabetes mellitus, obesity) metabolic disorders, focusing on the main promising results observed in human patients and discussing the critical hurdles preventing the definitive jump of this approach from the bench to the clinic.

Movement Disorders and Liver Disease

The association of movement disorders with structural or functional hepatic disease occurs in three principal scenarios: (1) combined involvement of both organ systems from a single disease entity, (2) nervous system dysfunction resulting from exposure to toxic compounds in the setting of defective hepatic clearance, or (3) hepatic and/or neurological injury secondary to exposure to exogenous drugs or toxins. An important early step in the workup of any patient with combined movement disorders and liver disease is the exclusion of Wilson's disease. Diagnostic delay remains common for this treatable disorder, and this has major implications for patient outcomes. Thereafter, a structured approach integrating variables such as age of onset, tempo of progression, nature and severity of liver involvement, movement disorder phenomenology, exposure to drugs/toxins and laboratory/neuroimaging findings is key to ensuring timely diagnosis and disease‐specific therapy. Herein, we provide an overview of disorders which may manifest with a combination of movement disorders and liver disease, structured under the three headings as detailed above. In each section, the most common disorders are discussed, along with important clinical pearls, suggested diagnostic workup, differential diagnoses and where appropriate, treatment considerations.

MPSBase: Comprehensive repository of differentially expressed genes for mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are lysosomal storage diseases (LSDs) caused by the deficiency of enzymes essential for the metabolism of extracellular matrix components called glycosaminoglycans (GAGs). To understand the physiopathology and alterations due to the lysosomal accumulation resulting from enzymatic deficiencies and their secondary outcomes can improve the diagnosis and treatment of rare genetic diseases. This work presents a database for differentially expressed genes from different public MPS data. We developed our database, including 13 studies previously deposited in the GEO (https://www.ncbi.nlm.nih.gov/geo/). The website is hosted in the UFRGS data processing center (CPD) and is available at <https://www.ufrgs.br/mpsbase/>. The site was constructed in PHP, and the analyses were performed in R. The organisms represented by the datasets are Canis lupus familiaris, Homo sapiens, Mus musculus, and Rattus norvegicus. The user can search for the differentially expressed genes and ontologies by species, MPS type, or tissue type. For each comparison, a heatmap with the 50 top differentially expressed genes is available as well as dot plots for the 30 top ontologies divided by biological process, cellular component, KEGG pathways, and molecular function. This data is also fully available in tables. There are 54 possible comparisons involving about 5000 to 10,000 genes each. This website is the only specific database for MPS with filtering and presenting their results in a one-click approach to the best of our knowledge. The development of such analytical and automated strategies accessible to health professionals is essential for fostering MPS research. The MPSBase is a web user-friendly, comprehensive repository of differentially expressed genes and ontologies regarding the MPS data.

Levels of Lyso GL-1 in Gaucher and Lyso GL-3 in Fabry patients from India: Diagnostic aids for these lysosomal storage disorders

BACKGROUND & AIMS

Lysosomal storage disorders (LSDs) remain a significant cause of morbidity in the Indian population and treatment is largely out of reach for most patients. Although data on enzymatic and molecular diagnosis of Gaucher disease (GD) and Fabry disease (FD) in Indian patients are available, the present study intended to establish the pathogenic levels of Lyso GL-1 and Lyso GL-3 in patients of GD and FD respectively as diagnostic aids.

MATERIALS AND METHODS

From 2017 to 2019, ninety confirmed Gaucher cases (by enzymatic and molecular analysis) were tested for chitotriosidase (fluorometrically) and Lyso GL-1 (LC-MS/MS) and ten confirmed Fabry cases were analyzed for Lyso GL-3 (LC-MS/MS).

RESULTS

Lyso GL-1 (median: 685.5 ng/mL, cut-off: 14) and Lyso GL-3 (median: 75.6 ng/mL, cut-off: 3.5) were found to be elevated in all enzymatically deficient patients of GD and FD respectively, however, no specific trend was observed between the levels of these biomarkers and the pathogenic variant(s) present in the patients of these disorders.

CONCLUSIONS

This is the first report on Lyso GL-1 and Lyso GL-3 levels in Indian patients of GD and FD respectively. These results will be useful for early diagnosis to improve management of these LSDs.

Metabolic Seizures

Metabolic diseases should always be considered when evaluating children presenting with seizures. This is because many metabolic disorders are potentially treatable and seizure control can be achieved when these diseases are appropriately treated. Seizures caused by underlying metabolic diseases (metabolic seizures) should be particularly considered in unexplained neonatal seizures, refractory seizures, seizures related to fasting or food intake, seizures associated with other systemic or neurologic features, parental consanguinity, and family history of epilepsy. Metabolic seizures can be caused by various amino acids metabolic disorders, disorders of energy metabolism, cofactor-related metabolic diseases, purine and pyrimidine metabolic diseases, congenital disorders of glycosylation, and lysosomal and peroxisomal disorders. Diagnosing metabolic seizures without delay is essential because the immediate initiation of appropriate therapy for many metabolic diseases can prevent or minimize complications.

Sphingolipid lysosomal storage diseases: from bench to bedside

Johann Ludwig Wilhelm Thudicum described sphingolipids (SLs) in the late nineteenth century, but it was only in the past fifty years that SL research surged in importance and applicability. Currently, sphingolipids and their metabolism are hotly debated topics in various biochemical fields. Similar to other macromolecular reactions, SL metabolism has important implications in health and disease in most cells. A plethora of SL-related genetic ailments has been described. Defects in SL catabolism can cause the accumulation of SLs, leading to many types of lysosomal storage diseases (LSDs) collectively called sphingolipidoses. These diseases mainly impact the neuronal and immune systems, but other systems can be affected as well. This review aims to present a comprehensive, up-to-date picture of the rapidly growing field of sphingolipid LSDs, their etiology, pathology, and potential therapeutic strategies. We first describe LSDs biochemically and briefly discuss their catabolism, followed by general aspects of the major diseases such as Gaucher, Krabbe, Fabry, and Farber among others. We conclude with an overview of the available and potential future therapies for many of the diseases. We strive to present the most important and recent findings from basic research and clinical applications, and to provide a valuable source for understanding these disorders.

Exploiting the Potential of Drosophila Models in Lysosomal Storage Disorders: Pathological Mechanisms and Drug Discovery

Lysosomal storage disorders (LSDs) represent a complex and heterogeneous group of rare genetic diseases due to mutations in genes coding for lysosomal enzymes, membrane proteins or transporters. This leads to the accumulation of undegraded materials within lysosomes and a broad range of severe clinical features, often including the impairment of central nervous system (CNS). When available, enzyme replacement therapy slows the disease progression although it is not curative; also, most recombinant enzymes cannot cross the blood-brain barrier, leaving the CNS untreated. The inefficient degradative capability of the lysosomes has a negative impact on the flux through the endolysosomal and autophagic pathways; therefore, dysregulation of these pathways is increasingly emerging as a relevant disease mechanism in LSDs. In the last twenty years, different LSD Drosophila models have been generated, mainly for diseases presenting with neurological involvement. The fruit fly provides a large selection of tools to investigate lysosomes, autophagy and endocytic pathways in vivo, as well as to analyse neuronal and glial cells. The possibility to use Drosophila in drug repurposing and discovery makes it an attractive model for LSDs lacking effective therapies. Here, ee describe the major cellular pathways implicated in LSDs pathogenesis, the approaches available for their study and the Drosophila models developed for these diseases. Finally, we highlight a possible use of LSDs Drosophila models for drug screening studies.

Gene therapy using haematopoietic stem and progenitor cells

Haematopoietic stem and progenitor cell (HSPC) gene therapy has emerged as an effective treatment modality for monogenic disorders of the blood system such as primary immunodeficiencies and β-thalassaemia. Medicinal products based on autologous HSPCs corrected using lentiviral and gammaretroviral vectors have now been approved for clinical use, and the site-specific genome modification of HSPCs using gene editing techniques such as CRISPR-Cas9 has shown great clinical promise. Preclinical studies have shown engineered HSPCs could also be used to cross-correct non-haematopoietic cells in neurodegenerative metabolic diseases. Here, we review the most recent advances in HSPC gene therapy and discuss emerging strategies for using HSPC gene therapy for a range of diseases.

Impact of COVID-19 related healthcare crisis on treatments for patients with lysosomal storage disorders, the first Italian experience

The direct and indirect effects of Coronavirus Disease-19 (COVID-19) pandemic, on Italian patients with lysosomal storage disorders receiving therapy, were analyzed by a phone questionnaire. No proved COVID-19 emerged among 102 interviewed. No problems were reported by patients receiving oral treatments. Forty-nine% of patients receiving enzyme replacement therapy in hospitals experienced disruptions, versus 6% of those home-treated. The main reasons of missed infusions were fear of infection (62.9%) and re-organization of the infusion centers (37%).

Health Status of French Young Patients with Inborn Errors of Metabolism with Lifelong Restricted Diet

OBJECTIVE

To describe the health status of young patients affected by inborn errors of metabolism that require adherence to a restricted diet (IEMRDs) and to describe and compare their self- and proxy (parent)-reported quality of life (QoL) with reference values.

STUDY DESIGN

A cross-sectional study was conducted in 2015-2017 in patients affected by IEMRDs (except phenylketonuria) younger than 18 years. Data collection was based on medical records, clinical examinations, parents' and children's interviews, and self-reported questionnaires. Measurements included clinical and healthcare data, child and family environment data, and self- and proxy (parent)-reported QoL.

RESULTS

Of the 633 eligible participants, 578 were recruited (50.3% boys; mean age: 8.7 years); their anthropometric status did not differ from the general population. Approximately one-half of them had at least 1 complication of the disease. Their self-reported global QoL did not differ from that of the general population. However, relations with friends and leisure activities QoL domains were negatively impacted, whereas relations with medical staff, relations with parents, and self-esteem QoL domains were positively impacted. Their proxy (parent)-reported QoL was negatively impacted.

CONCLUSIONS

Young patients affected by IEMRDs present a high rate of clinical complications. Although their proxy (parent)-reported QoL was negatively impacted, their self-reported QoL was variably impacted (both positively and negatively). These results may inform counseling for those who care for affected patients and their families.

Common metabolic disorder (inborn errors of metabolism) concerns in primary care practice

Inborn errors of metabolism (IEMs) are rare genetic or inherited disorders resulting from an enzyme defect in biochemical and metabolic pathways affecting proteins, fats, carbohydrates metabolism or impaired organelle function presenting as complicated medical conditions involving several human organ systems. They involve great complexity of the underlying pathophysiology, biochemical workup, and molecular analysis, and have complicated therapeutic options for management. Age of presentation can vary from infancy to adolescence with the more severe forms appearing in early childhood accompanied by significant morbidity and mortality. The understanding of these complex disorders requires special in-depth training, American Board of Medical Genetics and Genomics (ABMGG) certification and experience. Most primary care physicians (PCPs) are reluctant to deal with IEM due to unfamiliarity and rarity of such conditions compounded by prompt progression to crisis situations along with paucity of time involved in dealing with such complex disorders. While there are biochemical geneticists aka metabolic specialists' expertise available, mostly in larger academic medical centers, with expertise to deal with these rare complex issues, their initial clinical presentation in most newborns, children, adolescents or adults including asymptomatic positive newborn screen (NBS), occur in the out-patient PCP settings. Therefore, it is important that PCPs' comfort to recognize early signs and symptoms is important to initiate appropriate diagnostic and therapeutic interventions, and be able to make appropriate referrals. The following article reviews common IEM clinical presentations for a robust diagnostic differential and discuss evaluation and management approaches of patients with known or suspected IEM.