Hyperlipidaemia does not impair vascular endothelial function in glycogen storage disease type 1a

Glycogen storage disease type I patients with hyperlipidemia have no signs of early vascular dysfunction and premature atherosclerosis

BACKGROUND AND AIMS

Glycogen storage disease type I (GSD I) is associated with hyperlipidemia, a known risk factor for premature atherosclerosis. Few studies have addressed endothelial dysfunction in patients with GSD I, and these studies yielded controversial results.

METHODS AND RESULTS

We investigated vascular dysfunction in a cohort of 32 patients with GSD I (26 GSD Ia, 6 GSD Ib, mean age 20.7 (4.8-47.5) years) compared to 32 age-, gender-, and BMI-matched healthy controls using non-invasive techniques such as quantification of carotid intima media thickness, retinal vessel analysis and 24 h-blood pressure measurements. In addition, early biomarkers of inflammatory and oxidative endothelial stress were assessed in blood. Although GSD I patients had a clearly proatherogenic lipid profile, increased oxidative stress, higher levels of high sensitivity C-reactive protein and increased lipoprotein associated phospholipase A2 activity, functional and structural parameters including carotid intima media thickness and retinal vessel diameters did not indicate premature atherosclerosis in this patient cohort. Blood pressure values and pulse wave velocity were comparable in patients and healthy controls, while central blood pressure and augmentation index were higher in GSD patients.

CONCLUSION

Our data suggest that GSD I is not associated with early vascular dysfunction up to the age of at least 20 years. Further studies are needed to elucidate the possibly protective mechanisms that prevent early atherosclerosis is GSD I. Longer follow-up studies are required to assess the long-term risk of vascular disease with increased oxidative stress being present in GSD I patients.

De novo aortopathy and cardiovascular outcomes in paediatric liver transplant recipients

With the increase in long-term survival of post-transplant children, there is a paradigm shift in the emphasis of post-transplant care. We describe de novo cardiovascular abnormalities, which occurred in otherwise asymptomatic paediatric liver transplant recipients, who received liver allografts between 1991 and 2014 at the National University Hospital, Singapore, detected during routine post-transplant monitoring. A total of 96 paediatric liver transplants were performed in 90 children. After transplant, 7/90 (7.8%) recipients were identified with new-onset aortopathy. Glycogen storage disease type I (42.9% versus 2.4%; p<0.001) and recipient Epstein-Barr virus seropositivity (85.7 versus 31.0%, p=0.004) were significant risk factors for aortopathy on univariate analysis. On multivariate analysis, only glycogen storage disease type I remained as the significant risk factor (odds ratio 51.3 [95% confidence intervals: 1.1-2498.1, p=0.047]). Liver transplant is a double-edged sword that reverses certain cardiopulmonary complications of end-stage liver disease but may induce de novo structural cardiac injury in the form of aortic dilation.

[Characteristics of lipid metabolism and the cardiovascular system in glycogenosis types I and III]

Glycogen storage disease (GSD) is an inherited metabolic disorder characterized by early childhood lipid metabolic disturbances with potentially proatherogenic effects. The review outlines the characteristics of impaired lipid composition and other changes in the cardiovascular system in GSD types I and III. It analyzes the factors enabling and inhibiting the development of atherosclerosis in patients with GSD. The review describes the paradox of vascular resistance to the development of early atherosclerosis despite the proatherogenic composition of lipids in the patients of this group.

Diagnosis and management of glycogen storage disease type I: a practice guideline of the American College of Medical Genetics and Genomics

PURPOSE

Glycogen storage disease type I (GSD I) is a rare disease of variable clinical severity that primarily affects the liver and kidney. It is caused by deficient activity of the glucose 6-phosphatase enzyme (GSD Ia) or a deficiency in the microsomal transport proteins for glucose 6-phosphate (GSD Ib), resulting in excessive accumulation of glycogen and fat in the liver, kidney, and intestinal mucosa. Patients with GSD I have a wide spectrum of clinical manifestations, including hepatomegaly, hypoglycemia, lactic acidemia, hyperlipidemia, hyperuricemia, and growth retardation. Individuals with GSD type Ia typically have symptoms related to hypoglycemia in infancy when the interval between feedings is extended to 3–4 hours. Other manifestations of the disease vary in age of onset, rate of disease progression, and severity. In addition, patients with type Ib have neutropenia, impaired neutrophil function, and inflammatory bowel disease. This guideline for the management of GSD I was developed as an educational resource for health-care providers to facilitate prompt, accurate diagnosis and appropriate management of patients.

METHODS

A national group of experts in various aspects of GSD I met to review the evidence base from the scientific literature and provided their expert opinions. Consensus was developed in each area of diagnosis, treatment, and management.

RESULTS

This management guideline specifically addresses evaluation and diagnosis across multiple organ systems (hepatic, kidney, gastrointestinal/nutrition, hematologic, cardiovascular, reproductive) involved in GSD I. Conditions to consider in the differential diagnosis stemming from presenting features and diagnostic algorithms are discussed. Aspects of diagnostic evaluation and nutritional and medical management, including care coordination, genetic counseling, hepatic and renal transplantation, and prenatal diagnosis, are also addressed.

CONCLUSION

A guideline that facilitates accurate diagnosis and optimal management of patients with GSD I was developed. This guideline helps health-care providers recognize patients with all forms of GSD I, expedite diagnosis, and minimize adverse sequelae from delayed diagnosis and inappropriate management. It also helps to identify gaps in scientific knowledge that exist today and suggests future studies.

Glycogen Storage Disease type 1a - a secondary cause for hyperlipidemia: report of five cases

BACKGROUND AND AIMS

Glycogen storage disease type Ia (GSD Ia) is a rare metabolic disorder, caused by deficient activity of glucose-6-phosphatase-α. It produces fasting induced hypoglycemia and hepatomegaly, usually manifested in the first semester of life. Besides, it is also associated with growth delay, anemia, platelet dysfunction, osteopenia and sometimes osteoporosis. Hyperlipidemia and hyperuricemia are almost always present and hepatocellular adenomas and renal dysfunction frequent late complications.

METHODS

The authors present a report of five adult patients with GSD Ia followed in internal medicine appointments and subspecialties.

RESULTS

Four out of five patients were diagnosed in the first 6 months of life, while the other one was diagnosed in adult life after the discovery of hepatocellular adenomas. In two cases genetic tests were performed, being identified the missense mutation R83C in one, and the mutation IVS4-3C > G in the intron 4 of glucose-6-phosphatase gene, not previously described, in the other. Growth retardation was present in 3 patients, and all of them had anemia, increased bleeding tendency and hepatocellular adenomas; osteopenia/osteoporosis was present in three cases. All but one patient had marked hyperlipidemia and hyperuricemia, with evidence of endothelial dysfunction in one case and of brain damage with refractory epilepsy in another case. Proteinuria was present in two cases and end-stage renal disease in another case. There was a great variability in the dietary measures; in one case, liver transplantation was performed, with correction of the metabolic derangements.

CONCLUSIONS

Hyperlipidemia is almost always present and only partially responds to dietary and drug therapy; liver transplantation is the only definitive solution. Although its association with premature atherosclerosis is rare, there have been reports of endothelial dysfunction, raising the possibility for increased cardiovascular risk in this group of patients. Being a rare disease, no single metabolic center has experience with large numbers of patients and the recommendations are based on clinical experience more than large scale studies.

Asymmetric dimethylarginine (ADMA) and L-arginine levels in children with glycogen storage disease type I

Patients with glycogen storage disease type I (GSD-I) often have marked hyperlipidemia with abnormal lipoprotein profiles. This metabolic abnormality improves, but is not fully corrected, with dietary therapy; therefore, these patients may be at high risk for the development of atherosclerosis. A recently discussed cardiovascular risk factor, asymmetric dimethylarginine (ADMA), a naturally occuring product of asymmetric methylation of proteins, is an endogenous inhibitor of endothelial nitric oxide synthase. ADMA causes endothelial dysfunction, vasoconstriction, blood pressure elevation, atherosclerosis, and kidney disease progression. A high prevalence of elevated plasma ADMA levels is observed in adults with hypercholesterolemia, hypertension, chronic kidney disease, diabetes mellitus, peripheral arterial disease, coronary artery disease, preeclampsia, heart failure, liver disease, stroke, and many other clinical disorders. Therefore, we aimed to evaluate the endothelial function in patients with GSD-I by using ADMA levels. High-performance liquid chromatography - based method was used for measuring ADMA and L-arginine levels in plasma. The ADMA level was similar between children with GSD-I and the age-matched healthy control group (0.9±0.28 vs. 1.1±0.45 μmol/L; p=0.18). The L-arginine plasma levels in patients with GSD-I were found to be 55.7±41.3 and 91.6±50.2 μmol/L in healthy controls. The preservation of normal endothelial function may result from diminished platelet aggregation, increased levels of apolipoprotein E, decreased susceptibility of low-density lipoprotein to oxidation (possibly related to the altered lipoprotein fatty acid profile in GSD-I), and increased antioxidative defenses in plasma protecting against lipid peroxidation.

iPS cell modeling of cardiometabolic diseases

Cardiometabolic diseases encompass simple monogenic enzyme deficiencies with well-established pathogenesis and clinical outcomes to complex polygenic diseases such as the cardiometabolic syndrome. The limited availability of relevant human cell types such as cardiomyocytes has hampered our ability to adequately model and study pathways or drugs relevant to these diseases in the heart. The recent discovery of induced pluripotent stem (iPS) cell technology now offers a powerful opportunity to establish translational platforms for cardiac disease modeling, drug discovery, and pre-clinical testing. In this article, we discuss the excitement and challenges of modeling cardiometabolic diseases using iPS cell and their potential to revolutionize translational research.

Dietary dilemmas in the management of glycogen storage disease type I

Over the last 50 years, understanding the biochemical bases of glycogen storage disease type I has led to vastly improved survival and health outcomes but the management still centres around an extremely intensive dietary regimen. Patients' metabolic profiles are really determined by the whole of the diet and it can be very difficult to adjust therapy accordingly. In an iso-energetic diet with reference total energy intake, high carbohydrate intake could compromise other macro- and micro-nutrients; if carbohydrates are not restricted then total energy intake is excessive. The quality of the macronutrient such as the glycemic index of carbohydrate, the type of sugar and the proportion of medium-chain triglyceride and essential fatty acids also has a bearing on an individual's long-term metabolic control with potential clinical correlates. These factors as well as the different requirements between individuals and within individuals as they get older mean that the management of glycogen storage disease type I is particularly fraught. Regular clinical and dietary review is imperative as patients grow, ensuring adequate but not excessive low glycaemic index carbohydrate intake, appropriate dynamic biochemical profiles and suitable age appropriate eating patterns. Without diligent management, and education that empowers the patient, these individuals can struggle in adult life.

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.

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.

Vascular dysfunction in glycogen storage disease type I

OBJECTIVE

To determine cardiovascular disease risk in a larger cohort of patients with glycogen storage disease (GSD) I through the use of noninvasive measures of arterial function and anatomy.

STUDY DESIGN

Carotid intima media thickness (IMT), radial artery tonometry, and brachial artery reactivity were performed in 28 patients with GSD I (13F/15M, mean age 23 years) and 23 control subjects (19F/4M, mean age 23 years).

RESULTS

The primary outcome measure, mean left distal IMT was greater in the GSD cohort (0.500+/-0.055 mm) than in the control group (0.457+/-0.039 mm) (P= .002, adjusted for age, sex, and body mass index). Mean augmentation index measured by radial artery tonometry was higher in the GSD cohort (16.4%+/-14.0%) than in the control group (2.4%+/-8.7%) (P< .001). No significant difference was observed between mean brachial artery reactivity in the GSD cohort (6.3%+/-4.9% change) versus control subjects (6.6%+/-5.1% change) (P= .46).

CONCLUSIONS

GSD I is associated with arterial dysfunction evident by increased IMT and augmentation index. Patients with GSD I may be at increased risk for cardiovascular disease.

Advanced glycation end products and the absence of premature atherosclerosis in glycogen storage disease Ia

INTRODUCTION

Despite their unfavourable cardiovascular risk profile, patients with glycogen storage disease type Ia (GSD Ia) do not develop premature atherosclerosis. We hypothesized that this paradox might be related to a decreased formation of advanced glycation end products (AGEs) resulting from lifetime low plasma glucose levels and decreased oxidative stress.

METHODS

In 8 GSD Ia patients (age 20-34 years) and 30 matched controls we measured carotid intima-media thickness (IMT), skin autofluorescence (AF; a non-invasive index for AGEs), and specific AGEs (pentosidine, N-(carboxymethyl)lysine (CML), N-(carboxyethyl)lysine (CEL)) and collagen linked fluorescence (CLF, measured at excitation/emission wavelength combinations of 328/378 and 370/440 nm) in skin samples.

RESULTS

Carotid IMT was significantly lower in GSD Ia patients. Skin AF did not differ between patients and controls. The skin samples showed higher CEL levels in the patient group (p = 0.008), but similar levels of pentosidine, CML, and CLF. In the total group, skin AF correlated with CML (r = 0.39, p = 0.031), CLF 328/378 nm (r = 0.53; p = 0.002) and CLF 370/440 nm (r = 0.60; p = 0.001). In the control group, AF also correlated with the maximum carotid IMT (r = 0.6; p = 0.004).

CONCLUSION

Although our data confirm that GSD Ia patients present with a reduced burden of atherosclerosis, this phenomenon cannot be explained by differences in AGE accumulation as measured in the skin.

Lack of evident atherosclerosis despite multiple risk factors in glycogen storage disease type 1a with hyperadiponectinemia

We report a 60-year-old Japanese patient with glycogen storage disease type 1a (GSD1a) who was thoroughly evaluated for risk factors of atherosclerosis. As often observed in patients with GSD1a, this patient has multiple risk factors for atherosclerosis including hyperlipidemia, hypertension, glucose intolerance with insulin resistance, and chronic kidney disease. However, she lacked clinically evident atherosclerosis as generally observed in GSD1a patients. Unexpectedly, this patient had marked hyperadiponectinemia (27.6 microg/mL; reference range, 4.1-18.9 microg/mL) with increase in the ratio of high-molecular weight to total adiponectin. Although the reason for the hyperadiponectinemia was not clear, at least it seemed to protect against enhanced atherosclerogenesis otherwise promoted by a battery of risk factors. Although further studies are needed, hyperadiponectinemia in addition to hypoinsulinemia might explain at least in part the lack of evident atherosclerosis in patients with GSD1a.

Increased scavenger receptor class B type I-mediated cellular cholesterol efflux and antioxidant capacity in the sera of glycogen storage disease type Ia patients

Glycogen storage disease type Ia (GSD-Ia) is characterized by hypercholesterolemia, hypertriglyceridemia, decreased cholesterol in high density lipoprotein and increased cholesterol in low and very low density lipoprotein fractions. Despite this pro-atherogenic lipid profile, GSD-Ia patients are not at elevated risk for atherosclerosis. Studies have shown that reverse cholesterol transport and antioxidant capacity can be protective against atherosclerosis. In this study, we show that sera from GSD-Ia patients are more efficient than sera from control subjects in promoting the scavenger receptor class B type I (SR-BI)-mediated cellular cholesterol efflux, a key component in reverse cholesterol transport. The major determinants of the SR-BI-mediated cholesterol efflux are serum phospholipid (PL) and HDL-PL. Phospholipid and that ratio of HDL-PL to HDL are increased in GSD-Ia patients. We further show that sera from GSD-Ia patients have increased total antioxidant capacity compared to controls and this increase correlates with elevated levels of uric acid, a powerful plasma antioxidant. Taken together, the results suggest that the increase in SR-BI-mediated cellular cholesterol efflux and antioxidant capacity in the sera of GSD-Ia patients may contribute to protection against premature atherosclerosis.

Increased cellular cholesterol efflux in glycogen storage disease type Ia mice: A potential mechanism that protects against premature atherosclerosis

Glycogen storage disease type Ia (GSD-Ia) patients manifest a pro-atherogenic lipid profile but are not at elevated risk for developing atherosclerosis. Serum phospholipid, which correlates positively with the scavenger receptor class B type I (SR-BI)-mediated cholesterol efflux, and apolipoprotein A-IV and E, acceptors for ATP-binding cassette transporter A1 (ABCA1)-mediated cholesterol transport, are increased in GSD-Ia mice. Importantly, sera from GSD-Ia mice are more efficient than sera from control littermates in promoting SR-BI- and ABCA1-mediated cholesterol effluxes. As the first step in reverse cholesterol transport, essential for cholesterol homeostasis, these observations provide one explanation why GSD-Ia patients are apparently protected against premature atherosclerosis.

Decreased plasma concentration of von Willebrand factor antigen (VWF:Ag) in patients with glycogen storage disease type Ia

Despite highly increased blood lipids, patients with glycogen storage disease type Ia (GSD Ia) do not develop premature vascular complications. Since this could be due to changes of coagulation factors, coagulation tests (including von Willebrand factor (VWF) antigen (VWF:Ag) ELISA, VWF:collagen binding activity (VWF:CB) and VWF multimer analysis) were performed in 10 GSD Ia patients, single cases of other GSD types, and in both healthy and hyperlipidaemic controls. In 60% of GSD Ia patients we found abnormal results, with a decrease of VWF:Ag and multimer analysis showing reduced intensity of individual oligomers in the presence of all multimers with a normal triplet structure. We interpret these findings as an acquired 'von Willebrand syndrome type I' in GSD Ia. The underlying metabolic mechanism and a potential role in the protection from vascular complication still needs to be evaluated.

Increased levels of hemostatic proteins are independent of inflammation in glycogen storage disease type Ia

OBJECTIVES

Glycogen storage disease type Ia (GSD-Ia), a congenital deficiency of hepatic glucose-6-phosphatase activity, is often associated with hyperproteinemia. To document the mechanism of hyperproteinemia, the proteins of the hemostatic system were analyzed according to their site of synthesis: hepatocyte, endothelial cell, or both. The role of inflammation was investigated by the measurement of tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) levels in plasma.

METHODS

Twenty-seven patients with GSD-Ia were evaluated, as were 14 patients with other types of GSD and 30 healthy control subjects. Of the 41 patients with GSD, 15 also had hepatic adenoma (14 patients with GSD-Ia and 1 with GSD type III).

RESULTS

In patients with GSD-Ia, there was a two-fold increase in all hepatocyte-synthesized proteins (i.e., factor VII, protein C, C4b binding protein) compared with control subjects and patients with other types of GSD. The proteins with mixed endothelial and hepatocyte origin (i.e., antithrombin and protein S) also were significantly increased but to a lesser extent. In contrast, the mean concentration of von Willebrand factor, which is exclusively synthesized in endothelial cells, was normal, as was the concentration of TNF-alpha and IL-6.

CONCLUSIONS

These results suggest that the hyperproteinemia of GSD-Ia (including hemostatic proteins) is attributable to hepatocyte dysfunction and not related to an inflammatory process.

Guidelines for management of glycogen storage disease type I - European Study on Glycogen Storage Disease Type I (ESGSD I)

Life-expectancy in glycogen storage disease type I (GSD I) has improved considerably. Its relative rarity implies that no metabolic centre has experience of large series of patients and experience with long-term management and follow-up at each centre is limited. There is wide variation in methods of dietary and pharmacological treatment. Based on the data of the European Study on Glycogen Storage Disease Type I, discussions within this study group, discussions with the participants of the international SHS-symposium 'Glycogen Storage Disease Type I and II: Recent Developments, Management and Outcome' (Fulda, Germany; 22-25th November 2000) and on data from the literature, guidelines are presented concerning: (1). diagnosis, prenatal diagnosis and carrier detection; (2). (biomedical) targets; (3). recommendations for dietary treatment; (4). recommendations for pharmacological treatment; (5). metabolic derangement/intercurrent infections/emergency treatment/preparation elective surgery; and (6). management of complications (directly) related to metabolic disturbances and complications which may develop with ageing and their follow-up.

CONCLUSION

In this paper guidelines for the management of GSD I are presented.

Glycogen storage disease type I: diagnosis, management, clinical course and outcome. Results of the European Study on Glycogen Storage Disease Type I (ESGSD I)

Glycogen storage disease type I (GSD I) is a relatively rare metabolic disease and therefore, no metabolic centre has experience of large numbers of patients. To document outcome, to develop guidelines about (long-term) management and follow-up, and to develop therapeutic strategies, the collaborative European Study on GSD I (ESGSD I) was initiated. This paper is a descriptive analysis of data obtained from the retrospective part of the ESGSD I. Included were 231 GSD Ia and 57 GSD Ib patients. Median age of data collection was 10.4 years (range 0.4-45.4 years) for Ia and 7.1 years (0.4-30.6 years) for Ib patients. Data on dietary treatment, pharmacological treatment, and outcome including mental development, hyperlipidaemia and its complications, hyperuricaemia and its complications, bleeding tendency, anaemia, osteopenia, hepatomegaly, liver adenomas and carcinomas, progressive renal disease, height and adult height, pubertal development and bone maturation, school type, employment, and pregnancies are presented. Data on neutropenia, neutrophil dysfunction, infections, inflammatory bowel disease, and the use of granulocyte colony-stimulating factor are presented elsewhere (Visser et al. 2000, J Pediatr 137:187-191; Visser et al. 2002, Eur J Pediatr DOI 10.1007/s00431-002-1010-0).

CONCLUSION

there is still wide variation in methods of dietary and pharmacological treatment of glycogen storage disease type I. Intensive dietary treatment will improve, but not correct completely, clinical and biochemical status and fewer patients will die as a direct consequence of acute metabolic derangement. With ageing, more and more complications will develop of which progressive renal disease and the complications related to liver adenomas are likely to be two major causes of morbidity and mortality.

Plasma antioxidants in pediatric patients with glycogen storage disease, diabetes mellitus, and hypercholesterolemia

Oxidative modification of lipoproteins in vessel walls plays a key role in atherogenesis. Patients with glycogen storage disease type Ia (GSD Ia) do not develop premature atherosclerosis despite severe hyperlipidemia. We analyzed antioxidative defense and oxidative stress in plasma and serum of patients with GSD Ia (n = 17) compared to patients with type I diabetes mellitus (DMI, n = 17), familial hypercholesterolemia (FH, n = 18), and healthy controls (n = 20). We measured the total radical-trapping antioxidant parameter (TRAP), single antioxidants (sulfhydryl groups, uric acid, vitamin C, alpha-tocopherol, coenzyme Q10), malondialdehyde, oxidized low density lipoprotein (LDL) antibodies, lipid profile [cholesterol, triglyceride, lipoprotein (a)], homocysteine, and hemoglobin (Hb)A(1C). TRAP levels were elevated in the GSD Ia group (p <.01) and correlated with elevated uric acid levels (r = 0.72, p =.001). None of the other plasma antioxidants correlated with TRAP levels. DMI patients showed decreased sulfhydryl groups (p <.01) and a reduced ubiquinol-10 fraction (p <.01). Malondialdehyde (p <.001) and oxidized LDL autoantibodies (p <.05) were increased in the diabetic group. In FH patients, parameters of oxidative stress and TRAP did not differ from controls. We conclude that in GSD Ia an increased antioxidative defense in plasma may protect against lipid peroxidation and thus against premature atherosclerosis. Furthermore, we demonstrated that in DMI increased oxidative mechanisms are already present in childhood.

Glycogenosis type I and diabetes mellitus: a common mechanism for renal dysfunction?

Diabetes mellitus and glycogen storage disease type I (GSDI) may initially appear disparate in metabolic profile: one characterized by uncontrolled hyperglycaemia due to disturbed insulin function and the other by fasting hypoglycaemia caused by impaired gluconeogenesis and glycogenolysis. However, they share a remarkably similar pattern and progression of renal dysfunction. This may be, we suggest, due to a convergence of their metabolic sequelae in upregulation of flux through the pentose phosphate pathway. This pathway yields triose phosphate molecules, which are precursors of the lipid, diacylglycerol (DAG). DAG plays an important role in the intrarenal renin-angiotensin system via the protein kinase C pathway. GSDI may be an interesting model which helps to unravel further the contributions of the many, varied nephropathic influences in diabetes. Conversely patients with this rare disorders would have much to gain from the innovative and vastly greater body of research carried out in diabetes.

Increased lipogenesis and resistance of lipoproteins to oxidative modification in two patients with glycogen storage disease type 1a

We describe 2 patients with glycogen storage disease type 1a and severe hyperlipidemia without premature atherosclerosis. Susceptibility of low-density lipoproteins to oxidation was decreased, possibly related to the ~40-fold increase in palmitate synthesis altering lipoprotein saturated fatty acid contents. These findings are potentially relevant for antihyperlipidemic treatment in patients with glycogen storage disease type 1a.

Apolipoprotein E polymorphism and serum concentrations in patients with glycogen storage disease type Ia

In patients with glycogen storage disease type Ia (glucose-6-phosphatase deficiency), serum triglyceride concentrations are markedly raised, whereas phospholipids and cholesterol levels are only moderately elevated. In addition, both VLDL and LDL lipoprotein fractions are raised. Despite these abnormalities, endothelial vascular dysfunction and atherosclerosis seem to be rare in such patients. In view of the crucial role of apolipoprotein E (apoE) in lipid metabolism, we studied both apoE polymorphism (40 patients) and serum concentration (20 patients) in patients with glycogen storage disease type Ia. The distribution of each allele at the apoE locus was similar to that reported in the general population, whereas serum apoE concentrations were raised in our patients. Raised apoE levels in the serum could play an important role in counterbalancing the at-risk-for-atherosclerosis lipid profile of patients with glycogen storage disease type Ia. Moreover, E3 and E4 polymorphisms, predominant in our patients, have a high triglyceride binding capacity and are thus able to increase triglyceride clearance. However, the origin of raised concentrations of apoE is not completely clear though, bearing in mind previous reports regarding serum protein concentrations in such patients, increased hepatic synthesis is likely.

Blood lipids and endothelial function in glycogen storage disease type III

We have assessed early indicators of arterial disease in patients with glycogen storage disease type III (GSD III; McKusick 232400), investigating the plasma lipid and lipoprotein profile and endothelial function. Eleven patients, aged 10-39 years, were recruited together with age-, sex- and smoking status-matched controls. Brachial artery responses were assessed by high-resolution ultrasonographic measurement of the diameter of the brachial artery at baseline, after reactive hyperaemia and in response to sublingual glyceryl trinitrate (GTN). The means of plasma cholesterol (total and HDL and LDL subfractions), triglycerides, apo-A1, apo-B, Lp(a) and the atherogenic index were similar in both groups. Cardiac troponin I was below the lower limits of detection (< 0.03 g/L) in all subjects. The GSD III patients had similar body mass index (BMI) and brachial artery diameter to the control group (BMI 22.6 +/- 5.6 vs 22.3 +/- 5 kg/m2; brachial artery diameter 3.4 +/- 0.5 vs 3 +/- 0.7 mm). When compared to the baseline diameter, the maximal flow-mediated dilatation of the brachial artery after reactive hyperaemia was 9.3% +/- 2.1% (mean +/- SD) in the GSD III patients and 6.5% +/- 3.5% in the control group, a difference of 1.8% (95% CI 0.07% to 5.5%). The maximal dilatation of the brachial artery after GTN administration was 18.3% +/- 6.4% in the GSD III patients and 17.9% +/- 6.5% in the control group, a difference of 0.4% (95% CI-6.9% to 7.7%). In conclusion, we found no evidence of abnormal plasma lipid and lipoprotein profile or endothelial dysfunction in patients with GSD III. They are unlikely to be at increased risk of premature atherosclerosis.

Glycogen storage diseases. Phenotypic, genetic, and biochemical characteristics, and therapy

The glycogen storage diseases are caused by inherited deficiencies of enzymes that regulate the synthesis or degradation of glycogen. In the past decade, considerable progress has been made in identifying the precise genetic abnormalities that cause the specific impairments of enzyme function. Likewise, improved understanding of the pathophysiologic derangements resulting from individual enzyme defects has led to the development of effective nutritional therapies for each of these disorders. Meticulous adherence to dietary therapy prevents hypoglycemia, ameliorates the biochemical abnormalities, decreases the size of the liver, and results in normal or nearly normal physical growth and development. Nevertheless, serious long-term complications, including nephropathy that can cause renal failure and hepatic adenomata that can become malignant, are a major concern in GSD-I. In GSD-III, the risk for hypoglycemia diminishes with age, and the liver decreases in size during puberty. Cirrhosis develops in some adult patients, and progressive myopathy and cardiomyopathy occur in patients with absent GDE activity in muscle. It remains unclear whether these complications of glycogen storage disease can be prevented by dietary therapy. Glycogen storage diseases caused by lack of phosphorylase activity are milder disorders with a good prognosis. The liver decreases in size, and biochemical abnormalities disappear by puberty.

Glycogen storage disease: a basic understanding and guide to nursing care

Glycogen storage disease (GSD) is a group of genetic metabolic disorders resulting from a defect in the synthesis or degradation of glycogen. GSDs are classified according to the type of enzymatic defect and primary organs involved and are usually diagnosed in infancy or early childhood. Little is generally known about GSD and nurses may be unfamiliar with care requirements of the GSD patient. Nine distinct types of GSD are presented with the primary focus on type 1, the most common. Current treatment methods, roles of the nurse, and a sample nursing care plan are included.

The hepatic glycogen storage diseases--problems beyond childhood

The introduction of continuous nocturnal enteral glucose feeds and uncooked cornstarch has improved the prognosis for patients with the hepatic glycogen storage diseases. An increasing number of patients are surviving into adulthood in better health, but still at some medical cost. In this review we examine bone mineralization, renal function, hepatic tumours, and vascular endothelial function in GSD I and cardiac function in GSD III. All females over the age of 5 years with GSD I, III, VI and IX had morphologically polycystic ovaries. Thirteen adult GSD I patients have been studied, and been found to have poor bone mineralization and marked renal glomerular and tubular dysfunction. More than half of these patients also had focal hepatic lesions on sonography and yet vascular endothelial function was preserved in the face of hyperlipidaemia. In 12 GSD III patients, one had a focal hepatic lesion and 6 had pronounced left ventricular hypertrophy, although cardiorespiratory function was normal. These data emphasize the multisystem nature of these disorders and highlight the need for careful longterm follow-up.