A Noncoding Variant Near PPP1R3B Promotes Liver Glycogen Storage and MetS, but Protects Against Myocardial Infarction.

CONTEXT: Glycogen storage diseases are rare. Increased glycogen in the liver results in increased attenuation. OBJECTIVE: Investigate the association and function of a noncoding region associated with liver attenuation but not histologic nonalcoholic fatty liver disease. DESIGN: Genetics of Obesity-associated Liver Disease Consortium. SETTING: Population-based. MAIN OUTCOME: Computed tomography measured liver attenuation. RESULTS: Carriers of rs4841132-A (frequency 2%-19%) do not show increased hepatic steatosis; they have increased liver attenuation indicative of increased glycogen deposition. rs4841132 falls in a noncoding RNA LOC157273 ~190 kb upstream of PPP1R3B. We demonstrate that rs4841132-A increases PPP1R3B through a cis genetic effect. Using CRISPR/Cas9 we engineered a 105-bp deletion including rs4841132-A in human hepatocarcinoma cells that increases PPP1R3B, decreases LOC157273, and increases glycogen perfectly mirroring the human disease. Overexpression of PPP1R3B or knockdown of LOC157273 increased glycogen but did not result in decreased LOC157273 or increased PPP1R3B, respectively, suggesting that the effects may not all occur via affecting RNA levels. Based on electronic health record (EHR) data, rs4841132-A associates with all components of the metabolic syndrome (MetS). However, rs4841132-A associated with decreased low-density lipoprotein (LDL) cholesterol and risk for myocardial infarction (MI). A metabolic signature for rs4841132-A includes increased glycine, lactate, triglycerides, and decreased acetoacetate and beta-hydroxybutyrate. CONCLUSIONS: These results show that rs4841132-A promotes a hepatic glycogen storage disease by increasing PPP1R3B and decreasing LOC157273. rs4841132-A promotes glycogen accumulation and development of MetS but lowers LDL cholesterol and risk for MI. These results suggest that elevated hepatic glycogen is one cause of MetS that does not invariably promote MI.

Links between autophagy and disorders of glycogen metabolism - Perspectives on pathogenesis and possible treatments.

The glycogen storage diseases are a group of inherited metabolic disorders that are characterized by specific enzymatic defects involving the synthesis or degradation of glycogen. Each disorder presents with a set of symptoms that are due to the underlying enzyme deficiency and the particular tissues that are affected. Autophagy is a process by which cells degrade and recycle unneeded or damaged intracellular components such as lipids, glycogen, and damaged mitochondria. Recent studies showed that several of the glycogen storage disorders have abnormal autophagy which can disturb normal cellular metabolism and/or mitochondrial function. Here, we provide a clinical overview of the glycogen storage disorders, a brief description of autophagy, and the known links between specific glycogen storage disorders and autophagy.

Glucose and glycogen in the diabetic kidney: Heroes or villains?

Glucose metabolism in the kidney is currently foremost in the minds of nephrologists, diabetologists and researchers globally, as a result of the outstanding success of SGLT2 inhibitors in reducing renal and cardiovascular disease in individuals with diabetes. However, these exciting data have come with the puzzling but fascinating paradigm that many of the beneficial effects on the kidney and cardiovascular system seem to be independent of the systemic glucose lowering actions of these agents. This manuscript places into context an area of research highly relevant to renal glucose metabolism, that of glycogen accumulation and metabolism in the diabetic kidney. Whether the glycogen that abnormally accumulates is pathological (the villain), is somehow protective (the hero) or is inconsequential (the bystander) is a research question that may provide insight into the link between diabetes and diabetic kidney disease.

A novel PHKA2 mutation in a Chinese child with glycogen storage disease type IXa: a case report and literature review.

BACKGROUND: PHKA2 gene mutations can cause liver phosphorylase kinase (PhK) deficiency, resulting in glycogen storage disease type IXa (GSD IXa). Elevated liver transaminase levels and liver enlargement are the most frequent phenotypes of GSD IXa. However, whether the phenotypes are applicable to Chinese patients remains unclear. CASE REPORT: A boy aged 2 years and 8 months with a history of episodic fatigue and weakness since he was 2 years old was referred to our endocrinology clinic. Apart from symptomatic ketotic hypoglycemic episodes (palpitation, hand shaking, sweating, etc.), no abnormalities of liver transaminase levels or liver size were found. To identify the aetiology of his clinically diagnosed hypoglycaemia, the proband and his parents were screened for PHKA2 gene mutations by next-generation sequencing. A heterozygous mutation (c.2972C > G, p.G991A) in PHKA2 was found in the proband and his mother. Twenty-one Chinese cases with GSD IXa have been reported in the literature to date, and elevated liver transaminase levels (95%) and liver enlargement (91%) are the most frequent phenotypes of GSD IXa in Chinese patients. Hypoglycaemia may be one of the early onset symptoms in infants with GSD IXa. CONCLUSIONS: This study enriches our knowledge of the PHKA2 gene mutation spectrum and provides further information about the phenotypic characteristics of Chinese GSD IXa patients.

[Insulin edema in hepatic glycogenosis]. / Œdème insulinique au cours d'une glycogénose hépatique.

INTRODUCTION: Hepatic glycogenosis is a rare syndrome, which includes poorly controlled diabetes mellitus, hepatomegaly, delayed puberty, and growth delay. Insulin edema is sometimes associated. CASE REPORT: An 18-year-old woman presented with diffuse edema, hepatomegaly, amenorrhea, uncontrolled diabetes, and elevated transaminases and cholestasis. Hepatic ultrasonography and abdominal computed tomographic scan confirmed the hepatomegaly. The liver biopsy showed a massive glycogenosis and the diagnosis of hepatic glycogenosis was confirmed. Too large doses of insulin were responsible of diffuse edema. Diabetes equilibration and diminution of insulin intakes allow correction of this disorder. CONCLUSION: Excess of insulin can lead to excessive hepatic glycogen storage by activation of glycogenosis enzymes. Biological manifestations consist on elevated liver enzymes and hyperlactatemia. There is a link between administration of high dose of insulin and edema. Hepatic glycogenosis should be suspected when diabetes is uncontrolled and be considered as a differential diagnosis of steatosis. It may be associated and revealed by insulin edema directly related to excessive insulin intakes.

PGM1 deficiency diagnosed during an endocrine work-up of low IGF-1 mediated growth failure.

OBJECTIVE AND IMPORTANCE: Phosphoglucomutase 1 (PGM1) deficiency, first described as a glycogenosis (type XIV) is also a congenital disorder of glycosylation (CDG). We want to illustrate the wide clinical spectrum of PGM1 deficiency and in particular the associated disturbance in glucose metabolism and the endocrine dysfunction. Treatment with d-galactose is experimental. CASE PRESENTATION: PGM1 deficiency was diagnosed in an 8-year-old boy, who was referred because of an unexplained complex syndrome, including recurrent hypoglycaemia and low IGF-1 mediated growth failure. CONCLUSION: The timely diagnosis of this disorder is particularly important, because d-galactose treatment can improve the latter symptoms.

Pulmonary Interstitial Glycogenosis: A Reversible Underlying Condition Associated With D-Transposition of the Great Arteries and Severe Persistent Pulmonary Hypertension.

Transposition of the great arteries with intact ventricular septum and persistent pulmonary hypertension (TGA-IVS PPHN) is a rare association with a poor prognosis. We report the case of a term newborn with TGA-IVS PPHN successfully managed with perioperative extracorporeal membrane oxygenation (ECMO) and aggressive pulmonary vasodilation therapy that underwent successful arterial switch procedure. A lung biopsy obtained during the surgical procedure showed pulmonary interstitial glycogenosis, a reversible condition. Concerns over left ventricle deconditioning after ECMO could be minimized with appropriate management and monitoring of the ductus arteriosus and appropriate timing of surgery.

Glycogenic hepatopathy is an under-recognised cause of hepatomegaly and elevated liver transaminases in type 1 diabetes mellitus.

Glycogenic hepatopathy (GH) is an under-recognised complication of type 1 diabetes mellitus (T1DM) not controlled to target resulting in hepatomegaly and elevated liver transaminases. We report the case of a 19-year-old man with T1DM not controlled to target who presented with abdominal pain, hepatomegaly and deranged liver transaminases. He was subsequently diagnosed with GH on liver biopsy, with the mainstay of treatment being reduction in caloric intake and insulin.

New insights in the field of muscle glycogenoses.

PURPOSE OF REVIEW: This review highlights recent contributions regarding clinical heterogeneity, pathogenic mechanisms, therapeutic trials, and animal models of the muscle glycogenoses. RECENT FINDINGS: Most recent publications have dealt with the clinical effects of enzyme replacement therapy (ERT) in glycogenosis type II (Pompe disease), including the cognitive development of children with the infantile form who have reached school age. Standardized exercise testing has shown the similarity between McArdle disease and one of the most recently described muscle glycogenoses, phosphoglucomutase deficiency. Cycle ergometry in patients with glycogenosis type III (debrancher deficiency) without overt weakness has documented exercise intolerance relieved by glucose infusion, consistent with the glycogenolytic block. A mouse model of McArdle disease faithfully recapitulates most features of the human disease and will prove valuable for a better understanding of pathogenesis and therapeutic modalities. Polyglucosan body myopathy with cardiomyopathy has been associated with mutations in RBCK1, a ubiquitin ligase, which have also been reported in children with early-onset immune disorder. The role of polyglucosan storage in muscle and in both central and peripheral nervous systems has been confirmed in the infantile and late-onset forms of glycogenosis type IV (brancher enzyme deficiency). Additional novel findings include the involvement of the heart in one patient with phosphofructokinase (PFK) deficiency and the presence of tubular aggregates in a manifesting heterozygote with phosphoglycerate mutase deficiency. SUMMARY: Important recent developments in the field of muscle glycogenoses include a new disease entity, a new animal model of McArdle disease, and better knowledge of the pathogenesis in some glycogenoses and of the long-term effects of enzyme replacement therapy in Pompe disease.

Recurrent infantile hypoglycemia due to combined fructose-1,6-diphosphatase deficiency and growth hormone deficiency.

A 14-month-old female infant presented with recurrent episodes of acute gastroenteritis accompanied by severe metabolic acidosis and hypoglycemia. Physical examination showed hepatomegaly. Laboratory evaluation revealed elevated hepatic enzymes, prolonged prothrombin time, hyperuricemia, and extremely elevated lactate and alanine levels. Glucagon injection during hypoglycemia resulted in a further decrease of blood glucose. She was treated with glucose-containing intravenous fluids, with rapid improvement and normalization of her blood pH and glucose levels. Hormonal assessment during two episodes of hypoglycemia indicated growth hormone (GH) deficiency. However, as isolated GH deficiency could not explain all other concomitant features, such as severe lactic acidosis, hepatomegaly, impaired liver function, and hyperuricemia, the possibility of a combined defect was suggested. Further lymphocytic enzymatic investigation revealed fructose-1,6-diphosphatase deficiency and molecular genetic analysis demonstrated frame shift mutation in the FBP1 gene. This enzyme deficiency causes a rare metabolic disorder not previously described in combination with GH deficiency.

Clinical and morphologic changes in ewes and fetuses poisoned by Ipomoea carnea subspecies fistulosa.

Intoxication with Ipomoea carnea has been reported in goats, sheep, and cattle in tropical regions worldwide. The disease has been characterized only in goats; therefore, the present study was conducted in sheep. Nine animals were fed feed rations that contained 3 different concentrations of Ipomoea carnea subsp. fistulosa. Individual intake varied between 10.5 and 135.2 g of fresh plant per kilogram of body weight (BW) per day. Animals first showed clinical signs between day 43 and day 63. The maximum survival time was 133 days. Sheep presented with weight loss and neurologic abnormalities. Neurologic signs were dominated by marked depression, abnormal behavior, and musculoskeletal weakness, with poorly defined motor and proprioceptive deficits. In mature animals, cytoplasmic vacuolation, consistent with accumulation of secondary lysosomes, affected neurons, astrocytes, exocrine pancreatic acinar epithelia, hepatocytes and Kupffer cells, renal tubular epithelia, thyroid follicular epithelia, cortical adrenal epithelia, endothelia and perivascular cells, and macrophages in lymph nodes and spleen. In the central nervous system, there was axonal degeneration and astrogliosis. Abortion was observed as early as day 22 of the trial. In fetal tissues and placenta of chronically poisoned ewes, cytoplasmic vacuolation was histologically detected in neurons, exocrine pancreatic acinar epithelia, hepatocytes, renal tubular epithelia, and thyroid follicular epithelia. All the sheep developed a glycoprotein storage disease, with lysosomal accumulation of N-glycosidically linked oligosaccharides, which was indistinguishable from that induced by the alkaloid swainsonine alone.

Clinical resolution of glycogenic hepatopathy following improved glycemic control.

Glycogenic hepatopathy is an underrecognized complication of long-standing poorly controlled diabetes mellitus. It is characterized by abnormal glycogen accumulation in hepatocytes, elevated liver enzymes and hepatomegaly. This is a distinct entity from other causes of hepatomegaly and elevated liver enzymes in diabetics such as nonalcoholic fatty liver disease. It is important to distinguish this entity as it has the potential for resolution following improved glycemic control as described by this case report.

A role for AGL ubiquitination in the glycogen storage disorders of Lafora and Cori's disease.

Cori's disease is a glycogen storage disorder characterized by a deficiency in the glycogen debranching enzyme, amylo-1,6-glucosidase,4-alpha-glucanotransferase (AGL). Here, we demonstrate that the G1448R genetic variant of AGL is unable to bind to glycogen and displays decreased stability that is rescued by proteasomal inhibition. AGL G1448R is more highly ubiquitinated than its wild-type counterpart and forms aggresomes upon proteasome impairment. Furthermore, the E3 ubiquitin ligase Malin interacts with and promotes the ubiquitination of AGL. Malin is known to be mutated in Lafora disease, an autosomal recessive disorder clinically characterized by the accumulation of polyglucosan bodies resembling poorly branched glycogen. Transfection studies in HepG2 cells demonstrate that AGL is cytoplasmic whereas Malin is predominately nuclear. However, after depletion of glycogen stores for 4 h, approximately 90% of transfected cells exhibit partial nuclear staining for AGL. Furthermore, stimulation of cells with agents that elevate cAMP increases Malin levels and Malin/AGL complex formation. Refeeding mice for 2 h after an overnight fast causes a reduction in hepatic AGL levels by 48%. Taken together, these results indicate that binding to glycogen crucially regulates the stability of AGL and, further, that its ubiquitination may play an important role in the pathophysiology of both Lafora and Cori's disease.

Complete reversal of glycogen hepatopathy with pancreas transplantation: two cases.

Glycogen hepatopathy is the pathological overloading of hepatocytes with glycogen that is associated with poorly controlled diabetes mellitus. Clinically, it presents with abdominal discomfort, tender hepatomegaly and elevated transaminases. In this report, we describe our experience with two cases of type I diabetes mellitus and glycogen hepatopathy. The patients underwent isolated pancreas transplantation, following which, we have been able to demonstrate complete histological resolution of glycogen hepatopathy associated with control of glucose metabolism.

Perda auditiva neonatal associada a hiperbilirrubinemia por deficiência de glicose-6-fosfato desidrogenase: relato de caso / Neonatal hearing loss associated hyperbilirubinemia in a newborn with glucose-6-phosphate dehidrogenase deficêncy: case report

Objetivo: relatar um caso de grave perda auditiva neonatal assiaciada a hiperbilirrubinemia por deficiência de glicose-6 fosfato desidrogenase. Descrição: um recé-nascido a termo, adequado para a idade gestacional, realizou triagem auditiva neonatal por método de emissões otoacústicas / Objective: to report a case of serious neonatal loss associated to hypeerbilirubinemia in a newbornwith glucose-6-phosphate dehydrogenase deficiency...