Assessing the quality and value of metabolic chart data for capturing core outcomes for pediatric medium-chain acyl-CoA dehydrogenase (MCAD) deficiency.

Background: Generating rigorous evidence to inform care for rare diseases requires reliable, sustainable, and longitudinal measurement of priority outcomes. Having developed a core outcome set for pediatric medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, we aimed to assess the feasibility of prospective measurement of these core outcomes during routine metabolic clinic visits.

Methods: We used existing cohort data abstracted from charts of 124 children diagnosed with MCAD deficiency who participated in a Canadian study which collected data from birth to a maximum of 11 years of age to investigate the frequency of clinic visits and quality of metabolic chart data for selected outcomes.

Intrathecal delivery of a bicistronic AAV9 vector expressing β-hexosaminidase A corrects Sandhoff disease in a murine model: A dosage study.

The pathological accumulation of GM2 ganglioside associated with Tay-Sachs disease (TSD) and Sandhoff disease (SD) occurs in individuals who possess mutant forms of the heterodimer β-hexosaminidase A (Hex A) because of mutation of the and genes, respectively. With a lack of approved therapies, patients experience rapid neurological decline resulting in early death. A novel bicistronic vector carrying both and previously demonstrated promising results in mouse models of SD following neonatal intravenous administration, including significant reduction in GM2 accumulation, increased levels of Hex A, and a 2-fold extension of survival.

Characterization of a phenotypically severe animal model for human AB-Variant GM2 gangliosidosis.

AB-Variant GM2 gangliosidosis (ABGM2) is a rare and lethal genetic disorder caused by mutations in the gene that lead to fatal accumulation of GM2 gangliosides (GM2) in neurons of the central nervous system (CNS). encodes a transport protein known as GM2 activator (GM2A) protein, which is essential for degrading GM2 into their GM3 form. ABGM2 presents in infantile-, juvenile-, and adult-onset forms; of the three, the infantile-onset is the most prominent, and by far the most severe, as evidenced by high levels of GM2 accumulation, widespread neurodegeneration, and death by the age of 4.

Efficacy of Adeno-Associated Virus Serotype 9-Mediated Gene Therapy for AB-Variant GM2 Gangliosidosis.

GM2 gangliosidoses are a group of neurodegenerative lysosomal storage disorders that are characterized by the accumulation of GM2 gangliosides (GM2), leading to rapid neurological decline and death. The hydrolysis of GM2 requires the specific synthesis, processing, and combination of products of three genes-, , and -within the cell's lysosomes. Mutations in these genes result in Tay-Sachs disease, Sandhoff disease, or AB-variant GM2 gangliosidosis (ABGM2), respectively.

Biochemical Correction of GM2 Ganglioside Accumulation in AB-Variant GM2 Gangliosidosis.

GM2 gangliosidosis is a group of genetic disorders that result in the accumulation of GM2 ganglioside (GM2) in brain cells, leading to progressive central nervous system (CNS) atrophy and premature death in patients. AB-variant GM2 gangliosidosis (ABGM2) arises from loss-of-function mutations in the GM2 activator protein (GM2AP), which is essential for the breakdown of GM2 in a key catabolic pathway required for CNS lipid homeostasis. In this study, we show that intrathecal delivery of self-complementary adeno-associated virus serotype-9 (scAAV9) harbouring a functional human transgene () can prevent GM2 accumulation in in GM2AP-deficient mice ( mice).

Gene Expression Profile in the Sandhoff Mouse Brain with Progression of Age.

Sandhoff disease (SD) is a fatal neurodegenerative disorder belonging to the family of diseases called GM2 Gangliosidosis. There is no curative treatment of SD. The molecular pathogenesis of SD is still unclear though it is clear that the pathology initiates with the build-up of ganglioside followed by microglial activation, inflammation, demyelination and apoptosis, leading to massive neuronal loss.

Bridging clinical care and research in Ontario, Canada: Maximizing diagnoses from reanalysis of clinical exome sequencing data.

We examined the utility of clinical and research processes in the reanalysis of publicly-funded clinical exome sequencing data in Ontario, Canada. In partnership with eight sites, we recruited 287 families with suspected rare genetic diseases tested between 2014 and 2020. Data from seven laboratories was reanalyzed with the referring clinicians.

Immune Responses and Immunosuppressive Strategies for Adeno-Associated Virus-Based Gene Therapy for Treatment of Central Nervous System Disorders: Current Knowledge and Approaches.

Adeno-associated viruses (AAVs) are being increasingly used as gene therapy vectors in clinical studies especially targeting central nervous system (CNS) disorders. Correspondingly, host immune responses to the AAV capsid or the transgene-encoded protein have been observed in various clinical and preclinical studies. Such immune responses may adversely impact patients' health, prevent viral transduction, prevent repeated dosing strategies, eliminate transduced cells, and pose a significant barrier to the potential effectiveness of AAV gene therapy.

Families' healthcare experiences for children with inherited metabolic diseases: protocol for a mixed methods cohort study.

Introduction: Children with inherited metabolic diseases (IMDs) often have complex and intensive healthcare needs and their families face challenges in receiving high-quality, family centred health services. Improvement in care requires complex interventions involving multiple components and stakeholders, customised to specific care contexts. This study aims to comprehensively understand the healthcare experiences of children with IMDs and their families across Canada.

The clinical utility of procainamide-induced late potentials on the signal averaged ECG.

Background: Late potentials (LPs) identified on the signal averaged electrocardiogram (SAECG) are a marker for an increased risk of arrhythmias in Brugada syndrome (BrS). Procainamide is a sodium channel blocker used to diagnose BrS. The effects of Procainamide on the SAECG in those with BrS and the significance of Procainamide-induced LPs are unknown.

Treatment of GM2 Gangliosidosis in Adult Sandhoff Mice Using an Intravenous Self-Complementary Hexosaminidase Vector.

Background: GM2 gangliosidosis is a neurodegenerative, lysosomal storage disease caused by the deficiency of β-hexosaminidase A enzyme (Hex A), an α/β-subunit heterodimer. A novel variant of the human hexosaminidase α-subunit, coded by HEX M, has previously been shown to form a stable homodimer, Hex M, that hydrolyzes GM2 gangliosides (GM2) in vivo.

Materials & Methods: The current study assessed the efficacy of intravenous (IV) delivery of a self-complementary adeno-associated virus serotype 9 (scAAV9) vector incorporating the HEXM transgene, scAAV9/HEXM, including the outcomes based on the dosages provided to the Sandhoff (SD) mice.

Expanding the phenotype of ASXL3-related syndrome: A comprehensive description of 45 unpublished individuals with inherited and de novo pathogenic variants in ASXL3.

The study aimed at widening the clinical and genetic spectrum of ASXL3-related syndrome, a neurodevelopmental disorder, caused by truncating variants in the ASXL3 gene. In this international collaborative study, we have undertaken a detailed clinical and molecular analysis of 45 previously unpublished individuals with ASXL3-related syndrome, as well as a review of all previously published individuals. We have reviewed the rather limited functional characterization of pathogenic variants in ASXL3 and discuss current understanding of the consequences of the different ASXL3 variants.

Family Experiences with Care for Children with Inherited Metabolic Diseases in Canada: A Cross-Sectional Survey.

Background And Objective: Children with inherited metabolic diseases often require complex and highly specialized care. Patient and family-centered care can improve health outcomes that are important to families. This study aimed to examine experiences of family caregivers (parents/guardians) of children diagnosed with inherited metabolic diseases with healthcare to inform strategies to improve those experiences.

Core Outcome Sets for Medium-Chain Acyl-CoA Dehydrogenase Deficiency and Phenylketonuria.

Background: Evidence to guide treatment of pediatric medium-chain acyl-coenzyme A dehydrogenase (MCAD) deficiency and phenylketonuria (PKU) is fragmented because of large variability in outcome selection and measurement. Our goal was to develop core outcome sets (COSs) for these diseases to facilitate meaningful future evidence generation and enhance the capacity to compare and synthesize findings across studies.

Methods: Parents and/or caregivers, health professionals, and health policy advisors completed a Delphi survey and participated in a consensus workshop to select core outcomes from candidate lists of outcomes for MCAD deficiency and PKU.

Investigating Immune Responses to the scAAV9- Gene Therapy Treatment in Tay-Sachs Disease and Sandhoff Disease Mouse Models.

GM2 gangliosidosis disorders are a group of neurodegenerative diseases that result from a functional deficiency of the enzyme β-hexosaminidase A (HexA). HexA consists of an α- and β-subunit; a deficiency in either subunit results in Tay-Sachs Disease (TSD) or Sandhoff Disease (SD), respectively. Viral vector gene transfer is viewed as a potential method of treating these diseases.

A Comprehensive Review: Sphingolipid Metabolism and Implications of Disruption in Sphingolipid Homeostasis.

Sphingolipids are a specialized group of lipids essential to the composition of the plasma membrane of many cell types; however, they are primarily localized within the nervous system. The amphipathic properties of sphingolipids enable their participation in a variety of intricate metabolic pathways. Sphingoid bases are the building blocks for all sphingolipid derivatives, comprising a complex class of lipids.

Haploinsufficiency of PRR12 causes a spectrum of neurodevelopmental, eye, and multisystem abnormalities.

Purpose: Proline Rich 12 (PRR12) is a gene of unknown function with suspected DNA-binding activity, expressed in developing mice and human brains. Predicted loss-of-function variants in this gene are extremely rare, indicating high intolerance of haploinsufficiency.

Methods: Three individuals with intellectual disability and iris anomalies and truncating de novo PRR12 variants were described previously.

Haploinsufficiency of the Sin3/HDAC corepressor complex member SIN3B causes a syndromic intellectual disability/autism spectrum disorder.

Proteins involved in transcriptional regulation harbor a demonstrated enrichment of mutations in neurodevelopmental disorders. The Sin3 (Swi-independent 3)/histone deacetylase (HDAC) complex plays a central role in histone deacetylation and transcriptional repression. Among the two vertebrate paralogs encoding the Sin3 complex, SIN3A variants cause syndromic intellectual disability, but the clinical consequences of SIN3B haploinsufficiency in humans are uncharacterized.

Congenital Chylothorax and Hydrops Fetalis: A Novel Neonatal Presentation of Mutation.

Mutations in the gene are known to cause arteriovenous malformations (AVMs), with evidence of associated lymphatic malformations. We report for the first time, to the best of our knowledge, an infant with mutation presenting with hydrops fetalis and chylothorax, but without an associated AVM. Previously, researchers studying rodents have found chylothorax associated with mutations, and, in previous case reports, researchers have reported on infants with mutations born with hydrops fetalis and AVMs.

Metabolism of Glycosphingolipids and Their Role in the Pathophysiology of Lysosomal Storage Disorders.

Glycosphingolipids (GSLs) are a specialized class of membrane lipids composed of a ceramide backbone and a carbohydrate-rich head group. GSLs populate lipid rafts of the cell membrane of eukaryotic cells, and serve important cellular functions including control of cell-cell signaling, signal transduction and cell recognition. Of the hundreds of unique GSL structures, anionic gangliosides are the most heavily implicated in the pathogenesis of lysosomal storage diseases (LSDs) such as Tay-Sachs and Sandhoff disease.

Liver transplantation for Gaucher disease presenting as neonatal cholestasis: Case report and literature review.

Background: We present a rare case of neonatal cholestasis in a female infant with Gaucher Disease (GD), who received liver transplantation. We review the relevant literature on similar disease presentations.

Methods: A chart review of the index case was performed.