Liver fibrosis during clinical ascertainment of glycogen storage disease type III: a need for improved and systematic monitoring.

PURPOSE: In glycogen storage disease type III (GSD III), liver aminotransferases tend to normalize with age giving an impression that hepatic manifestations improve with age. However, despite dietary treatment, long-term liver complications emerge. We present a GSD III liver natural history study in children to better understand changes in hepatic parameters with age. METHODS: We reviewed clinical, biochemical, histological, and radiological data in pediatric patients with GSD III, and performed a literature review of GSD III hepatic findings. RESULTS: Twenty-six patients (median age 12.5 years, range 2-22) with GSD IIIa (n = 23) and IIIb (n = 3) were enrolled in the study. Six of seven pediatric patients showed severe fibrosis on liver biopsy (median [range] age: 1.25 [0.75-7] years). Markers of liver injury (aminotransferases), dysfunction (cholesterol, triglycerides), and glycogen storage (glucose tetrasaccharide, Glc4) were elevated at an early age, and decreased significantly thereafter (p < 0.001). Creatine phosphokinase was also elevated with no significant correlation with age (p = 0.4). CONCLUSION: Liver fibrosis can occur at an early age, and may explain the decrease in aminotransferases and Glc4 with age. Our data outlines the need for systematic follow-up and specific biochemical and radiological tools to monitor the silent course of the liver disease process.

Genetic analysis and clinical assessment of four patients with Glycogen Storage Disease Type IIIa in China.

BACKGROUND: Glycogen Storage Disease Type III (GSD III) is a rare autosomal recessive metabolic disorder caused by AGL gene mutation. There is significant heterogeneity between the clinical manifestations and the gene mutation of AGL among different ethnic groups. However, GSD III is rarely reported in Chinese population. CASE PRESENTATION: In this study, we aimed to study the genetic and clinical characteristics of four patients with GSD IIIa from China, especially the neurological manifestations. Meanwhile, we conducted a literature review of GSD IIIa cases reported in Chinese population to investigate the relationship between genotype and phenotype. CONCLUSIONS: Three different AGL gene mutations were identified in our patients: c.206dupA, c.1735 + 1G > T and c.2590 C>T. Moreover, progressive myopathy accompanied by elevated creatine kinase level was the main manifestation of our patients in adolescents. Our results showed that AGL c.206dupA was a novel mutation and caused severe clinical manifestations. AGL c.1735 + 1G > T might be a recurrent mutation in the Chinese population. Genetic analysis of AGL gene mutation combined with muscle magnetic resonance imaging (MRI) might provide greater benefit to the patient in diagnosing GSD IIIa, rather than an invasive diagnostic procedure of biopsy.

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. Liver expression 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.

Natural Progression of Canine Glycogen Storage Disease Type IIIa.

Glycogen storage disease type IIIa (GSD IIIa) is caused by a deficiency of glycogen debranching enzyme activity. Hepatomegaly, muscle degeneration, and hypoglycemia occur in human patients at an early age. Long-term complications include liver cirrhosis, hepatic adenomas, and generalized myopathy. A naturally occurring canine model of GSD IIIa that mimics the human disease has been described, with progressive liver disease and skeletal muscle damage likely due to excess glycogen deposition. In the current study, long-term follow-up of previously described GSD IIIa dogs until 32 mo of age (n = 4) and of family-owned GSD IIIa dogs until 11 to 12 y of age (n = 2) revealed that elevated concentrations of liver and muscle enzyme (AST, ALT, ALP, and creatine phosphokinase) decreased over time, consistent with hepatic cirrhosis and muscle fibrosis. Glycogen deposition in many skeletal muscles; the tongue, diaphragm, and heart; and the phrenic and sciatic nerves occurred also. Furthermore, the urinary biomarker Glc4, which has been described in many types of GSD, was first elevated and then decreased later in life. This urinary biomarker demonstrated a similar trend as AST and ALT in GSD IIIa dogs, indicating that Glc4 might be a less invasive biomarker of hepatocellular disease. Finally, the current study further demonstrates that the canine GSD IIIa model adheres to the clinical course in human patients with this disorder and is an appropriate model for developing novel therapies.

Pathological characteristics of glycogen storage disease III in skeletal muscle.

We report a 25-year-old man with glycogenosis III who presented with a progressive 2 year history of fatigue, hand stiffness and cramping. The glycogenoses are a group of rare metabolic disorders which develop as a result of deficiencies in various enzymes involved in the metabolism of glycogen. Some, but not all, glycogenoses, may result in skeletal muscle pathology. Among those that result in vacuolar myopathic changes, glycogen storage disease III or debrancher enzyme deficiency, an autosomal recessive condition, is less commonly encountered than acid maltase (Type II) and myophosphorylase (Type V) deficiencies. Many patients with debrancher enzyme deficiency also have liver involvement. The neurological examination of our patient showed mild proximal limb weakness and decreased reflexes. He had elevated creatine kinase and aldolase levels. He also demonstrated some elevations in his liver function tests, suggesting possible liver involvement. A skeletal muscle biopsy demonstrated vacuolar myopathic changes (acid phosphatase negative) accompanied by focal endomysial fibrosis and chronic inflammation. An ultrastructural examination showed that his vacuoles were filled with glycogen material. An enzyme assay of skeletal muscle tissue showed a significant decrease in debrancher enzyme activity (11% of normal). We review the typical clinical presentation of patients with glycogenosis III and discuss the differential diagnoses of glycogenosis III versus the other glycogenoses resulting in vacuolar myopathy.

Molecular and biochemical characterization of a novel intronic single point mutation in a Tunisian family with glycogen storage disease type III.

Genetic deficiency of the glycogen debranching enzyme causes glycogen storage disease type III, an autosomal recessive inherited disorder. The gene encoding this enzyme is designated as AGL gene. The disease is characterized by fasting hypoglycemia, hepatomegaly, growth retardation, progressive myopathy and cardiomyopathy. In the present study, we present clinical features and molecular characterization of two consanguineous Tunisian siblings suffering from Glycogen storage disease type III. The full coding exons of the AGL gene and their corresponding exon-intron boundaries were amplified for the patients and their parents. Gene sequencing identified a novel single point mutation at the conserved polypyrimidine tract of intron 21 in a homozygous state (IVS21-8A>G). This variant cosegregated with the disease and was absent in 102 control chromosomes. In silico analysis using online resources showed a decreased score of the acceptor splice site of intron 21. RT-PCR analysis of the AGL splicing pattern revealed a 7 bp sequence insertion between exon 21 and exon 22 due to the creation of a new 3' splice site. The predicted mutant enzyme was truncated by the loss of 637 carboxyl-terminal amino acids as a result of premature termination. This novel mutation is the first mutation identified in the region of Bizerte and the tenth AGL mutation identified in Tunisia. Screening for this mutation can improve the genetic counseling and prenatal diagnosis of GSD III.

Glycogen storage disease type III with hypoketosis.

A rare case of glycogen storage disease type III with unusually absent ketone body production during hypoglycemia is presented. A 10-month-old boy presented with asymptomatic hepatomegaly. GOT/GPT 2555/1160 IU/L, CK 302 IU/L, triglycerides 1223 mg/dL, cholesterol 702 mg/dL and uric acid 7.9 mg/dL. After a 9-hour fast, glucose was 27 mg/dL and adequate lipolysis without ketogenesis was observed (total/free carnitine 34.5/20 micromol/L, free fatty acids 1620 micromol/L and beta-hydroxybutyrate 172 micromol/L). Result of MCT (medium-chain triglycerides) load test: basal hydroxybutyrate 29 micromol/L rose to 5748 micromol/L. Treatment with a fat-restricted diet supplemented with formula containing MCT was initiated and the patient presented a satisfactory initial evolution. Three months later, CK were 3000 IU/L. Muscle biopsy was diagnostic of glycogenosis. Enzymatic activity in skin fibroblasts was 0% for amylo-1,6-glucosidase. The diagnosis of glycogenosis type III was established. Echocardiography performed at that time showed non-obstructive ventricular hypertrophy. Until now hypoketosis during hypoglycemia has only been described in glycogenosis type I.

An association among iron, copper, zinc, and selenium, and antioxidative status in dyslipidemic pediatric patients with glycogen storage disease types IA and III.

Dyslipidemia in patients with glycogen storage disease types Ia (GSD Ia) and III (GSD III) does not lead to premature atherosclerosis. The aim of this study was to investigate the association among serum copper (Cu), zinc (Zn), iron (Fe), and selenium (Se) concentrations, and their carrier proteins: ceruloplasmin, albumin, and related antioxidant enzyme activities [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), paraoxonase (PON), and arylesterase (ARYL)] in 20 GSD Ia and 14 III patients compared to age and sex matched 20 healthy subjects. Erythrocyte oxidative stress was measured by erythrocyte thiobarbituric acid reactive substances (eTBARSs). Hypertriglyceridemia [333 (36-890)mg/dL] in GSD Ia and hypercholesterolemia with elevated LDL-cholesterol [188 (91-313)mg/dL] and decreased HDL-cholesterol [32(23-58)mg/dL] levels in GSD III were found. Serum Cu, Fe, and Zn showed no significant differences between groups. However, Se 60 (54-94), 81 (57-127) microg/L, ceruloplasmin 21 (10-90), 27 (23-65) microg/L, and albumin 2.4 (1.7-5.1), 2.8 (1.8-4.06)g/dL levels were decreased in GSD Ia and III groups, respectively, in comparison with the controls [Se 110 (60-136) microg/L, ceruloplasmin 72 (32-94) microg/L, and albumin 4.4 (4-4.8)g/dL)]. In spite of high oxidative stress in erythrocyte detected by elevated eTBARS/Hb levels in GSD group [674.8 (454.6-948.2) for GSD Ia, 636.3 (460.9-842.1) for GSD III, and 525.6 (449.2-612.6)], the activities of CAT, SOD, ARYL, and PON in GSD patients were not different from the controls. GPx activity was decreased in GSD Ia [3.7 (1.8-7.1)U/mL] and GSD III [4.2 (2.2-8.6)U/mL] compared with healthy controls [7.1 (2.9-16.2)U/mL]. In conclusion, this study supplied the data for trace elements, their carrier, and antioxidative enzymes in the patients with GSD Ia and III. The trace elements and anti-oxidative enzyme levels in GSD patients failed to explain the atherosclerotic escape phenomenon reported in these patients.

Adult polyglucosan body disease: case description of an expanding genetic and clinical syndrome.

A non-Jewish patient is described who had adult polyglucosan body disease (APBD) and glycogen branching enzyme (GBE) deficiency without GBE mutation. A heterozygous polymorphism (Val160Ile) was found, and also discovered in 1 of 50 normal individuals. Magnetic resonance imaging demonstrated increased T2 signal in the midbrain, medullary olives, dentate nuclei, cerebellar peduncles, and internal and external capsules, with vermian atrophy. Both muscle and nerve biopsy revealed perivascular inflammatory infiltrates. These findings expand the clinical and genetic spectrum of APBD. Factors other than mutation of the expressed GBE gene may cause enzyme deficiency and varied expression and development of APBD.

Fatal liver cirrhosis and esophageal variceal hemorrhage in a patient with type IIIa glycogen storage disease.

A 45-year-old woman with type IIIa glycogen storage disease (GSD IIIa) died of variceal hemorrhage secondary to liver cirrhosis. The postmortem examination disclosed increased intracellular glycogen in the liver as well as in the heart and skeletal muscle. Although most liver injuries in GSD IIIa have been considered to be non-progressive in adulthood, liver cirrhosis can be a cause of death in some patients.

Some properties of fibroblasts from a patient with debrancher deficiency.

Glycogenosis Type III is characterized by a deficiency of debranching enzyme (amylo-1,6-glucosidase, E.C. 3. 2. 1. 33) in most tissues. Low activity of liberating glucose from limited dextrin in the biopsied muscle can be demonstrated in a patient with this disease. We cultured fibroblasts from a skin biopsy from a patient with debrancher deficiency and examined the metabolism of glycogen in these cultured fibroblasts. Debrancher activity in the post-mitochondrial supernatant obtained from these fibroblasts showed a good concentration dependent manner but had approximately half of that from normal human fibroblasts (YH-1). Although the enzymatic activity of debrancher in the cultured fibroblasts from the skin was reduced essentially to the same levels as observed in muscle biopsy, little glycogen granules were accumulated in the cytoplasm of these fibroblasts as revealed by either light- or electron-microscopic observation. The fibroblasts obtained in the present study may be useful for the analysis of molecular mechanism of the debrancher deficiency disease, glycogenosis Type III.

Accumulation of glycogen in sural nerve axons in adult-onset type III glycogenosis.

A 42-year-old man with adult-onset type III glycogenosis (Cori's disease) developed a gradually progressive polyneuropathy with markedly reduced activity of muscle amylo-1,6-glucosidase and glycogen accumulation within all elements of biopsied sural nerve, including axons, as shown by ultrastructural assessment.

Insular amyloid in a case of type III glycogenosis with a special reference to the origin of amyloid fibrils.

Amyloid depositions of pancreatic islets were investigated with electron microscopy in a case of type III glycogenosis. Beta cells adjoining small amyloid depositions were shown to have cytoplasmic invaginations where closely packed amyloid fibrils were disclosed regularly orientated amyloid bundles. In the cytoplasm of the beta cells, some membrane-bounded vesicles contained amyloid fibrils and a few beta granules directly transformed into the fibrils within the vesicles. These findings indicate that, at least in this case, the beta cells play a crucial role in the formation of insular amyloid.

Type III glycogenosis with multicore structures.

A case of an infantile type III glycogenosis (Forbes disease), confirmed by morphologic and biochemical studies, had light-microscopic, histochemical, and electron-microscopic evidence of multicore structures and type 1 fiber predominance with hypotrophy. This association is discussed with relation to the unusual clinical findings. The authors conclude that two distinct disease entities--Forbes disease and multicore myopathy--may coexist.

[Serum lipoproteins in the generalized form of type III glycogenosis]. / Lipoproteidy syvorotki krovi pri generalizovannoi forme glikogenoza III tipa.

Distinct accumulation of glycogen, anomalous in structure, and absence of amylo-1,6-glucosidase activity were observed in studies of material obtained by biopsy from liver and muscle tissues of a patient with generalized form of glycogenosis type III. Anamalous glycogen (limitdextrin) was also found in erythrocytes. Concentration of lipoproteins, especially of low density lipoproteins 12.20 S and 0-12 S, was increased in blood serum. Spectrum of lipoproteins acquired a tendency to normalization simultaneously with clinical improvement after intravenous administration of glucose and treatment with cholesterolamine per os.

Some cases of Type III glycogen storage disease.

Five patients with glycogen storage disease are described. Hypoglycemia was observed in all patients after an overnight fast, and glycemic and lactatemic curves obtained after oral administration of glucose or galactose were typical of those seen in Type III glycogenosis. An increase of liver glycogen up to 12-16% and complete absence of liver amylo-1,6-glucosidase were found in liver tissue samples obtained by needle biopsy. The patients were diagnosed as having Type III glycogenosis. In two patients the absence of amylo-1,6-glycosidase was accompanied by a sharp decline of liver phosphorylase activity. In one patient a decline of glucose-6-phosphatase activity was observed. The structure of liver glycogen was different in different patients, and so were the types of glycemic and lactatemic curves obtained upon protein tolerance tests. The above phenomena might be explained by some secondary disturbances in the activity of enzymes (phosphorylase, glucose-6-phosphatase) involved in the metabolism of liver glycogen of these patients.

[Study of glycogen metabolism in the liver in type III glycogenosis (limit dextrinosis)]. / Issledovanie obmean glikogena v pecheni pri glikogenoze III tipa (limitdekstrinoze)

Data on biochemical study of a patient with glycogenosis of the III type (limit dextrinosis) are presented. In a punctate of liver tissue absence of amylo-1,6-glucosidase activity and significant accumulation of glycogen, which was anomalous in structure, were noted. Loading with galactose and adrenaline caused alterations typical for the III type of glycogenosis. Content of glucose and lactate in blood were also studied in response to the peroral administration of glucose and protein. In erythrocytes of the patient the polysaccharide structure was shown to be anomalous; it resembled the structure of a polysaccharide from liver tissue of the patient.