Normoglycemia alone is insufficient to prevent long-term complications of hepatocellular adenoma in glycogen storage disease type Ib mice☆

Background/Aims

Glycogen storage disease type Ib (GSD-Ib) patients deficient in a glucose-6-phosphate transporter (G6PT) manifest disturbed glucose homeostasis, myeloid dysfunctions, and hepatocellular adenoma (HCA). This study was conducted to evaluate whether maintaining normoglycemia in GSD-Ib could prevent HCA.

Methods

We infused neonatal GSD-Ib mice with adeno-associated virus (AAV) carrying G6PT and examined their metabolic and myeloid phenotypes for the 72-week study.

Results

The AAV vector delivered the G6PT transgene to the liver and bone marrow. Long-term metabolic correction was achieved alongside a transient myeloid correction. Hepatic G6PT activity was 50% of wild-type levels at 2 weeks post-infusion but declined rapidly thereafter to reach 3% of wild-type levels by age 6 to 72 weeks. Despite this, the infused mice maintained normoglycemia throughout the study, exhibited near normal growth and normalized serum metabolite profiles. However, all five AAV-treated GSD-Ib mice that lived over 50 weeks accumulated excessive hepatic glycogen and fat. Two mice developed steatohepatitis and multiple HCAs with one undergoing malignant transformation.

Conclusions

Normoglycemia alone cannot prevent hepatic steatosis and glycogen accumulation or the development of HCAs in GSD-Ib, providing one explanation why GSD-Ib patients maintaining normoglycemia under intense dietary therapy continue at risk for this long-term complication.

Abbreviations: GSD-Ib, glycogen storage disease type Ib, G6P, glucose-6-phosphate, G6PT, glucose-6-phosphate transporter, HCA, hepatocellular adenoma, AAV, adeno-associated virus, G6P, glucose-6-phosphate, G6Pase, glucose-6-phosphatase, G-CSF, granulocyte colony stimulating factor

Keywords: Glycogen storage disease type Ib, Glucose-6-phosphate transporter, Hepatocellular adenoma, Malignant transformation, Adeno-associated virus, Gene therapy