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Kidney Week

Abstract: PO1706

Clinical Course of a Patient with FSGS and a Basement Membrane Defect

Session Information

Category: Trainee Case Report

  • 1201 Glomerular Diseases: Fibrosis and Extracellular Matrix

Authors

  • Portugal, Frank A., Robert Wood Johnson University Hospital, New Brunswick, New Jersey, United States
  • Khalil, Steve I., Robert Wood Johnson University Hospital, New Brunswick, New Jersey, United States
Introduction

We present a case of a patient with a familial basement membrane abnormality who developed nephrotic syndrome and worsening CKD due to FSGS and outline her response to immunosuppressive therapy over 15 months. Our case suggests that immunosuppressive therapy may benefit such patients and delay progression to ESRD.

Case Description

A 38-year-old woman with microscopic hematuria was found to have a urine Pr/Cr ratio of 2.4 during pregnancy. Her s.Cr was 1.4-1.6 mg/dL and she had over 13g of proteinuria during pregnancy. After delivery, the serum creatinine stabilized between 1.1-1.3 mg/dL and her urine Pr/Cr ratio was 8.0 with an unrevealing serologic workup. She has no family history of renal insufficiency, but her father and 14-year-old daughter have microscopic hematuria. A renal biopsy revealed FSGS with ultrastructural GBM alterations including thinning and lamellation as well as nearly complete foot process effacement. Collagen IV staining demonstrated a normal IF pattern for α2 and α5 chains. She was started on prednisone, however, her glycemic control deteriorated and therapy was stopped after 1 week. She was then treated with Losartan and Cyclosporine and her Pr/Cr ratio improved to 1.3-1.5 mg/dL but her serum creatinine gradually rose to 2.0 mg/dL. Losartan was changed to Diltiazem and CsA was changed to MMF. Her s.Cr has trended down to 1.4 mg/dL with a urine Pr/Cr of 1.9 fifteen months after diagnosis. She was referred for genetic testing and was found to be heterozygous for a mutation of COL4A4 (Exon 39, c.3679G>A, p.Gly1227Arg).

Discussion

Prior case series have demonstrated the coexistence of familial FSGS and hereditary GBM abnormalities. However, it has not been fully elucidated whether FSGS occurs as a primary process or secondary to the GBM abnormalities nor is it known whether such patients benefit from immunosuppression. Our case details the course of a patient with nephrotic syndrome due to FSGS and thin basement membrane changes with normal collagen IV staining found to have a genetic COL4A mutation which is not known to be a pathogenic variant. She demonstrated a partial response to immunosuppression with greater than 75% improvement in proteinuria and stabilization of the serum creatinine with treatment with MMF suggesting that immunosuppressive therapy may alter the course of disease in patients with a dual diagnosis of FSGS and thin basement membrane abnormalities.