Project description:BackgroundGlycogen storage disease type I (GSD I), also known as von Gierk disease, is a metabolic disorder leading to the excessive accumulation of glycogen and fat in organs, characterized by hepatomegaly, hypoglycemia, lactic acidemia, hyperlipidemia, hyperuricemia, puberty delay and growth retardation, which can be indicated by height, weight, blood glucose and blood lipids.Case presentationHere we present a 16-year-old male patient with GSD Ia complicated with hepatic adenoma and combined with hepatitis B. As a chronic hepatitis B patient, the patient was admitted to hospital in order to further clarify the nature of hepatic space occupancy because of suspicion of hepatocellular carcinoma. However, the imaging studies did not support hepatocellular carcinoma certainly. And by tracing his clinical history, we suggested that he might suffer from GSD I. Finally the diagnosis was confirmed by MRI (Gd-EOB-DTPA), liver biopsy and whole exome sequencing (WES). The WES discovered a homozygous point mutation at the exon 5 of G6PC gene at 17th chromosome, c.G648 T (p.L216 L, NM_000151, rs80356484). This pathogenic mutation causes CTG changing to CTT at protein 216. Though both codons encode leucine, this silent mutation creates a new splicing site 91 bp downstream of the authentic splice site. According to previous research, this mutation is a disease causal variant for GSD Ia, and has a high frequency among GSD patients in China and Japan. This patient was finally diagnosed as GSD Ia complicated with hepatic adenoma and combined with chronic hepatitis B, and received corn starch therapy immediately after GSD was suspected. After receiving corn starch therapy, the height and weight of the patient were increased, and the secondary sexual characteristics were developed, including beard, pubic hair and seminal emission. Unexpectedly, the liver adenomas were still increasing, and we did not find any cause to explain this phenomenon.ConclusionThis patient was diagnosed as GSD Ia combined with chronic hepatitis B, who responded to corn starch intervention. For childhood patients with hypoglycaemia, hyperlipidemia, puberty delay and growth retardation, GSD should be considered. Gene sequencing is valuable for the quick identification of GSD subtypes.
Project description:Glycogen storage disease type Ia (GSD Ia) is caused by autosomal mutations in glucose-6-phosphatase α catalytic subunit (G6PC) and can present with severe hypoglycemia, lactic acidosis and hypertriglyceridemia. In both children and adults with GSD Ia, there is over-accumulation of hepatic glycogen and triglycerides that can lead to steatohepatitis and a risk for hepatocellular adenoma or carcinoma. Here, we examined the effects of the commonly used peroxisomal proliferated activated receptor α agonist, fenofibrate, on liver and kidney autophagy and lipid metabolism in 5-day-old G6pc -/- mice serving as a model of neonatal GSD Ia. Five-day administration of fenofibrate decreased the elevated hepatic and renal triglyceride and hepatic glycogen levels found in control G6pc -/- mice. Fenofibrate also induced autophagy and promoted β-oxidation of fatty acids and stimulated gene expression of acyl-CoA dehydrogenases in the liver. These findings show that fenofibrate can rapidly decrease hepatic glycogen and triglyceride levels and renal triglyceride levels in neonatal G6pc -/- mice. Moreover, since fenofibrate is an FDA-approved drug that has an excellent safety profile, our findings suggest that fenofibrate could be a potential pharmacological therapy for GSD Ia in neonatal and pediatric patients as well as for adults. These findings may also apply to non-alcoholic fatty liver disease, which shares similar pathological and metabolic changes with GSD Ia.
Project description:Glycogen storage disease type Ia (GSDIa, von Gierke disease) is the most common glycogen storage disorder. It is caused by the deficiency of glucose-6-phosphatase, an enzyme which catalyses the final step of gluconeogenesis and glycogenolysis. Clinically, GSDIa is characterized by fasting hypoglycaemia and hepatic glycogen and triglyceride overaccumulation. The latter leads to steatohepatitis, cirrhosis, and the formation of hepatic adenomas and carcinomas. Currently, little is known about the function of various organelles and their impact on metabolism in GSDIa. Accordingly, we investigated mitochondrial function in cell culture and mouse models of GSDIa. We found impairments in oxidative phosphorylation and changes in TCA cycle metabolites, as well as decreased mitochondrial membrane potential and deranged mitochondrial ultra-structure in these model systems. Mitochondrial content also was decreased, likely secondary to decreased mitochondrial biogenesis. These deleterious effects culminated in the activation of the mitochondrial apoptosis pathway. Taken together, our results demonstrate a role for mitochondrial dysfunction in the pathogenesis of GSDIa, and identify a new potential target for the treatment of this disease. They also provide new insight into the role of carbohydrate overload on mitochondrial function in other hepatic diseases, such as non-alcoholic fatty liver disease.
Project description:Glycogen storage disease type Ia (GSD-Ia), characterized by impaired glucose homeostasis and chronic risk of hepatocellular adenoma (HCA), is caused by a deficiency in glucose-6-phosphatase-α (G6Pase-α or G6PC) activity. In a previous 70-90 week-study, we showed that a recombinant adeno-associated virus (rAAV) vector-mediated gene transfer that restores more than 3% of wild-type hepatic G6Pase-α activity in G6pc (-/-) mice corrects hepatic G6Pase-α deficiency with no evidence of HCA. We now examine the minimal hepatic G6Pase-α activity required to confer therapeutic efficacy. We show that rAAV-treated G6pc (-/-) mice expressing 0.2% of wild-type hepatic G6Pase-α activity suffered from frequent hypoglycemic seizures at age 63-65 weeks but mice expressing 0.5-1.3% of wild-type hepatic G6Pase-α activity (AAV-LL mice) sustain 4-6 h of fast and grow normally to age 75-90 weeks. Despite marked increases in hepatic glycogen accumulation, the AAV-LL mice display no evidence of hepatic abnormalities, hepatic steatosis, or HCA. Interprandial glucose homeostasis is maintained by the G6Pase-α/glucose-6-phosphate transporter (G6PT) complex, and G6PT-mediated microsomal G6P uptake is the rate-limiting step in endogenous glucose production. We show that hepatic G6PT activity is increased in AAV-LL mice. These findings are encouraging for clinical studies of G6Pase-α gene-based therapy for GSD-Ia.
Project description:Glucose-6-phosphatase α (G6Pase) deficiency, also known as von Gierke's Disease or Glycogen storage disease type Ia (GSD Ia), is characterized by decreased ability of the liver to convert glucose-6-phosphate to glucose leading to glycogen accumulation and hepatosteatosis. Long-term complications of GSD Ia include hepatic adenomas and carcinomas, in association with the suppression of autophagy in the liver. The G6pc-/- mouse and canine models for GSD Ia were treated with the pan-peroxisomal proliferator-activated receptor agonist, bezafibrate, to determine the drug's effect on liver metabolism and function. Hepatic glycogen and triglyceride concentrations were measured and western blotting was performed to investigate pathways affected by the treatment. Bezafibrate decreased liver triglyceride and glycogen concentrations and partially reversed the autophagy defect previously demonstrated in GSD Ia models. Changes in medium-chain acyl-CoA dehydrogenase expression and acylcarnintine flux suggested that fatty acid oxidation was increased and fatty acid synthase expression associated with lipogenesis was decreased in G6pc-/- mice treated with bezafibrate. In summary, bezafibrate induced autophagy in the liver while increasing fatty acid oxidation and decreasing lipogenesis in G6pc-/- mice. It represents a potential therapy for glycogen overload and hepatosteatosis associated with GSD Ia, with beneficial effects that have implications for non-alcoholic fatty liver disease.
Project description:A deficiency in glucose-6-phosphatase-α (G6Pase-α) in glycogen storage disease type Ia (GSD-Ia) leads to impaired glucose homeostasis and metabolic manifestations including hepatomegaly caused by increased glycogen and neutral fat accumulation. A recent report showed that G6Pase-α deficiency causes impairment in autophagy, a recycling process important for cellular metabolism. However, the molecular mechanism underlying defective autophagy is unclear. Here we show that in mice, liver-specific knockout of G6Pase-α (L-G6pc-/-) leads to downregulation of sirtuin 1 (SIRT1) signaling that activates autophagy via deacetylation of autophagy-related (ATG) proteins and forkhead box O (FoxO) family of transcriptional factors which transactivate autophagy genes. Consistently, defective autophagy in G6Pase-α-deficient liver is characterized by attenuated expressions of autophagy components, increased acetylation of ATG5 and ATG7, decreased conjugation of ATG5 and ATG12, and reduced autophagic flux. We further show that hepatic G6Pase-α deficiency results in activation of carbohydrate response element-binding protein, a lipogenic transcription factor, increased expression of peroxisome proliferator-activated receptor-γ (PPAR-γ), a lipid regulator, and suppressed expression of PPAR-α, a master regulator of fatty acid β-oxidation, all contributing to hepatic steatosis and downregulation of SIRT1 expression. An adenovirus vector-mediated increase in hepatic SIRT1 expression corrects autophagy defects but does not rectify metabolic abnormalities associated with G6Pase-α deficiency. Importantly, a recombinant adeno-associated virus (rAAV) vector-mediated restoration of hepatic G6Pase-α expression corrects metabolic abnormalities, restores SIRT1-FoxO signaling, and normalizes defective autophagy. Taken together, these data show that hepatic G6Pase-α deficiency-mediated down-regulation of SIRT1 signaling underlies defective hepatic autophagy in GSD-Ia.
Project description:A young female with recurrent tophaceous gout and infertility presented to our clinic. On clinical evaluation, hypoglycaemia, hypertriglyceridaemia, lactic acidosis, and hepatomegaly were noted. Targeted gene sequencing revealed a novel composite heterozygous c.190G>T/c.508C>T mutation in the G6PC gene of the patient, leading to a diagnosis of glycogen storage disease type Ia. Her father possessed a heterozygous c.190G>T mutation, and her mother possessed a heterozygous c.508C>T mutation. A search of the previous literature revealed 16 reported cases of glycogen storage disease type Ia with gout. Here, we describe a female patient with gout, review previous cases, and discuss the mechanisms of gout and hyperuricaemia in glycogen storage disease type Ia.
Project description:Glucose-6-phosphatase-α (G6Pase-α or G6PC) deficiency in glycogen storage disease type-Ia (GSD-Ia) leads to impaired hepatic autophagy, a recycling process important for cellular metabolism and homeostasis. Autophagy can be regulated by several energy sensing pathways, including sirtuin 1 (SIRT1), forkhead box O (FoxO), AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor-α (PPAR-α), and mammalian target of rapamycin (mTOR). Using 10-day old global G6pc-deficient (G6pc-/-) mice, hepatic autophagy impairment was attributed to activation of mTOR and inhibition of AMPK signaling. In other studies, using adult liver-specific G6pc-deficient mice at both pre-tumor and tumor stages, hepatic autophagy impairment was attributed to downregulation of SIRT1 signaling and mTOR was not implicated. In this study, we provide a detailed analysis of the major autophagy pathways in young G6pc-/- mice over the first 4 weeks of life. We show that impaired SIRT1, FoxO3a, AMPK, and PPAR-α signaling are responsible for autophagy impairment but mTOR is involved minimally. Hepatic SIRT1 overexpression corrects defective autophagy, restores the expression of FoxO3a and liver kinase B1 but fails to normalize impaired PPAR-α expression or metabolic abnormalities associated with GSD-Ia. Importantly, restoration of hepatic G6Pase-α expression in G6pc-/- mice corrects defective autophagy, restores SIRT1/FoxO3a/AMPK/PPAR-α signaling and rectifies metabolic abnormalities. Taken together, these data show that hepatic autophagy impairment in GSD-Ia is mediated by downregulation of SIRT1/FoxO3a/AMPK/PPAR-α signaling.
Project description:Background & aimsGlycogen storage disease type Ia (GSDIa) is an inborn error of carbohydrate metabolism caused by pathogenic variants in the glucose-6-phosphatase catalytic subunit 1 (G6PC1) gene and is associated with hepatocellular adenoma (HCA) formation. Data on risk factors for HCA occurrence in GSDIa are scarce. We investigated HCA development in relation to sex, G6PC1 genotype, and serum triglyceride concentration (TG).MethodsAn observational study of patients with genetically confirmed GSDIa ≥12 years was performed. Patients were categorised for sex; presence of 2, 1, or 0 predicted severe G6PC1 variant (PSV); and median TG during childhood (<12 years; stratified for above/below 5.65 mmol/L, i.e. 500 mg/dl).ResultsFifty-three patients (23 females) were included, of which 26 patients developed HCA at a median (IQR) age of 21 (17-25) years. At the age of 25 years, 48% of females and 30% of males had developed HCA (log-rank p = 0.045). Two-thirds of patients with GSDIa carried 2 PSVs, 20% carried 1, and 13% carried none. Neither the number of PSVs nor any specific G6PC1 variants were associated with HCA occurrence. Childhood TG was 3.4 (3.0-4.2) mmol/L in males vs. 5.6 (4.0-7.9) mmol/L in females (p = 0.026). Childhood TG >5.65 mmol/L was associated with HCA development at younger age, compared with patients with childhood TG <5.65 mmol/L (18 vs. 33 years; log-rank p = 0.001). Cox regression analysis including TG, sex, and TG-sex interaction correction revealed childhood TG >5.65 mmol/L as an independent risk factor for HCA development (hazard ratio [HR] 6.0; 95% CI 1.2-29.8; p = 0.028).ConclusionsIn patients with GSDIa, high childhood TG was associated with an increased risk of HCA, and earlier onset of HCA development, independent of sex-associated hypertriglyceridaemia, and G6PC1 genotype.Lay summaryGlycogen storage disease type Ia (GSDIa) is a rare, inherited metabolic disease that can be complicated by liver tumours (hepatocellular adenomas), which in turn may cause bleeding or progress to liver cancer. Risk factors associated with hepatocellular adenoma formation in patients with GSDIa are largely unknown. In our study, we found that high serum triglyceride concentrations during childhood, but not specific genetic variants, were associated with increased risk of hepatocellular adenoma diagnosis later in life.
Project description:Glycogen storage disease type Ia (GSD-Ia) patients deficient in glucose-6-phosphatase-alpha (G6Pase-alpha or G6PC) manifest disturbed glucose homeostasis. We examined the efficacy of liver G6Pase-alpha delivery mediated by AAV-GPE, an adeno-associated virus (AAV) serotype 8 vector expressing human G6Pase-alpha directed by the human G6PC promoter/enhancer (GPE), and compared it to AAV-CBA, that directed murine G6Pase-alpha expression using a hybrid chicken beta-actin (CBA) promoter/cytomegalovirus (CMV) enhancer. The AAV-GPE directed hepatic G6Pase-alpha expression in the infused G6pc(-/-) mice declined 12-fold from age 2 to 6 weeks but stabilized at wild-type levels from age 6 to 24 weeks. In contrast, the expression directed by AAV-CBA declined 95-fold over 24 weeks, demonstrating that the GPE is more effective in directing persistent in vivo hepatic transgene expression. We further show that the rapid decline in transgene expression directed by AAV-CBA results from an inflammatory immune response elicited by the AAV-CBA vector. The AAV-GPE-treated G6pc(-/-) mice exhibit normal levels of blood glucose, blood metabolites, hepatic glycogen, and hepatic fat. Moreover, the mice maintained normal blood glucose levels even after 6 hours of fasting. The complete normalization of hepatic G6Pase-alpha deficiency by the G6PC promoter/enhancer holds promise for the future of gene therapy in human GSD-Ia patients.