Beneficial Effects of Modified Atkins Diet in Glycogen Storage Disease Type IIIa.

INTRODUCTION: Glycogen storage disease Type III (GSD III) is an autosomal recessive disease caused by the deficiency of glycogen debranching enzyme, encoded by the AGL gene. Two clinical types of the disease are most prevalent: GSD IIIa involves the liver and muscle, whereas IIIb affects only the liver. The classical dietetic management of GSD IIIa involves prevention of fasting, frequent feeds with high complex carbohydrates in small children, and a low-carb-high-protein diet in older children and adults. Recently, diets containing high amount of fat, including ketogenic and modified Atkins diet (MAD), have been suggested to have favorable outcome in GSD IIIa. METHODS: Six patients, aged 3-31 years, with GSD IIIa received MAD for a duration of 3-7 months. Serum glucose, transaminases, creatine kinase (CK) levels, capillary ketone levels, and cardiac parameters were followed-up. RESULTS: In all patients, transaminase levels dropped in response to MAD. Decrease in CK levels were detected in 5 out of 6 patients. Hypoglycemia was evident in 2 patients but was resolved by adding uncooked cornstarch to diet. CONCLUSION: Our study demonstrates that GSD IIIa may benefit from MAD both clinically and biochemically.

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

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

Peripheral neuropathy in glycogen storage disease type III: Fact or myth?

INTRODUCTION: The aim of this study was to assess whether peripheral neuropathy is a feature of glycogen storage disease type IIIa (GSD IIIa) in adult patients. METHODS: Medical records of a cohort of adult GSD IIIa patients who underwent electromyography (EMG) and nerve conduction studies (NCS) were reviewed, and the results were correlated with physical examination findings. RESULTS: Sixteen patients underwent EMG and NCS; 4 complained of exercise intolerance, 1 of foot paresthesia, and 11 of muscle weakness (3 proximal, 8 distal). None of the patients had sensory deficits on clinical examination. All motor and sensory conduction velocities and sensory amplitudes were within reference ranges. EMG showed myopathic motor unit potentials in 15 of the 16 patients. CONCLUSIONS: Based on the clinical examination and the NCS and EMG results, we did not identify any peripheral nerve involvement in our adult patients diagnosed with GSD III.

Mouse model of glycogen storage disease type III.

Glycogen storage disease type IIIa (GSD IIIa) is caused by a deficiency of the glycogen debranching enzyme (GDE), which is encoded by the Agl gene. GDE deficiency leads to the pathogenic accumulation of phosphorylase limit dextrin (PLD), an abnormal glycogen, in the liver, heart, and skeletal muscle. To further investigate the pathological mechanisms behind this disease and develop novel therapies to treat this disease, we generated a GDE-deficient mouse model by removing exons after exon 5 in the Agl gene. GDE reduction was confirmed by western blot and enzymatic activity assay. Histology revealed massive glycogen accumulation in the liver, muscle, and heart of the homozygous affected mice. Interestingly, we did not find any differences in the general appearance, growth rate, and life span between the wild-type, heterozygous, and homozygous affected mice with ad libitum feeding, except reduced motor activity after 50 weeks of age, and muscle weakness in both the forelimb and hind legs of homozygous affected mice by using the grip strength test at 62 weeks of age. However, repeated fasting resulted in decreased survival of the knockout mice. Hepatomegaly and progressive liver fibrosis were also found in the homozygous affected mice. Blood chemistry revealed that alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) activities were significantly higher in the homozygous affected mice than in both wild-type and heterozygous mice and the activity of these enzymes further increased with fasting. Creatine phosphokinase (CPK) activity was normal in young and adult homozygous affected mice. However, the activity was significantly elevated after fasting. Hypoglycemia appeared only at a young age (3 weeks) and hyperlipidemia was not observed in our model. In conclusion, with the exception of normal lipidemia, these mice recapitulate human GSD IIIa; moreover, we found that repeated fasting was detrimental to these mice. This mouse model will be useful for future investigation regarding the pathophysiology and treatment strategy of human GSD III.

A monocentric pilot study of an antioxidative defense and hsCRP in pediatric patients with glycogen storage disease type IA and III.

BACKGROUND AND AIMS: Patients with glycogen storage disease type Ia (GSD Ia) and III (GSD III) do not develop premature atherosclerosis despite hyperlipidemia. The aim of the study was to investigate the oxidative-antioxidative conditions and high sensitivity C-reactive protein (hsCRP) levels in patients with glycogen storage disease type Ia and III. METHODS: We measured lipid profile and lipid peroxidation products in comparison with hsCRP and antioxidative status: trolox equivalent antioxidant capacity, total antioxidant activity, proteinaceous antioxidant enzymes (catalase, superoxide dismutase, paraoxonase, arylesterase), aqueous antioxidants (vitamin C, uric acid, bilirubin, total protein) and lipid-soluble antioxidants (alpha-tocopherol, beta-carotene). The study included 50 individuals: 22 with GSD Ia, 9 with GSD III, and 19 healthy subjects. RESULTS: GSD Ia patients showed a marked hypertriglyceridemia, whereas GSD III patients demonstrated hypercholesterolemia with elevated LDL-cholesterol and decreased HDL-cholesterol levels. Lipid peroxidation levels increased in both GSD groups. The antioxidant activity elevated in GSD Ia group. No significant differences were found in the activities of antioxidant enzymes. Uric acid and alpha-tocopherol levels increased, however, vitamin C and beta-carotene reduced in both GSD groups. The hsCRP levels did not differ among the groups. CONCLUSIONS: In summary our study revealed normal levels of hsCRP in spite of the dyslipidemic status in both GSD patients. The increased plasma antioxidative defense in GSD Ia might be attributed not only to the elevated uric acid but also to the supplemented vitamin E levels. These findings should motivate further investigations in the area of atherosclerotic escape of GSDs.

Serum lipid and lipoprotein profile of patients with glycogen storage disease types I, III and IX.

With current dietary therapy, life expectancy in glycogen storage disease (GSD) has improved considerably and more children reach adulthood. Notwithstanding intensive dietary therapy, moderate to severe hyperlipidaemia is still observed frequently. There is limited information about the type and extent of hyperlipidaemia. We studied the lipid profile in 20 patients, aged 8-54 years, of the three (types I, III and IX) most common forms of adult GSD. Hyperlipidaemia was shown to be type-specific, affecting predominantly patients with GSD type Ia, who showed marked combined hypercholesterolaemia and hypertriglyceridaemia. By contrast, a heterogeneous distribution of HDL was found in patients with GSD I and III. There was no significant difference in Apo Al and Apo B concentrations between groups. In addition, mass measurements of the fractions of VLDL1, VLDL2 and IDL were raised in all patients with GSD Ia by comparison with all other patients with GSD. Patients with GSD type Ia have lipid concentrations and individual mass measurements that are consistent with ranges found in patients who have a significant risk of atherosclerosis. Accumulated evidence, however, suggest GSD type Ia patients do not have an increased risk of atherosclerotic cardiovascular disease (CVD) but the reason remains unknown. Intervention to reduce their lipid levels could therefore be on the basis of seeking to prevent the risk of pancreatitis rather than that of CVD.

Elevated serum biotinidase activity in hepatic glycogen storage disorders--a convenient biomarker.

An elevated serum biotinidase activity in patients with glycogen storage disease (GSD) type Ia has been reported previously. The aim of this work was to investigate the specificity of the phenomenon and thus we expanded the study to other types of hepatic GSDs. Serum biotinidase activity was measured in a total of 68 GSD patients and was compared with that of healthy controls (8.7 +/- 1.0; range 7.0-10.6 mU/ml; n = 26). We found an increased biotinidase activity in patients with GSD Ia (17.7 +/- 3.9; range: 11.4-24.8; n = 21), GSD I non-a (20.9 +/- 5.6; range 14.6-26.0; n = 4), GSD III (12.5 +/- 3.6; range 7.8-19.1; n = 13), GSD VI (15.4 +/- 2.0; range 14.1-17.7; n = 3) and GSD IX (14.0 +/- 3.8; range: 7.5-21.6; n = 22). The sensitivity of this test was 100% for patients with GSD Ia, GSD I non-a and GSD VI, 62% for GSD III, and 77% for GSD IX, indicating reduced sensitivity for GSD III and GSD IX, respectively. In addition, we found elevated biotinidase activity in all sera from 5 patients with Fanconi-Bickel Syndrome (15.3 +/- 3.7; range 11.0-19.4). Taken together, we propose serum biotinidase as a diagnostic biomarker for hepatic glycogen storage disorders.

Reduced bone mineral density in glycogen storage disease type III: evidence for a possible connection between metabolic imbalance and bone homeostasis.

INTRODUCTION: Glycogen storage disease type III (GSDIII) is an inborn error of carbohydrate metabolism caused by deficient activity of glycogen debranching enzyme (GDE). It is characterized by liver, cardiac muscle and skeletal muscle involvement. The presence of systemic complications such as growth retardation, ovarian polycystosis, diabetes mellitus and osteopenia/osteoporosis has been reported. The pathogenesis of osteopenia/osteoporosis is still unclear. OBJECTIVES: The aim of the current study was to evaluate the bone mineral density (BMD) in GSDIII patients and the role of metabolic and endocrine factors and physical activity on bone status. METHODS: Nine GSDIII patients were enrolled (age 2-20years) and compared to eighteen age and sex matched controls. BMD was evaluated by Dual-emission-X-ray absorptiometry (DXA) and Quantitative ultrasound (QUS). Clinical and biochemical parameters of endocrine system function and bone metabolism were analyzed. Serum levels of the metabolic control markers were evaluated. Physical activity was evaluated by administering the International Physical Activity Questionnaire (IPAQ). RESULTS: GSDIII patients showed reduced BMD detected at both DXA and QUS, decreased serum levels of IGF-1, free IGF-1, insulin, calcitonin, osteocalcin (OC) and increased serum levels of C-terminal cross-linking telopeptide of type I collagen (CTX). IGF-1 serum levels inversely correlated with AST and ALT serum levels. DXA Z-score inversely correlated with cholesterol and triglycerides serum levels and directly correlated with IGF-1/IGFBP3 molar ratio. No difference in physical activity was observed between GSDIII patients and controls. DISCUSSION: Our data confirm the presence of reduced BMD in GSDIII. On the basis of the results, we hypothesized that metabolic imbalance could be the key factor leading to osteopenia, acting through different mechanisms: chronic hyperlipidemia, reduced IGF-1, Insulin and OC serum levels. Thus, the mechanism of osteopenia/osteoporosis in GSDIII is probably multifactorial and we speculate on the factors involved in its pathogenesis.

Alterations in erythrocyte membrane fluidity and fatty acid composition in glycogen storage disease.

Liver glycogen storage diseases (GSD) are disorders associated with severe dyslipidaemia which can induce cell membrane alterations. Reduced erythrocyte membrane fluidity has been associated with ischaemic cardiovascular disease. Our study has been designed to investigate membrane erythrocyte fluidity, and to determine its lipid composition and peroxidation parameters. Membrane erythrocyte fluidity has been studied by electron spin resonance (ESR) with two fatty acid nitroxide probes (5NS and 16NS). Twenty-five GSD cases aged 1-27 years and 15 controls aged 1-28 years were included. The erythrocyte membrane of GSD patients appeared less fluid with the two probes (P < 0.001). The membrane fatty acid pattern explained this reduced fluidity. Patients showed a relative saturated fatty acid (SFA) increase and polyunsaturated fatty acid (PUFA) decrease which induced lower PUFA/SFA ratio than in controls. We have provided evidence that the PUFA decrease was independent of the oxidative process. These findings should be taken into account for the management of the dietary treatment of GSD patients.

Lens opacities in glycogenoses type I and III.

OBJECTIVE: The glycogen storage diseases (GSD) or glycogenoses comprise several inherited diseases caused by abnormalities of the enzymes that regulate the synthesis or degradation of glycogen. This report presents lens opacities not previously described in patients with type I or III GSD. PARTICIPANTS: Eleven patients with type I and III GSD. METHODS: We examined a series of 11 consecutive patients (aged 13-40 years) with type I and III GSD by full ophthalmologic examination. RESULTS: We found changes of the lens on 7 of 11 patients (aged 23-40 years) with glycogenoses I and III. In 6 patients, the lens showed multiple, bilateral, punctate, and peripheral opacities; only 1 patient showed a posterior subcapsular opacity in both eyes. We did not observe changes in the cornea and the posterior pole correlated to the accumulation of glycogen and lipids. CONCLUSIONS: In this series, we found that 60% of patients with type I and III GSD show lens opacities. These opacities are bilateral, peripheral, multiple, and small; they do not give any visual disturbance. Considering that subjects with age ranging from 13 to 23 years had no lens opacities, we postulate that they could progressively develop over time because of exposure to recurrent attacks of hypoglycemia, which lead to a progressive depletion of hexokinase.

The effect of tailoring of cornstarch intake on stature in children with glycogen storage disease type III.

AIM: To determine the individual fasting tolerance for patients with glycogen storage disease type III (GSD III) and to assess their linear growth velocity after tailoring of dose intervals of oral uncooked cornstarch. PATIENTS AND METHODS: A prospective cohort study included 32 patients with GSD III aged 6 months-11.5 years (median: 3.3 years). The fasting tolerance of each patient was determined as the time interval between starch administration until the drop in blood glucose level was below 60 mg/dL. RESULTS: Some 27 patients (84.4%) developed hypoglycemia. The intervals between oral cornstarch administration were tailored for each child according to his/her individual fasting tolerance. After a 6-month follow up there was a significant reduction in seizure attacks (p<0.01) and liver size (p<0.01), but there was no statistically significant difference in liver transaminase and serum lactate levels. There was a significant improvement in height (p<0.01) and linear growth velocity (p<0.05) of these patients after at least a 12-month follow up. CONCLUSION: Adjusting the intervals between the cornstarch doses for each patient with GSD III, according to individual fasting tolerance test was very beneficial and resulted in improvement of the linear growth velocity and reduction in the frequency of hypoglycemic seizures as well as the size of the liver. Individual scheduling of cornstarch doses prevents complications in those who develop hypoglycemia at short intervals; it also allows some relaxation in schedule for those who can tolerate longer fasting hours to improve their appetite and prolong their uninterrupted sleep hours.

Efficacy of cornstarch therapy in type III glycogen-storage disease.

Type III glycogen-storage disease (GSD-III), due to decreased activity of the glycogen debranching enzyme amylo-1,6 glucosidase, may cause hepatic dysfunction, growth failure, and myopathy. The prevention of hypoglycemia by nocturnal intragastric formula infusion has been shown to enhance growth and improve the metabolic abnormalities associated with GSD-III. Cornstarch therapy was effective in preventing hypoglycemia in a few patients with GSD-III who were previously treated with nocturnal enteral formula infusion, but oral cornstarch had not been evaluated as an initial treatment. We studied three patients with GSD-III who exhibited growth failure, elevated serum aminotransferase concentrations, and asymptomatic hypoglycemia. Cornstarch therapy was associated with maintenance of normoglycemia, increased growth velocity, and decreased serum aminotransferase concentrations in all patients. Our experience suggests that cornstarch therapy can be effective as an initial treatment for patients with GSD-III.

Amino acid disturbances in type III glycogenosis: differences from type I glycogenosis.

The plasma glucose, insulin, glucagon, lactate and amino acid response patterns to glucose and protein meals were examined in 11 patients with type III glycogen storage disease (GSD-III). The amino acid metabolism in GSD-III was shown to differ from that observed in normal subjects and in type I glycogen storage disease (GSD-I) patients. The outstanding findings involved the principal gluconeogenic amino acid, alanine. Postabsorptive levels of alanine in GSD-III were significantly below those of normal controls. Following glucose ingestion, alanine rose markedly in GSD-III, which differed from normal subjects in whom no change occurred, and from GSD-I patients in whom a sharp fall was observed. Following beef ingestion, the direction of change of alanine was similar in the three groups, but the circulating levels in GSD-III were significantly less than those observed in GSD-I and normal controls. The possibility that gluconeogenesis is enhanced in GSD-III was supported by the prompt rise in blood glucose observed following beef ingestion, which differed from GSD-I and normal subjects, in which no rise in glucose was observed.

Hepatic ultrasound findings in the glycogen storage diseases.

Hepatic ultrasonography was performed on 70 patients with the hepatic glycogen storage diseases (GSDs) to assess parenchymal echogenicity. 27 patients had GSD-I, 24 had GSD-III and 19 had GSDs-VI/IX; ages varied from 0.6 to 35.7 years (median 11.7). 31 (44%) had normal or mild parenchymal changes, and 41% (11/27) of those with GSD-I, 25% (6/24) with GSD-III and 11% (2/19) with GSDs-VI/IX had marked changes. No relationships were found between the ultrasonographic appearances and other indices of metabolic control, including plasma triglycerides, total cholesterol or height standard deviation score. Seven adult patients (21-29 years) were found to have hepatic tumours: six with GSD-I and one with GSD-III. Those with GSD-I and tumours tended to have the more severe hepatic parenchymal changes. We conclude that ultrasonography may be useful in identifying patients with GSD-I at risk of hepatic tumour formation.

Glycogen storage disease type III: modified Atkins diet improves myopathy.

BACKGROUND: Frequent feeds with carbohydrate-rich meals or continuous enteral feeding has been the therapy of choice in glycogen storage disease (Glycogenosis) type III. Recent guidelines on diagnosis and management recommend frequent feedings with high complex carbohydrates or cornstarch avoiding fasting in children, while in adults a low-carb-high-protein-diet is recommended. While this regimen can prevent hypoglycaemia in children it does not improve skeletal and heart muscle function, which are compromised in patients with glycogenosis IIIa. Administration of carbohydrates may elicit reactive hyperinsulinism, resulting in suppression of lipolysis, ketogenesis, gluconeogenesis, and activation of glycogen synthesis. Thus, heart and skeletal muscle are depleted of energy substrates. Modified Atkins diet leads to increased blood levels of ketone bodies and fatty acids. We hypothesize that this health care intervention improves the energetic balance of muscles. METHODS: We treated 2 boys with glycogenosis IIIa aged 9 and 11 years with a modified Atkins diet (10 g carbohydrate per day, protein and fatty acids ad libitum) over a period of 32 and 26 months, respectively. RESULTS: In both patients, creatine kinase levels in blood dropped in response to Atkins diet. When diet was withdrawn in one of the patients he complained of chest pain, reduced physical strength and creatine kinase levels rapidly increased. This was reversed when Atkins diet was reintroduced. One patient suffered from severe cardiomyopathy which significantly improved under diet. Patients with glycogenosis IIIa benefit from an improved energetic state of heart and skeletal muscle by introduction of Atkins diet both on a biochemical and clinical level. Apart from transient hypoglycaemia no serious adverse effects were observed.

Glycogen storage disease type III in Egyptian children: a single centre clinico-laboratory study.

BACKGROUND AND STUDY AIMS: Glycogen storage disease type III (GSD III) is an autosomal recessive disorder caused by deficiency of glycogen debrancher enzyme and is characterised by clinical variability. PATIENTS AND METHODS: We herein describe the clinical and laboratory findings in 31 Egyptian patients with GSD III presenting to the Paediatric Hepatology Unit, Cairo University, Egypt. RESULTS: Eighteen patients (58%) were males. Their ages ranged between 6 months to 12 years. The main presenting complaint was progressive abdominal distention in 55%. Twelve patients (38.7%) had a history of recurrent attacks of convulsions; four had an erroneous diagnosis of hypocalcaemia and epilepsy. Doll-like facies was noted in 90%. Abdominal examination of all cases revealed abdominal distention and soft hepatomegaly which had bright echogenicity by ultrasound. Hypertriglyceridaemia was present in 93.6%, hyperlactacidaemia in 51.6% and hyperuricaemia in 19.4%. Liver biopsy showed markedly distended hepatocytes with well distinct cytoplasmic boundaries and 32% had macrovesicular fatty changes. Serum creatine kinase was elevated in 64.6% of patients and correlated positively and significantly with age (r=0.7 and P=<0.001), while serum triglycerides correlated negatively with age (r=-0.4 and P=0.05). CONCLUSION: Blood glucose assessment and search for hepatomegaly in an infant with recurrent seizures may prevent delay in the diagnosis. A huge soft liver reaching the left midclavicular line that appears echogenic on ultrasonography is characteristic of GSD III. A distended hepatocyte with rarified cytoplasm is pathognomonic but not diagnostic. Hypertriglyceridaemia correlates negatively with age, in contrary to CK level.

Characterization of a canine model of glycogen storage disease type IIIa.

Glycogen storage disease type IIIa (GSD IIIa) is an autosomal recessive disease caused by deficiency of glycogen debranching enzyme (GDE) in liver and muscle. The disorder is clinically heterogeneous and progressive, and there is no effective treatment. Previously, a naturally occurring dog model for this condition was identified in curly-coated retrievers (CCR). The affected dogs carry a frame-shift mutation in the GDE gene and have no detectable GDE activity in liver and muscle. We characterized in detail the disease expression and progression in eight dogs from age 2 to 16 months. Monthly blood biochemistry revealed elevated and gradually increasing serum alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) activities; serum creatine phosphokinase (CPK) activity exceeded normal range after 12 months. Analysis of tissue biopsy specimens at 4, 12 and 16 months revealed abnormally high glycogen contents in liver and muscle of all dogs. Fasting liver glycogen content increased from 4 months to 12 months, but dropped at 16 months possibly caused by extended fibrosis; muscle glycogen content continually increased with age. Light microscopy revealed significant glycogen accumulation in hepatocytes at all ages. Liver histology showed progressive, age-related fibrosis. In muscle, scattered cytoplasmic glycogen deposits were present in most cells at 4 months, but large, lake-like accumulation developed by 12 and 16 months. Disruption of the contractile apparatus and fraying of myofibrils was observed in muscle at 12 and 16 months by electron microscopy. In conclusion, the CCR dogs are an accurate model of GSD IIIa that will improve our understanding of the disease progression and allow opportunities to investigate treatment interventions.