Glycogen Storage Disease Type Research Articles

Reporting a Novel Gene Mutation in Glycogen Storage Disease Type VII (Tarui Disease)

Reporting a Novel Gene Mutation in Glycogen Storage Disease Type VII (Tarui Disease)

Precision-cut liver slices as an ex vivo model to assess impaired hepatic glucose production

Fasting hypoglycemia is a severe and incompletely understood symptom of various inborn errors of metabolism (IEM). Precision-cut liver slices (PCLS) represent a promising model for studying glucose production ex vivo. This study quantified the net glucose production of human and murine PCLS in the presence of different gluconeogenic precursors. Dihydroxyacetone-supplemented slices from the fed mice yielded the highest rate, further stimulated by forskolin and dibutyryl-cAMP. Moreover, using 13C isotope tracing, we assessed the contribution of glycogenolysis and gluconeogenesis to net glucose production over time. Pharmacological inhibition of the glucose 6-phosphate transporter SLC37A4 markedly reduced net glucose production and increased lactate secretion and glycogen storage, while glucose production was completely abolished in PCLS from glycogen storage disease type Ia and Ib patients. In conclusion, this study identifies PCLS as an effective ex vivo model to study hepatic glucose production and opens opportunities for its future application in IEM research and beyond.

Experiences of living with GSD5 (McArdle) disease: challenges and strategies. A qualitative study in the Netherlands

Purpose Glycogen Storage Disease type 5 (GSD5 or McArdle disease) is caused by deficient glycogen phosphorylase enzyme activity in skeletal muscles. Individuals with GSD5 experience symptoms like muscle pain, fatigue, and tachycardia during exertion. Our study aimed to explore the lived experiences of individuals with GSD5, focusing on their daily challenges, the process of being diagnosed, and management strategies. Methods Participants were invited to share their life experiences through in-depth, semi-structured interviews, and the collected data was analyzed using thematic analysis. Results Using purposeful sampling, 13 individuals with GSD5 were recruited for the study. The analysis identified four key themes: “experiencing incomprehensible difficulties,” “diagnosis as an explanation,” “finding ways to manage daily challenges,” and “listening to your body.” These themes reflect diverse experiences of daily functioning, physical challenges faced, the pivotal role of diagnosis in understanding symptoms, and the adoption of management strategies like using the ‘second wind’ phenomenon. Participants emphasized the importance of support networks and adaptive lifestyle changes in effectively managing their condition. Conclusions Early diagnosis and tailored management strategies are critical for improving outcomes and quality of life in individuals with GSD5. Timely diagnosis and comprehensive multidisciplinary care are essential for effectively managing the complexities of this rare metabolic disorder.

In silico analysis of point mutation (c.687dupC; p. Met230Hisfs*6) in PGAM2 gene that causes Glycogen Storage Disease (GSD) Type X

Glycogen storage disease (GSD) type X is an autosomal recessive disorder that affects skeletal muscles and is caused by PGAM-2 (Phosphoglycerate Mutase-2) enzyme deficiency. This deficiency is due to a mutation in the PGAM-2 gene at chromosome number 7p13. A novel insertion mutation (c.687dupC) was reported recently in the Pakistani population. This study aimed to computationally study the effect of that mutation at the molecular level. Several in silico approaches were employed to understand the molecular mechanism behind PGAM2 enzyme deficiency. Modeling the wild-type and mutant PGAM2 protein revealed an absence of an alpha helix from the c-terminus. Binding site analysis showed the absence of a critical residue, Lysine-100, from the mutant. Moreover, changes in the binding affinities, intramolecular interactions, and intermolecular interactions were also observed.

Outcomes of Pediatric Liver Transplantation in Glycogen Storage Disease Type 1b-A Single-Center Experience.

Liver transplantation (LT) normalizes fasting tolerance in glycogen storage disease type (GSD) 1b. However, reported outcomes post-LT with respect to correction of neutropenia, infection risk and growth are varied. Sodium-glucose cotransporter-2 (SGLT2) inhibitors have been recently shown to improve neutropenia in GSD1b patients. In this single-center retrospective study, we reviewed all children who underwent LT for GSD1b. Neutropenia, dose of granulocyte colony-stimulating factor (G-CSF), unplanned hospital attendance, anthropometrics, graft rejection, survival, and the effects of dapagliflozin were analyzed. Data from protocol biopsies obtained at 1, 5, and 10 years post-LT and immunosuppression levels were collected. Eight children (6 female), all on G-CSF pre-transplant, underwent cadaveric LT for GSD1b at median age 3.6 years (IQR 3.3-5.1) with mean follow-up time of 10.3 years (95% CI 7.5-13.1). Neutrophil count and G-CSF requirement did not improve post-LT. Although a reduction in unplanned hospital attendance due to infection (0.98 [95% CI 0.76-1.26] vs. 0.49 [95% CI 0.41 to 0.57] per person-year, p < 0.01) was observed, gastrointestinal complaints and graft dysfunction accounted for a similar hospitalization burden pre- versus post-LT. Body mass index (BMI) reduced post-LT (Z-score 1.47 [95%CI 0.39-2.23] vs. 0.56 [95% CI -0.74 to 1.45], p = 0.02), with no significant change in height. Although all children and grafts have survived, 75% of recipients developed rejection, despite adequate immunosuppression levels, with two children having been found to have developed significant fibrosis on their 5-year protocol biopsy. Although dapagliflozin allowed cessation of G-CSF, no improvement in neutrophil count was observed. Despite this, a reduction in gastrointestinal and infection-related morbidity was noted following dapagliflozin. Although LT normalizes fasting tolerance in GSD1b and reduces hospital attendance due to infection, morbidity from infection and gastrointestinal manifestations persist. Children in our cohort experienced high rates of rejection necessitating titration of immunosuppression to balance risk of infection against organ rejection. Future studies should investigate whether early introduction of SGLT2 inhibitors post-LT impact morbidity in this group.

Glycogen Storage Disease Type I and Bone: Clinical and Cellular Characterization.

Glycogen storage disease (GSD) is the most prevalent inherited disorder of glycogen metabolism for which no causal treatment is available. In recent years, thanks to the improved clinical management, the life expectancy of these patients extended, disclosing previously unidentified adverse conditions in other organs. In this study, we evaluated the clinical bone complications and the cellular responses in 20 patients (aged 14.1 ± 3.4years) affected by GSD type I. Fragility fractures were reported in 35% of the patients, which were older than unfractured patients. They involved appendicular skeletal segments, while no vertebral deformity was detected. 60% of the patients had a bone mineral density (BMD) "below the expected range for age", and lumbar spine (LS) BMD Z-scores positively correlated with muscle strength. Circulating mineral and bone markers showed reduction in the older subjects, with no increase in the pubertal age. Significant correlations could not be detected between circulating markers and LS BMD Z-scores, except for sclerostin levels, which also correlated with muscle strength. The osteoclasts differentiated from patients' peripheral blood mononuclear cells did not show cell-autonomous alterations. However, circulating osteoclast precursors from healthy individuals cultured in the presence of patients' sera exhibited increased osteoclastogenesis compared to control sera suggesting that GSD type I serum factors could affect osteoclast function in a non-autonomous manner. In contrast, circulating osteoprogenitors were unremarkable.

SLC37A4, gene responsible for glycogen storage disease type 1b, regulates gingival epithelial barrier function via JAM1 expression

Solute carrier family 37 member 4 (SLC37A4) is known to regulate glucose-6-phosphate transport from cytoplasm to the lumen of the endoplasmic reticulum, which serves to maintain glucose homeostasis. Glycogen storage disease type 1b (GSD1b) is caused by a mutation of SLC37A4, leading to a glycogenolysis defect. Although GSD1b cases are known to be complicated by periodontitis, the etiological molecular basis remains unclear. The present study investigated the effects of SLC37A4 on gingival barrier function. Examinations of immortalized human gingival epithelial (IHGE) cells showed SLC37A4 localized in the endoplasmic reticulum. SLC37A4 knockout decreased expression of JAM1, a tight junction-related protein, in IHGE cells. Using in silico analysis to investigate potential transcription factor binding sites, H6 family homeobox 3 (HMX3) was shown to be related to JAM1 expression. In HMX3-knockdown IHGE cells, JAM1 expression was markedly suppressed. Furthermore, HMX3 was scarcely detected in SLC37A4-knockout cells, while HMX3 overexpression restored JAM1 expression in those cells. Finally, using a three-dimensional multilayered gingival epithelial tissue model, knockout of SLC37A4 was also found to increase permeability to lipopolysaccharide and peptidoglycan, which was dependent on JAM1 expression. Specific downregulation of HMX3 by SLC37A4 and the consequent decrease in JAM1 expression provides findings indicating a molecular basis for the reduction in barrier function of gingival epithelial tissues in GSD1b cases.

Endocrine Complications in Hepatic Glycogen Storage Diseases: A Long-term Perspective.

Patients with hepatic type of glycogen storage diseases (GSDs) can manifest endocrine features such as hypoglycemia, dyslipidemia, or osteoporosis. This study aimed to investigate the long-term endocrine consequences in patients with hepatic GSDs. This study included 64 patients from 52 families with hepatic GSDs including GSD type Ia (41 patients from 37 families), Ib (3 unrelated), III (8 from 6 families), IV (one patient), and IX (11 from 5 families). All patients were genetically confirmed. Clinical and endocrine findings were retrospectively analyzed. The median age at diagnosis and current age were 2.4 years (range, 0.1-42.4 years) and 17.6 years (range, 1.0-47.8 years), respectively. The mean height SDS at diagnosis was -3.5 ± 1.4, and short stature was observed in 35.6% of patients. Patients diagnosed after the age of 3.4 years exhibited a high risk of short stature (OR = 36.1; P-value < 0.001). Among 33 patients who reached final height, 23 (69.7%) showed delayed puberty. Hypertriglyceridemia was observed in 46 patients (71.9%), whereas 25 patients (39%) had elevated low-density lipoprotein cholesterol levels during the follow-up period. Among 24 patients who underwent dual energy X-ray absorptiometry, 22 showed a low bone mineral density Z-score of -3.0 ± 1.3 at the L-spine. This study described the long-term endocrine consequences in patients with hepatic GSDs. Pediatric endocrinologists should be aware of the presenting features and long-term endocrine sequelae of GSDs to provide proper management and decrease its morbidities.

Myopathy in glycogen storage disease type IV: case report of a family

Aim. To study the clinical presentation and differential diagnosis of a rare hereditary disease glycogen storage disease type IV with progressive skeletal myopathy in a case report of a family.Materials and methods. Two patients were followed up in the specialized neurology unit of the regional clinical hospital and in the outpatient setting.Results. Long-term follow-up and examination in two clinically similar cases of myopathy in siblings allowed us to diagnose a hereditary metabolic disease. The congenital muscular form of glycogen storage disease type IV was manifested by myopathy and peripheral tetraparesis with the development of bone deformities. Difficulty in the diagnosis was due to isolated myopathy progression with no signs of liver involvement. The diagnosis was established with account of clinical manifestations, the progressive course of the disease, electromyography findings, and the results of molecular genetic testing for pathogenic mutations associated with hereditary neuromuscular diseases.Conclusion. Glycogen storage disease type IV can clinically manifest itself by progressive myopathy without liver involvement and changes in blood biochemistry. The presented clinical cases in siblings are identical. Myopathy does not have clinical features that are significant for the differential diagnosis with other hereditary neuromuscular diseases. Genetic testing identified a mutation in the GBE1 gene and is considered as the main diagnostic criterion of the disease.

6765 Surveillance For Side Effects Of Glycemic Control: Von Gierke Disease And Recurrent Diarrhea With Hospitalized Approach

Abstract Disclosure: J. Gone: None. E. Fegahli: None. T. Thompson: None. Background: Von Gierke disease is an autosomal recessive disorder leading to the inability to break down glycogen. Clinical features manifest at 3-6 months including symptoms of hypoglycemia, short stature, thin legs, round face, protruding abdomen, muscular hypotonia, and psychomotor retardation. Workup shows hypoglycemia, lactic acidosis, hyperuricemia, hyperlipidemia, anemia, hepatomegaly, and renomegaly. Patients may develop inflammatory bowel disease, osteopenia, renal failure, hepatic tumors, and pulmonary hypertension. Molecular sequencing confirms the diagnosis. Feeding glucose at regular intervals prevents hypoglycemia. One should avoid fructose, lactose, sucrose, and galactose. Oral citrate or bicarbonate is used to treat lactic acidosis. Gout, hyperlipidemia, anemia, IBD and osteoporosis are managed accordingly. Regular screening for osteoporosis, renal failure, hepatic tumors, and pulmonary hypertension is recommended. Liver transplantation results in optimal management. Gene therapy clinical trials are underway. Clinical Case: We present a case of von Gierke disease in a 20-year-old male presenting to the Emergency Department for recurrent nausea, emesis, poor oral intake, water diarrhea and subjective fever. Inpatient workup showed lactic acidosis, hyperuricemia, hypertriglyceridemia, transaminitis, and fibrofatty hepatomegaly. Intravenous fluids, antiemetics and cornstarch were given. Symptoms including nausea, emesis, and diarrhea improved, most notably after adjustments made to cornstarch dosage and frequency. The patient was discharged with an antiemetic and an antidiarrheal and with recommendations to continue scheduled cornstarch. Patient was educated about the importance of proper diet compliance and close outpatient follow up. Hence, management of von Gierke disease should include not only strict glycemic control but also close surveillance for possible side effects, such as diarrhea. Moreover, future studies are necessary to support empiric modifications in management despite a basis of a hypothetical rationale. Conclusion: An essential goal of managing GSD-1 is not only strict glycemic control but also close surveillance for possible side effects, such as diarrhea. Adjustments to maintaining normoglycemia may be mandatory by manipulating factors including dosage and frequency of oral carbohydrates, such as cornstarch, to reduce the recurrence of side effects as much as possible. Treatment regimens should be individualized to each case because the initial presentation and response to treatment in every patient can be different, whether it is minor or major. Future studies about the mechanisms regarding possible side effects of treatment, such as diarrhea, are warranted to corroborate empiric changes in management, like adjusting dosage and frequency or medications, despite having a hypothetical rationale. Presentation: 6/1/2024

644P Muscle MRI in Glycogen Storage disease type 5 (McArdle disease) – single centre experience

644P Muscle MRI in Glycogen Storage disease type 5 (McArdle disease) – single centre experience

Early Intervention with Angiotensin Blockade to Reverse Proteinuria in Glycogen Storage Disease Type Ia (GSD Ia)

Early Intervention with Angiotensin Blockade to Reverse Proteinuria in Glycogen Storage Disease Type Ia (GSD Ia)

531P The French registry of glycogen storage disease type 3

531P The French registry of glycogen storage disease type 3

Global birth prevalence of Pompe disease: A systematic review and meta-analysis

BackgroundPompe disease, also known as Glycogen storage disease type II, is an autosomal recessive disorder caused by defects in alpha-glucosidase, resulting in abnormal glycogen accumulation. MethodsTo conduct a systematic review and meta-analysis of birth prevalence of Pompe disease, the MEDLINE and EMBASE databases were searched for original research articles on the epidemiology of Pompe disease from inception until July 01, 2024. Meta-analysis was performed to estimate global birth prevalence of Pompe disease. The funnel plot was used to describe potential publication bias. ResultsTwenty-two studies, screened out of 945 records, were included for data extraction. Studies that fulfilled inclusion criteria involved 15 areas/countries. Global birth prevalence of Pompe disease was 2.0 cases (95% CI: 1.5–2.4) per 100,000 live births. Global birth prevalence of infantile-onset Pompe disease was 1.0 cases (95% CI: 0.5–1.5) per 100,000 live births. Global birth prevalence of late-onset Pompe disease was 2.4 cases (95% CI: 1.8–3.0) per 100,000 live births. The main limitations are that no study was assessed as high-quality and approximately half of the studies were from Europe. ConclusionsQuantitative data on the global epidemiology of Pompe disease could be the fundamental to evaluate the global efforts on building a better world for Pompe disease patients.

Nutrition Management in Children Less than 5 Years of Age with Glycogen Storage Disease Type I: Survey Results.

Background: Nutrition management for GSD Type I (GSDI; OMIM #232200, 232220) is complex, with the goal being to maintain euglycemia while minimizing metabolic derangements. Management guidelines were published in 2002 and 2014. However, there is limited information on the nuances of nutrition management and the unique feeding challenges of children. Methods: A REDCap survey focusing on staffing and current practices in the nutrition management of children with GSD I who were <5 years of age was sent to the metabolic dietitian's listserv and GMDI membership in 8/2023. Results: There were 21 North American respondents. In 17/21 clinics (81%), Prosobee® was the primary choice for infant formula. Dietitians used different methods to determine hourly glucose needs. Fasting recommendations ranged from 1 to 3 h, and the use of nighttime continuous feeding was common. Cornstarch was started between 6 and 12 months of age. Most clinics did not use Glycosade® for children <5 years of age. Oral motor dysfunction, gagging, and lack of interest in food were common. Continuous glucose monitoring (CGM) devices were recommended in 20 clinics (95%). Most clinics followed patients on an outpatient basis. All clinics provided a hypoglycemia management plan; however, there was wide variability in practice. Conclusion: This survey highlights the variability in the care of individuals <5 years of age with GSD I. Updated guidelines are needed to help address the unique nutrition challenges in this age group.

McArdle's Disease: A Differential Diagnosis of Metabolic Myopathies.

McArdle's disease, also known as glycogen storage disease type V or McArdle syndrome, is a pure muscle myopathy with an autosomal recessive inheritance pattern. It is caused by mutations in the gene that encodes muscle phosphorylase. Symptoms typically begin in late adolescence or early adulthood, presenting as exercise intolerance. This review focuses on the diagnosis of McArdle's disease, initially manifesting as a clinical picture of rhabdomyolysis in an 18-year-old male patient with a history of minor thalassemia who had been followed in pediatric consultation since age three for failure to thrive. After excluding common causes such as alcohol consumption, drug use, traumatic muscle compression, and other conditions, the diagnosis of McArdle's disease was considered. The diagnosis was supported by laboratory tests showing myoglobinuria and elevated creatine kinase levels, as well as the absence of increased serum lactate following ischemic exercise. Genetic testing confirmed the presence of mutations in the PYGM gene, corroborating the diagnosis. Treatment includes administering a diet rich in slow-absorbing carbohydrates, regular low-intensity physical exercise, and, in some cases, supplementation with vitamin B6 and creatine. The prognosis is generally favorable with proper disease management, although vigorous exercise should be avoided to prevent complications such as severe muscle injury and rhabdomyolysis. Although McArdle's disease is a rare condition, it is likely underdiagnosed. Ideally, it should be considered in the differential diagnosis of rhabdomyolysis in all patients with symptoms of exercise intolerance and/or recurrent myoglobinuria.

A specific serum lipid signature characterizes patients with glycogen storage disease type Ia

Glycogen storage disease type Ia (GSDIa) is a rare, inherited glucose-6-phosphatase-α (G6Pase-α) deficiency-induced carbohydrate metabolism disorder. Although hyperlipidemia is a hallmark of GSDI, the extent of lipid metabolism disruption remains incompletely understood. Lipidomic analysis was performed to characterize the serum lipidome in patients with GSDIa, by including age- and sex-matched healthy controls and age-matched hypercholesterolemic controls. Metabolic control and dietary information biochemical markers were obtained from patients with GSDIa. Patients with GSDIa showed higher total serum lysophosphatidylcholine (Fold Change, (FC) 2.2, P < 0.0001), acyl-acyl-phosphatidylcholine (FC 2.1, P < 0.0001), and ceramide (FC 2.4, P < 0.0001) levels and bile acid (FC 0.7, P < 0.001), acylcarnitines (FC 0.7, P < 0.001), and cholesterol esters (FC 1.0, P < 0.001) than those of healthy controls, and higher di- (FC 1.1, P < 0.0001; FC 0.9, P < 0.01) and triacylglycerol (FC 6.3, P < 0.0001; FC 3.9, P < 0.01) levels than those of healthy controls and hypercholesterolemic subjects. Both total cholesterol and triglyceride values correlated with Cer (d16:1/22:0), Cer (d18:1/20:0), Cer (d18:1/20:0(OH)), Cer (d18:1/22:0), Cer (d18:1/23:0), Cer (d18:1/24:1), Cer (d18:2/22:0), Cer (d18:2/24:1). Total cholesterol also correlated with Cer (d18:1/24:0), Cer (d18:2/20:0), HexCer (d16:1/22:0), HexCer (d18:1/18:0), and Hex2Cer (d18:1/20:0). Triglyceridelevels correlated with Cer (d18:0/24:1). Alanine aminotransferase values correlated with Cer (d18:0/22:0), insulin with Cer (d18:1/22:1) and Cer (d18:1/24:1), and HDL with hexosylceramide (HexCer) (d18:2/23:0). These results expand on the currently known involvement of lipid metabolism in GSDIa. Circulating Cer may allow for refined dietary assessment compared with traditional biomarkers. Because specific lipid species are relatively easy to assess, they represent potential novel biomarkers of GSDIa.

Late Cardiac Involvement of the Glycogen Storage Disease Type IIIa with Massive Left Ventricular Hypertrophy and Late Gadolinium Enhancement.

Late Cardiac Involvement of the Glycogen Storage Disease Type IIIa with Massive Left Ventricular Hypertrophy and Late Gadolinium Enhancement.

Clinical features and genetic analysis of 5 cases of infantile-type glycogen storage disease type II: Case reports.

Clinical and genetic mutation analysis was performed on 5 infantile glycogen storage disease type II children in Chinese mainland. Clinical data of 5 children with infantile-type glycogen storage disease type II due to the acidic α-glucosidase (GAA) gene variants diagnosed and treated at Hebei Provincial Children's Hospital from January 2018 to April 2020 were retrospectively analyzed. Among the 5 cases, 1 was female and 4 were male, and the age at first diagnosis was from 2 months to 7 months. The first symptoms of all 5 cases showed progressive muscle weakness, hypotonia, and motor developmental backwardness, and all of them had abnormally elevated creatine kinase, and the echocardiograms suggested different degrees of myocardial hypertrophy, with ejection fractions ranging from 44% to 67%. Analysis of GAA gene variations: all 5 cases were compound heterozygous, and a total of 12 variant loci were detected, of which c.2024_2026delACA, c.2853G > A, c.1124G > T, c.574G > A, c.2509C > T, and c.2013G > A were new mutations that had not been reported. All 5 children died before 1 year of age, and the age of death ranged from 7 months to 11.5 months, with a mean survival time of 9.8 months. Peripheral blood GAA gene testing and alpha-glucosidase enzyme activity testing is an effective method for diagnosing this disease.

Impaired Glucose Metabolism, Primary Cilium Defects, and Kidney Cystogenesis in Glycogen Storage Disease Type Ia.

Glycogen Storage Disease type Ia (GSDIa) is a rare metabolic disorder caused by mutations in the catalytic subunit of glucose-6 phosphatase (G6PC1). This leads to severe hypoglycemia and most young GSDIa patients develop CKD. The kidney pathology is characterized by the development of cysts, which typically occur at an advanced stage of CKD. To elucidate the molecular mechanisms responsible for cyst formation, we characterized renal metabolism, molecular pathways involved in cell proliferation and integrity primary cilium integrity, using mice in which G6pc1 was specifically deleted in the kidney from in utero stage. GSDIa mice exhibited renal fibrosis, high-inflammation, and cyst formation, leading to kidney dysfunction. In addition, the loss of G6PC1 led to the ectopic accumulation of glycogen and lipids in the kidneys, and a metabolic shift towards a Warburg-like metabolism. This metabolic adaptation was due to an excess of glucose-6 phosphate, which supports cell proliferation, driven by the MEK/ERK and AKT/mTOR pathways. Treatment of GSDIa mice with rapamycin, a target of the mTOR pathway, reduced cell proliferation and kidney damage. Our results also identified lipocalin 2 as a contributor to renal inflammation and an early biomarker of CKD progression in GSDIa mice. Its inactivation partially prevented kidney lesions in GSDIa. Importantly, primary cilium defects were observed in the kidneys of GSDIa mice. Metabolic adaptations due to glucose-6 phosphate accumulation in GSDIa renal tubules, towards a Warburg-like metabolism, appeared to promote cell proliferation and cyst formation in a similar manner to that observed in various cystic kidney diseases. This was associated with down-regulation of primary cilium gene expression and consequently, altered cilium morphology.