Development of hepatocellular adenomas and carcinomas in mice with liver-specific G6Pase-α deficiency

Unveiling the role of PYGB in pancreatic cancer: a novel diagnostic biomarker and gene therapy target

PURPOSE

Pancreatic cancer (PC) is a highly malignant tumor that poses a severe threat to human health. Brain glycogen phosphorylase (PYGB) breaks down glycogen and provides an energy source for tumor cells. Although PYGB has been reported in several tumors, its role in PC remains unclear.

METHODS

We constructed a risk diagnostic model of PC-related genes by WGCNA and LASSO regression and found PYGB, an essential gene in PC. Then, we explored the pro-carcinogenic role of PYGB in PC by in vivo and in vitro experiments.

RESULTS

We found that PYGB, SCL2A1, and SLC16A3 had a significant effect on the diagnosis and prognosis of PC, but PYGB had the most significant effect on the prognosis. Pan-cancer analysis showed that PYGB was highly expressed in most of the tumors but had the highest correlation with PC. In TCGA and GEO databases, we found that PYGB was highly expressed in PC tissues and correlated with PC's prognostic and pathological features. Through in vivo and in vitro experiments, we found that high expression of PYGB promoted the proliferation, invasion, and metastasis of PC cells. Through enrichment analysis, we found that PYGB is associated with several key cell biological processes and signaling pathways. In experiments, we validated that the MAPK/ERK pathway is involved in the pro-tumorigenic mechanism of PYGB in PC.

CONCLUSION

Our results suggest that PYGB promotes PC cell proliferation, invasion, and metastasis, leading to poor patient prognosis. PYGB gene may be a novel diagnostic biomarker and gene therapy target for PC.

Single-cell and genetic multi-omics analysis combined with experiments confirmed the signature and potential targets of cuproptosis in hepatocellular carcinoma

Background: Cuproptosis, as a recently discovered type of programmed cell death, occupies a very important role in hepatocellular carcinoma (HCC) and provides new methods for immunotherapy; however, the functions of cuproptosis in HCC are still unclear. Methods: We first analyzed the transcriptome data and clinical information of 526 HCC patients using multiple algorithms in R language and extensively described the copy number variation, prognostic and immune infiltration characteristics of cuproptosis related genes (CRGs). Then, the hub CRG related genes associated with prognosis through LASSO and Cox regression analyses and constructed a prognostic prediction model including multiple molecular markers and clinicopathological parameters through training cohorts, then this model was verified by test cohorts. On the basis of the model, the clinicopathological indicators, immune infiltration and tumor microenvironment characteristics of HCC patients were further explored via bioinformation analysis. Then, We further explored the key gene biological function by single-cell analysis, cell viability and transwell experiments. Meantime, we also explored the molecular docking of the hub genes. Results: We have screened 5 hub genes associated with HCC prognosis and constructed a prognosis prediction scoring model. And the model results showed that patients in the high-risk group had poor prognosis and the expression levels of multiple immune markers, including PD-L1, CD276 and CTLA4, were higher than those patients in the low-risk group. We found a significant correlation between risk score and M0 macrophages and memory CD4+ T cells. And the single-cell analysis and molecular experiments showed that BEX1 were higher expressed in HCC tissues and deletion inhibited the proliferation, invasion and migration and EMT pathway of HCC cells. Finally, it was observed that BEX1 could bind to sorafenib to form a stable conformation. Conclusion: The study not only revealed the multiomics characteristics of CRGs in HCC but also constructed a new high-accuracy prognostic prediction model. Meanwhile, BEX1 were also identified as hub genes that can mediate the cuproptosis of hepatocytes as potential therapeutic targets for HCC.

Ciclopirox Olamine Induces Proliferation Inhibition and Protective Autophagy in Hepatocellular Carcinoma

Hepatocellular carcinoma is one of the most common fatal malignancies worldwide. Thus far, the hepatocellular carcinoma prognosis has been bleak due to deficiencies in the identification and diagnosis of early hepatocellular carcinoma. Ciclopirox olamine (CPX) is a synthetic antifungal agent and has been considered as an anti-cancer candidate drug recently, though the detailed mechanisms related to its anti-cancer effect in hepatocellular carcinoma have not yet been revealed. Here, we found that CPX could inhibit proliferation in HCC cells but not in intrahepatic cholangiocarcinoma cells by arresting the cell cycle. Moreover, the anti-cancer effects of CPX in HCC cells were also attributed to CPX-triggered ROS accumulation and DJ-1 downregulation. Additionally, CPX could promote complete autophagic flux, which alleviated the anti-cancer effect of CPX in HCC cells, whereas the ROS scavenger (NAC) would attenuate CPX-induced protective autophagy. Interestingly, CPX could also induce glycogen clustering in HCC cells. Altogether, this study provides a new insight into the detailed molecular mechanisms of CPX as an anti-cancer therapy and a strategy for treating hepatocellular carcinoma.

Urine-Derived Epithelial Cells as a New Model to Study Renal Metabolic Phenotypes of Patients with Glycogen Storage Disease 1a

Glycogen storage diseases (GSDs) represent a model of pathological accumulation of glycogen disease in the kidney that, in animal models, results in nephropathy due to abnormal autophagy and mitochondrial function. Patients with Glycogen Storage Disease 1a (GSD1a) accumulate glycogen in the kidneys and suffer a disease resembling diabetic nephropathy that can progress to renal failure. In this study, we addressed whether urine-derived epithelial cells (URECs) from patients with GSD1a maintain their biological features, and whether they can be used as a model to study the renal and metabolic phenotypes of this genetic condition. Studies were performed on cells extracted from urine samples of GSD1a and healthy subjects. URECs were characterized after the fourth passage by transmission electron microscopy and immunofluorescence. Reactive oxygen species (ROS), at different glucose concentrations, were measured by fluorescent staining. We cultured URECs from three patients with GSD1a and three healthy controls. At the fourth passage, URECs from GSD1a patients maintained their massive glycogen content. GSD1a and control cells showed the ciliary structures of renal tubular epithelium and the expression of epithelial (E-cadherin) and renal tubular cells (aquaporin 1 and 2) markers. Moreover, URECs from both groups responded to changes in glucose concentrations by modulating ROS levels. GSD1a cells were featured by a specific response to the low glucose stimulus, which is the condition that more resembles the metabolic derangement of patients with GSD1a. Through this study, we demonstrated that URECs might represent a promising experimental model to study the molecular mechanisms leading to renal damage in GSD1a, due to pathological glycogen storage.

Studies on glycogen storage disease type 1a animal models: a brief perspective

Glycogen storage disease type 1 (GSD1) is a rare hereditary monogenic disease characterized by the disturbed glucose metabolism. The most widespread variant of GSD1 is GSD1a, which is a deficiency of glucose-6-phosphatase-ɑ. Glucose-6-phosphatase-ɑ is expressed only in liver, kidney, and intestine, and these organs are primarily affected by its deficiency, and long-term complications of GSD1a include hepatic tumors and chronic liver disease. This article is a brief overview of existing animal models for GSD1a, from the first mouse model of 1996 to modern CRISPR/Cas9-generated ones. First whole-body murine models demonstrated exact metabolic symptoms of GSD1a, but the animals did not survive weaning. The protocol for glucose treatment allowed prolonged survival of affected animals, but long-term complications, such as hepatic tumorigenesis, could not be investigated. Next, organ-specific knockout models were developed, and most of the metabolic research was performed on liver glucose-6-phosphate-deficient mice. Naturally occuring mutation was also discovered in dogs. All these models are widely used to study GSD1a from metabolic and physiological standpoints and to develop possible treatments involving gene therapy. Research performed using these models helped elucidate the role of glycogen and lipid accumulation, hypoxia, mitochondrial dysfunction, and autophagy impairment in long-term complications of GSD1a, including hepatic tumorigenesis. Recently, gene replacement therapy and genome editing were tested on described models, and some of the developed approaches have reached clinical trials.

ROS generation attenuates the anti-cancer effect of CPX on cervical cancer cells by inducing autophagy and inhibiting glycophagy

Cervical cancer is one of the most common gynecological malignancies with poor prognosis due to constant chemoresistance and repeated relapse. Ciclopirox olamine (CPX), a synthetic antifungal agent, has recently been identified to be a promising anti-cancer candidate. However, the detailed mechanisms related to its anti-cancer effects remain unclear and need to be further elucidated. In this study, we found that CPX could induce proliferation inhibition in cervical cancer cells by targeting PARK7. Further results demonstrated that CPX could induce cytoprotective autophagy by downregulating the expression of PARK7 to activate PRKAA1 or by PARK7-independent accumulation of ROS to inhibit mTOR signaling. Meanwhile, CPX treatment increased the glycogen clustering and glycophagy in cervical cancer cells. The presence of N-acetyl-l-cysteine (NAC), a ROS scavenger, led to further clustering of glycogen in cells by reducing autophagy and enhancing glycophagy, which promoted CPX-induced inhibition of cervical cancer cell proliferation. Together, our study provides new insights into the molecular mechanisms of CPX in the anti-cancer therapy and opens new avenues for the glycophagy in cancer therapeutics.

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CPX induces cytoprotective autophagy and inhibits proliferation of cervical cancer cells by targeting PARK7.

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ROS generation attenuates the anticancer effect of CPX by inducing cytoprotective autophagy and inhibiting glycophagy.

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ROS-triggered glycogen clustering and inactivation of YAP1 are involved in the anti-cancer effects of CPX.

Exosomal MicroRNAs as Potential Biomarkers of Hepatic Injury and Kidney Disease in Glycogen Storage Disease Type Ia Patients

Glycogen storage disease type Ia (GSDIa) is an inherited metabolic disorder caused by mutations in the enzyme glucose-6-phosphatase-α (G6Pase-α). Affected individuals develop renal and liver complications, including the development of hepatocellular adenoma/carcinoma and kidney failure. The purpose of this study was to identify potential biomarkers of the evolution of the disease in GSDIa patients. To this end, we analyzed the expression of exosomal microRNAs (Exo-miRs) in the plasma exosomes of 45 patients aged 6 to 63 years. Plasma from age-matched normal individuals were used as controls. We found that the altered expression of several Exo-miRs correlates with the pathologic state of the patients and might help to monitor the progression of the disease and the development of late GSDIa-associated complications.

Modeling Phenotypic Heterogeneity of Glycogen Storage Disease Type 1a Liver Disease in Mice by Somatic CRISPR/CRISPR-associated protein 9-Mediated Gene Editing

BACKGROUND AND AIMS

Patients with glycogen storage disease type 1a (GSD-1a) primarily present with life-threatening hypoglycemia and display severe liver disease characterized by hepatomegaly. Despite strict dietary management, long-term complications still occur, such as liver tumor development. Variations in residual glucose-6-phosphatase (G6PC1) activity likely contribute to phenotypic heterogeneity in biochemical symptoms and complications between patients. However, lack of insight into the relationship between G6PC1 activity and symptoms/complications and poor understanding of the underlying disease mechanisms pose major challenges to provide optimal health care and quality of life for GSD-1a patients. Currently available GSD-1a animal models are not suitable to systematically investigate the relationship between hepatic G6PC activity and phenotypic heterogeneity or the contribution of gene-gene interactions (GGIs) in the liver.

APPROACH AND RESULTS

To meet these needs, we generated and characterized a hepatocyte-specific GSD-1a mouse model using somatic CRISPR/CRISPR-associated protein 9 (Cas9)-mediated gene editing. Hepatic G6pc editing reduced hepatic G6PC activity up to 98% and resulted in failure to thrive, fasting hypoglycemia, hypertriglyceridemia, hepatomegaly, hepatic steatosis (HS), and increased liver tumor incidence. This approach was furthermore successful in simultaneously modulating hepatic G6PC and carbohydrate response element-binding protein, a transcription factor that is activated in GSD-1a and protects against HS under these conditions. Importantly, it also allowed for the modeling of a spectrum of GSD-1a phenotypes in terms of hepatic G6PC activity, fasting hypoglycemia, hypertriglyceridemia, hepatomegaly and HS.

CONCLUSIONS

In conclusion, we show that somatic CRISPR/Cas9-mediated gene editing allows for the modeling of a spectrum of hepatocyte-borne GSD-1a disease symptoms in mice and to efficiently study GGIs in the liver. This approach opens perspectives for translational research and will likely contribute to personalized treatments for GSD-1a and other genetic liver diseases.

Glycogen accumulation and phase separation drives liver tumor initiation

Glucose consumption is generally increased in tumor cells to support tumor growth. Interestingly, we report that glycogen accumulation is a key initiating oncogenic event during liver malignant transformation. We found that glucose-6-phosphatase (G6PC) catalyzing the last step of glycogenolysis is frequently downregulated to augment glucose storage in pre-malignant cells. Accumulated glycogen undergoes liquid-liquid phase separation, which results in the assembly of the Laforin-Mst1/2 complex and consequently sequesters Hippo kinases Mst1/2 in glycogen liquid droplets to relieve their inhibition on Yap. Moreover, G6PC or another glycogenolysis enzyme-liver glycogen phosphorylase (PYGL) deficiency in both human and mice results in glycogen storage disease along with liver enlargement and tumorigenesis in a Yap-dependent manner. Consistently, elimination of glycogen accumulation abrogates liver growth and cancer incidence, whereas increasing glycogen storage accelerates tumorigenesis. Thus, we concluded that cancer-initiating cells adapt a glycogen storing mode, which blocks Hippo signaling through glycogen phase separation to augment tumor incidence.

Construction and comprehensive analysis of a competitive endogenous RNA network to reveal potential biomarkers for the malignant differentiation of glioma

BACKGROUND

Long noncoding RNAs (lncRNAs) can act as microRNA (miRNA) sponges to regulate protein-coding gene expression; therefore, lncRNAs are considered major components of the competitive endogenous RNA (ceRNA) network and have attracted growing attention. This study explored the regulatory mechanisms and functional roles of lncRNAs as ceRNAs in the malignant differentiation of low-grade glioma (LGG) to glioblastoma (GBM) and their potential impact on the prognosis of patients with GBM.

METHODS

LncRNA and messenger RNA (mRNA) data were extracted from the Cancer Genome Atlas (TCGA) database from 156 GBM samples and 529 LGG samples. Separately, the miRNA expression data were downloaded from the Gene Expression Omnibus database, with the GSE112009 dataset containing miRNA expression data from 10 GBM samples and 15 LGG samples. Weighted gene coexpression network analysis was performed to screen the glioma grade-related lncRNAs. Then, a ceRNA network was established. The database for annotation, visualization, and integrated discovery was adopted to conduct functional enrichment analysis based on 57 upregulated differentially expressed mRNAs in the ceRNA network. Finally, Kaplan-Meier curves were created for the survival analysis of 13 hub lncRNA by combining the clinical data of GBM patients in TCGA.

RESULTS

A ceRNA network including 16 lncRNAs, 18 miRNAs, and 78 mRNAs specific to the malignant differentiation of LGG to GBM was established. The 57 upregulated differentially expressed mRNAs in the ceRNA network were significantly enriched in 35 gene ontology terms and 5 pathways. The survival analysis showed that 2 lncRNAs (LINC00261 and HOXA10-AS) were prognostic biomarkers for patients with GBM in TCGA.

CONCLUSION

The proposed ceRNA network may help elucidate the regulatory mechanism by which lncRNAs function as ceRNAs and contribute to the malignant differentiation of LGG to GBM. Importantly, the candidate lncRNAs, miRNAs, and mRNAs involved in the ceRNA network can be further evaluated as potential therapeutic targets and prognostic biomarkers for GBM.

Hepatocellular carcinoma (HCC): Epidemiology, etiology and molecular classification

Hepatocellular carcinoma (HCC), the primary malignancy of hepatocytes, is a diagnosis with bleak outcome. According to National Cancer Institute's SEER database, the average five-year survival rate of HCC patients in the US is 19.6% but can be as low as 2.5% for advanced, metastatic disease. When diagnosed at early stages, it is treatable with locoregional treatments including surgical resection, Radio-Frequency Ablation, Trans-Arterial Chemoembolization or liver transplantation. However, HCC is usually diagnosed at advanced stages when the tumor is unresectable, making these treatments ineffective. In such instances, systemic therapy with tyrosine kinase inhibitors (TKIs) becomes the only viable option, even though it benefits only 30% of patients, provides only a modest (~3months) increase in overall survival and causes drug resistance within 6months. HCC, like many other cancers, is highly heterogeneous making a one-size fits all option problematic. The selection of liver transplantation, locoregional treatment, TKIs or immune checkpoint inhibitors as a treatment strategy depends on the disease stage and underlying condition(s). Additionally, patients with similar disease phenotype can have different molecular etiology making treatment responses different. Stratification of patients at the molecular level would facilitate development of the most effective treatment option. With the increase in efficiency and affordability of "omics"-level analysis, considerable effort has been expended in classifying HCC at the molecular, metabolic and immunologic levels. This review examines the results of these efforts and the ways they can be leveraged to develop targeted treatment options for HCC.

Circulating exosomal microRNAs as potential biomarkers of hepatic injury and inflammation in a murine model of glycogen storage disease type 1a

Most patients affected by glycogen storage disease type 1a (GSD1a), an inherited metabolic disorder caused by mutations in the enzyme glucose-6-phosphatase-α (G6Pase-α), develop renal and liver complications, including the development of hepatocellular adenoma/carcinoma. The purpose of this study was to identify potential biomarkers of the pathophysiology of the GSD1a-affected liver. To this end, we used the plasma exosomes of a murine model of GSD1a, the LS-G6pc ^{-/ -} mouse, to uncover the modulation in microRNA expression associated with the disease. The microRNAs differentially expressed between LS-G6pc ^-/- and wild-type mice, LS-G6pc ^-/- mice with hepatocellular adenoma and LS-G6pc ^-/- mice without adenoma, and LS-G6pc ^-/- mice with amyloidosis and LS-G6pc ^-/- mice without amyloidosis were identified. Pathway analysis demonstrated that the target genes of the differentially expressed microRNA were significantly enriched for the insulin signaling pathway, glucose and lipid metabolism, Wnt/β-catenin, telomere maintenance and hepatocellular carcinoma, and chemokine and immune regulation signaling pathways. Although some microRNAs were common to the different pathologic conditions, others were unique to the cancerous or inflammatory status of the animals. Therefore, the altered expression of several microRNAs is correlated with various pathologic liver states and might help to distinguish them during the progression of the disease and the development of late GSD1a-associated complications.

Characterization of high- and low-risk hepatocellular adenomas by magnetic resonance imaging in an animal model of glycogen storage disease type 1A

Hepatocellular adenomas (HCAs) are benign tumors, of which the most serious complications are hemorrhage and malignant transformation to hepatocellular carcinoma (HCC). Among the various subtypes of HCA, the β-catenin-activated subtype (bHCA) is associated with greatest risk of malignant transformation. Magnetic resonance imaging (MRI) is an important tool to differentiate benign and malignant hepatic lesions, and preclinical experimental approaches may help to develop a method to identify MRI features associated with bHCA. HCAs are associated with various pathologies, including glycogen storage disease 1a (GSD1a). Here, we utilized a mouse model for GSD1a that develops HCA and HCC, and analyzed the mice in order to distinguish low-risk from high-risk tumors. Animals were scanned by MRI using a hepato-specific contrast agent. The mice were sacrificed after MRI and their lesions were classified using immunohistochemistry. We observed that 45% of the animals developed focal lesions, and MRI identified four different patterns after contrast administration: isointense, hyperintense and hypointense lesions, and lesions with peripheral contrast enhancement. After contrast administration, only bHCA and HCC were hypointense in T1-weighted imaging and mildly hyperintense in T2-weighted imaging. Thus, high-risk adenomas display MRI features clearly distinguishable from those exhibited by low-risk adenomas, indicating that MRI is a reliable method for early diagnosis and classification of HCA, necessary for correct patient management.

Dietary exacerbation of metabolic stress leads to accelerated hepatic carcinogenesis in glycogen storage disease type Ia

BACKGROUND & AIMS

Glycogen storage disease type Ia (GSDIa) is a rare genetic disease associated with glycogen accumulation in hepatocytes and steatosis. With age, most adult patients with GSDIa develop hepatocellular adenomas (HCA), which can progress to hepatocellular carcinomas (HCC). In this study, we characterized metabolic reprogramming and cellular defense alterations during tumorigenesis in the liver of hepatocyte-specific G6pc deficient (L.G6pc^-/-) mice, which develop all the hepatic hallmarks of GSDIa.

METHODS

Liver metabolism and cellular defenses were assessed at pretumoral (four months) and tumoral (nine months) stages in L.G6pc^-/- mice fed a high fat/high sucrose (HF/HS) diet.

RESULTS

In response to HF/HS diet, hepatocarcinogenesis was highly accelerated since 85% of L.G6pc^-/- mice developed multiple hepatic tumors after nine months, with 70% classified as HCA and 30% as HCC. Tumor development was associated with high expression of malignancy markers of HCC, i.e. alpha-fetoprotein, glypican 3 and β-catenin. In addition, L.G6pc^-/- livers exhibited loss of tumor suppressors. Interestingly, L.G6pc^-/- steatosis exhibited a low-inflammatory state and was less pronounced than in wild-type livers. This was associated with an absence of epithelial-mesenchymal transition and fibrosis, while HCA/HCC showed a partial epithelial-mesenchymal transition in the absence of TGF-β1 increase. In HCA/HCC, glycolysis was characterized by a marked expression of PK-M2, decreased mitochondrial OXPHOS and a decrease of pyruvate entry in the mitochondria, confirming a "Warburg-like" phenotype. These metabolic alterations led to a decrease in antioxidant defenses and autophagy and chronic endoplasmic reticulum stress in L.G6pc^-/- livers and tumors. Interestingly, autophagy was reactivated in HCA/HCC.

CONCLUSION

The metabolic remodeling in L.G6pc^-/- liver generates a preneoplastic status and leads to a loss of cellular defenses and tumor suppressors that facilitates tumor development in GSDI.

LAY SUMMARY

Glycogen storage disease type Ia (GSD1a) is a rare metabolic disease characterized by hypoglycemia, steatosis, excessive glycogen accumulation and tumor development in the liver. In this study, we have observed that GSDIa livers reprogram their metabolism in a similar way to cancer cells, which facilitates tumor formation and progression, in the absence of hepatic fibrosis. Moreover, hepatic burden due to overload of glycogen and lipids in the cells leads to a decrease in cellular defenses, such as autophagy, which could further promote tumorigenesis in the case of GSDI.

Hepatocellular Carcinoma in Fanconi-Bickel Syndrome

Fanconi-Bickel syndrome is a rare autosomal recessive disorder due to mutations in the facilitative glucose transporter 2 ( GLUT2 or SLC2A2) gene resulting in excessive glycogen storage predominantly in the liver and kidney. Previous case reports of this condition have described liver biopsies with glycogen storage and variable steatosis and/or fibrosis. Unlike in other types of glycogen storage disease, hepatocellular adenomas and carcinomas have not been described to date in this syndrome. A 6-year-old boy with consanguineous parents had short stature, poorly controlled rickets, hepatosplenomegaly, and renal tubular dysfunction clinically consistent with Fanconi-Bickel Syndrome. Sequencing of the SLC2A2 gene showed a homozygous variant of unknown significance [c.474A > C (p.Arg158Ser)] causing a missense mutation in an evolutionarily conserved residue. An incidental single hepatic lesion was discovered on imaging, and subsequent resection showed a 2.6 cm well-differentiated hepatocellular carcinoma with moderate atypia, diffuse immunoreactivity for glypican-3, and nuclear b-catenin, and with focal complete loss of the reticulin framework. The non-neoplastic liver showed marked glycogen accumulation with mild periportal fibrosis, rare bridging fibrosis, and no regenerative or adenomatous nodules. By electron microscopy, tumor cells had pleomorphic nuclei, prominent nucleoli, and scant cytoplasm with numerous mitochondria. Well-developed canaliculi were occasionally seen. The non-neoplastic liver showed glycogenosis with abundant cytoplasmic free (non-membrane bound) glycogen. Hepatocellular carcinoma should be considered as a possible complication of Fanconi-Bickel syndrome. This well differentiated carcinoma did not appear to be associated with hepatic adenomatosis as has been described in some hepatocellular carcinomas associated with other hepatic glycogen storage disorders. The nuclear beta-catenin immunoreactivity indicates a role for the Wnt signaling pathway in the pathogenesis of this tumor.

Recent development and gene therapy for glycogen storage disease type Ia

Glycogen storage disease type Ia (GSD-Ia) is an autosomal recessive metabolic disorder caused by a deficiency in glucose-6-phosphatase-α (G6Pase-α or G6PC) that is expressed primarily in the liver, kidney, and intestine. G6Pase-α catalyzes the hydrolysis of glucose-6-phosphate (G6P) to glucose and phosphate in the terminal step of gluconeogenesis and glycogenolysis, and is a key enzyme for endogenous glucose production. The active site of G6Pase-α is inside the endoplasmic reticulum (ER) lumen. For catalysis, the substrate G6P must be translocated from the cytoplasm into the ER lumen by a G6P transporter (G6PT). The functional coupling of G6Pase-α and G6PT maintains interprandial glucose homeostasis. Dietary therapies for GSD-Ia are available, but cannot prevent the long-term complication of hepatocellular adenoma that may undergo malignant transformation to hepatocellular carcinoma. Animal models of GSD-Ia are now available and are being exploited to both delineate the disease more precisely and develop new treatment approaches, including gene therapy.

Molecular genetic analysis and phenotypic characteristics of a consanguineous family with glycogen storage disease type Ia

Glycogen storage disease type‑Ia (GSD‑Ia) is a rare autosomal recessive disease caused by a mutation in the gene encoding glucose‑6‑phosphate‑α (G6PC). The present study reported the case of a 3‑month‑old female Chinese patient with GSD‑Ia born to consanguineous parents. The aim of the present study was to identify the precise mutation of the G6PC gene associated with this family and to describe the phenotypic characteristics of the patient. A comprehensive examination was performed on the patient, including physical examination, vein blood gas analysis, abdominal sonography and biochemical analyses. In addition, gene sequencing was performed on the coding region of the G6PC gene to identify the mutation. The patient was diagnosed with GSD‑Ia and a G6PC missense mutation of c.518T>C (p.L173P) located in a highly conserved area was identified. The mutation is in a non‑helical region of the protein, which previous studies have suggested should result in a lesser effect on G6PC enzymatic activity and milder phenotypic characteristics compared with mutations located in helical regions. However, the severity of the disease phenotype in the subject of the present study was inconsistent with that predicted from her genotype. The patient suffered from serious hypoglycemia, lactic acidosis, increased triglycerides, hepatic dysfunction, clear hepatomegaly and nephromegaly. The incidence of the p.L173P mutation may be relatively high in the Chinese population. Knowledge of the various phenotypic presentations of the p.L173P mutation may beneficial for future investigations.