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Objective Glycogen storage disease type 1a (GSD Ia) is a rare inherited metabolic disorder caused by mutations in the glucose-6-phosphatase (G6PC1) gene. When untreated, GSD Ia leads to severe fasting-induced hypoglycemia. Although current intensive dietary management aims to prevent hypoglycemia, patients still experience hypoglycemic events. Poor glycemic control in GSD Ia is associated with hypertriglyceridemia, hepatocellular adenoma and carcinoma, and also with an increased bleeding tendency of unknown origin. Methods To evaluate the effect of glycemic control on leukocyte levels and coagulation in GSD Ia, we employed hepatocyte-specific G6pc1 deficient (L-G6pc−/−) mice under fed or fasted conditions, to match good or poor glycemic control in GSD Ia, respectively. Results We found that fasting-induced hypoglycemia in L-G6pc−/− mice decreased blood leukocytes, specifically proinflammatory Ly6Chi monocytes, compared to controls. Refeeding reversed this decrease. The decrease in Ly6Chi monocytes was accompanied by an increase in plasma corticosterone levels and was prevented by the glucocorticoid receptor antagonist mifepristone. Further, fasting-induced hypoglycemia in L-G6pc−/− mice prolonged bleeding time in the tail vein bleeding assay, with reversal by refeeding. This could not be explained by changes in coagulation factors V, VII, or VIII, or von Willebrand factor. While the prothrombin and activated partial thromboplastin time as well as total platelet counts were not affected by fasting-induced hypoglycemia in L-G6pc−/− mice, ADP-induced platelet aggregation was disturbed. Conclusions These studies reveal a relationship between fasting-induced hypoglycemia, decreased blood monocytes, and disturbed platelet aggregation in L-G6pc−/− mice. While disturbed platelet aggregation likely accounts for the bleeding phenotype in GSD Ia, elevated plasma corticosterone decreases the levels of proinflammatory monocytes. These studies highlight the necessity of maintaining good glycemic control in GSD Ia., Highlights • Fasting-induced hypoglycemia in hepatocyte-specific G6pc1 deficiency disturbs platelet aggregation. • Fasting-induced hypoglycemia in hepatocyte-specific G6pc1 deficiency decreases blood monocytes. • Fasting-induced hypoglycemia in hepatocyte-specific G6pc1 deficiency increases plasma corticosterone.

Gene therapy is currently considered as the optimal treatment for inborn errors of metabolism (IEMs), as it aims to permanently compensate for the primary genetic defect. However, emerging gene editing approaches such as CRISPR‐Cas9, in which the DNA of the host organism is edited at a precise location, may have outperforming therapeutic potential. Gene editing strategies aim to correct the actual genetic mutation, while circumventing issues associated with conventional compensation gene therapy. Such strategies can also be repurposed to normalize gene expression changes that occur secondary to the genetic defect. Moreover, besides the genetic causes of IEMs, it is increasingly recognized that their clinical phenotypes are associated with epigenetic changes. Because epigenetic alterations are principally reversible, this may offer new opportunities for treatment of IEM patients. Here, we present an overview of the promises of epigenetics in eventually treating IEMs. We discuss the concepts of gene and epigenetic editing, and the advantages and disadvantages of current and upcoming gene‐based therapies for treatment of IEMs.

Oncogene-induced metabolic reprograming supports cell growth and proliferation. Yet, it also links cancer cell survival to certain metabolic pathways and nutrients. In order to synthesise amino acids and nucleotidesde novofor growth and proliferation, cancer cells depend on glycolysis, the cytoplasmic oxidation of glucose, which generates necessary metabolic intermediates and ATP. During glycolysis, NAD+ is used as the oxidizing agent and is thereby reduced into NADH. To ensure high glycolysis rates and maintain NADH/NAD+ homeostasis, cytoplasmic NAD+ has to be regenerated. The mitochondria are the major sites of NADH reoxidation into NAD+ where NADH-derived electrons enter the electron transport chain for ATP production. Since NADH/NAD+ cannot cross membranes, the malate-aspartate shuttle (MAS) or the glycerol-3-phosphate shuttle (GPS) are used as intermediate electron carriers. In addition, cytoplasmic NAD+ is generated by NADH-electron transfer to pyruvate, reducing it to lactate (the Warburg effect). NADH/NAD+ homeostasis plays a pivotal role in cancer cell survival, but our knowledge about the involved regulatory mechanisms is still limited. Here, we show that the proto-oncogenic transcription factor C/EBPβ-LIP stimulates both glycolysis and the MAS. Inhibition of glycolysis with ongoing C/EBPβ-LIP-induced MAS activity results in NADH depletion and apoptosis that can be rescued by inhibiting either the MAS or other NADH-consuming processes. Therefore, beyond the discovery of C/EBPβ-LIP as a dual activator of glycolysis and the MAS, this study indicates that simultaneous inhibition of glycolysis and lowering of the NADH/NAD+ ratio may be considered to treat cancer.