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Kidney Week

Abstract: FR-PO634

The Underappreciated Renal Phenotype of EGFR Deficiency: Could It Be that Complex?

Session Information

  • Pediatric Nephrology - II
    November 03, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

  • 1900 Pediatric Nephrology

Authors

  • Alshammasi, Walaa Abbas, The Hospital for Sick Children, Toronto, Ontario, Canada
  • Lemaire, Mathieu JM, The Hospital for Sick Children, Toronto, Ontario, Canada
Introduction

Epidermal Growth Factor Receptor (EGFR) is a cell signaling receptor implicated in cell proliferation, survival, and tissue growth. Neonatal inflammatory skin and bowel disease type 2 is caused by EGFR recessive deficiency (OMIM 616069). Among the 22 known cases, nephromegaly is the only notable renal phenotype. A review of published cases and a new case suggests NISBD2 is frequently associated with tubulopathy.

Case Description

A 10-year-old girl was diagnosed with NISBD2 caused by homozygous pathogenic EGFR variants (NM_005228.3: c.1283G>A; p.G428D). Ultrasound revealed large echogenic kidneys with poor corticomedullary differentiation and many small cysts. We documented hypomagnesemia 0.5 mmol/L and hypokalemia 2.6 mmol/L caused by excessive urinary magnesium wasting FeMg 14%. We also observed mild chronic hypernatremia 155 mmol/L due to a urinary concentration defect UOsm 400 mOsm/kg water. Finally, low-molecular-weight proteinuria and glucosuria without hyperphosphaturia or aminoaciduria suggest partial proximal tubulopathy.

Discussion

In EGFR signaling, there are various downstream pathways, so mutations affect cell proliferation and homeostasis. We will discuss with an in-depth insight into the disease, the potential pathophysiology of the associated tubulopathy and PKD, and its presence in previously reported under-recognized cases.
Conclusion:
Hypomagnesemia is well-known in EGFR inhibitors but not in EGFR deficiency. Additionally, EGFR deficiency causes enlarged kidneys. The renal phenotype, however, is much more complex, involving hypokalemia, hypernatremia, cystic disorder, and tubulopathy. Electrolytes can be monitored more precisely in cases of EGFR deficiency to determine the significance of this association.