Abnormal Glycogen Accumulation Research Articles

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.

Brain glycogen build-up measured by magnetic resonance spectroscopy in classic infantile Pompe disease.

Classic infantile Pompe disease is caused by abnormal lysosomal glycogen accumulation in multiple tissues, including the brain due to a deficit in acid α-glucosidase. Although treatment with recombinant human acid α-glucosidase has dramatically improved survival, recombinant human acid α-glucosidase does not reach the brain, and surviving classic infantile Pompe patients develop progressive cognitive deficits and white matter lesions. We investigated the feasibility of measuring non-invasively glycogen build-up and other metabolic alterations in the brain of classic infantile Pompe patients. Four classic infantile patients (8-16 years old) and 4 age-matched healthy controls were scanned on a 7 T MRI scanner. We used T2-weighted MRI to assess the presence of white matter lesions as well as 1H magnetic resonance spectroscopy and magnetic resonance spectroscopy imaging to obtain the neurochemical profile and its spatial distribution, respectively. All patients had widespread white matter lesions on T2-weighted images. Magnetic resonance spectroscopy data from a single volume of interest positioned in the periventricular white matter showed a clear shift in the neurochemical profile, particularly a significant increase in glycogen (result of acid α-glucosidase deficiency) and decrease in N-acetyl-aspartate (marker of neuronal damage) in patients. Magnetic resonance spectroscopy imaging results were in line and showed a widespread accumulation of glycogen and a significant lower level of N-acetyl-aspartate in patients. Our results illustrate the unique potential of 1H magnetic resonance spectroscopy (imaging) to provide a non-invasive readout of the disease pathology in the brain. Further study will assess its potential to monitor disease progression and the correlation with cognitive decline.

Nutritional support in glycogen storage diseases: evolution of treatment and unresolved contradictions

Hepatic forms of glycogen storage diseases (GSD) are a group of diseases in which abnormal accumulation or cleavage of glycogen leads to potentially life-threatening hypoglycemic conditions and metabolic disorders. The use of specialized diet therapy with the addition of raw corn starch has significantly improved the results of GSD treatment, turning a pathology previously considered fatal into a condition in which people can feel satisfactory with proper care. Despite many years of research, there is no consensus on the optimal dietary treatment of GSD. This article describes the evolution of dietary therapy of hepatic forms of GSD (types 0, I, III, VI, IX and XI), presents historical and modern approaches to the prevention of hypoglycemia and related complications.

THU368 A Rare Case Of Glycogenic Hepatopathy With Persistent Lactic Acidosis

Abstract Disclosure: M. Shah: None. S. Challagulla: None. Background: Glycogenic hepatopathy (GH) is an under-recognized complication of poorly controlled diabetes. It is caused by abnormal glycogen accumulation in hepatocytes leading to hepatomegaly and transient elevation of liver transaminases. Diagnosis is often delayed as liver biopsy is needed to distinguish it from other causes of liver injury. Complete resolution can be achieved with intensive glucose control. We present a case of GH diagnosed in a patient who developed increasing liver transaminases and persistent lactic acidosis after resolution of DKA. Clinical Case: We present a 21-year-old female with uncontrolled Type 1 diabetes who presented with fatigue, nausea, and generalized body aches. Patient was hemodynamically stable. Laboratory work up on admission showed a serum glucose of 834 mg/dL, serum bicarbonate less than 5 mEq/L, beta hydroxybutyrate was elevated to 8.7 mmol/L (normal <0.4 mmol/L), lactic acid was also elevated to 7.9 mmol/L (normal <2.0 mmol/L). She was diagnosed with DKA and treated with IV fluids and insulin drip. Over the next five days the patient’s symptoms improved and DKA resolved with beta hydroxybutyrate falling to <0.1 mmol/L. Her lactic acidosis however persisted, she had no apparent infection and no episodes of hypotension to explain this finding. CT scan of the abdomen revealed hepatomegaly not compatible with steatosis. Liver enzymes on admission were mildly elevated AST 57 IU/L and ALT 61 IU/L however values continued to rise and peaked at AST 2372 IU/L and ALT 681 IU/L five days later. Further laboratory studies revealed no evidence of viral hepatitis, no presence of drugs or toxins. Chronic liver disease work up revealed normal ANA, AMA, SPEP, ceruloplasmin, and iron levels. Patient ultimately underwent liver biopsy which revealed glycogenic hepatopathy, mild steatosis, and mild fibrosis. Patient’s lactic acidosis eventually improved with supportive care, and she was discharged. On follow up 3 months later the patient's liver enzymes had returned to normal. Discussion: Glycogenic hepatopathy is a rare diagnosis usually seen in patients with uncontrolled diabetes and elevated liver transaminases. It is hypothesized that pathogenesis of GH involves insulin increasing glycogen synthesis in the liver resulting in congested hepatocytes. Persistent lactic acidosis can also be seen; it has been proposed that increased insulin and dextrose administration prevents gluconeogenesis in the liver, therefore decreased conversion of pyruvate to glucose and increased lactate production. GH is important to understand and differentiate from other causes of liver injury and disease as treatment and prognosis is unique. Prompt liver biopsy should be pursued to elucidate diagnosis of GH. If patients are treated with aggressive glycemic control, hepatopathy can completely resolve. Presentation: Thursday, June 15, 2023

Analysis of Cell Glycogen with Quantitation and Determination of Branching Using Liquid Chromatography-Mass Spectrometry.

Glycogen is a highly branched biomacromolecule that functions as a glucose buffer. It is involved in multiple diseases such as glycogen storage disorders, diabetes, and even liver cancer, where the imbalance between biosynthetic and catabolic enzymes results in structural alterations and abnormal accumulation of glycogen that can be toxic to cells. Accurate and sensitive glycogen quantification and structural determination are prerequisites for understanding the phenotypes and biological functions of glycogen under these conditions. In this research, we furthered cell glycogen characterization by presenting a highly sensitive method to measure the glycogen content and degree of branching. The method employed a novel fructose density gradient as an alternative to the traditional sucrose gradient to fractionate glycogen from cell mixtures using ultracentrifugation. Fructose was used to avoid the large glucose background, allowing the method to be highly quantitative. The glycogen content was determined by quantifying 1-phenyl-3-methyl-5-pyrazolone (PMP)-derivatized glucose residues obtained from acid-hydrolyzed glycogen using ultra-high-performance liquid chromatography/triple quadrupole mass spectrometry (UHPLC/QqQ-MS). The degree of branching was determined through linkage analysis where the glycogen underwent permethylation, hydrolysis, PMP derivatization, and UHPLC/QqQ-MS analysis. The new approach was used to study the effect of insulin on the glycogen phenotypes of human hepatocellular carcinoma (Hep G2) cells. We observed that cells produced greater amounts of glycogen with less branching under increasing insulin levels before reaching the cell's insulin-resistant state, where the trend reversed and the cells produced less but higher-branched glycogen. The advantage of this method lies in its high sensitivity in characterizing both the glycogen level and the structure of biological samples.

Gene therapy for glycogen storage diseases.

Glycogen storage disorders (GSDs) are inherited disorders of metabolism resulting from the deficiency of individual enzymes involved in the synthesis, transport, and degradation of glycogen. This literature review summarizes the development of gene therapy for the GSDs. The abnormal accumulation of glycogen and deficiency of glucose production in GSDs lead to unique symptoms based upon the enzyme step and tissues involved, such as liver and kidney involvement associated with severe hypoglycemia during fasting and the risk of long-term complications including hepatic adenoma/carcinoma and end stage kidney disease in GSD Ia from glucose-6-phosphatase deficiency, and cardiac/skeletal/smooth muscle involvement associated with myopathy +/- cardiomyopathy and the risk for cardiorespiratory failure in Pompe disease. These symptoms are present to a variable degree in animal models for the GSDs, which have been utilized to evaluate new therapies including gene therapy and genome editing. Gene therapy for Pompe disease and GSD Ia has progressed to Phase I and Phase III clinical trials, respectively, and are evaluating the safety and bioactivity of adeno-associated virus vectors. Clinical research to understand the natural history and progression of the GSDs provides invaluable outcome measures that serve as endpoints to evaluate benefits in clinical trials. While promising, gene therapy and genome editing face challenges with regard to clinical implementation, including immune responses and toxicities that have been revealed during clinical trials of gene therapy that are underway. Gene therapy for the glycogen storage diseases is under development, addressing an unmet need for specific, stable therapy for these conditions.

Polysaccharide storage myopathy in two Percheron horses

Polysaccharide storage myopathy (PSSM) is a genetic disorder or by undetermined cause characterized by the abnormal accumulation of glycogen and polysaccharides in skeletal muscle fibers. The present report describes two Percheron horses, from different properties in the municipality of Pouso Redondo - SC, with locomotor clinical signs that started after work. The clinical signs observed were rigid gait, mainly of the pelvic limbs, muscle weakness, and recumbency. In the first case, the animal was diagnosed with severe multifocal rhabdomyonecrosis, moderate multifocal myoglobin nephrosis and severe diffuse transmural fibrinonecrotic gastritis. PSSM was confirmed by the presence of polysaccharide inclusions in myofiber sarcolemma visualized by periodic acid-Schiff (PAS) staining. In the second case, the horse presented two episodes of muscle disorder after work. The therapeutic protocol was based on penicillin, flunixin meglumine and fluid therapy with ringer lactate. An increase in creatine kinase (669.0 UI/L) and aspartate aminotransferase (669.0 UI/L) was observed in the serum biochemical evaluation. Research for mutation in the GYS1 gene was performed, with a positive heterozygote result. After rest and gradual recovery, the horse was only submitted to light work, with no return of the clinical condition since then. Thus, this report describes two cases of PSSM with distinct clinical evolution and diagnostic methods.

The Liver and Glycogen: In Sickness and in Health

The liver is a major store of glycogen and is essential in maintaining systemic glucose homeostasis. In healthy individuals, glycogen synthesis and breakdown in the liver are tightly regulated. Abnormal glycogen metabolism results in prominent pathological changes in the liver, often manifesting as hepatic glycogenosis or glycogen inclusions. This can occur in genetic glycogen storage disease or acquired conditions with insulin dysregulation such as diabetes mellitus and non-alcoholic fatty liver disease or medication effects. Some primary hepatic tumors such as clear cell hepatocellular carcinoma also demonstrate excessive glycogen accumulation. This review provides an overview of the pathological manifestations and molecular mechanisms of liver diseases associated with abnormal glycogen accumulation.

Induced pluripotent stem cell for modeling Pompe disease.

Pompe disease (PD) is a rare, autosomal recessive, inherited, and progressive metabolic disorder caused by α-glucosidase defect in lysosomes, resulting in abnormal glycogen accumulation. Patients with PD characteristically have multisystem pathological disorders, particularly hypertrophic cardiomyopathy, muscle weakness, and hepatomegaly. Although the pathogenesis and clinical outcomes of PD are well-established, disease-modeling ability, mechanism elucidation, and drug development targeting PD have been substantially limited by the unavailable PD-relevant cell models. This obstacle has been overcome with the help of induced pluripotent stem cell (iPSC) reprogramming technology, thus providing a powerful tool for cell replacement therapy, disease modeling, drug screening, and drug toxicity assessment. This review focused on the exciting achievement of PD disease modeling and mechanism exploration using iPSC.

Storage and Utilization of Glycogen by Mouse Liver during Adaptation to Nutritional Changes Are GLP-1 and PASK Dependent.

Glucagon-like peptide 1 (GLP-1) and PAS kinase (PASK) control glucose and energy homeostasis according to nutritional status. Thus, both glucose availability and GLP-1 lead to hepatic glycogen synthesis or degradation. We used a murine model to discover whether PASK mediates the effect of exendin-4 (GLP-1 analogue) in the adaptation of hepatic glycogen metabolism to nutritional status. The results indicate that both exendin-4 and fasting block the Pask expression, and PASK deficiency disrupts the physiological levels of blood GLP1 and the expression of hepatic GLP1 receptors after fasting. Under a non-fasted state, exendin-4 treatment blocks AKT activation, whereby Glucokinase and Sterol Regulatory Element-Binding Protein-1c (Srebp1c) expressions were inhibited. Furthermore, the expression of certain lipogenic genes was impaired, while increasing Glucose Transporter 2 (GLUT2) and Glycogen Synthase (GYS). Moreover, exendin-4 treatment under fasted conditions avoided Glucose 6-Phosphatase (G6pase) expression, while maintaining high GYS and its activation state. These results lead to an abnormal glycogen accumulation in the liver under fasting, both in PASK-deficient mice and in exendin-4 treated wild-type mice. In short, exendin-4 and PASK both regulate glucose transport and glycogen storage, and some of the exendin-4 effects could therefore be due to the blocking of the Pask expression.

Targeting Gys1 with AAV-SaCas9 Decreases Pathogenic Polyglucosan Bodies and Neuroinflammation in Adult Polyglucosan Body and Lafora Disease Mouse Models.

Many adult and most childhood neurological diseases have a genetic basis. CRISPR/Cas9 biotechnology holds great promise in neurological therapy, pending the clearance of major delivery, efficiency, and specificity hurdles. We applied CRISPR/Cas9 genome editing in its simplest modality, namely inducing gene sequence disruption, to one adult and one pediatric disease. Adult polyglucosan body disease is a neurodegenerative disease resembling amyotrophic lateral sclerosis. Lafora disease is a severe late childhood onset progressive myoclonus epilepsy. The pathogenic insult in both is formation in the brain of glycogen with overlong branches, which precipitates and accumulates into polyglucosan bodies that drive neuroinflammation and neurodegeneration. We packaged Staphylococcus aureus Cas9 and a guide RNA targeting the glycogen synthase gene, Gys1, responsible for brain glycogen branch elongation in AAV9 virus, which we delivered by neonatal intracerebroventricular injection to one mouse model of adult polyglucosan body disease and two mouse models of Lafora disease. This resulted, in all three models, in editing of approximately 17% of Gys1 alleles and a similar extent of reduction of Gys1 mRNA across the brain. The latter led to approximately 50% reductions of GYS1 protein, abnormal glycogen accumulation, and polyglucosan bodies, as well as ameliorations of neuroinflammatory markers in all three models. Our work represents proof of principle for virally delivered CRISPR/Cas9 neurotherapeutics in an adult-onset (adult polyglucosan body) and a childhood-onset (Lafora) neurological diseases.

Dexamethasone-induced activation of heat shock response ameliorates seizure susceptibility and neuroinflammation in mouse models of Lafora disease

Heat shock response (HSR) is a conserved cytoprotective pathway controlled by the master transcriptional regulator, the heat shock factor 1 (HSF1), that activates the expression of heat shock proteins (HSPs). HSPs, as chaperones, play essential roles in minimizing stress-induced damages and restoring proteostasis. Therefore, compromised HSR is thought to contribute to neurodegenerative disorders. Lafora disease (LD) is a fatal form of neurodegenerative disorder characterized by the accumulation of abnormal glycogen as Lafora bodies in neurons and other tissues. The symptoms of LD include progressive myoclonus epilepsy, dementia, and cognitive deficits. LD is caused by the defects in the gene coding laforin phosphatase or the malin ubiquitin ligase. Laforin and malin are known to work upstream of HSF1 and are essential for the activation of HSR. Herein, we show that mice deficient for laforin or malin show reduced levels of HSF1 and their targets in their brain tissues, suggesting compromised HSR; this could contribute to the neuropathology in LD. Intriguingly, treatment of LD animals with dexamethasone, a synthetic glucocorticoid analogue, partially restored the levels of HSF1 and its targets. Dexamethasone treatment was also able to ameliorate the neuroinflammation and susceptibility to induced seizures in the LD animals. However, dexamethasone treatment did not show a significant effect on Lafora bodies or autophagy defects. Taken together, the present study establishes a role for HSR in seizure susceptibility and neuroinflammation and dexamethasone as a potential antiepileptic agent, suitable for further studies in LD.

Modeling CNS Involvement in Pompe Disease Using Neural Stem Cells Generated from Patient-Derived Induced Pluripotent Stem Cells.

Pompe disease is a lysosomal storage disorder caused by autosomal recessive mutations in the acid alpha-glucosidase (GAA) gene. Acid alpha-glucosidase deficiency leads to abnormal glycogen accumulation in patient cells. Given the increasing evidence of central nervous system (CNS) involvement in classic infantile Pompe disease, we used neural stem cells, differentiated from patient induced pluripotent stem cells, to model the neuronal phenotype of Pompe disease. These Pompe neural stem cells exhibited disease-related phenotypes including glycogen accumulation, increased lysosomal staining, and secondary lipid buildup. These morphological phenotypes in patient neural stem cells provided a tool for drug efficacy evaluation. Two potential therapeutic agents, hydroxypropyl-β-cyclodextrin and δ-tocopherol, were tested along with recombinant human acid alpha-glucosidase (rhGAA) in this cell-based Pompe model. Treatment with rhGAA reduced LysoTracker staining in Pompe neural stem cells, indicating reduced lysosome size. Additionally, treatment of diseased neural stem cells with the combination of hydroxypropyl-β-cyclodextrin and δ-tocopherol significantly reduced the disease phenotypes. These results demonstrated patient-derived Pompe neural stem cells could be used as a model to study disease pathogenesis, to evaluate drug efficacy, and to screen compounds for drug discovery in the context of correcting CNS defects.

GYS1 or PPP1R3C deficiency rescues murine adult polyglucosan body disease.

ObjectiveAdult polyglucosan body disease (APBD) is an adult‐onset neurological variant of glycogen storage disease type IV. APBD is caused by recessive mutations in the glycogen branching enzyme gene, and the consequent accumulation of poorly branched glycogen aggregates called polyglucosan bodies in the nervous system. There are presently no treatments for APBD. Here, we test whether downregulation of glycogen synthesis is therapeutic in a mouse model of the disease.MethodsWe characterized the effects of knocking out two pro‐glycogenic proteins in an APBD mouse model. APBD mice were crossed with mice deficient in glycogen synthase (GYS1), or mice deficient in protein phosphatase 1 regulatory subunit 3C (PPP1R3C), a protein involved in the activation of GYS1. Phenotypic and histological parameters were analyzed and glycogen was quantified.ResultsAPBD mice deficient in GYS1 or PPP1R3C demonstrated improvements in life span, morphology, and behavioral assays of neuromuscular function. Histological analysis revealed a reduction in polyglucosan body accumulation and of astro‐ and micro‐gliosis in the brains of GYS1‐ and PPP1R3C‐deficient APBD mice. Brain glycogen quantification confirmed the reduction in abnormal glycogen accumulation. Analysis of skeletal muscle, heart, and liver found that GYS1 deficiency reduced polyglucosan body accumulation in all three tissues and PPP1R3C knockout reduced skeletal muscle polyglucosan bodies.InterpretationGYS1 and PPP1R3C are effective therapeutic targets in the APBD mouse model. These findings represent a critical step toward the development of a treatment for APBD and potentially other glycogen storage disease type IV patients.

A Novel Gene Therapy Approach for GSD III Using an AAV Vector Encoding a Bacterial Glycogen Debranching Enzyme

Glycogen storage disease type III (GSD III) is an inherited disorder caused by a deficiency of glycogen debranching enzyme (GDE), which results in the accumulation of abnormal glycogen (limit dextrin) in the cytoplasm of liver, heart, and skeletal muscle cells. Currently, there is no curative treatment for this disease. Gene therapy with adeno-associated virus (AAV) provides an optimal treatment approach for monogenic diseases like GSD III. However, the 4.6 kb human GDE cDNA is too large to be packaged into a single AAV vector due to its small carrying capacity. To overcome this limitation, we tested a new gene therapy approach in GSD IIIa mice using an AAV vector ubiquitously expressing a smaller bacterial GDE, Pullulanase, whose cDNA is 2.2 kb. Intravenous injection of the AAV vector (AAV9-CB-Pull) into 2-week-old GSD IIIa mice blocked glycogen accumulation in both cardiac and skeletal muscles, but not in the liver, accompanied by the improvement of muscle functions. Subsequent treatment with a liver-restricted AAV vector (AAV8-LSP-Pull) reduced liver glycogen content by 75% and reversed hepatic fibrosis while maintaining the effect of AAV9-CB-Pull treatment on heart and skeletal muscle. Our results suggest that AAV-mediated gene therapy with Pullulanase is a possible treatment for GSD III.

Spectrum of amyloglucosidase mutations in Asian Indian patients with Glycogen storage disease type III.

Glycogen storage disease type III (GSD III) is a rare autosomal recessive inborn error of glycogen degradation pathway due to deficiency or reduced activity of glycogen debranching enzyme (GDE) that results in accumulation of abnormal glycogen in the liver, muscle, and heart. The cardinal hallmarks are hepatomegaly, fasting hypoglycemia, seizures, growth retardation, progressive skeletal myopathy, and cardiomyopathy in few. To date, 258 mutations in amyloglucosidase (AGL) gene have been identified worldwide. However, the mutation spectrum in the Asian Indian region is yet to be well characterized. We investigated 24 patients of Asian origin from 21 unrelated families with a provisional diagnosis of GSD III based on clinical and biochemical criteria. Molecular diagnosis was assessed by bidirectional sequencing and the impact of novel missense variants on the tertiary (three-dimensional) structure of GDE was evaluated by molecular modeling approach. Eighteen different pathogenic variants were identified, out of which 78% were novel. Novel variants included five nonsense, three small duplications and two small deletions, a splice site variant, and three missense variants. Variations in Exons 4, 14, 19, 24, 27, and 33 accounted for 61% of the total pathogenic variants identified and Allele p.Gly798Alafs*3 showed a high allele frequency of 11%. Molecular modeling study of novel pathogenic missense variants indicated the probable underlying molecular mechanism of adverse impact of variations on the structure and catalytic function of human GDE. Our study is the first large study on GSD III from the Asian subcontinent, which further expands the mutation spectrum of AGL.

Development of Hepatocellular Carcinoma in Patients with Glycogen Storage Disease: a Single Center Retrospective Study.

BackgroundGlycogen storage disease (GSD) is an inherited disorder leading to abnormal glucose metabolism and glycogen accumulation, and is associated with various complications including hepatic adenoma and hepatocellular carcinoma. The aim of this study was to analyze the risk factors for hepatic adenoma and its malignant change, and the hepatocellular carcinoma-free survival rate in patients with GSD who developed adenoma.MethodsA total of 72 patients with GSD who were enrolled from March 1982 to September 2013 at Seoul National University Children's Hospital were retrospectively analyzed, and the median follow-up period was 19.2 years.ResultsThirty-two patients (44.4%) developed hepatic adenoma at an age range of 7.9–26.3 years (median, 14.3 years). Among the 32 patients with hepatic adenoma, 4 patients (12.5%) developed hepatocellular carcinoma on an average interval of 6.7 years between the diagnosis of adenoma and the development of hepatocellular carcinoma. GSD type I and portacaval shunt operation were found to be the risk factors for hepatic adenoma development. The hepatocellular carcinoma-free survival rate at 10 years from adenoma development was 82%.ConclusionThe present study found that portacaval shunt operation increases the risk of development of hepatic adenoma in GSD patients, especially in GSD type I. The hepatic adenoma in GSD patients has a potential of malignant transformation, which should be keep in mind in follow-up process of the disease.

A Liver Model of Infantile-Onset Pompe Disease Using Patient-Specific Induced Pluripotent Stem Cells.

Infantile-onset Pompe disease (IOPD) is a life-threatening multi-organ disease caused by an inborn defect of lysosomal acid α-glucosidase (GAA), which can degrade glycogen into glucose. Lack of GAA causes abnormal accumulation of glycogen in the lysosomes, particularly in the skeletal muscle, liver, and heart. Enzyme replacement therapy (ERT) with recombinant human GAA (rhGAA) is the only available treatment; however, its effect varies by organ. Thus, to fully understand the pathomechanism of IOPD, organ-specific disease models are necessary. We previously generated induced pluripotent stem cells (iPSCs) from three unrelated patients with IOPD and establish a skeletal muscle model of IOPD. Here, we used the same iPSC lines as the previous study and differentiated them into hepatocytes. As a result, hepatocytes differentiated from iPSC of IOPD patients showed abnormal accumulation of lysosomal glycogen, the hallmark of Pompe disease. Using this model, we also demonstrated that glycogen accumulation was dose-dependently restored by rhGAA treatment. In conclusion, we have successfully established an in vitro liver model of IOPD using patient-specific iPSCs. This model can be a platform to elucidate the underlying disease mechanism or to be applied to drug-screening. Moreover, our study also suggest that an iPSC-based approach is suitable for modeling of diseases that affect multiple organs like Pompe disease.

Congenital disorder of glycosylation type 1T with a novel truncated homozygous mutation in PGM1 gene and literature review

The congenital disorders of glycosylation are a group of clinically and biochemically heterogeneous diseases characterized by multisystem involvement due to glycosylation defect of protein and lipid. Here we report a 49-year-old man with exercise-induced fatigue and pain of muscle, tachypnea, cleft palate and bifid uvula. Exercise induced elevation of serum creatine kinase (CK), ammonia and lactic acid was recorded. The abnormal levels of myoglobin, CK-MB and LDH as well as S-T elevation in electrocardiogram were observed in repeated hospitalization recordings. Electromyography showed myopathic damage. Repetitive nerve stimulation test of low rates showed decrement in the left deltoid muscle. He was identified with a novel homozygous frameshift variant in Phosphoglucomutase type 1 gene (c.405delT p.N135Kfs*9) by whole exome sequencing. Muscle biopsy exhibited minimal variation in fiber size without abnormal glycogen accumulation. Compared with controls’, the patient's sample showed no signal at ∼61 kDa using N- or C-terminus antibody of Phosphoglucomutase type 1 in western blotting. A signal at ∼20 kDa was detected in patient using N-terminus antibody. Immunofluorescence revealed trace expression of C-terminus and a much lower expression of N-terminus on the sarcolemma than normal. Our findings indicate that c.405delT encodes a truncated protein with abnormal distribution and expression in skeletal muscle. In conclusion, genes associated with congenital disorders of glycosylation should be analyzed in patients with maxillofacial dysplasia, exertional weakness, cardiac involvement and exercise-induced-ammoniemia, without glycogen storage in skeletal muscle.

Hyperandrogenism and Insulin Resistance-Induced Fetal Loss: Evidence for Placental Mitochondrial Abnormalities and Elevated ROS Production in PCOS-Like Pregnant Rats

Women with polycystic ovary syndrome (PCOS) commonly suffer from miscarriage, but the underlying mechanism of PCOS-induced fetal loss during pregnancy is unclear. We used pregnant rats treated with 5α-dihydrotestosterone (DHT) and insulin to investigate the effects of hyperandrogenism and insulin resistance on fetal survival and to determine the molecular link between PCOS conditions and placental dysfunction during pregnancy. We show that pregnant rats chronically treated with a combination of DHT and insulin exhibited endocrine aberrations such as hyperandrogenism and insulin resistance that mirror pregnant PCOS patients. Compared to normal pregnant rats, PCOS-like pregnant rats had greater fetal loss and subsequently decreased litter sizes. This negative effect was accompanied by impaired trophoblast differentiation, abnormal glycogen accumulation, and decreased angiogenesis in the placenta. We report that over-production of reactive oxygen species (ROS) in the placenta, mitochondrial dysfunction, and disturbed SOD1 and Keap1/Nrf2 antioxidant responses constitute important contributors to fetal loss in PCOS-like pregnant rats. Furthermore, dose-dependent treatment with the antioxidant N-acetylcysteine (NAC) improved fetal survival in PCOS-like pregnant rats dependent on Keap1/Nrf2 and NFκB signaling molecules. However, similar treatment resulted in fetal loss in normal pregnant rats, most likely due to PCOS-like endocrine abnormality induced by NAC. Our work suggests that the deleterious effects of hyperandrogenism and insulin resistance on fetal survival are related to a constellation of mitochondrial-ROS-SOD1/Nrf2 changes in the placenta. Our findings also suggest that physiological levels of ROS are required for normal placental formation and fetal survival during pregnancy. Funding: This work was supported by the Swedish Medical Research Council (grant number 10380), the Swedish federal government under the LUA/ALF agreement (grant number ALFGBG-147791), the Jane and Dan Olsson’s Foundation, and the Adlerbert Research Foundation to HB and LRS as well as the National Natural Science Foundation of China (grant number 81774136), the Project of Young Innovation Talents in Heilongjiang Provincial University (grant number UNPYSCT-2015121), the Project of Innovation Talents (Young Reserve Talents) in Harbin city (grant number 2015RAQYJ089), and the Scientific Research Foundation of the Heilongjiang Province for Returned Chinese Scholars to YZ. ANSP is supported by a Royal Society Dorothy Hodgkin Research Fellowship. Declaration of Interest: The authors declare that no competing interests exist. Ethical Approval: The study was approved and authorized by the Animal Care and Use Committee of the Heilongjiang University of Chinese Medicine, China (HUCM 2015-0112), and followed the National Institutes of Health guidelines on the care and use of animals.