Papillary renal cell carcinoma in two young adults with glycogen storage disease type Ia

Impaired Glucose Metabolism, Primary Cilium Defects, and Kidney Cystogenesis in Glycogen Storage Disease Type Ia

Key Points

Background

Glycogen storage disease type Ia (GSDIa) is a rare metabolic disorder caused by mutations in the catalytic subunit of glucose-6 phosphatase (G6PC1). This leads to severe hypoglycemia, and most young patients with GSDIa develop CKD. The kidney pathology is characterized by the development of cysts, which typically occur at an advanced stage of CKD.

Methods

To elucidate the molecular mechanisms responsible for cyst formation, we characterized renal metabolism, molecular pathways involved in cell proliferation, and primary cilium integrity using mice in which G6pc1 was specifically deleted in the kidney from an in utero stage.

Results

GSDIa mice exhibited kidney fibrosis, high inflammation, and cyst formation, leading to kidney dysfunction. In addition, the loss of G6PC1 led to the ectopic accumulation of glycogen and lipids in the kidneys and a metabolic shift toward a Warburg-like metabolism. This metabolic adaptation was due to an excess of glucose-6 phosphate, which supports cell proliferation, driven by the mitogen-activated protein kinase/extracellular signal–regulated kinases and protein kinase B/mammalian target of rapamycin pathways. Treatment of GSDIa mice with rapamycin, a target of the mammalian target of rapamycin pathway, reduced cell proliferation and kidney damage. Our results also identified lipocalin 2 as a contributor to renal inflammation and an early biomarker of CKD progression in GSDIa mice. Its inactivation partially prevented kidney lesions in GSDIa. Importantly, primary cilium defects were observed in the kidneys of GSDIa mice.

Conclusions

Metabolic adaptations because of glucose-6 phosphate accumulation in GSDIa renal tubules, toward a Warburg-like metabolism, promoted cell proliferation and cyst formation in a similar manner to that observed in various cystic kidney diseases. This was associated with downregulation of primary cilium gene expression and, consequently, altered cilium morphology.

Papillary renal cell carcinoma in two young adults with glycogen storage disease type Ia

Glycogen storage disease type Ia (GSD Ia) is a rare metabolic disease due to glucose‐6‐phosphatase deficiency. Chronic kidney disease is a frequent complication that may manifest itself by glomerular lesions and tubular dysfunction from the second decade of life. We report two young GSDIa patients with malignant renal tumor. The first patient was a 25‐year‐old man. He had chronic metabolic imbalance without kidney involvement. The tumor, a type 2 papillary renal carcinoma, was accidentally discovered during follow‐up. The second patient was a 27‐year‐old woman with chronic metabolic imbalance and chronic kidney involvement. The tumor, a grade 2 papillary carcinoma, was accidentally discovered during follow‐up. These two observations are, to date, the first to be reported. We suggest that annual monitoring of kidney imaging in GSDI patients should be systematic to detect renal cancer, from the second decade of life.