Glycogen Storage Disease Type III Research Articles

METABOLIC DISTURBANCES IN NEUROMUSCULAR DISEASES: I.1A journey through the growing world of muscle glycogenosis

Muscle glycogenosis constitute a growing number of inborn errors of glycogen metabolism. Deficiencies of virtually all enzymes which intervene in the synthesis or degradation of glycogen, may cause glycogen storage disease (GSD) because of aberrant storage or utilization of glycogen. The different GSDs are each denoted by a roman numeral that reflects the historical sequence of their discovery and often also by the name of the author of the first description. Muscle glycogenosis may be subclassified into the following categories: disorders of glycogen synthesis; disorders of glycogen breakdown; disorders of glycolysis; and lysosomal glycogenosis. Clinical features are closely related to the enzyme deficiency, with either exercise intolerance associated with rhabdomyolysis episodes, or permanent muscle weakness. Other organs may also be involved such as heart or liver, depending on the involved enzyme and severity of enzyme deficiency. In-vivo metabolic studies with exercise tests and muscle biopsy are important tools allowing precise diagnosis, but the place of dedicated gene panels is rapidly increasing. The most frequent muscle glycogenosis is McArdle disease (GSDV), Pompe disease (GSDII) and debranching enzyme deficiency (GSDIII), but the field of glycogenosis has been greatly expanded over the past few years with the discovery of new metabolic diseases that have allowed new metabolic pathways to be deciphered. We will emphasize on the clinical and pathological features of recently described muscle glycogenosis caused by GYG1, RBCK1 and PGM1 gene mutations. The initial steps of glycogen synthesis are involved in deficiencies of glycogenin-1 (GYG1). Phosphoglucomutase deficiency disrupts two metabolic pathways: the connection between galactose and glycogen on the one hand, and glucose metabolism on the other. On the other hand, the metabolic consequences of mutations in the ubiquitin ligase gene RBCK1 are still poorly understood.

Whole-Body Muscle Magnetic Resonance Imaging in Glycogen-Storage Disease Type III.

The main objective of this study was to describe muscle involvement on whole-body magnetic resonance imaging scans in adults at different stages of glycogen-storage disease type III (GSDIII). Fifteen patients, 16-59 years of age, were examined on a 3-T system. The examinations consisted of coronal and axial T1-weighted images or fat images with a Dixon technique, and were scored for 47 muscles using Mercuri's classification. Muscle changes consisted of internal bright signals of fatty replacement. Distribution across muscles showed predominant signal alteration in the lower limbs and postural muscles. This finding is consistent with the overall clinical presentation of GSDIII and the results of heatmap scores. Review of the MRI scans provided new information regarding recurrent muscle changes, particularly in the soleus, gastrocnemius medial head, and thoracic extensor muscles. Whole-body muscle imaging provides clinically relevant information regarding muscle involvement in GSDIII. A severity score may contribute to improved patient management. Muscle Nerve, 2019.

Elucidating the role of Agl in bladder carcinogenesis by generation and characterization of genetically engineered mice.

Amylo-α-1,6-glucosidase,4-α-glucanotransferase (AGL) is an enzyme primarily responsible for glycogen debranching. Germline mutations lead to glycogen storage disease type III (GSDIII). We recently found AGL to be a tumor suppressor in xenograft models of human bladder cancer (BC) and low levels of AGL expression in BC are associated with poor patient prognosis. However, the impact of low AGL expression on the susceptibility of normal bladder to carcinogenesis is unknown. We address this gap by developing a germline Agl knockout (Agl-/-) mouse that recapitulates biochemical and histological features of GSDIII. Agl-/- mice exposed to N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) had a higher BC incidence compared with wild-type mice (Agl+/+). To determine if the increased BC incidence observed was due to decreased Agl expression in the urothelium specifically, we developed a urothelium-specific conditional Agl knockout (Aglcko) mouse using a Uroplakin II-Cre allele. BBN-induced carcinogenesis experiments repeated in Aglcko mice revealed that Aglcko mice had a higher BC incidence than control (Aglfl/fl) mice. RNA sequencing revealed that tumors from Agl-/- mice had 19 differentially expressed genes compared with control mice. An 'Agl Loss' gene signature was developed and found to successfully stratify normal and tumor samples in two BC patient datasets. These results support the role of AGL loss in promoting carcinogenesis and provide a rationale for evaluating Agl expression levels, or Agl Loss gene signature scores, in normal urothelium of populations at risk of BC development such as older male smokers.

Neuromuscular Involvement in Glycogen Storage Disease Type III in Fifty Tunisian Patients: Phenotype and Natural History in Young Patients.

Our aim was to describe the natural history of neuromuscular involvement (NMI) in glycogen storage disease type III (GSDIII). We conducted a longitudinal study of 50 Tunisian patients, 9.87 years old in average. NMI was diagnosed at an average age of 2.66 years and was clinically overt in 85% of patients. Patients with clinical features were older (p = 0.001). Complaints were dominated by exercise intolerance (80%), noticed at 5.33 years in average. Physical signs, observed at 6.75 years in average, were dominated by muscle weakness (62%). Functional impairment was observed in 64% of patients, without any link with age (p = 0.255). Among 33 patients, 7 improved. Creatine kinase (CK) and aspartate aminotransferase (AST) levels were higher with age.Electrophysiological abnormalities, diagnosed in average at 6.5 years, were more frequent after the first decade (p = 0.0005). Myogenic pattern was predominant (42%). Nerve conduction velocities were slow in two patients. Lower caloric intake was associated with more frequent clinical and electrophysiological features. Higher protein intake was related to fewer complaints and physical anomalies. Neuromuscular investigation is warranted even in asymptomatic patients, as early as the diagnosis of GSDIII is suspected. Muscle involvement can be disabling even in children. Favorable evolution is possible in case of optimal diet.

Glucose-free/high-protein diet improves hepatomegaly and exercise intolerance in glycogen storage disease type III mice

Glycogen disease type III (GSDIII), a rare incurable autosomal recessive disorder due to glycogen debranching enzyme deficiency, presents with liver, heart and skeletal muscle impairment, hepatomegaly and ketotic hypoglycemia. Muscle weakness usually worsens to fixed myopathy and cardiac involvement may present in about half of the patients during disease. Management relies on careful follow-up of symptoms and diet. No common agreement was reached on sugar restriction and treatment in adulthood.We administered two dietary regimens differing in their protein and carbohydrate content, high-protein (HPD) and high-protein/glucose-free (GFD), to our mouse model of GSDIII, starting at one month of age. Mice were monitored, either by histological, biochemical and molecular analysis and motor functional tests, until 10 months of age.GFD ameliorated muscle performance up to 10 months of age, while HPD showed little improvement only in young mice. In GFD mice, a decreased muscle glycogen content and fiber vacuolization was observed, even in aged animals indicating a protective role of proteins against skeletal muscle degeneration, at least in some districts. Hepatomegaly was reduced by about 20%. Moreover, the long-term administration of GFD did not worsen serum parameters even after eight months of high-protein diet. A decreased phosphofructokinase and pyruvate kinase activities and an increased expression of Krebs cycle and gluconeogenesis genes were seen in the liver of GFD fed mice.Our data show that the concurrent use of proteins and a strictly controlled glucose supply could reduce muscle wasting, and indicate a better metabolic control in mice with a glucose-free/high-protein diet.

Distinct Clinical and Genetic Findings in Iranian Patients With Glycogen Storage Disease Type 3.

Glycogen storage disease type 3 (GSD-III) is a rare inherited metabolic disorder caused by glycogen debranching enzyme deficiency. Various pathogenic mutations of the AGL gene lead to abnormal accumulation of glycogen in liver, skeletal, and cardiac muscles. Here, we report distinct clinical and genetic data of Iranian patients with GSD-III. Clinical and laboratory data of 5 patients with GSD-III were recorded. Genetic investigation was performed to identify the causative mutations. Three patients had typical liver involvement in childhood and one was diagnosed 2 years after liver transplantation for cirrhosis of unknown etiology. Four patients had vacuolar myopathy with glycogen excess in muscle biopsy. All patients had novel homozygous mutations of the AGL gene namely c.378T>A, c.3295T>C, c.3777G>A, c.2002-2A>G, and c.1183C>T. This is the first comprehensive report of patients with GSD-III in Iran with 2 uncommon clinical presentations and 5 novel mutations in the AGL gene.

A preliminary study of telemedicine for patients with hepatic glycogen storage disease and their healthcare providers: from bedside to home site monitoring

BackgroundThe purpose of this project was to develop a telemedicine platform that supports home site monitoring and integrates biochemical, physiological, and dietary parameters for individual patients with hepatic glycogen storage disease (GSD).Methods and resultsThe GSD communication platform (GCP) was designed with input from software developers, GSD patients, researchers, and healthcare providers. In phase 1, prototyping and software design of the GCP has occurred. The GCP was composed of a GSD App for patients and a GSD clinical dashboard for healthcare providers. In phase 2, the GCP was tested by retrospective patient data entry. The following software functionalities were included (a) dietary registration and prescription module, (b) emergency protocol module, and (c) data import functions for continuous glucose monitor devices and activity wearables. In phase 3, the GSD App was implemented in a pilot study of eight patients with GSD Ia (n = 3), GSD IIIa (n = 1), and GSD IX (n = 4). Usability was measured by the system usability scale (SUS). The mean SUS score was 64/100 [range: 38–93].ConclusionsThis report describes the design, development, and validation process of a telemedicine platform for patients with hepatic GSD. The GCP can facilitate home site monitoring and data exchange between patients with hepatic GSD and healthcare providers under varying circumstances. In the future, the GCP may support cross-border healthcare, second opinion processes and clinical trials, and could possibly also be adapted for other diseases for which a medical diet is the cornerstone.

Late Presentation of Glycogen Storage Disease Type Ia and Iii in Children with Short Stature and Hepatomegaly*

Late Presentation of Glycogen Storage Disease Type Ia and Iii in Children with Short Stature and Hepatomegaly*

Glycogen Storage Disease in Pediatric Population

Introduction: The pathway of glycogen metabolism is regulated by many hormones such as insulin, glucagon, and corticosteroids. Glycogen storage diseases (GSD) most commonly affect muscles, liver, or both and occur in each 20000 to 43000 live birth. They are classified into 12 subtypes, but types I, II, and IX are the most common. Methodology: We conducted this review using a comprehensive search of MEDLINE, PubMed, and EMBASE, from January 2001, through February 2017. The following search terms were used: glycogen storage diseases, Von Gierke disease, Pompe’s disease, Cori Disease, Forbes disease, Andersen’s disease, McArdle disease, neonatal hypoglycemia, neonatal hepatomegaly. Aim: In this review, we aim to study the genetic basis, diagnosis, presentation, and different management approach to various common types of glycogen storage diseases prevalent in pediatric population. Conclusion: There are no cures for any type of glycogen storage diseases presently. Most treatments are designed to control signs and symptoms. The overall goals are primarily avoiding hypoglycemia, hyperlactatemia, hyperuricemia, and hyperlipidemia. Liver transplantation should be deliberated for patients with GSD type IV and for other progressive hepatic types of GSDs in order to avoid hepatic failure or malignancy. More research must be carried out to develop newer and more effective ways of management.

Rescue of GSDIII Phenotype with Gene Transfer Requires Liver- and Muscle-Targeted GDE Expression.

Glycogen storage disease type III (GSDIII) is an autosomal recessive disorder caused by a deficiency of glycogen-debranching enzyme (GDE), which results in profound liver metabolism impairment and muscle weakness. To date, no cure is available for GSDIII and current treatments are mostly based on diet. Here we describe the development of a mouse model of GSDIII, which faithfully recapitulates the main features of the human condition. We used this model to develop and test novel therapies based on adeno-associated virus (AAV) vector-mediated gene transfer. First, we showed that overexpression of the lysosomal enzyme alpha-acid glucosidase (GAA) with an AAV vector led to a decrease in liver glycogen content but failed to reverse the disease phenotype. Using dual overlapping AAV vectors expressing the GDE transgene in muscle, we showed functional rescue with no impact on glucose metabolism. Liverexpression of GDE, conversely, had a direct impact on blood glucose levels. These results provide proof of concept of correction of GSDIII with AAV vectors, and they indicate that restoration of the enzyme deficiency in muscle and liver is necessary to address both the metabolic and neuromuscular manifestations of the disease.

Generation of a GDE heterozygous mutation human embryonic stem cell line WAe001-A-14 by CRISPR/Cas9 editing

Glycogen debranching enzyme (GDE) plays a critical role in glycogenolysis. Mutations in the GDE gene are associated with a metabolic disease known as glycogen storage disease type III (GSDIII). We generated a mutant GDE human embryonic stem cell line, WAe001-A-14, using the CRISPR/Cas9 editing system. This cell line contains a 24-nucleotide deletion within exon-13 of GDE, resulting in 8 amino acids (TRLGISSL) missing of the GDE protein from amino acid position 567 to 575. The WAe001-A-14 cell line maintains typical stem cell morphology, pluripotency and in vitro differentiation potential, and a normal karyotype.

Medical-Nutritional Intervention in a Jordanian Child with Glycogen Storage Disease Type IIIA: Case Report

Abstract Background: Glycogen storage disease (GSD) type IIIa is a rare inborn error of metabolism characterized by a deficiency in glycogen disbranching enzymes. Nutritional intervention is a cornerstone in the medical care plane. Case presentation: A 2-year-old Jordanian male, who is known to have GSD IIIa since he was 4 months was admitted because of infection. The child was on a special diet (small, frequent meals of complex carbohydrates and protein, avoiding simple sugars and fasting is prohibited). The child showed good activity level and a good appetite. Method: The medical-nutritional intervention of GSD IIIa was evaluated by retrograde reviewing the child BMI, blood and biochemical tests on presentation and a month later visit. Results: The biochemical tests included: blood glucose, urea, creatinine, cholesterol, triglycerides, albumin, total bilirubin, aspartate amino transferase (AST), alanine aminotransferase (ALT) and WBCs were decreased after nutritional intervention, however, the RBCs blood test was increased. On presentation, the child’s weight and height were documented as above the 15th and at 97th percentile respectively for his age, no change after the one month later visit was observed. Conclusion: The biochemical and blood tests improved at the one-month follow-up visit vs. baseline. The individualized medical-nutritional intervention is a cornerstone in the management of GSD IIIa as part of a comprehensive medical care process.

P.364 - Autophagy impairment in muscle biopsies from debranching enzyme deficiency (GSDIII) patients: pinpointing novel therapeutic perspectives

P.364 - Autophagy impairment in muscle biopsies from debranching enzyme deficiency (GSDIII) patients: pinpointing novel therapeutic perspectives

Glycogen storage disease IIIa: A private homozygous splice site mutation in AGL gene

BackgroundGlycogen storage disease III (GSD III) is an autosomal recessive metabolic disorder due to disease-causing mutations in amylo-alpha-1, 6-glucosidase, 4-alpha-glucanotransferase (AGL), the gene encoding glycogen debrancher enzyme (GDE). GSD III is usually presented with clinical findings of liver, cardiac muscle, and skeletal muscle. The purpose of this study was to report a 43-year-old Iranian patient affected by a GSD IIIa who had muscle weakness and hepatic and cardiac abnormalities. Materials and methodsTo find the genetic cause of this familial case of GSD, whole exome sequencing utilizing next generation sequencing on an Illumina platform was performed on DNA sample from the proband. In addition, to confirm a novel identified mutation in this patient, Sanger sequencing was carried out using both forward and reverse primers. Moreover, different bioinformatics software and database were used to predict the pathogenicity of this mutation. ResultsA homozygous splice-site mutation in AGL gene (NM_000642.2: c.3837-1G>A) in the patient affected by GSD type IIIa was identified. Using Sanger sequencing, this new mutation was confirmed as homozygous state in the proband. Moreover, this mutation has not been identified in all database and our database, namely BayanGene which represents data of around 500 whole exome sequencing of Iranian Individuals. ConclusionsA deleterious splice site mutation in AGL gene was identified in our patient and adds to many other previous reports and extends the spectrum of GSD IIIa. Such reports help confirm the diagnosis of the disease and to perform accurate genetic counselling for their family members.

Long term longitudinal study of muscle function in patients with glycogen storage disease type IIIa.

Glycogen storage disease type III (GSDIII) is an autosomal recessive disorder caused by mutations in the AGL gene coding for the glycogen debranching enzyme. Current therapy is based on dietary adaptations but new preclinical therapies are emerging. The identification of outcome measures which are sensitive to disease progression becomes critical to assess the efficacy of new treatments in upcoming clinical trials. In order to prepare future longitudinal studies or therapeutic trials with large cohorts, information about disease progression is required. In this study we present preliminary longitudinal data of Motor Function Measure (MFM), timed tests, Purdue pegboard test, and handgrip strength collected over 5 to 9years of follow-up in 13 patients with GSDIII aged between 13 and 56years old. Follow-up for nine of the 13 patients was up to 9years. Similarly to our previous cross-sectional retrospective study, handgrip strength significantly decreased with age in patients older than 37years. MFM scores started to decline after the age of 35. The Purdue pegboard score also significantly reduced with increasing age (from 13years of age) but with large inter-visit variations. The time to stand up from a chair or to climb 4 stairs increased dramatically in some but not all patients older than 30years old. In conclusion, this preliminary longitudinal study suggests that MFM and handgrip strength are the most sensitive muscle function outcome measures in GSDIII patients from the end of their third decade. Sensitive muscle outcome measures remain to be identified in younger GSDIII patients but is challenging as muscle symptoms remain discrete and often present as accumulated fatigue.

Forbes Disease: A Case Report

Glycogen storage disease (GSD) type 3 (Forbes disease) is an autosomal recessive inborn error of metabolism caused by loss of function mutations of the glycogen debranching enzyme (Amylo- 1, 6-glucosidase [AGL]) and (oligo-1,4-1,4-glucanotransferase) gene, which is located at chromosome band 1p21.2. GSD 3 is characterized by the storage of structurally abnormal glycogen, termed limit dextrin, in both skeletal and cardiac muscle and/or liver, with great variability in resultant organ dysfunction. Here we describe a 16 yearold boy diagnosed as a case of epilepsy at the ageof 8. He presented to us with inadequately controlled seizure, profound proximal weakness, hepatosplenomegaly and right-sided ballotable kidney. The final diagnosis of glycogen storage disease was made by clinical features, lab reports and liver histopathology that revealed PAS positive diastase labile glycogen accumulation within swollen hepatocytes. The particular interest of this paper is to present a case of glycogen storage disease and demonstrate the difference between that entity and other storage diseases.Birdem Med J 2017; 7(1): 60-63

Glycogen storage disease type III: diagnosis, genotype, management, clinical course and outcome.

Glycogen storage disease type III (GSDIII) is a rare disorder of glycogenolysis due to AGL gene mutations, causing glycogen debranching enzyme deficiency and storage of limited dextrin. Patients with GSDIIIa show involvement of liver and cardiac/skeletal muscle, whereas GSDIIIb patients display only liver symptoms and signs. The International Study on Glycogen Storage Disease (ISGSDIII) is a descriptive retrospective, international, multi-centre cohort study of diagnosis, genotype, management, clinical course and outcome of 175 patients from 147 families (86 % GSDIIIa; 14 % GSDIIIb), with follow-up into adulthood in 91 patients. In total 58 AGL mutations (non-missense mutations were overrepresented and 21 novel mutations were observed) were identified in 76 families. GSDIII patients first presented before the age of 1.5 years, hepatomegaly was the most common presenting clinical sign. Dietary management was very diverse and included frequent meals, uncooked cornstarch and continuous gastric drip feeding. Chronic complications involved the liver (hepatic cirrhosis, adenoma(s), and/or hepatocellular carcinoma in 11 %), heart (cardiac involvement and cardiomyopathy, in 58 % and 15 %, respectively, generally presenting in early childhood), and muscle (pain in 34 %). Type 2 diabetes mellitus was diagnosed in eight out of 91 adult patients (9 %). In adult patients no significant correlation was detected between (non-) missense AGL genotypes and hepatic, cardiac or muscular complications. This study demonstrates heterogeneity in a large cohort of ageing GSDIII patients. An international GSD patient registry is warranted to prospectively define the clinical course, heterogeneity and the effect of different dietary interventions in patients with GSDIII.Electronic supplementary materialThe online version of this article (doi:10.1007/s10545-016-9932-2) contains supplementary material, which is available to authorized users.

Crystal structure of glycogen debranching enzyme and insights into its catalysis and disease-causing mutations.

Glycogen is a branched glucose polymer and serves as an important energy store. Its debranching is a critical step in its mobilization. In animals and fungi, the 170 kDa glycogen debranching enzyme (GDE) catalyses this reaction. GDE deficiencies in humans are associated with severe diseases collectively termed glycogen storage disease type III (GSDIII). We report crystal structures of GDE and its complex with oligosaccharides, and structure-guided mutagenesis and biochemical studies to assess the structural observations. These studies reveal that distinct domains in GDE catalyse sequential reactions in glycogen debranching, the mechanism of their catalysis and highly specific substrate recognition. The unique tertiary structure of GDE provides additional contacts to glycogen besides its active sites, and our biochemical experiments indicate that they mediate its recruitment to glycogen and regulate its activity. Combining the understanding of the GDE catalysis and functional characterizations of its disease-causing mutations provides molecular insights into GSDIII.

A Novel Nonsense Mutation of the AGL Gene in a Romanian Patient with Glycogen Storage Disease Type IIIa.

Background. Glycogen storage disease type III (GSDIII) is a rare metabolic disorder with autosomal recessive inheritance, caused by deficiency of the glycogen debranching enzyme. There is a high phenotypic variability due to different mutations in the AGL gene. Methods and Results. We describe a 2.3-year-old boy from a nonconsanguineous Romanian family, who presented with severe hepatomegaly with fibrosis, mild muscle weakness, cardiomyopathy, ketotic fasting hypoglycemia, increased transaminases, creatine phosphokinase, and combined hyperlipoproteinemia. GSD type IIIa was suspected. Accordingly, genomic DNA of the index patient was analyzed by next generation sequencing of the AGL gene. For confirmation of the two mutations found, genetic analysis of the parents and grandparents was also performed. The patient was compound heterozygous for the novel mutation c.3235C>T, p.Gln1079⁎ (exon 24) and the known mutation c.1589C>G, p.Ser530⁎ (exon 12). c.3235 >T, p.Gln1079⁎ was inherited from the father, who inherited it from his mother. c.1589C>G, p.Ser530⁎ was inherited from the mother, who inherited it from her father. Conclusion. We report the first genetically confirmed case of a Romanian patient with GSDIIIa. We detected a compound heterozygous genotype with a novel mutation, in the context of a severe hepatopathy and an early onset of cardiomyopathy.

History of settlement of villages from Central Tunisia by studying families sharing a common founder Glycogenosis type III mutation

Glycogen storage disease type III (GSD III; Cori disease; Forbes disease) is an autosomal recessive inherited metabolic disorder resulting from deficient glycogen debrancher enzyme activity in liver and muscle. In this study, we focused on a single AGL gene mutation p.W1327X in 16 Tunisian patients from rural area surrounding the region of Mahdia in Central Tunisia. This constitutes the largest pool of patients with this mutation ever described. This study was performed to trace the history of the patients’ ancestries in a single region. After extraction of genomic DNA, exon 31 of AGL gene was sequenced. The patients were investigated for the hypervariable segment 1 of mitochondrial DNA and 17 Y-STR markers. We found that the p.W1327X mutation was a founder mutation in Tunisia Analysis of maternal lineages shows an admixture of autochthonous North African, sub-Saharan and a predominance of Eurasian haplogroups. Heterogeneity of maternal haplogroups indicates an ancient settlement. However, paternal gene flow was highly homogeneous and originates from the Near East. We hypothesize that the p.W1327X mutation was introduced into the Tunisian population probably by a recent migration event; then the mutation was fixed in a small region due to the high rate of consanguineous marriages and genetic drift. The screening for this mutation should be performed in priority for GSD III molecular diagnosis, for patients from the region of Mahdia and those from regions sharing the same settlement history.